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Commissioning of Damper Dynamometer

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

Improvements and Operation Of the Damper Dynamometer
Andrew Chau 20264212 Michael Li 10758152 Tiong Kun Ooi 20256339

School of Mechanical Engineering, University of Western Australia

Supervisor: Lynn O. Kirkham School of Mechanical Engineering, University of Western Australia

MECH3402 Final Report School of Mechanical Engineering University of Western Australia

Submitted: October 16th, 2009

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

Project Summary

Dampers, also known as shock absorbers, are an integral part of a motor vehicle, especially vehicles used in motorsports. The use of different dampers will inevitably affect the handling and stability of a race car as different dampers will have different characteristics and therefore, the dissipation of kinetic energy in the springs will be different. An onsite damper dynamometer will allow UWAM, University of Western Australia Motorsport team, to readily test their dampers to determine their characteristics and also tune them to their desired properties. A damper dynamometer has been manufactured and a data acquisition software, DAQ, already written by previous years projects. The purpose of this project will be to finalise the damper dynamometer.

The original scope of the project was to implement safety measures for the damper dynamometer, determine the robustness of the dynamometer, make adjustments so that the dynamometer is able to test the Kinetic™ H2 Suspension System and then to test the Kinetic™ H2 Suspension System and finally, write an operation manual for the dynamometer. Due to several factors not all the initial objectives were completed. The robustness of the damper dynamometer was not verified with certainty and the Kinetic™ H2 Suspension System was not tested. Other adjustments made to the dynamometer are the creation of an interface for the DAQ software and assembly of a new strain voltage regulator and gauge amplifier. Future work will include verifying the damper dynamometer by testing a damper with known characteristics and the calibration of the Kinetic™ H2 Suspension System.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 TABLE OF CONTENTS 1. Introduction UWAM History of UWAM’s Damper Dynamometer Project Objectives

Improvements and Operation of the Damper Dynamometer

5 6 6

2. Dampers Overview Description of Dampers Characteristics of Dampers Dampers in Vibrating System Role of Dampers during Vehicle Movement

8 9 12 13 15

3. Kinetic™ H2 Suspension System Testing of Kinetic™ H2 System

17 20

4. Machine Improvements Placement bracket Voltage Regulator Charge amplifier Force Transducer calibration

23 23 26 26 29

5. Hardware Operation Manual Introduction Illustration of Machine General Safety Issues Quick Set-up for your Damper and Dynamometer Proper Set-up Software Preparation Testing of Damper 31 32 39 40 42 43 44

6. Software Operation Manual Introduction 46

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 Quick Start Guide Capturing data from Dynamometer Processing data Graphing Modify Program Parameters Known limitations Section Conclusion

Improvements and Operation of the Damper Dynamometer 47 52 56 58 62 68 68

7. Conclusion and Future Works

69

8. References

70

9. Appendix Hardware Software – Main.m Software – capture.m Software – processDataH.m Software – graph1H.m

72 72 74 86 89 93

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 1. Introduction

Improvements and Operation of the Damper Dynamometer

Dampers are a vital part of a suspension system and therefore, have a significant effect on the performance of a motor vehicle. The purpose of the suspension system is to maintain the contact between the tyres and the road and provide vehicle stability and handling (Hillier 1991). To achieve this purpose, dampers are implemented to provide controlled friction into the suspension system (Dixon, 2007), which dissipates the kinetic energy stored in the springs (Guzzomi, 2004). The suitability of a suspension system in a motor vehicle is dependent on the requirements set by the user. Therefore, different dampers are required for different performances of a motor vehicle. Here lies the importance of a damper dynamometer. In order to determine the suitability of dampers for a particular suspension system, the characteristics of the dampers must be known. A damper dynamometer provides a means to obtain the characteristics of the dampers.

UWAM UWAM, formally known as University of Western Australia Motorsport, is University of Western Australia’s motorsport team. UWAM participates in F-SAE, which is student design, build and race competition organised by SAE, formally known as Society of Automotive Engineers. The competition comprises of compact racetracks and restrictive engine regulations; hence vehicle suspension greatly affects the overall race car performance (Guzzomi 2004).

The first car produced by UWAM for the F-SAE competition was the 2001 car, UWAM01. The dampers fitted on this car were FOX Vanilla RC dampers. Following years continued the use of FOX Vanilla RC dampers until the production of the 2004 UWAM car, ACT-070. Testing conducted by Finalyson concluded that the FOX Vanilla RC dampers were not appropriate for use by UWAM on their racing vehicles (Finalyson 2003).

In 2004, UWAM implemented the Kinetic™ H2 Suspension system, which is a patent by Kinetic™ Suspension Technology, in their 2004 car. The system consists of four custom designed and built dampers connected to valve units and accumulators through hydraulic lines. This configuration of the suspension system decouples the vehicle modes and allows

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

for low warp rates and high heave, pitch and roll rates (Roshier 2009). Due to the success of the Kinetic™ H2 Suspension system, UWAM has continued utilising the system up to today.

History of UWAM’s Damper Dynamometer UWAM has an interest in the damper dynamometer since, as to date; there have been no data that characterises the dampers of the Kinetic™ H2 Suspension system. The creation and use of a damper dynamometer will allow UWAM to characterise and calibrate their custom dampers. This will increase their efficiency in tuning the car’s dampers, as the dampers can be tuned to their desired characteristic before being installed onto to the car, instead of tuning through track testing.

The creation of the damper dynamometer started with North (2008), who designed a damper dynamometer based on a commercial one. CAD drawings were produced for the future manufacture of the damper dynamometer. While North was designing the damper dynamometer, Newman (2008) developed the data acquisition (DAQ) process and software for the dynamometer.

Bansal (2009) finalised North’s design and manufactured the damper dynamometer. Park (2009) then rectified a mistake in Newman’s software and produced valid hysteresis graphs using the newly constructed damper dynamometer.

Project Objectives The initial objective of the project was to finalise the damper dynamometer and its software. In completing this task, an operation manual will be written to allow UWAM to safely operate the damper dynamometer. The dampers for the 2009 UWAM car will then be tested to obtain their characteristic curves and the dampers will also be calibrated. However, the 2009 dampers will not be completely manufactured before the submission of this report and therefore, the dampers could not be tested and calibrated.

To finalise the damper dynamometer, a brief literature review is needed in order to gain an understanding of dampers. Improvements will be made on the damper dynamometer if the improvements are deemed necessary. The tasks will be split up into three parts one part for each group member. Andrew will primarily undertake the literature review and provide Page 6

Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

assistance to Tiong Kun and Michael, Tiong Kun will improve the DAQ software by implementing an interface and verify the operation of the electrical components on the damper dynamometer and Michael will upgrade the current dynamometer so that the Kinetic™ H2 system can be tested and write a comprehensive operation manual for the damper dynamometer. This report can therefore be used as a thorough guide to using the damper dynamometer.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 2. Dampers Overview

Improvements and Operation of the Damper Dynamometer

Dampers, or the more commonly known shock absorbers, are mechanical devices which are designed and used to dissipate kinetic energy due to sudden impulses or shocks and vibrations. In a motor vehicle, the dampers are used to improve handling and stability as the vehicle traverses over the terrain. The need for dampers came about due to the roll and pitch experienced during vehicle manoeuvring and the roughness of the road. At the end of the nineteenth century, the use of the internal combustion engine provided a new means of travel. The increase in power and speed that can be obtained using the new internal combustion engine coupled with the generally poor road quality started the fitting of dampers to motor vehicles (Dixon 2007).

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 Description of Dampers

Improvements and Operation of the Damper Dynamometer

Dampers are classified into five categories, lever vane, lever cam in-line, lever cam parallel piston, lever rod piston and telescopic (Dixon 2007). The dampers which will be examined will be the telescopic damper as it is the most common (Guzzomi 2004) and since the damper dynamometer is designed for such a damper. A telescopic damper dissipates kinetic energy by moving a piston through a damping fluid causing friction and hence, energy dissipation.

The telescopic damper consists of a piston connected to a rod, with the piston moving in a liquid filled chamber. The chamber is connected to the chassis of the vehicle while the rod is connected to the suspension. When the damper is contracted, i.e. when piston moves further into the chamber, it is known as bump, while damper extension, piston moving towards the rod end of the chamber, is know as rebound. The compression (rebound) chamber is the part of the chamber which the piston moves into while the damper is compressed the extension (rebound) chamber is the part of the chamber which the piston moves into when the damper is extended. A schematic of a telescopic damper is shown below.

Figure 2.1 Schematic of a telescopic damper (Dixon 2007)

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

As the piston moves into either bump or rebound chamber, the damping fluid is directed around a set of shim stacks to the piston orifices which then flows into the other chamber. The shim stack obstructs the flow of the fluid and along with the piston orifices provides two flow resistances in series (Starkdey & Talbott 2002). The resistance in the flow results in a pressure differential between the two chambers. The pressure differential opposes the motion of the piston, hence providing the damping force. At high flow rates, the pressure differential can become large enough to deflect the shim allowing additional flow passage to the fixed orifices (Guzzomi 2004).

Figure 2.2 Flow paths through orifice during low speed (red) and high speed (blue) (Starkey & Talbott 2002)

The flow through the damper valve, i.e. around the shim and through the piston orifice, has two main phases: fixed orifice flow and variable orifice flow. Fixed orifice flow occurs at low piston speeds, implying low flow rate. At low speeds the pressure differential is small and therefore, shim deflection is also minimal. The resisting force due to fixed orifice flow is proportional to the flow rate squared (Guzzomi 2004). At higher flow rates, the pressure differential is able to deflect the shim and hence, provides additional passages of flow to the orifices. This results in variable orifice flow. When the shim is deflected, also known as blow-off, the damping curve becomes linear (Guzzomi 2004). Therefore, at low speeds the damping curve is parabolic and at high speeds the damping curve is linear.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

Figure 2.3 Damper force vs. Velocity graph of a typical damper (Dixon 1999)

The graph in Figure 2.3 is a typical force vs. velocity curve for a damper. Stage 1 is the fixed orifice flow and Stage 3 is the variable orifice flow. Stage 2 is the combination of fixed and variable orifice flow, which is also know as the transition region.

Another component of the damper system is the accumulator. The accumulator purpose is to allow fluid displacement during bump and prevent fluid cavitation (Guzzomi 2004). The accumulator consists of pressurised gas and a floating piston dividing the gas and the damping fluid. It can be an internal reservoir, hose connected external reservoir, piggyback external reservoir or internal reservoir with foot valves. The various locations of the accumulator is shown in Fig …. Fluid cavitation occurs when there rapid pressure loss which causes the fluid to vaporise. This can occur when the damper is rapidly compressed or extended. The gas pressure within the accumulator increases the pressure inside the damper so that pressure in the damper does not fall below the cavitation pressure of the fluid (Rouelle 2004).

Overall, a telescopic damper consists of a damper body containing damping fluid with a piston moving in bump and rebound causing fluid to move from one end of the chamber to the other end. The valve in the damper restricts the flow of the fluid through the orifices giving rise to different damping characteristics in low and high speed damping. The internally or externally connected accumulator allows fluid flow during bump and provides a pressure to prevent cavitation.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 Characteristics of Dampers

Improvements and Operation of the Damper Dynamometer

Modern racing cars widely use adjustable hydraulic dampers as they are the simplest and quickest to tune (Park 2009). The characteristics of a damper can be determined by its force vs. displacement, force vs. velocity and force vs. absolute velocity graphs. These graphs can be obtained by testing the damper using a damper dynamometer. The force diagram can be used to determine wether the damping force is adequate for the dampers application. The following figure shows the typical graphs of a simple damper.

Figure 2.4 Typical graphs of a basic damper (Dixon 2007)

A damper with a more complex design will have valve units which implement shims to alter the flow path of the damping fluid at different velocities. In this case, the force graphs can be seen to have three phases as seen in Figure 2.3. Different valve designs will achieve different damping forces at different velocities. The valves will also affect the velocity in which blowoff will occur.

Damper hysteresis is the separation of accelerating and decelerating bump and rebound damping (Park 2009). Hysteresis can be seen in the force vs. velocity graph as the area between the curves. A few causes of hysteresis when testing the damper dynamometer are valve friction due to valve wear, coulomb friction due to compressibility effects of damping fluid and damper lag during testing (Dixon 2007). The figure below shows a damper force vs. velocity plot with hysteresis.

