INTRODUCTION Background
Driving Simulators are used for entertainment as well as in training of driver's education courses taught in educational institutions and private businesses. They are also used for research purposes in the area of human factors and medical research, to monitor driver behavior, performance, and attention and in the car industry to design and evaluate new vehicles or new advanced driver assistance systems (ADAS). Training Driving simulators are being increasingly used for training drivers all over the world. Research has shown that driving simulators are proven to be excellent practical and effective educational tools to impart safe driving training techniques for all drivers. Uses
• • • • • • •

User training Training in critical driving conditions Training for impaired users Analysis of the driver behaviours Analysis of driver responses Analysis of the user performances Evaluating user performances in different conditions (handling of controls)

Entertainment Apart from training drivers, driving simulators are also used for entertainment purposes like giving video games a more realistic feel. Steering wheels and seats can be purchased and synchronised with game consoles to be used when playing racing games.

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Research Driving simulators are used at research facilities for many purposes. Some vehicle manufacturers operate driving simulators. Many universities also operate simulators for research. In addition to studying driver training issues, driving simulators allow researchers to study driver behavior under conditions in which it would be illegal and/or unethical to place drivers. For instance, studies of driver distraction would be dangerous and unethical (because of the inability to obtain informed consent from other drivers) to do on the road. With the increasing use of various in-vehicle information systems (IVIS) such as satellite navigation systems, cell phones, DVD players and e-mail systems, simulators are playing an important role in assessing the safety and utility of such devices.

Objective
The objective of this project is to design the mechanical part of a driving simulator that has the ability to reproduce the car response and behavior of a driver in reality.

Scope
Driving simulators can encompass a vast variety of scenarios that require more than a 13 week time frame to intricately and accurately incorporate in our design. Hence our project is limited to a few scenarios of driving namely accelerating, cruising, braking, turning and overcoming a minor obstacle such as a hump. Furthermore, we will limit our design to the mechanical aspects of the simulator and neglect the programming and majority of the electronic aspects.

Research on Existing Driving Simulators

In the existing market for driving simulators, there are a variety of designs with each manufacturer claiming to have a product with better performance and reliability compared to the rest. We will now take a closer look at some of these products to analyse their pros and cons so that we can come up with a design that is best suited to our consumer requirements.

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1)

CarSim

CarSim simulates the dynamic behavior of racecars, passenger cars, light trucks, and utility vehicles. It animates simulated tests and has the ability to output over 700 calculated variables to plot and analyze. The outputs can also be exported to other softwares such as MATLAB, Excel, and optimization tools for further analysis. Some positive features of this product are: Ease of Use

With CarSim’s modern graphical user interface, you can run a simulated test, see an animation, or view engineering plots of results with just one mouse click. The CarSim math models are parametric, involving measurable properties that are commonly used by OEM's and supplier companies. As a result, CarSim users can usually get results for new vehicles with minimal time.

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Accurate The CarSim math models are built on decades of research in characterizing vehicles and reproducing their behavior with mathematical models. Validation testing continues as new features are added. OEM users consistently find close agreement between CarSim predictions and actual test results. Fast CarSim combines a complete vehicle math model with high computational speed. The software development team at Mechanical Simulation uses the VehicleSim Lisp symbolic multibody program to generate the equations for the vehicle math models. The machine-generated equations are highly optimized to provide fast computation and correct nonlinear equations for fairly complicated models.