Figure 2.5 Force vs. velocity graph showing hysteresis (Guzzomi 2004)

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 Dampers in Vibrating System

Improvements and Operation of the Damper Dynamometer

A damped vibrating system consists of a mass, spring and damper and the system is governed by three forces, inertial, damper and spring forces. The inertial force is the acceleration of the mass, the damper force is the damping effect of the damper and the spring force is force associated with the displacement of the spring. When an external force is applied to the mass in this system, the spring will compress or extend and then begins to oscillate as it attempts to return to its original position. The damper in this system produces a force to retard the movement of the spring and therefore, limit the oscillations that is felt by the mass.

Figure 2.5 Diagram of simple spring damper system (Milliken & Milliken 1995)

The system that represents the vehicle is more complex than the single mass, spring and damper system. A car can be modelled as having two springs, an unsprung mass, damper and a body mass. The diagram of the system is shown in Figure 2.5. The spring with constant k T represents the flexibility of the tyres and the unsprung mass is the mass of the suspension system and any mass below the suspension system, such as the tyres. The other spring is the spring in the suspension system. The body mass represents the sprung mass which is the mass above the suspension system, which includes the car body and the driver.

Figure 2.6 Model of car using spring, damper and mass (Milliken & Milliken 1995)

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

As the vehicle moves over a bump or dip in the road it causes the tyres to flex and the unsprung mass to move up or down. This in turn will cause the spring in the suspension system to compress or extend and then attempt to return to its original position, hence causing oscillations. The effect of the damper in this system controls the vertical acceleration and oscillations experienced by the body mass.

Increasing the damping ratio of the damper will limit the oscillation of the body mass, but it also increases the acceleration on the mass. A measure for passenger discomfort is the vertical acceleration experienced by the passengers in the car (Milliken & Milliken 1995). Therefore, increasing the damping ratio past a certain extent will cause passenger discomfort. A compromise is needed between the body mass acceleration and the amount of oscillation.

Figure 2.7 Graph showing that increasing damping ratio increases acceleration felt by the passengers (Milliken & Milliken 1995)

Figure 2.8 Graph showing that increasing damping ratio increases the wheel resonance transmissibility (oscillation felt by passengers) (Milliken & Milliken 1995)

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 Role of Dampers during Vehicle Movement

Improvements and Operation of the Damper Dynamometer

As a vehicle traverses a track, it can experience four modes of suspended vehicle movement. The four modes are heave, pitch, roll and warp. A vehicles transverse axis is the axis between the front and back of the car, while the longitudinal axis is the axis between the left and right side of the car. During heave, the vehicle has uniform wheel displacement along the horizontal plane and when in pitch, the vehicle experiences rotation about its transverse axis. Roll occurs when the vehicle rotates about the longitudinal axis and warp is a combination of pitch and roll. Figure 2.8 shows the four modes. A vehicle will experience these modes of movement due to the lateral and longitudinal acceleration which is a result of irregularities in the road and vehicle cornering (Park 2009).

Figure 2.9 2000)

The four modes of suspended vehicle movement (Zapletal

During vehicle movement the dampers will act to control the load variation, minimise oscillations and control the motion of the sprung and unsprung masses (Young 2003). When a vehicle is cornering it moves through three phases: entry, steady state and exit. As the car is entering or exiting a corner the car will first experience pitch as it slows or speeds up. When slowing down, the weight is transferred from the back to the front wheels and conversely for speeding up. The reduction of low speed rebound in the rear dampers will increase the rate at which the weight is transferred to the front tyres while reduction of low speed rebound in the front dampers will increase the rate at which the weight is transferred to the back tyres (Hise 08).

During vehicle corner entry and exit, the car also experiences roll as the car leans towards the centre of the turn. The dampers will provide a resistant force as dampers on one side of the car compresses and the other side extends. Therefore, the dampers provide roll resistance and

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

alter the tyre load distribution, which will affect the overall handling and balance of the vehicle (Milliken & Milliken 1995). When the vehicle breaks or accelerates, the change in pitch angle due to the longitudinal load transfer will cause pitch oscillation as the car attempts to return to its original pitch angle. If undamped, the pitch angle can oscillate at its natural frequency causing the vehicle to be undrivable. The use of dampers will allow the pitch angle to vary smoothly with little or no overshoot (Dixon 2007).

Similarly for roll, if the oscillation of the roll angle is undamped the vehicle will also be undriavble. The implementation of dampers will limit the oscillation of the roll angle by allowing the roll angle to vary smoothly with little or no overshoot (Dixon 2007).

Therefore, dampers improve the handling and stability of the vehicle by limiting the oscillations due to pitch and roll, which occurs during vehicle cornering. It also affects the load on the tyres, which affect tyre grip, and the rate at which the load is transferred. The dampers provide friction into the suspension system to maximise tyre grip and minimise tyre load variation (Park 2009).

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

3.

Kinetic™ H2 Suspension System

Kinetic™ H2 Suspension System Overview The Kinetic™ H2 system is a suspension system designed and patented by Kinetic™ Suspension Technology for use by UWAM. The system is basically a set of dampers, with external valve units and accumulators all interlinked by hydraulic hoses. The dampers are diagonally cross-linked as well as being interconnected to the dampers on the same side. Each damper is connected to a bump and rebound valve units which in turn is connected to an accumulator. The dampening of the fluid occurs in the valve units. A schematic of the system is shown below in Figure 3.1.

Figure 3.1 Schematic of the Kinetic™ H2 Suspension System (Guzzomi 2004)

The dampers in the Kinetic™ H2 system are telescopic mono-tube and have outlets for liquid flowing through the bump and rebound chambers. The valve units in the system are contained in valve housings, with each housing containing two Tenneco valve units, one for bump and one for rebound. The damping force occurs in these valve units. The Tenneco valve unit uses shims and also coil springs for blow-off, which allows for a smooth transition from low to high speed damping (Guzzomi 2004). Accumulators in this system are gas pressurised cylindrical containers with a floating piston separating the damping fluid and the gas. The figures below is the Solidwork™ drawings of the dampers, valve units and accumulator of the Kinetic™ H2 system.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

Figure3.2 Damper

Figure 3.3 Valve unit

Figure 3.4 Accumulator

In this configuration, the Kinetic™ H2 system allows decoupling of vehicle modes. By crosslinking diagonal dampers and interconnecting the dampers to the accumulator, the system provides low warp stiffness without compromising roll stiffness (Guzzomi 2004). Also, the interconnection of dampers on one side of the car allows for softer corner springs and hence, smoother handling over rough surfaces (Bansal 2009).

During vehicle roll, the dampers on the one side of the car compresses whilst the other side extends. The side that compresses will force the fluid in the damper out of the bump chamber and the side that extends forces fluid out from the rebound chamber. As the bump chambers on one side of the car is connected to the rebound chambers on the other side, the fluid is passed into the same accumulator. The accumulator then provides the force to resist the damper movement in both sides of the car (Guzzomi 2004).

When the vehicle experiences warp, the fluid is forced from one damper to the other damper that is diagonally opposite. The fluid will be passed from bump or rebound chamber of one damper to the opposite, rebound or bump, of the other damper. This allows the pistons in the dampers to move without being affected by the accumulator. Therefore, the vehicle will have

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

low warp stiffness as the cross-linking of diagonal dampers allow warp to occur (Guzzomi 2004).

The Kinetic™ H2 system was implemented by UWAM due to two main reasons. The system provided an increase in tyre grip and allowed for greater range of vehicle suspension tuning. Since the system decouples the four vehicle modes, i.e. pitch, heave, roll and warp, each mode can be tuned separately. The pitch and heave of the vehicle is controlled by the third springs located at the front and back of the car while roll stiffness is controlled by the gas pressure in the accumulator (Guzzomi 2004).

The Kinetic™ H2 system decreases the load variation on the tyres, hence increases tyre grip, as the vehicle traverses a track with irregularities and allows for more predictable vehicle behaviour during cornering (Guzzomi 2004). The success of the Kinetic™ H2 system can be seen in the success which UWAM has in their dynamic performance in FSAE.

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Improvements and Operation of the Damper Dynamometer

Testing of Kinetic™ H2 System The Kinetic™ H2 Suspension System is to be tested with only one damper, valve unit and accumulator. As a result of having only one damper, valve unit and accumulator connected, the bump and rebound settings will have to be tested separately, i.e. test and record data for bump first then rebound. Once the characteristics for bump and rebound have been obtained, the results can be combined together to obtain the overall characteristic of the Kinetic™ H2 system.

Setup of Bracket 1. Trace the outline of the valve unit, accumulator and their required fittings on a piece of paper. 2. Use the outlines to determine the position of the parts on the bracket. Make sure there is sufficient room between each part for the hydraulic hoses. 3. Mark out holes on the bracket so that the valve unit and accumulator can be held securely by reusable zip ties (see Figure 3.5). 4. Drill the marked holes into the bracket. 5. Connect the valve unit to the accumulator with the hydraulic hose and fasten the valve unit and accumulator using reusable zip ties onto the bracket. 6. Determine appropriate places where zip ties are needed to secure the loose hydraulic line. 7. Mark and drill the holes for the new zip ties if necessary. Then fasten the hydraulic line to the bracket, if applicable. 8. Determine whether the hydraulic hose connecting the damper to the valve unit will need to be secured to the bracket. 9. Mark and drill the holes for the new zip ties if necessary. Then fasten the hydraulic line to the bracket, if applicable. 10. Check that the valve unit, accumulator and hydraulic hoses are all fastened securely to the bracket.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

Figure 3.5 Bracket, valve unit and accumulator with zip holes marked

Setup of Damper onto the Dynamometer 1. Determine whether the original damper mountings are appropriate for the dampers. Thread the screw through the mounting and damper and tighten the nut. The damper should fit into the mountings so that the damper does not have any free play. 2. If the current mountings can not be used, bring the mountings to the Mechanical Engineering Workshop and ask the technicians to manufacture a similar mounting for the damper, with a M6 hole on top. 3. Choose a crank offset radius so that the damper will not bottom or top out. If the damper bottoms or tops out in the chosen offset radius, the force transducer can be moved down or up so that the position of the damper is lower or higher and hence preventing bottoming or topping out. 4. Once the damper position and offset radius have been set, turn the lathe by hand and ensure that the damper does not bottom or top out. Setting the lathe to its fast speed setting will allow for easier turning of lathe by hand.

Attaching Kinetic™ H2 System to Damper Dynamometer Page 21

Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

1. Detach the Kinetic™ H2 system from the damper dynamometer and its shelf 2. Decide whether the system is to be tested in bump or rebound 3. Cover the fittings on the dampers and valve units which will not be connected by hydraulic lines. 4. Fit the Kinetic™ H2 system together, connecting dampers, valve units and accumulators with hydraulic lines and filling the system with damping fluid. 5. Fasten the damper to the damper mountings, the valve units and accumulator to the bracket and secure the loose hydraulic hoses. 6. Check that the Kinetic™ H2 System is securely fastened to the dynamometer and its shelf.

Running the Damper Dynamometer 1. Determine the maximum speed which the damper will operate at. Typical blow-off is about 150mm/s (Finlayson 2003). Therefore, the lathe should be set to the rpm determined by referring to Table … 2. Run the lathe at the desired speed. 3. Run the DAQ software to record the data. 4. Change the bump or rebound setting. 5. Repeat steps 2 and 3 for different bump or rebound setting. 6. After testing the damper for all the possible settings in bump or rebound, repeat ‘Attaching Kinetic™ H2 System’ for the other direction, rebound or bump. 7. Repeat steps 2 to 5 for the new direction. 8. Use the DAQ software to compare the graphs to determine which setting in bump and rebound is most suitable for UWAM

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 4. Machine Improvements

Improvements and Operation of the Damper Dynamometer

Placement Brackets One thing that troubles the operator during an experiment is too many things are hanging around the dynamometer. Therefore a solution is needed for this matter in order to improve the safety as well as protecting the dynamometer. The bracket and the shelf design in below can solve the problem. The bracket is used for placing the damper’s valve unit and accumulator. It is screwed on the front-left of the dynamometer. The material used for making it is called sheet steel-zinc flash. This material is lightweight, cheap and ductile. It has good corrosion resistance, fairly good stiffness and shear stress. These properties are important because after putting the valve unit and accumulator on, the bracket need to have enough strength to support those added weight. It needs to have enough stiffness to resist bending and vibrations, but it also has to be ductile to allow some twisting. According the size of the accumulator and the valve unit, the operator can decide where to put them on then simply drill some holes on the bracket and use zip-tie to tie them on.

The design of the bracket:

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

On the right hand side of the dynamometer is the shelf for holding the terminal box and batteries. It is a steel box, which is taken from a computer’s power supply. It has holes on it to allow electric wires to go through. However on the bottom of the shelf there is a piece of metal made of sheet steel-zinc flash. The purpose of this sheet metal is to protect the shelf from bent over. Below is showing the difference the additional sheet metal can make.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 Force transducer

Improvements and Operation of the Damper Dynamometer

A major component of the dynamometer is the force transducer attached to the top of the damper during testing. This is the core of the experiment because it measures how much force is transmitted to the FSAE Motorsport car and how different dampers will affect the handling performance of the car. Thus, the force transducer has to provide an accurate and consistent reading throughout the test. In order for the force transducer to provide an accurate result, it has to first be calibrated and a regression coefficient has to be calculated. Apart from that, it’s also essential that a regulated voltage is supplied to the transducer and the output is put through a charge amplifier before being fed into the DAQ. The components Basically the force transducer is a device to convert force within its working range into electrical signals. This is first done by building the device in such an arrangement so that any load applied would intentionally deform the built in strain gauges. These strain gauges convert the deformation into electrical signals and are usually arranged in a Wheatstone bridge configuration. The picture beside shows the Wheatstone bridge configuration and wire connections for the BongShin DBBP 200 Load Cell used in this dynamometer. The electrical signal output is however, in the milivolts and requires amplification by a charge amplifier before it could be picked up by the DAQ hardware and a linear algorithm is applied afterwards to calculate the force value. Deriving the algorithm will be explained in the later part of this section. The voltage regulator is a simple circuit to supply a near constant stream of direct current at a fixed voltage irrelevant to the range of load conditions. The quality of the voltage regulator is assessed based on three main parameters: • • • Line regulation – the ability to maintain a constant output voltage regardless of changes to the input voltage Load regulation – the ability to maintain a constant output voltage regardless of the size of the system’s load Temperature dependence – the ability to maintain a constant output voltage regardless of changes in components temperature especially semiconductor based devices Page 25

Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

A good voltage regulator is crucial for use with a force transducer because its output voltage will tremendously affect the force transducer’s output and it is essential to keep the output voltage from the regulator as constant as possible to achieve a consistent result. Since a force transducer has a recommended working voltage range, its own output will depend linearly on the input voltage. If the voltage supplied by the regulator fluctuates at all, this effect will be inherited to the output voltage from the transducer. A charge amplifier, on the other hand, is required to amplify the outputs from the force transducer. Its function is to obtain a voltage proportional to the charge output from the transducer and yield a low output impedance. Charge amplifiers are usually constructed using op amps with a feedback capacitor and thus act in a similar manner to an integrator. Since a transducer acts in a similar manner to a differentiator, the two transfer function cancels out and the output voltage is proportional to the charge produced by the transducer. A charge amplifier usually has a gain control to enable the use to change the gain on the transfer function and thus increase or decrease the output voltage. The problem One major problem that we’ve encountered while trying to fix up the machine was that the original voltage regulator and charge amplifier is not giving reliable results. Although they’re housed in the same box, the original voltage regulator and charge amplifier are running on separate circuits. Both the circuits have their own problems. The voltage regulator consistently took about 10 minutes to reach a regulated 10v which is the selected voltage to power the force transducer. This is abnormal as it usually takes about 1-2 seconds maximum to reach the selected voltage. As with the charge amplifier, we sent it to the electrical technician, Gerald to perform some test and he too concluded that there were obvious problems with the charge amplifier. Thus, we set out to rebuild a new voltage regulator and charge amplifier circuit. The solution This new voltage regulator and charge amplifier is designed to be built on a single piece of PCB in order to save space and prevent too many wires hanging all over the place. This design has been finalized by Gerald Wright in 2008 and we were provided the schematic drawings for it. We were also provided with all the required components and tools in order to assemble the circuit.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

The schematic diagram of the circuit and the instrumentation amplifier IC that’s used:

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

This new voltage regulator has 2 jumpers for output voltage selection and for the gain. It has also got a pot trimmer in order to fine tune the phase shifts. There are 3 voltages that this regulator could produce 2.5v, 5v and 7.5v. These voltages are all lower than 9 volts because it’s supplied by a 9 volt dry cell and any voltage drop would also affect the performance of the regulator. It’s recommended that 2.5v is used for the load cell for this particular application as it’s the safest against dropping voltages (the dry cell could be used for a long time and significant voltage drop would not affect the output voltage of the regulator. The second jumper on the circuit board acts as the gain control. A user could specify their desired gain by changing this jumper position. They would have 3 choices: 100x, 200x and 500x. The gain control acts as a multiplier to the charge amplifier. Basically, the board is supplied by a 9v dry cell block and has 2 regulated output terminals supplying the chosen voltage. It has also got 4 input terminals for the force transducer’s very weak output that needs to be amplified and 2 outputs that have gone through the charge amplifier. Once the circuit has been assembled, its pot trimmer has to be tuned to give a correct ‘zero point voltage’ and to ensure that it doesn’t saturate when the transducer is in tension and compression. This is better explained in the diagram below. The diagram shows an oscillating load being applied to the force transducer and the corresponding output from the connected charge amplifier in volts. The voltages are just arbitrarily picked to demonstrate this process. As we can see, the horizontal lines on ±4v are the saturation voltage of the circuit and must be avoided during normal operation. The reason behind this is because the saturation voltage is the highest and lowest voltage that the circuit is capable of producing its output will not be proportional to the input after this point. This said, we have to tune the pot trimmer Page 28
Output will stay at -4 volts even though it should go lower Adjusting the pot trimmer will move this up and down

Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

until its output voltage has a ‘zero point’ falling directly in the middle of both saturation voltages so that normal force transducer usage will not cause it to go beyond any side of the saturation voltage.

Force Transducer calibration As we all know, before producing any force reading, a force transducer needs to be properly calibrated to measure how much its input affects the output, in another words, the transfer function. As both the transducer and charge amplifier are linear systems, it’s pretty easy to test and obtain the required coefficients. The concept is to subject the force transducer to a static measureable load while switched on (ie: energized with a regulated voltage source) and then measuring the output voltage which has been amplified through the charge amplifier. This is repeated over a number of points and then plotted. The result should very closely resemble a straight line with a positive gradient. As our force transducer’s load range is well within the small Instron machine’s capability, we used it to exert a static load on the force transducer powered by the voltage regulator that we built earlier at 2.5v, the corresponding output is fed back into the charge amplifier and amplified with a gain of 100x. The results obtained is attached on the next page.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

Voltage (mV) -10.4 -27.5 -31.5 -43 -152.5 -301 -464 -611 -12.2 51.3 136.5 256 392 541 699 57

Force (N) 0 -44 -54 -85 -375 -770 -1190 -1630 0 168 394 710 1070 1460 1870 2020 Excel has been used to compute the line of best fit and the coefficient of regression is 0.999 indicating a very good fit indeed. The line has a positive gradient signifying that a compression load on the load cell produces a negative

voltage and a tension load on the load cell produces a positive voltage, this is consistent with what we have been anticipating. The final algorithm has been calculated to be: Voltage = 2.6521 x Force + 25.96

Thus, our linear coefficients are a = 2.6521 and b = 25.96. These numbers are hardwired into the script assuming that the same force transducer and settings will be used in future testings.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 5. Hardware Operation Manual

Improvements and Operation of the Damper Dynamometer

Introduction The UWA Motorsport team builds a new car every year to compete in Formula SAE. Together with the new car, new dampers are being made as well. Damper is a small mechanical device that keeps the car wheels on the track. Therefore it is important to study the performance of each year’s new damper. The most reliable way of testing the dampers in UWA is to use the lathe bed.

This operating manual is for the people who are doing the damper testing in the future. It contains all the useful information and background knowledge along with a full detailed experiment procedure. The aim for this manual is to help people to understand the machine and the purples of this test quickly. Most importantly, people who follow this operation manual will be able to start on the actual testing easily without asking people around, or reading many papers just to pick up relevant information.

This manual covers the information about the lathe bed and other testing equipments. A quick set-up and a full detailed set-up procedure for both ready-to-test lathe bed and ‘empty’ lathe bed situations. There is also a step-by-step guild to help people complete the test. Finally it includes the people who may able to give a helping hand during the testing.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 Illustration of Machine

Improvements and Operation of the Damper Dynamometer

2.1 Lathe bed

The machine that will be used for damper testing is called a lathe bed. This type of machine is capable of a wide range of machining such as cutting, drilling and knurling. It has many components and switches. However in the suspension damper testing only few of them is used.

Below is a picture of the lathe bed when it’s not connected with the dynamometer, which is designed by a UWA mechanical student Gurkaran Bansal in 2007. It is required for this suspension damper testing. The complete set-up section will talk about how to put the dynamometer and other equipments on the lathe bed in detail.

Figure 1 (The lathe bed)

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

When the lathe bed is fully connected with other required components. It should look like this second picture. In this case it is ready to test the damper. The quick set-up section can guild the operator to run the testing straightaway.

Figure 2 (The lathe bed Connected)

2.2 Headstock

On the left of the lathe bed is the headstock. It has three shifts and a clutch that control the speed of the spindle. There are two speed-modes, fast and slow, three gears and three RPMselections. This makes up 18 different speeds in total. On slow mode the speed starts from 47 RPM till 250 RPM. However if higher speed is needed, switch to fast then the speed begins with 300 RPM to 1600 RPM.

Below the shifts is the clutch. To let the spindle start spinning, the operator must shift to a gear then pull the clutch towards to the operator slowly. Pulling it further back to lock it in position so that the operator can release the handle to get a constant speed. On the other hand, pushing the handle towards to the lathe bed will reduce the spindle’s speed. Pushing it further to let the spindle stop quicker.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

2.3 Cardan shaft & Protecting net The double Cardan shaft should be connected to the spindle and the dynamometer. It is a red linkage that turns the drive disk inside the dynamometer. The Cardan shaft consists of two universal joints along with 1/8th inch wall thickness and 3 inches outer diameter imperial steel circular hollow section. It is extendable to maximum 840mm. The wire netting goes on top of the linkage in order to prevent people put their hands around the linkage while it is spinning. The Cardan shaft and the protecting net should be placed on top of the carriage. When the double Cardan shaft is spinning it can cause bending moment on its middle section. This leads to fatigue concerns especially when the middle section is a lot thinner then the rest of it. Although it extendable, it’s still a better idea to keep it short. So it’s recommended to be 85mm long, which is the shortest distance from one end to the other when putting it on the lathe bed.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

Figure 4

Figure 5 (Carriage & Tool rest)

2.4 Dynamometer

The Dynamometer is a rectangular steel box. It is very heavy (approximately 80 Kg). Inside of the Dynamometer is a slider-crank mechanism that similar to the one shown Figure 6. The mechanism has a drive disk that rotates simultaneously with the lathe bed’s spindle. As it rotates, it also moves the links up and down. The upper link is designed to move only in

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

vertical direction so that it can compress the damper. Beside the disk there is an optical sensor recording the position of the rotation. It works by sending a 0 volt signal to a computer through Agilent™ DAQ (Appendix A) every time it sense a gap in the disc. When it sees the small gaps that means the upper link is pushing the damper. However when it sees the big gap that means the crank has reached the top/bottom dead centre, which means the damper is zero velocity and changing the moving direction.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

Figure 8 (Inside of the Dynamometer) The velocity of the slider is: Velocity = RPM × Crank radii × 2π/60 × √ ((Crank radii)2 – (Crank length)2) v = ω√(r2 – x2) The maximum velocity is when the crank is horizontal to the ground (perpendicular to the direction of the slider). x = cos(90o) × connection rod length = 0 vmax = ω√r2 The crank radii can be changed from the drive disk. It’s up to the operator to decide the crank radii. By changing the rotation speed of the spindle and the length of crank, the operator can verify the velocity of the slider, which is also the stroke velocity.