2) The NADS MiniSim Driving Simulator

The NADS MiniSim driving simulator is a PC-based simulator system equipped with the same world-class technology used in the NADS-1 simulator. It is a low-cost alternative to the more sophisticated NADS-1, and has a more flexible structure. It can be easily customized to address specific needs while remaining compatible with the powerful tools developed at NADS for creating realistic virtual environments and complex scenarios. Advantages of this simulator are: 4

Versatility The MiniSim is a modular system that can be configured for different needs. It uses two regular PCs as the simulator computational engine. Off-the-shelf products can be used for local network connection, visual display, audio components, steering wheel and pedals, and instruments. Advanced Software Technology The MiniSim’s software consists of nine modules: front end operator GUI, terrain database manager, vehicle dynamics, scenario/behavior controller, visuals, audio, control input/feedback system, motion controller, and run configuration manager. This structure is almost identical to that of the software running on the NADS simulator, and most of the upper-level source codes are shared, including terrain database manager, vehicle dynamics, scenario/behavior controller, and run configuration manager. The MiniSim does not require all eight modules to be present, although some modules are considered necessary for the most basic driving simulator configuration. These include the control input/feedback system, terrain database manager, vehicle dynamics, and visuals. The front end GUI provides a user-friendly interface that allows the operator of the MiniSim simulator to select the content of the simulator run and take full control of each drive and playback.

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Realisitc Several tools of the behavior/scenario controller have been developed and refined to design realistic virtual environments and complex scenarios for the simulation tasks run on the MiniSim. For the most realistic driving experience, a cab modified from a real vehicle can be custom built, with force feedback and full instrumentation. In a less expensive configuration, an off-the-shelf steering wheel and pedals set can be installed, with a choice of genuine instrument panel, simplified gauges, or virtual panel shown in the visual display. For a baseline set-up, keyboard and mouse control is sufficient for driving the MiniSim simulator. 3)

The CXC MP II Simulator is equipped with a highly advanced computer driven full-motion system using sophisticated electro-mechanical actuation. You’ll feel every sensation of the car you’re driving, with racing car choices ranging from Lotus to a high intensity F1 car. This simulator is greatly affiliated to professional driving and gives users a feel of what it is like to be a race car driver.

Advantages of this simulator are:

Intensity

Intensity is fully adjustable, but at maximum settings, jump on an F1 car’s gas pedal and acceleration will slam you back into the seat with every shift. Brake hard and you’ll pitch forward against your fourpoint safety harness. In a long sweeper, you’ll experience increasing side load and the nuances of lateral 6

grip as your car dances on the edge of adhesion. These are tactile sensations that professional drivers feel and depend on – available to a degree never before possible in an affordable simulator.

Technology The heart of the MP II lives in an electronics rack hidden in the base of the simulator, a purposebuilt, leading edge simulation PC powered by a multi-core processor, with a high-end graphics card to drive either video display choice. It is mounted on rails for easy inspection or removal. All connections for controls and the motion system are made through a special connector system hidden along the edge of the base plate. The MP II Simulator features a force-feedback steering system made exclusively for CXC to provide ultra-sensitive steering resistance and tactile feedback. Its high torque and responsiveness set new standards in consumer racing simulation, good enough to test driver reaction and stamina levels.

Sturdy Design and Construction CXC racing simulators are individually constructed and assembled with space-age materials including laser-cut steel, billet aluminum, carbon fiber and titanium. Virtually all control systems are designed to be quickly adjustable without tools so the MP II Simulator can be set up to exactly match size and driving preferences. .

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4) ZEN DRIVING TRAINING SIMULATOR (ZEN DTS™)

Zen Driving Training Simulator is a versatile indoor training system for light, medium and heavy vehicle trainee drivers. The simulator facilitates training in a ‘to scale’ vehicle cabin with actual indicators and controls, thereby creating a realistic driving environment. The simulator is manufactured for both Left and Right Hand drives. The basic system is supplied with an Instructor Station and a Driver Station. However, up to 10 Driver Stations can be configured with an Instructor Station. The driving training simulator is ideal for institutes imparting basic driver training. A number of simulators can be networked if so required.