Table 1

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 2.5 Force Transducer

Improvements and Operation of the Damper Dynamometer

A force transducer is a device that transfers force into voltage. The university provides a force transducer that has an input supplied with a S-type load cell rated at 2 KN. Positive output voltage means the force transducer is in tension and negative voltage means compression. The calibration of the force transducer will be explained in section 4. During the testing, the voltage data is logged by an Agilent™ data Acquisition System. This data will be collected and calculated in MatLab® program.

2.6 Damper The damper need to be tested is the same kind of damper being used on the UWAW racing car. The normal stroke velocity of UWAM FSAE dampers is 300mm/s (Gurkaran, 2007). The operator should try as many possible velocities up to this velocity by changing the RPM and the crank radii. The operator should also choose some higher velocities because the top stroke velocity ever experienced by UWAM FSAE dampers is 500mm/s (Gurkaran, 2007). therefore it is important to test the damper’s performance at higher stroke velocity.

The damper usually has two adjustments, rebound and compression. Rebound is how quick the damper tent to return to it’s original position. Compression is the stiffness of the damper.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 GENERAL SAFETY ISSUES
• • •

Improvements and Operation of the Damper Dynamometer

Must wear safety glasses in workshop all the time. Switch off the 240V power supply before operating the lathe bed manually. Wash your hands before touching the spindle and the Dynamometer otherwise they will become rusted.



When turning the spindle manually, the gear must be put on “Neutral” to protect the gears inside of the lathe.



After finish using the lathe, put the gear back on “Slow mode”, because the next person who is going to operate the machine may not aware that is still on Neutral gear.



The front panel does not carry any loads. It is the only panel that can be removed or modified. Its purpose is to stop people putting their hands around the hinge and drive disk.



Before placing the damper on the machine, check if any bolt is rusted or lose, especially the large threaded rod at the top.



Before running the lathe bed, cover up all the turning parts and don’t put hands around them.

• •

Always start the lathe bed at a low speed and then move up. Remember to disengage clutch before changing to another speed, fail to do so will damage the gears inside.

• • •

Must wait till the spindle stops turning before changing shifting gears Do not put your hand around the damper when the lathe bed is running Do not touch any switches other than the shifts and the clutch, because they are irrelevant to this experiment.

• • •

Know how to quickly stop the machine in case of emergency. Never leave the chuck (Appendix A) on the spindle. The person who is operating the lathe bed must not wear bracelet, necklace, wallet chain, scarf, and gloves or lose cloths.



If hear any noises coming from the machine during an operation, disengage the clutch immediately.



Never run the lathe when you are alone. At least another person from your group must be in the room and be able to help you in case of injury. Page 39

Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 QUICK SET-UP FOR YOUR DAMPER AND DYNAMOMETER

Improvements and Operation of the Damper Dynamometer

Follow these steps only when the lathe bed is connected like shown in Figure 2.

Refer to Appendix A for pictures of other equipments mentioned in below

3.1 Setting up the damper
• • • • •

Make sure the lathe bed is switched off before setting up the dynamometer. Screw the dynamometer on the Dynamometer. Fit the testing damper on the Dynamometer and screw the top and bottom. Connect the dynamometer to a constant 10V power supply. Connect a 9V battery to the sensor, which is located behind the hinge on the right hand side.



Turning the lathe bed manually and check if the voltmeter gives a reasonable reading. Going up is increasing voltage; going down is decreasing.

3.2 Setting up your computer
• • • •

Turn on your computer. Connect the Agilent™® USB cable to a USB port on the computer. Start up MatLab®. Run the Agilent™ IO Libraries Suite.

3.3 Setting up your Dyno


Connect the load cell cables into the power supply box matching the colors of the cable heads to the ports in the box. The red and black cables connect to the black and red ports on the left side of the box when looking at the ports.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339


Improvements and Operation of the Damper Dynamometer

The other black and red ports will be connected to the terminal block with the red connected to pin 3 and the black to pin 39

• • • • • •

Connect the TDC sensor to pin 2 and the common black pin to pin 11 Connect the angle sensor to pin 1 Connect the terminal block to the Agilent™ DAQ with the SCSI-II 68 pin cable. Connect the other end of the USB cable into the Agilent™ DAQ. Connect the Agilent™ DAQ and power supply box to a power source. Turn on the power to the Agilent™ DAQ, power supply box and the lathe bed

CAUTION! -Always connect all the cables before turning on the power. 3.4 Starting up the lathe bed
• • • • • •

Put the gear on 'Slow'. Check if everyone has stood away from the lathe bed and the damper. Turn on the power supply. Press the 'Forward' button. Turn on the lathe bed and start testing at low speed. Pull the clutch slowly. Make sure all the spinning parts are covered up.

Note: a) For emergency situations press the stop button and push the clutch at the same time to stop the machine. b) Follow the instruction in order.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 PROPER SET-UP

Improvements and Operation of the Damper Dynamometer

Follow this procedure when the lathe and everything else are disconnected.

Refer to Appendix A for pictures of other equipments mentioned below.

The double Cardan shaft and the wired netting are being put on first. One end is screwed on the spindle and the other end is connected to the dynamometer’s drive disk, both with four bolts. The one with a shining silver end goes into the hole in the middle of the spindle and the bolts fits on the spindle. The other end is fitted on the Dynamometer. The eight bolts must be fastened otherwise it can be extremely dangerous. Then the wire netting is fitted to the front of the carriage. Sometimes the carriage can be in the way when putting the double Cardan shaft and the net on the lathe bed. In this case, move its position by turning the two wheel handles.

The Dynamometer is the second to be put on the lathe bed. As it weights more than 80Kg, therefore the workshop staffs must handle the assembly. It may take some time to complete the assembly so it’s the best to ask their time availability beforehand. The Dynamometer must be placed exactly 84.5cm away from the left hand side of the spindle to avoid bending and stress on the double Cardan shaft later on.

After the Dynamometer is up, the next step is to screw up the bracket and the shelf (Appendix A), one on each side. They must be checked for bending before screw them on. This is because once the lathe bed starts running, it can cause them to vibrate. Additionally it could cause the terminal box or the valve unit and the accumulator to fall into the Dynamometer.

The next thing to do is to choose a desired crank radius. It has several different settings. These settings are for adjustments on the damper’s stroke velocity. It is a good idea to use them in order to achieve more velocities. In Table 1 there is a list of stroke velocity vs. RPM and crank radii.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

Next is the force transducer. First the operator must fit on the top of the dynamometer, below the large threat rode. The screw must be tightened so that there is no room for the force transducer to move up and down under large forces. The force transducer is connected to a charge amplifier and a 9V battery. The charge amplifier is to the transducer a steady input voltage. Also it amplifies the output voltage from the force transducer.

The last step is the installation of damper. The operator should the turn spindle manually until the crank reaches the bottom dead centre. Compressing the damper by hand to fit it in. Two long screws are used for securing the top and bottom of the damper. Until now the lathe bed is fully connected. The rest is to connect the electronic equipments. It is the same as the quick set-up procedure.

SOFTWARE PREPARATION

In order to start testing the damper, the following programs and drives must be installed.

For more information, please refer to the software operation manual.

1. MatLab® R2007a or later,

2. Agilent™ IO Libraries Suite 15.0,

3. Agilent™ USB Modular Instruments 2300A & 2700A series

• • • •

Install the Hardware Driver Install the Measurement Manager Install the IVI-COM driver (typical option) Install Agilent™ MatLab® DAQ adaptor

The latest version of MatLab® for example MatLab® 2009a hasn’t been confirmed to support the Agilent™ IO Libraries suite 15.0. In case it doesn’t support, the best way is to use an earlier version of MatLab® instead. Page 43

Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 TESTING OF DAMPER

Improvements and Operation of the Damper Dynamometer

The first priority of testing the damper is safety. There are few safety tips that have been addressed in the ‘Safety Issues’ sections. Everyone who is involved in this project must read it and understand it completely before actually doing the testing.

A few things need to check if testing the dampers for the first time. Firstly everything must be connected as described in the previous sections. The programs need to be working smoothly because more than one big program such as MatLab® is running in order to record data. This is important because MatLab® will take infinite number of data and therefore it takes lots of RAM. If the computer is not capable for this task the experiment won’t be completed. Thirdly, there shouldn’t be any wires and cables hanging around the dynamometer. After all of this are checked then the operator may turn on the power for the Agilent™ DAQ, and the lathe bed. Everyone except the operator must stand clear to the machine.

The operator can now press the forward button and choose a desired speed from the table next to the gears. Eighty-eight RPM is a good starting point to choose. Then the operator may pull the clutch and let the lathe bed run for a few seconds before start running the MatLab® code on computer. After about 15-20 seconds the computer has collected enough data for analysis. Now the operator can push back the clutch to let the damper cool down. This is important because inside of the damper is like a hydraulic system. The temperature changing on the fluid in the damper has a great influence on its performance. Therefore if the damper didn’t get time to cool down the next experiment will give wrong result, which can affect the analysis later.

One common mistake need to be aware of is that people tend to use their hands to touch the damper to check its temperature. This is strictly forbidden. The correct way of doing this is just simply release the clutch and let it cool by itself. If the damper has ran for a long time at high speed, i.e. 60 seconds and 256 RPM then the operator must give it a fairly long cooling time.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

After the damper has cooled to room temperature the operator may choose a higher speed and pull the clutch again. This experiment needs to be repeated several times to ensure that enough data has been collected.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 6. Software Operation Manual

Improvements and Operation of the Damper Dynamometer

Introduction In order to extract valuable and comprehensible information from the dynamometer, raw data from the optical sensor, TDC sensor and force transducer captured has to be extensively processed first to yield the position of the crankshaft and thus calculate the instantaneous velocity and acceleration as well as the force exerted by the damper on the transducer. As Newman (2008) has designed, these calculations are to be run on MATLAB and Alicia Park (2009) has done numerous alterations and improvements to the original code. This part of the report will cover changes to the software and new scripts that we’ve written as part of our EP to improve user-friendly-ness of the software. We’ve inspected the latest codes from Alicia and the mechanics of it looks correct. We have thus done no more modifications to the core code but instead, we’ve created a user interface to simplify the operation of it. Alicia’s final code is split into several sections that can be called to perform their individual tasks separately as opposed to the original code which runs everything at once. This way, a user could execute the required actions individually and has more flexibility over their testing. Apart from that, some codes were added to enable more functions not included in the original code such as saving each run as a separate file for future reference as well as incorporating debugging features. The aim of the user interface is to enable one to operate the machine and get the required result without having to understand too much mechanics behind the calculations and minor housekeeping involved. In essence, our interface has to comply with the following rules: • • • • • • Keep the number of flaws and bugs to a minimum Incorporate error checking to automatically correct obvious errors Robust User configurable parameters Data logging Intuitive and simple

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 Quick-start guide

Improvements and Operation of the Damper Dynamometer

This section serves to get the user up and running in no time and covers the basic workings of the software. The Main interface consists of the following options: 1. Capture Data from dynamometer 2. Load data to workspace 3. Process data (optional) 4. Graph currently loaded data 5. Modify processing parameters 0. Exit As mentioned, we try to keep our programs as intuitive and self-explanatory as possible. Presented with the abovementioned list of options, hopefully users could start using the program without reading the operations manual. The following list details the action for each option. Option Actions 1 Initializes capturing parameters and starts capturing data from DAQ saving the captured data as well as user specified capturing parameters from the workspace into 2 files namely ‘lastCaptured.mat’ and ‘.mat’ then returns to main menu. 2 List files available to be loaded into workspace on the current folder and prompts user for file to be loaded. If user input is valid, loads specified file into workspace for further processing. Return to main menu after loading. 3 Runs the script to process loaded data and produces workspace variables required to plot data. Returns to main menu after processing. 4 Presents user with a list of graphs available to plot. Choosing a specific graph will cause program to reprocess loaded data to ensure no errors when plotting just in case the previously processed workspace variable is tampered with. User could choose to return to main menu. 5 Allows user to modify certain processing parameters temporarily while program is running. Restarting program will cause all values to be reverted to default values. User could choose to return to main menu after modifying parameters 6 Clears all workspace variables to avoid confusion when working with MATLAB later. Prompts user for confirmation to exit and clear workspace.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

A safety debugging feature is also built into the program. From the Main menu, a user could type ‘3127’ to immediately break the program while retaining all workspace data. This is not intended for use by a normal user and thus isn’t listed in the Main menu.

Detailed explanation of program built up As mentioned previously, Alicia’s code for capturing, processing and graphing the data has been split into sections corresponding on their individual functions and could be called up separately. These mini-scripts are included in the appendix and are listed as follow: • • • • • • • • • • • • capture.m processDataH.m graph1H.m graph2H.m graph3H.m graph4H.m graph5H.m graph6H.m graph7H.m graph8H.m graph9H.m graph10H.m

Script details - captured.m This script has been slightly modified to start by asking the user if he/she wants to load the default capture parameters list as follow: Samples per trigger: 30000 samples Sampling Rate: 15000 samples per second DAQ Capture Timeout: 30 seconds Lathe RPM: 88 rev per minute (not required for calculations, included for future program expansion or verification purpose If user chooses not to use default values, they will be asked to input custom capturing parameters. Apart from that, the user could also define the total capturing time and the samples per trigger will be automatically calculated. Page 48

Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

Once all parameters has been defined, MATLAB will start the capture process provided the appropriate DAQ drivers and MATLAB Agilent interface has been installed. The following files will be produced: • capturedData – a 4 x N matrix where N = number of samples captured. First column is the voltage from the optical sensor and should closely resemble pulses as slots on the rotating disk cause voltage to rise and fall rapidly. Each cycle represents a 1 degree rotation of the drive shaft. • • • RPM – Rev per minute of the drive shaft set by the user samplesPerTrigger - Samples to capture per trigger set by user or default value sampleRate – Sampling rate of DAQ set by user or default value

Once capturing is completed, these workspace variables will be saved to ‘.mat’ for future reference and further processing if needed. Another file ‘lastCaptured.mat’ which is exactly similar to ‘.mat’ will be produced just in case the user would like to load the files that are last captured. This file will also help MATLAB identify which file is last created and is replaced with the latest data every time the capture script is run. Once the capture script finishes, the program will return to the Main interface and user could proceed with processing the data or graphing it.

Script details – processDataH.m This script segments Alicia’s final processing code to analyse the raw data provided it’s already loaded in the workspace. It first checks the workspace to ensure ‘capturedData’ is loaded before proceeding to process the raw data. Otherwise, an error message will be returned to the user to prevent MATLAB from throwing an unhandled exception. If the required data is loaded and ready for processing, the code strips ‘capturedData’ into 4 separate 1 x N matrix for the 3 channels as well as corresponding time from start of capture. This script will then produce a few variables needed for graphing and will end by displaying the average RPM calculated from the given data. This can then be matched against the RPM set by the user on the lathe. Once done, script will terminate and return user to the Main menu.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 Script Details – Graph1H to Graph 10H

Improvements and Operation of the Damper Dynamometer

This script is just a simple script utilising results produced from the ‘processDataH.m’ script to plot various data that has been filtered and analysed. When called, this script will check the variable ‘saveAsJPG’ to determine if it’s ‘ON’ or ‘OFF’. If the variable is ‘ON’, the script will plot the required data and save the plot into a JPG file in the current folder and vice versa. Please not that the JPG file will be overwritten each time the same script is run and only the latest JPG file is retained. The variable ‘saveAsJPG’ can be toggled between ‘ON’ and ‘OFF’ in the ‘Set user parameters’ section on the Main menu.

Script Details – Main.m This is the main script for the program. It can only be run correctly when all the supporting sub-scripts are in the same folder. When executed, this program will present the user with a list of all available options and this is called the ‘Main menu’. It will then wait for the user’s input and loop through to check that a user doesn’t input a non integer or an integer greater than the available options. This is to prevent MATLAB from throwing an unhandled illegal exception and to return a more user friendly error message. It will then return to prompting for a user input and keep looping until it receives a valid instruction. Every care has been taken to make sure this program could handle an erroneous user input and to make it as robust as possible so as to prevent MATLAB from throwing an unhandled illegal. We are however, unable to prevent a user from entering a string input when prompted and this will ultimately cause the script to crash.

Detailed explanation of program behavior This section provides a more detailed operating instruction compared to 'Basics of the program'. User should thoroughly read through the operation manual in this report on safely operating the dynamometer before actually operating the machine as some of the problems that the user might encounter are not as obvious and might be missed out. In order to achieve a consistent and accurate result from the machine, the user has to also fully understand the operation of this MATLAB Dynamometer Interface software. We will start by assuming the dynamometer is fully setup, all electronic connections has been made and appropriate software installed, these has been explained in the previous parts of this report.

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The user will start by launching MATLAB on their computer and then browsing to the folder where all the scripts are located. Type 'Main' in the command line and this will kick start the program by firstly checking that all required files are present in the working folder. Files that are checked: • • • • • • • • • • • • capture.m processDataH.m graph1H.m graph2H.m graph3H.m graph4H.m graph5H.m graph6H.m graph7H.m graph8H.m graph9H.m graph10H.m

If any of the files are missing, a message will be displayed as follow and the user could choose to either proceed running the program (with limited functionality and higher chances of MATLAB crashing) or terminate the program immediately to try to locate the file.

********************************************************** Dynamometer MATLAB Interface v 1.10.2 ********************************************************** capture.m is missing. Continue? 1. NO 2. YES Please choose an option : |

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If all files are verified to be present in the working folder, program proceeds to initializing start up variables and loading the Main menu as follow: ********************************************************** Dynamometer MATLAB Interface v 1.10.2 **********************************************************

Main Menu ********************************************************** Please choose from options below : 1. Capture data from dynamometer 2. Load data to workspace 3. Process data (optional) 4. Graph currently loaded data 5. Modify processing parameters 0. Exit ********************************************************** No data loaded Choose option : |

Capturing Data To start the test, the user would first need to capture raw physical data from the dynamometer itself. These three data streams are split into 3 channels namely the optical sensor voltage on channel one, TDC sensor voltage on channel two and force transducer voltage on channel three. The time elapsed since start is also captured so appropriate calculations such as velocity and acceleration could be made. The optical sensor is triggered via slots on the rotating disk attached to the shaft of the dynamometer and each pulse corresponds to a 1 degree rotation of the shaft. This combined with the TDC sensor voltage which behaves in the same way, will enable us to map the position of the shaft and thus the position of piston at each point in time. When selecting the first option, the ‘capture.m’ script is run. This is a modified and enhanced version of the original piece of code written by Keith Newman in 2008. The following functionalities were added to the original code:

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Allows user to use default capturing parameters pre-defined in the script when capturing so that they do not need to re-define all the parameters which are usually quite consistent. The default capturing parameters are as follow: o Sample Rate = 15000 samples per second o Samples Per Triger = 30000 samples o RPM set by user = 88 rpm o DAQ timeout = 30 seconds



Allows user to specify the required total capturing time and Samples Per Trigger will be automatically calculated and set (Samples Per Trigger = Sample Rate per second * Intended capturing time in seconds)



Includes status messages at each point of the capturing operation informing the user what MATLAB is currently doing to assist them in debugging the system as well as identify potential errors (eg: taking too long for a particular task)



Saves every capture’s workspace data (‘capturedData’, ’samplesPerTrigger’, ’sampleRate’, ’RPM’) into a .mat file for future references and comparison purposes. RPM is not currently used in the calculations but future versions of this script might include extended functionalities which would need it. Apart from that, the saved file is programmed to be automatically named with the date and time of the capture up to the very second so every capture file would have a unique name. The same file is also replicated and named ‘lastCaptured.mat’ so it’s easier for user to find and load the files they’ve just captured given the very long numerical filename



Displays a user friendly message indicating that the capturing process is completed

All the user has to do is to follow the prompts by MATLAB to define the required parameters before capturing will start. Once capturing is done, the variable ‘justCaptured’ will be given a value of ‘1’ to indicate that a new capture has been performed since the program has started. This enables the user to process and graph the data without having the need to manually loading it again from the 2nd option.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 Load Data

Improvements and Operation of the Damper Dynamometer

If the user has just started the program and would like to load and process data that has been captured in the past, they’ll need to select option 2 – load data. This is a totally new function not present Keith Newman (2008) and Alicia Park’s (2009) code. Running it will first display a list of files ending with the ‘.mat’ extension (typically files with workspace variables created when capturing) that is in the current working directory. A screenshot of the list of files is shown below: Files available to load : **********************************************************

200992110036.mat 20099211012.mat 200992110191.mat 2009921103156.mat 2009921104625.mat 2009921104647.mat 2009921105228.mat 20099211110.mat

200992194841.mat 200992194915.mat 200992195259.mat 200992195348.mat 2009923152811.mat 2009923152821.mat 2009923154810.mat 200992316122.mat

200992316435.mat 200992316730.mat capturedRun1.mat capturedRun2.mat capturedSlowRun.mat lastCaptured.mat

********************************************************** Choose file to load (including .mat extension) : |

The program will them prompt the user for a file to load reminding them to include the .mat extension on the file as the filename provided by the user will be searched in the folder and if it exist, program will proceed to loading it. Otherwise, the program will return an error message telling the user to re-specify the file name as follows:

File not found. Try again. Files available to load : **********************************************************

200992110036.mat 20099211012.mat

200992194841.mat 200992194915.mat

200992316435.mat 200992316730.mat

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 200992110191.mat 2009921103156.mat 2009921104625.mat 2009921104647.mat 2009921105228.mat 20099211110.mat 200992195259.mat 200992195348.mat 2009923152811.mat 2009923152821.mat 2009923154810.mat 200992316122.mat

Improvements and Operation of the Damper Dynamometer capturedRun1.mat capturedRun2.mat capturedSlowRun.mat lastCaptured.mat

********************************************************** Choose file to load (including .mat extension) : lastCaptured.mat

Data Loaded!

Main Menu ********************************************************** Please choose from options below : 1. Capture data from dynamometer 2. Load data to workspace 3. Process data (optional) 4. Graph currently loaded data 5. Modify processing parameters 0. Exit ********************************************************** Data Loaded : lastCaptured.mat Choose option : | An important thing to note here is that if the user has successfully run a capturing sequence in the same program session, there is no need to reload the ‘lastCaptured.mat’ as the program will automatically do it if the ‘justCaptured’ variable is equal to 1. In this case, the ‘justCaptured’ variable is set to 1 immediately when the capturing is completed effectively telling the program that a capture has just happened within this program session and the ‘lastCaptured.mat’ data is the latest data file available and should be loaded automatically when processDataH.m or any graphing script is called upon. The program will display the file that is currently loaded so the user knows what file are they processing and graphing on the

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Main menu. If no file is loaded, the program will also display “No data loaded”. This is done by checking if the variable ‘fileToLoad’ and ‘capturedData’ both exists at the same time. Assuming that the user has either captured or loaded a new file, they should proceed to processing the raw data. Most of the processing part has been retained from the original Keith Newman’s code but some minor improvements or modification has been made to it so it’s more user-friendly. Among the improvements and amendments to the code were: • Addition of data verification to ensure data is properly loaded before the actual processing • • Displays the estimated RPM of the machine derived from average angular speed Allows user to temporary change the force transducer coefficients if they choose to use another force transducer which has a different calibration and coefficients. • Allows user to change channel 1 and channel 2 threshold voltages for ON and OFF state • Allows user to specify a different crank radius, TDC offset and con rod length

Process Data When the Process Data function called, it will first check if data has been recently captured. The program will immediately load ‘lastCaptured.mat’ and proceed to processing it if the variable ‘justCaptured ‘ is equal to 1 indicating a capture run has just been performed. If no data is loaded and processDataH.m is called to run, it will return the following error message and brings the user back to the main menu: No data loaded to process! Please run capture or load data from option 2!