Key Features: • • • • • • • Simulates realistic motion, visuals and sounds One instructor can control multiple Driver Stations simultaneously Allows centralized or individual trainee control by instructor Simulator cabin is provided with real controls and the steering, brakes accelerator and all hand-and-foot-operated controls provide the same feel and response of actual vehicles Gear mechanism is as per the original vehicle Motion Platform provides a touch of realism to driving experience Simulates realistic driving conditions 8

• •

Scenarios are 3D CGI based Realistic sound simulation is created through synchronization of sound and action for exercises like engine start and idle conditions, changing of gears, acceleration, crashing, brake operation, tyre bursts

• •

Offers training under different environmental conditions. Records trainees’ errors and illustrates trainees’ actions such as time taken to shift the foot from accelerator to brake; right gear vs. right speed; accidents, speeding; lane violation, dangerous turns and switching on ignition with gear engaged.

•

Electric Motion Platform for the cabin providing movements like pitch, roll, forward and backward motion, abrupt braking and crashing movement is optional

Cons

All the simulators described above have very interesting features and use the latest technologies in their design and controls. However, no design is perfect and what may seem ideal for some may not be the same for others. These simulators too have certain disadvantages which shall now be discussed in more detail. We will strive to reduce these disadvantages in our own design.

1. Costly

These simulators may seem cost effective to their manufacturers, but in truth they only see it that way because they are comparing the prices among similar expensive products. They are still out of budget for many people and thus not everyone is able to experience simulation driving before taking on the real thing.

2. Complex Design

What a customer needs is a product that is easey to operate and control. However, as seen in the products above, all of the designs use the most advanced technology and complicated controls which may not be understandable to many customers and thus pose a problem to them. 9

3. Size

As seen in the pictures above, the simulators are fairly large in size and this means that customers who purchase the product would require an even bigger space to store the simulator. This would pose a hindrance to many potential customers who may not have sufficient space.

Conceptual Design

Functional Analysis Diagram Function Analysis helps us to focus on the essential functions that the product must have in order to give value, functionality and quality to the end user. It is based on a method of problem decomposition and is a technique used to identify the labor competencies inherent in a productive function. Such function may be defined at the level of an occupational sector, an enterprise, a group of enterprises or a whole sector of production or services. It is thus evident the flexibility of functional analysis. It is a working approach to the required competencies by means of a deductive strategy. It begins by establishing the main purpose of the productive function or service under study and then questions are asked to find out what functions need to be performed in order for the previous function to be achieved.

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Morphological chart Morphological Chart ensures that we consider all the possible methods (that we can think of) of achieving each essential function before making a decision on our final concept. It is a table based on the function analysis. The functions are listed on the left side of the chart, while on the right side, a different number of mechanisms corresponding to the functions listed are drawn. It is a visual aid used to come up with different ideas and this is accomplished by creating single systems from different mechanisms illustrated in the morphological chart. It is advised to generate several feasible designs using different mechanisms for each function for each concept.

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Concepts From our morphological chart, we conceptualized three different designs for our driving simulator. Following that, a matrix evaluation chart was performed on these designs. The table below shows the choices made for each concept based on the functions listed in the morphological chart.

Concept 1 Function Movement Hydraulic Actuators

Concept 2 Choice Gears

Concept 3

Electro-Mechanical Actuators

Position of Actuator Shock Reducer Vibration Mechanism Safety

Triangular Air Suspension Magnetic Diagonal Seat Belt

Nil Damper Cam Horizontal Seat Belt Reclining Mechanism

Stewart Platform Spring Suspension Magnetic Two Vertical Straps Reclining Mechanism

Backrest Adjustment Spring-Lock Mechanism Stability (Base) Seat Material Mechanism Rectangular Leather

Circular Cotton

4-Block Base Polyester

The following figures depict the three different concepts with their respective components and mechanisms.

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Matrix analysis

The evaluation criteria above are some basic considerations we felt were necessary in helping us choose our final design. Maneuverability and low cost were given the highest weighting factor as we felt our design should be oriented towards that direction. These factors are followed closely behind in importance by safety, stability and light weight construction and ease of consumer operation (ergonomics).

In the next table, all the criteria were given ratings V, based on their significance in each of the concepts and this was multiplied by their weighting factor W, defined earlier to give each criterion a final value. All the values for each concept were then added up to get an overall value for each of the three concepts. The concept with the highest overall value would be chosen as our final design.