Main Menu ********************************************************** Please choose from options below : 1. Capture data from dynamometer 2. Load data to workspace 3. Process data (optional) 4. Graph currently loaded data

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 5. Modify processing parameters 0. Exit

Improvements and Operation of the Damper Dynamometer

********************************************************** No data loaded

Choose option : |

If data is present and everything goes well, various arrays and variables will be created to facilitate the creation of graphs afterwards. User will be presented with the average angular velocity calculated from the raw data as well as an estimated RPM calculated from the average angular velocity in the following screenshot: Main Menu ********************************************************** Please choose from options below : 1. Capture data from dynamometer 2. Load data to workspace 3. Process data (optional) 4. Graph currently loaded data 5. Modify processing parameters 0. Exit ********************************************************** Data Loaded : lastCaptured.mat Choose option : 3

average_angular_velocity = 9.4721

Estimated_RPM = 90.4523 Processing completed. Program will then return to the main menu awaiting user input. The next step to extracting useful information would be graphing the available data. This part has been significantly modified from the original ones to handle graph production more efficiently and provides the

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user more flexibility even though it draws the exact same graphs as the original ones. Among the changes were: • • • Each graph is segmented into an individual script so it’s easier to be handled User is given the choice to choose what graphs they would like to plot User could also specify if they’d like to save the graph as a JPG file when plotting it via the ‘Modify processing parameters’ function • • If no data is loaded, program will display a message and returns to main menu If data has just been captured in the same session (ie: ‘justCaptured’ is equal to 1) and no other data is loaded (ie: exist(‘capturedData’) ~= 1, ‘lastCaptured.mat’ will be loaded similar to option 3 – Process data. Graph Data Similar to the Process Data function, this graphing function will check whether the variable ‘justCaptured’ is equal to 1 and if it is, ‘lastCaptured.mat’ will be loaded. When the program can’t find data present and capturing has not been recently run, it will return the following:

No data loaded to graph! Please run capture first or load data from option 2.

Main Menu ********************************************************** Please choose from options below : 1. Capture data from dynamometer 2. Load data to workspace 3. Process data (optional) 4. Graph currently loaded data 5. Modify processing parameters 0. Exit ********************************************************** No data loaded

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 Choose option : |

Improvements and Operation of the Damper Dynamometer

Otherwise, user will be presented with a list of available graphs to plot. Graphs available to plot ********************************************************** 1. Unfiltered analog sensor outputs from channel 1,2 and 3 2. Filtered data of triggered channels after one revolution of TDC 3. Digital channel graph (discrete value) 4. Angle vs Displacement 5. Angle vs Velocity 6. Angle vs Acceleration 7. Force vs Displacement 8. Force vs Velocity 9. Force vs Acceleration 10. Force vs Absolute Velocity 0. Back to Main Menu **********************************************************

Choose graph type to plot : |

The graphing technique has been mostly inherited from Keith Newman’s (2008) code and only minor changes have been made to it. Among the changes are: • Ability to plot only graphs that user require as oppose to drawing all the graphs at once • Ability to specify if user would like to save the graphs as JPEG files when plotting them as oppose to the original files which saves every plot as a JPEG file creating a lot of unwanted files in the folder

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The graph above is the most important plot to make sure all the electrical connections are correctly connected and the power supplies are at their correct working voltage. As we can see, there are a few dips every second from the TDC sensor indicating that the shaft completes a few rotations every second. Apart from that, we could also see pulses from the optical sensor in the enlarged image on the bottom verifying that the optical sensor is indeed working properly pulsing voltage from the slots on the disk. It is essential to check this graph before proceeding with the analysis as this ensures that the right data is captured.

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A snapshot of the other graphs available is shown on the bottom:

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Modifying program parameters On the Main menu, there’s also option 5 for modifying the various parameters associated with the function of the program. Choosing option 5 will give the following screenshot:

Procesing Parameters ********************************************************** 1. Channel 1 Trigger Voltage (V) 2. Channel 2 Trigger Voltage (V) 3. TDC offset clockwise positive (deg) 4. Crank Radius (mm) 5. Con rod length (mm) 6. Save file as JPG when graphing : : : : : : 3 5 10 10 255 OFF

7. Change Force Transducer Coefficients (ax+b) 9. Load default values 0. Back to Main Menu **********************************************************

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 Choose option : |

Improvements and Operation of the Damper Dynamometer

Firstly, the trigger voltage for channel 1 and 2 is the voltage where MATLAB will consider the channels as ON or OFF. Consider the following:

When the voltage increases beyond this 3 volts point, MATLAB considers this pulse as ‘triggered’ and is marked as a one degree increment in angle.

The trigger voltage has to be carefully configured if the dynamometer has not been used for a long period of time or a new battery has been replaced. This is due to the fact that the peak voltage will be the maximum voltage supplied to the optical sensors. If the battery is weak and has a lower than usual voltage, the peak voltage will naturally be lower and the program has to be told of this. If the trigger voltage is set above the peak voltage for that particular channel, that channel might not be triggered at all causing the system to not register any degree increment and thus not be able to produce useful results. The following screenshot shows the result after voltage has been cut off at 3 volts. The pulses are more significant and could be easily read by MATLAB.

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On top of that, user could also specify the TDC offset which is the angle difference between the true TDC position and the vertical axis of the crank. This is essential for MATLAB to calculate the displacement of the damper at each point in time and thus calculate the velocity and acceleration. Park (2009) defines this process as: The offset (θ) is measured as the angle between the TDC and the vertical axis of the crank. Assume the sensor starts retrieving data from index 0. The TDC location will then be measured after rotation by (90-θ) deg, i.e. at index (90-θ). Thus, to reassign index from the TDC location, the previously retrieved array of angular displacement needs to be shifted by (90-θ), rather than by the offset (θ), as done originally. This reassigned index then returns an array for both sensors as well as the force input, which corresponds to a complete cycle of the damper. Apart from that, the user could also change the crank radius and connecting rod length if they happen to change the radius configuration which serves to provide different maximum speeds actuating the damper. This table on the next page provides the crank radius required to achieve certain speeds (Gurkaran, 2009). Page 64

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In the ‘Modify processing parameters’ section, there’s also an option to choose whether the user would like to have JPEG files generated when plotting the graphs. This is particularly useful if they’d like to automatically generate a JPEG file every time they plot a graph to attach it to an email or a document. This feature has been hardwired into the original program we got from Park (2009) and it’s been generating quite a few graphs every single time the program runs. Basically how this works is, the programs starts by assigning a ‘OFF’ to the ‘saveAsJPG’ variable and the user simply toggles it between ‘ON’ and ‘OFF’. Whenever a graph is generated, it will then check this variable whether it contains ‘OFF’ or ‘ON’ and thus decide if it should save the graph.

6. Save file as JPG when graphing 6. Save file as JPG when graphing

: :

OFF ON

Function 7 enables the user to temporarily change the force transducer coefficients in the event that they are temporarily using a different force transducer from the one which is normally used with this machine. When activated, the program displays the current value programmed into the system (which is the default value for the normal force transducer Page 65

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usually used with this machine programmed into the script) and then asks for a new value. The values for ‘a’ and ‘b’ are used to calculate the force by substituting into F = ax+b. In our case, it’s obtained by physically testing the machine on the Instron machine and comparing the output voltage. This is further explained in the second part of this report. A sample output from the function is attached below:

Current a value : 874.3117451 Specify new a value : |

Finally, if a user unintentionally changes a value and couldn’t remember what values to change it back, there’s always a ‘Load default values’ option to reload values that has been programmed into the script. This of course is dependent on the machine setup but is less likely to be different from the default values. As the user finishes all capturing and plotting with the program, they may exit by simply selecting function ‘0’ at the Main menu. Please note that this will cause all workspace variables to be erased but captured files with the .mat extension present in the same folder will not be touched. The reason behind this is the massive amount of workspace variables generated throughout the program might coincide with another workspace variable that the user might be using after the program and will confuse them with a different result. A confirmation prompt has been built into the program to prevent accidental quitting of the program and the user losing all their work. Some screenshots of the exit confirmation message:

Main Menu ********************************************************** Please choose from options below : 1. Capture data from dynamometer 2. Load data to workspace 3. Process data (optional) 4. Graph currently loaded data 5. Modify processing parameters 0. Exit

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********************************************************** No data loaded

Choose option : 0

Exiting will clear all workspace data. Confirm? 1. YES 2. NO Confirm? : |

The workspace is also cleared when the program starts to ensure no foreign workspace variables interrupt its normal operation. Before the user exits, it’s also important to note that there’s a backdoor function built in to force the program to break from the Main menu without MATLAB throwing illegal exceptions. By typing ‘3127’ as the function code when prompted at the Main menu, a simple break command is sent to MATLAB interrupting the ‘while’ loop which is waiting for user to input a function causing the whole program to end prematurely. This function is only useful for debugging and inspecting the current workspace variables since the program will clear all workspace variables when exiting.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 Known limitations

Improvements and Operation of the Damper Dynamometer

This limitation is avoidable if the program is used correctly as it deals with errors in user input and will not affect the results of the program • While prompting user for any input, the default MATLAB ‘input’ function is used and will throw an unhandled exception causing the program to grind to a halt. This issue is quite severe in a sense that numerical errors in input could be easily detected and user would be warned but if a string or character is fed to the system, there is currently no way of handling this efficiently Section Conclusion Much time and effort has been put into compiling this program that integrates what the other students have done in the previous years for this machine. It’s hoped that this program would facilitate the user in getting the test done more easily and safely without going through too much mechanics on the software side of things. An appendix is attached to the end of this report with the full MATLAB codes for all the scripts involved in the program.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 7. Conclusion and Future Works

Improvements and Operation of the Damper Dynamometer

The damper dynamometer has been upgraded to test the Kinetic™ H2 Suspension system and a user friendly interface has been implemented in the DAQ software. Since the operation of the electrical component has been verified and any faulty components fixed, the damper dynamometer functionality has been verified. This project can now be used as a guide to the operation of the damper dynamometer.

To completely validate the robustness of the damper dynamometer, a commercial damper should be purchased and tested. The results obtained from the damper dynamometer should then be compared to the force-velocity graph acquired from the manufacturer. The testing of the Kinetic™ H2 Suspension system was not accomplished in this project as initially planned. Therefore, future work will also include the testing of the Kinetic™ H2 system to obtain the characteristics of the system. The damper dynamometer should also be used to calibrate the dampers to determine the effects of changing the settings in the Kinetic™ H2 system.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 8. References

Improvements and Operation of the Damper Dynamometer

Bansal, G 2009, ‘Commissioning of a Damper Dynamometer for the Calibration of FSAE Dampers’, Bachelor of Engineering Honours Thesis, University of Western Australia

Dixon, JC 1999, ‘The Shock Absorber Handbook’, Society of Automotive Engineers, Warrendale, PA, USA.

Dixon, JC 2007, ‘The Shock Absorber Handbook’, Professional Engineering Publishing Ltd and John Wiley and Sons Ltd, West Sussex, England.

Finlayson, D 2003, ‘Design, optimisation, & development of a FSAE Suspension System’, Bachelor of Engineering Honours Thesis, University of Western Australia.

Guzzomi, F 2004, ‘Modification, Testing and Analysis of Formula SAE Dampers’, Bachelor of Engineering Honours Thesis, University of Western Australia.

Hillier, VAC 1991, ‘Fundamentals of MOTOR VEHICLE Technology’, Nelosn Thornes Ltd, Cheltenham, United Kingdom

Hise, B 2008, ‘Suspension Technical Article - Issue #1’, Internet Brand Inc. Available from: [2 October 2009]

Milliken, WF & Milliken, DL 1995, ‘Race Car Vehicle Dynamics’, Society of Automotive Engineers, Warrendale, PA, USA.

Newman, K 2008, ‘Software and Hardware required to Build a Suspension Damper Dynamometer’, Bachelor of Engineering Third Year Project, University of Western Australia

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North, O, 2007, ‘Design of a Suspension Damper Dynamometer Testing Facility for UWA Motorsport’, Third Engineering Project, University of Western Australia, Perth

Park, A 2008, ‘Modification to Damper Dynamometer Software and Interpretation of Damper Hysteresis’, Bachelor of Engineering Third Year Project, University of Western Australia

Roshier, N 2009, ‘World Champions!’, Race Magazine. Available from: [5 October 2009]

Rouelle, C 2004, OptimumG – ‘Race Car Dynamics for Students’, Motec, Melbourne.

Starkey, J & Talbott, MS 2002, ‘An Experimentally Validated Physical Model of a HighPerformance Mono-Tube Damper’, SAE technical paper No. 2002-01-3337, Society of Automotive Engineers, Warrendale USA. th Young, WC & Budynas RG 2002, ‘Roark's Formulas for Stress and Strain 7 ed.’, McGraw Hill International Edition, Sydney

Zapletal, E 2000, ‘Balanced Suspension’, SAE technical paper No. 2000-01-3572, Society of Automotive Engineers, Warrendale USA.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 9. Appendix

Improvements and Operation of the Damper Dynamometer

Hardware

A chuck is used for tighten and untighten the spindle.

Figure 12

The bracket is for hanging the damper valve and the accumulator. It should be placed on the right hand side of the dynamometer.

The design of this bracket is explained in the hardware improvement section.

Figure 13

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 The self is for holding the terminal box and the battery for the optical sensor.

Improvements and Operation of the Damper Dynamometer

The design of this bracket is explained in the hardware improvement section.

Figure 14

Agilent™ DAQ is a data acquisition system.

It utilizes the optical sensor and the force transducer and then sends the data to MatLab® for analyzing.

Figure 15

The terminal box and the SCSI-II 68 pin cable.

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 Software – Main.m
%% Main Program interface

Improvements and Operation of the Damper Dynamometer

%Clears workspace and initializes required variables clc; clear; userOption = 99; justCaptured = 0; %Version number is basically 1.month.date disp('**********************************************************') disp(' Dynamometer MATLAB Interface ') disp(' v 1.10.16 ') disp('**********************************************************') % Default values (Change here if permanently changed) defchannel1on = 3; defchannel2on = 5; defoffset = 10; defr = 10; defl = 255; defFTa = 0.37706; defFTb = -9.78847; saveAsJPG = 'OFF'; % Assigning default values to working variables channel1on = defchannel1on; channel2on = defchannel2on; offset = defoffset; r = defr; l = defl; FTa = defFTa; FTb = defFTb; % Verifying all required files are present if exist('processDataH.m','file') == 0 disp('processDataH.m is missing. Continue?') disp('1. NO') disp('2. YES') continueMissing = 99; while continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 continueMissing = input('Please choose an option : '); fprintf('\n'); if continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 disp('Input Error. Try again.'); end end if continueMissing == 1 clear; break

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 end end

Improvements and Operation of the Damper Dynamometer

if exist('capture.m','file') == 0 disp('capture.m is missing. Continue?') disp('1. NO') disp('2. YES') continueMissing = 99; while continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 continueMissing = input('Please choose an option : '); fprintf('\n'); if continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 disp('Input Error. Try again.'); end end if continueMissing == 1 clear break end end if exist('graph1H.m','file') == 0 disp('graph1H.m is missing. Continue?') disp('1. NO') disp('2. YES') continueMissing = 99; while continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 continueMissing = input('Please choose an option : '); fprintf('\n'); if continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 disp('Input Error. Try again.'); end end if continueMissing == 1 clear break end end if exist('graph2H.m','file') == 0 disp('graph2H.m is missing. Continue?') disp('1. NO') disp('2. YES') continueMissing = 99; while continueMissing < 1 || continueMissing > 2 || continueMissing - ...

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floor(continueMissing) ~=0 continueMissing = input('Please choose an option : '); fprintf('\n'); if continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 disp('Input Error. Try again.'); end end if continueMissing == 1 clear break end end if exist('graph3H.m','file') == 0 disp('graph3H.m is missing. Continue?') disp('1. NO') disp('2. YES') continueMissing = 99; while continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 continueMissing = input('Please choose an option : '); fprintf('\n'); if continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 disp('Input Error. Try again.'); end end if continueMissing == 1 clear break end end if exist('graph4H.m','file') == 0 disp('graph4H.m is missing. Continue?') disp('1. NO') disp('2. YES') continueMissing = 99; while continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 continueMissing = input('Please choose an option : '); fprintf('\n'); if continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 disp('Input Error. Try again.'); end end if continueMissing == 1; clear

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 break end end

Improvements and Operation of the Damper Dynamometer

if exist('graph5H.m','file') == 0 disp('graph5H.m is missing. Continue?') disp('1. NO') disp('2. YES') continueMissing = 99; while continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 continueMissing = input('Please choose an option : '); fprintf('\n'); if continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 disp('Input Error. Try again.'); end end if continueMissing == 1 clear break end end if exist('graph6H.m','file') == 0 disp('graph6H.m is missing. Continue?') disp('1. NO') disp('2. YES') continueMissing = 99; while continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 continueMissing = input('Please choose an option : '); fprintf('\n'); if continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 disp('Input Error. Try again.'); end end if continueMissing == 1 clear break end end if exist('graph7H.m','file') == 0 disp('graph7H.m is missing. Continue?') disp('1. NO') disp('2. YES') continueMissing = 99;

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

while continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 continueMissing = input('Please choose an option : '); fprintf('\n'); if continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 disp('Input Error. Try again.'); end end if continueMissing == 1 clear break end end if exist('graph8H.m','file') == 0 disp('graph8H.m is missing. Continue?') disp('1. NO') disp('2. YES') continueMissing = 99; while continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 continueMissing = input('Please choose an option : '); fprintf('\n'); if continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 disp('Input Error. Try again.'); end end if continueMissing == 1 clear break end end if exist('graph9H.m','file') == 0 disp('graph9H.m is missing. Continue?') disp('1. NO') disp('2. YES') continueMissing = 99; while continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 continueMissing = input('Please choose an option : '); fprintf('\n'); if continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 disp('Input Error. Try again.'); end end

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 if continueMissing == 1 clear break end end

Improvements and Operation of the Damper Dynamometer

if exist('graph10H.m','file') == 0 disp('graph10H.m is missing. Continue?') disp('1. NO') disp('2. YES') continueMissing = 99; while continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 continueMissing = input('Please choose an option : '); fprintf('\n'); if continueMissing < 1 || continueMissing > 2 || continueMissing - ... floor(continueMissing) ~=0 disp('Input Error. Try again.'); end end if continueMissing == 1 clear break end end

% Entering into 'while' loop so user will be returned to the main menu each % time they're finished with a function while userOption ~= 0 % Error checking codes like this are used whenever possible to prevent % user from inputting numerical errors while userOption - floor(userOption) ~= 0 || userOption < 0 || userOption > 5.... && userOption ~= 3127 fprintf('\n'); disp(' Main Menu ') disp('**********************************************************') disp('Please choose from options below :'); disp('1. Capture data from dynamometer'); disp('2. Load data to workspace'); disp('3. Process data (optional)'); disp('4. Graph currently loaded data'); disp('5. Modify processing parameters'); disp('0. Exit'); disp('**********************************************************')

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

if exist('fileToLoad') == 1 && exist('capturedData') == 1; fprintf('Data Loaded : %s\n',fileToLoad); else disp('No data loaded'); end fprintf('\n') userOption = input('Choose option : '); fprintf('\n');

if userOption - floor(userOption) ~= 0 || userOption < 0 || userOption > 5.... && userOption ~= 3127 clc; fprintf('Input Error!!!! \n'); end end % Backdoor function to force program to quit loop prematurely, % retaining all workspace variables if userOption == 3127 break end if userOption == 0 disp(''); disp('Exiting will clear all workspace data. Confirm?'); disp('1. YES') disp('2. NO') confirmExit = 99; % Requesting for exit confirmation while confirmExit < 1 || confirmExit > 2 || confirmExit - ... floor(confirmExit) ~=0 confirmExit = input('Confirm? : '); fprintf('\n'); if confirmExit < 1 || confirmExit > 2 || confirmExit - ... floor(confirmExit) ~=0 disp('Input Error. Try again.'); end end if confirmExit == 1 clear; break else userOption = 99; end end if userOption == 1 run capture; userOption = 99; end

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

if userOption == 2 clear fileToLoad; while exist('fileToLoad') == 0 disp('Files available to load :') disp('**********************************************************') ls *.mat disp('**********************************************************') fileToLoad = input('Choose file to load (including .mat extension) : ','s'); % Checks if files exist if exist(fileToLoad) == 0 clc; disp('File not found. Try again.'); clear fileToLoad; end end fprintf('\n') load (fileToLoad); disp('Data Loaded!') userOption = 99; end if userOption == 3 % Automatically loads last captured file if certain criteria are % satisfied if justCaptured == 1 && exist('capturedData') ~= 1; disp('No files specified to load, lastCaptured.mat is automatically loaded'); load lastCaptured.mat; fileToLoad = 'lastCaptured.mat'; end run processDataH; userOption = 99; end if userOption == 4 if justCaptured == 1 && exist('capturedData') ~= 1; disp('No files specified to load, lastCaptured.mat is automatically loaded'); load lastCaptured.mat; fileToLoad = 'lastCaptured.mat'; end % Checks if data is present to be plotted if exist('capturedData') == 1 fprintf('\n'); disp(' Graphs available to plot ') disp('**********************************************************')

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 and 3')

Improvements and Operation of the Damper Dynamometer

disp('1. Unfiltered analog sensor outputs from channel 1,2 disp('2. Filtered data of triggered channels after one revolution of TDC') disp('3. Digital channel graph (discrete value)') disp('4. Angle vs Displacement') disp('5. Angle vs Velocity') disp('6. Angle vs Acceleration') disp('7. Force vs Displacement') disp('8. Force vs Velocity') disp('9. Force vs Acceleration') disp('10. Force vs Absolute Velocity') disp('0. Back to Main Menu') disp('**********************************************************') while exist('userGraphOption') == 0 || userGraphOption floor(userGraphOption)... ~= 0 || userGraphOption < 0 || userGraphOption > 10 fprintf('\n') userGraphOption = input ('Choose graph type to plot : '); if exist('userGraphOption') == 0 || userGraphOption floor(userGraphOption)... ~= 0 || userGraphOption < 0 || userGraphOption > 10 disp('Input Error.') end end if userGraphOption == 1 doNotClear = 1; run graph1H; end if userGraphOption == 2 doNotClear = 1; run graph2H; end if userGraphOption == 3 doNotClear = 1; run graph3H; end if userGraphOption == 4 doNotClear = 1; run graph4H; end if userGraphOption == 5 doNotClear = 1; run graph5H; end

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 if userGraphOption == 6 doNotClear = 1; run graph6H; end if userGraphOption == 7 doNotClear = 1; run graph7H; end if userGraphOption == 8 doNotClear = 1; run graph8H; end if userGraphOption == 9 doNotClear = 1; run graph9H; end if userGraphOption == 10 doNotClear = 1; run graph10H; end if userGraphOption == 0 doNotClear = 1; clear userGraphOption; userOption = 99; end else

Improvements and Operation of the Damper Dynamometer

clc; disp('No data loaded to graph! Please run capture first or load data from option 2.'); end end

while userOption == 5 userParameterOption = 99; % Displays the currently assigned values in this menu disp(' Procesing Parameters ') disp('**********************************************************') fprintf('1. Channel 1 Trigger Voltage (V) : %5.0f\n',channel1on); fprintf('2. Channel 2 Trigger Voltage (V) : %5.0f\n',channel2on); fprintf('3. TDC offset clockwise positive (deg) : %5.0f\n',offset) fprintf('4. Crank Radius (mm) : %5.0f\n',r)

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

fprintf('5. Con rod length (mm) : %5.0f\n',l) fprintf('6. Save file as JPG when graphing : %s \n',saveAsJPG) fprintf('7. Change Force Transducer Coefficients (ax+b)\n') disp('9. Load default values') disp('0. Back to Main Menu') disp('**********************************************************') while userParameterOption - floor(userParameterOption) ~= 0 || userParameterOption... < 0 || userParameterOption > 9 || userParameterOption == 8; userParameterOption = input('Choose option : '); if userParameterOption - floor(userParameterOption) ~= 0 || userParameterOption... < 0 || userParameterOption > 9 || userParameterOption == 8; disp('Input Error!') end end if userParameterOption == 1 % Trigger voltages can pretty much be any voltage, thus no % error checking is implemented channel1on = input('Input Channel 1 Trigger Voltage : '); end if userParameterOption == 2 channel2on = input('Input Channel 2 Trigger Voltage : '); end if userParameterOption == 3 % Force program into 'while' loop to start the prompting and % error checking process offset = 0.1; while offset - floor(offset) ~= 0 offset = input('Specify TDC offset to nearest degree : '); if offset - floor(offset) ~= 0 disp('Please enter whole numbers only.') fprintf('\n'); end end end if userParameterOption == 4 r = input('Specify crank radius in mm : '); end if userParameterOption == 5 l = input('Specify con rod length in mm : '); end

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 if userParameterOption == 6 if strcmp(saveAsJPG,'OFF') == 1; saveAsJPG = 'ON'; else saveAsJPG = 'OFF'; end end if userParameterOption == 7 fprintf('Current a value FTa = input('Specify new fprintf('Current b value FTb = input('Specify new end

Improvements and Operation of the Damper Dynamometer

: a : b

%7.7f\n',FTa); value : '); %7.7f\n',FTb); value : ');

% Load all to default values specified at the beginning of the file if userParameterOption == 9 channel1on = defchannel1on; channel2on = defchannel2on; offset = defoffset; r = defr; l = defl; FTa = dFTa; FTb = dFTb; saveAsJPG = 'OFF'; disp('Default values loaded!') end if userParameterOption == 0 userOption = 99; end end % Returns user back to graphing options if they've just finish plotting % a graph if exist('userGraphOption') == 1 userOption = 4; else userOption = 99; end clear userGraphOption; end

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 capture.m

Improvements and Operation of the Damper Dynamometer

function [capturedData] = capture() %% Prompting capture parameters % Default parameters dsampleRate = 15000; dsamplesPerTrigger = 30000; dRPM = 88; dtimeout = 30; useDefault = 99; disp('Do you want to use default capture settings?') disp('1. YES') disp('2. NO') disp('0. Back to Main Menu') while useDefault-floor(useDefault)~= 0 || useDefault2; useDefault = input('Use default capture settings? : '); if useDefault-floor(useDefault)~= 0 || useDefault2 disp('Input Error.') end end if useDefault == 1 RPM = dRPM; sampleRate = dsampleRate; samplesPerTrigger = dsamplesPerTrigger; timeout = dtimeout; end if useDefault == 2 sampleRate = input('Sampling rate per second : '); samplesPerTrigger = input('Samples to collect, or enter zero if defining total capturing time : '); RPM = input('Approximated RPM : '); if samplesPerTrigger == 0 capturingTime = input('Input capturing time in seconds : '); samplesPerTrigger = sampleRate * capturingTime; end timeout = input('Timeout (seconds) : '); end if useDefault == 0 return; end %% Channel input % Stops any running DAQ and erases any previously stored arrays openDAQ=daqfind; for i=1:length (openDAQ); stop (openDAQ (i)); delete (openDAQ (i)); end

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

% Creates an analog input object connectted to Agilent Driver U2300 ai=analoginput('agilentu2300'); % Assign first 3 hardware channels to 3 index channels addchannel (ai, 0); addchannel (ai, 1); addchannel (ai, 2); %% Channel Set % Now, let's set up the analog input object % per-channel rate at which analog data is converted to digital set (ai, 'SampleRate', sampleRate); % number of samples to acquire for each channel for each trigger set (ai, 'SamplesPerTrigger', samplesPerTrigger); % additional waiting time to extract or queue data set (ai, 'Timeout', timeout); % Execute ai start (ai); fprintf('Capturing data from DAQ...'); [d,t] = getdata (ai); % measures the sample-time pairs, with relative time (sec) taken to log % the data since the first sample % stops DAQ and deletes all initial values stop (ai); fprintf('done!\n'); delete (ai); clear ai; % channel1 % channel3 channel1=d channel2=d channel3=d and channel2 are optical sensors -angle and TDC is force transducer (:,1); (:,2); (:,3);

% end data collection %% Creating 1 matrix for all captured data % Column 1 = output from optical sensor % Column 2 = output fromk TDC sensor % Column 3 = output from force transducer % Column 4 = corresponding time d(:,4)=t; capturedData = d; %% Saving captured data to file % This part automatically creates 2 identical output files, one with the date % and time in the file name and the other one is named to 'lastCaptured.m'

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

% which will be used when running the programs immediately after capturing. % This saves time typing the different file names each time. timeNow = fix(clock); fprintf('Creating unique filename...') filename = [num2str(timeNow(1)) num2str(timeNow(2)) num2str(timeNow(3))... num2str(timeNow(4)) num2str(timeNow(5)) num2str(timeNow(6))]; fprintf('done!\n') fprintf('Saving %s...',filename); save(filename,'capturedData','samplesPerTrigger','sampleRate','RPM'); fprintf('done!\n'); fprintf('Saving lastCaptured...'); save('lastCaptured','capturedData','samplesPerTrigger','sampleRate','RP M'); fprintf('done!\n'); justCaptured = 1; %% Confirmation message fprintf('Data capture completed. 2 files created.') end

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 processDataH.m

Improvements and Operation of the Damper Dynamometer

% Close all figures and graphs clf; close all; if exist('capturedData') ~= 1 clc; disp('No data loaded to process! Please run capture or load data from option 2!'); break end % %% Values set at default, or can be custom entered -suppress either one. % % % % *****Automatic default input***** % % Specify offset in degrees (whole numbers only) % % offset between TDC and vertical axis, measured positive clockwise % offset=10; % % specify crank radius mm % r=10; % % specify the con rod length mm % l=255; % % k samples to be taken % ; % % channel1on for angle sensor % channel1on= 5; % % channel2on also needs be introduced for TDC sensor % channel2on= 7; %% calculation of other values % k samples to be taken k=samplesPerTrigger; % ratio used later for calculation index q=l/r; % channel1 and channel2 are optical sensors -angle and TDC % channel3 is force transducer channel1=capturedData (:,1); channel2=capturedData (:,2); channel3=capturedData (:,3); t = capturedData (:,4);

%% Algorithm in KN's EP, 2008, p .18 % *****ALICIA'S CODE Finds first TDC and truncate data***** % initialise indexing parameters i=1; j=1; % Activation loop to find first TDC (S2 ON) % increment i until sample exhausts at i=k OR reaches S2 ON % Detects the 'fall' of TDC sensor while (i channel2on); i=i+1;

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 end % Now, detect the 'pick up' of TDC sensor while (i channel2on % value used for intermediate check skippedIToReachTDC = i;

Improvements and Operation of the Damper Dynamometer

%% Alicia's Algorithm -FILTER OUT VALUES FOR ONE REVOLUTION OF TDC % *****Start of the rotation at TDC slot***** triggeredch1 = []; triggeredch2 = []; triggeredch3 = []; triggertime = []; newtriggeredch1=[]; for i = skippedIToReachTDC : k-1; if channel1(i) < channel1on; triggeredch1 (j)=channel1 (i); triggeredch2 (j)=channel2 (i); triggeredch3 (j)=channel3 (i); triggertime (j)=t(i); j=j+1; end end % i is now at the start of the 'fall' of TDC sensor jvalue=j-1; % number of available samples for filtering % *****NOW, FILTER OUT A SINGLE SIGNAL FOR EACH ANGLE SLOTS***** % initialised a=1; b=1; triggeredch1(1,1); newtriggeredch1(1)=triggeredch1(1); % filters out data corresponding to two full rotation for a=1:360*2 % while going down on S2 cycle, record the new smaller value as % newtriggeredch1 if b < jvalue-1; while triggeredch1(b+1) < newtriggeredch1(a); newtriggeredch1(a)=triggeredch1(b+1); newtriggeredch2(a)=triggeredch2(b+1); newtriggeredch3(a)=triggeredch3(b+1); newtriggertime(a)=triggertime(b+1); b=b+1;

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 end Improvements and Operation of the Damper Dynamometer

% OR while going up on S2 cycle, do nothing while triggeredch1(b+1) >= triggeredch1(b); b=b+1; end % assigns a maximum value for next cycle newtriggeredch1(a+1)=triggeredch1(b); else % prints out an error message if data is exhausted fprintf('Error. Insufficient data available.\n Ensure to record at least two full rotations of crank.\n'); break; end end % ensures minimum value is recorded at the last entry a=a+1; while triggeredch1(b+1) < newtriggeredch1(a) && b < jvalue-1 newtriggeredch1(a)=triggeredch1(b+1); newtriggeredch2(a)=triggeredch2(b+1); newtriggeredch3(a)=triggeredch3(b+1); newtriggertime(a)=triggertime(b+1); b=b+1; end %% Top dead center is located in % location of TDC along recorded % e.g. if TDC=0, then 0 delay in % e.g. if TDC=5, then 5 delay in tdc=offset-90; % adjust TDC for a revolution if tdc < 0 tdc = 360 + tdc; end % array of pheta values % NOTE: overlabs at 0=360 deg pheta=0:1:360; newch1=newtriggeredch1(tdc+1:tdc+361); newch2=newtriggeredch2(tdc+1:tdc+361); newch3=newtriggeredch3(tdc+1:tdc+361); newtime=newtriggertime(tdc+1:tdc+361); %% Calculation %check for variations in angular velocity, dividing into 45deg segments w00_45=(pi/4)/(newtime(46)-newtime(1)); w45_90=(pi/4)/(newtime(91)-newtime(46)); w90_135=(pi/4)/(newtime(136)-newtime(91)); w135_180=(pi/4)/(newtime(181)-newtime(136)); w180_225=(pi/4)/(newtime(226)-newtime(181)); w225_270=(pi/4)/(newtime(271)-newtime(226)); array at offset+c array array and 1st recorded value is TDC array and 6th recorded value is TDC

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339

Improvements and Operation of the Damper Dynamometer

w270_315=(pi/4)/(newtime(316)-newtime(271)); w315_360=(pi/4)/(newtime(361)-newtime(316)); average_angular_velocity=2*pi/(newtime(361)-newtime(1)) Estimated_RPM = average_angular_velocity*60/(2*pi) % average angular velocity is unsupressed and shown on MATLAB command for % user verification purposes %convert pheta from degrees to radians pheta_rad=pheta./180.*pi; % ***movement of damper, calculation from p .9 - 10 *** % Displacement : length of y, then displacement is y-l x = r.*(cos (pheta_rad)+q-1./(2.*q)*(sin(pheta_rad)).^21./(8.*q.^3)*(sin (pheta_rad)).^4-1./(16.*q.^5).*(sin (pheta_rad)).^6)l; % Velocity v = -average_angular_velocity.*r.*(sin (pheta_rad)+1/(2*q).*sin (2*pheta_rad)+1/(8*q^3)*(sin (2*pheta_rad)-1/2*sin (4*pheta_rad))); % Acceleration acc=-average_angular_velocity.^2.*r.*(cos (pheta_rad)+1/(q).*cos (2*pheta_rad)+1/(4*q^3)*(cos (2*pheta_rad)-cos (4*pheta_rad))); % now calculate the force reading in newtons from the voltage readings % a and b values are found by experimentally calibrating the force transducer a= FTa; %default = 874.3117451; b= FTb; %default = -1929.651207; % force is multiplied by 1000 to convert kN to N force=(a*newch3+b)*1000; disp('Processing completed.') % END OF PROCESSING FUNCTION

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Andrew Chau, 20264212 Michael Li, 10758152 Tiong Kun Ooi, 20256339 Graph1H.m

Improvements and Operation of the Damper Dynamometer

%% GRAPHS % Process required Data run processDataH; clf; % Graph 1 : Unfiltered analog sensor outputs from channel 1,2 and 3 figure (1) hold on; plot (t,channel1,'b') plot (t,channel2,'r') plot (t,channel3,'g') h = legend('Sensor1: Angle','Sensor2: TDC','Sensor3: Force',3); set(h,'Interpreter','none') title ('Optical Sensor & Transducer Output -Original') xlabel ('Time (s)') ylabel ('Voltage reading of sensor (V)') if strcmp(saveAsJPG,'ON') == 1 saveas(gcf,'Unfiltered Sensor Reading.jpg'); end break

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