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As seen in the table above, Concept 1had the highest ratings for most of the criteria and hence a highest overall value, making it the choice for our final design.

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Final design of the selection of parts from the sub-functions
Sub functions Movement up/down left/right Selection of parts Actuator Reason It is a more effective way as other methods requires a longer time, takes greater effort or creates more noise disturbance. We choose Triangular formation because it requires less actuator then square formation and can provide the required stability. Steward Platform is far too expensive. Air suspension has a high shock resistance and is used in real life vehicle. Spring is not strong and firm enough to support the weight. Using magnetic field to function the vibrator is the most trustable and stable form. To make the simulator look more realistic, diagonal seat belt is choosen. It secures the user when experiencing a sudden shock. It is a simple yet effective method to adjust the seat to one’s comfort level. We choose rectangular formation as it provides a bigger surface area and greater stability. As most cars uses leather material on their seat, our simulator decides to follow to make the seat look more real.

Position of Actuator

Triangular

Reduce Shock

Air Suspension

Vibration

Magnetic Vibrator

Safety

Diagonal Seat Belt

Backrest Adjustor Base Stability

Spring Lock Mechanism Rectangular

Material

Leather

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EMBODIMENT DESIGN
Some mechanical assemblies work better than others- we know it when we operate them. Whether by luck or by design, the arrangement of the mechanical systems are more robust than others. It could be a better shape or physical arrangement of the components, better ergonomics, better safety, more reliable, better aesthetics and so on. Embodiment rules and principles assist us in achieving these ends.

The rules of Clarity, Simplicity, and Safety are qualitative rules generally applicable to all engineering disciplines and should be considered constantly throughout the embodiment design phase. Clarity speaks to the aim of having a clearly defined role for each component and subcomponent in the design. Simplicity refers to the aim to keep the overall design (and the design of each component) as simple as possible while still accomplishing the overall goal. Complexity in shape makes the outcome more difficult to predict, while adding more parts and subassemblies complicates assembly and maintenance.

We will try our best to incorporate the above mentioned rules as much as possible in our chosen design, trying to maintain a certain level of aestheticism without sacrificing any of the basic mechanical functions that were decided earlier.

1) Actuator

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Hydraulic Actuator - Motion

Pneumatic actuators are normally used to control processes requiring quick and accurate response, as they do not require a large amount of motive force. However, when a large amount of force is required to operate a valve, hydraulic actuators are normally used. A typical piston-type hydraulic actuator consists of a cylinder, piston, spring, hydraulic supply and returns line, and stem. The piston slides vertically inside the cylinder and separates the cylinder into two chambers. The upper chamber contains the spring and the lower chamber contains hydraulic oil.

2) Air Suspension

Air suspension is a type of vehicle suspension powered by an engine driven or electric air pump or compressor. This pump pressurizes the air, using compressed air as a spring. Air suspension replaces conventional steel springs. If the engine is left off for an extended period, the car will settle to the ground. The purpose of air suspension is to provide a smooth ride quality and in some cases self-leveling.

Air suspensions have a wide turning range and don't require the adjustments that steel springs

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would require to reach the same level of turning capacity. Most air springs progressively adjust to different compression levels, which often provide a greater level of handling than spring systems.

3) Vibrator using magnetic field

The vibrator is used in out design to simulate the vehicle moving. Here, we use magnetic field to function the vibrator. At the starting position, current flows through the top half of the transformer primary to the vibrator coil. This causes the vibrator contacts to be attracted upwards, making the top contact. The top contact shorts out the vibrator coil, and causes a heavy current to flow through the top half of the primary winding. The de-energized vibrator coil allows the vibrator contacts to swing through the starting position, and make contact with the lower contact. This interrupts the current through the top half of the primary winding and causes a heavy current to flow through the bottom half of the primary winding, reversing the magnetic field. This also removes the short across the vibrator coil, allowing it to once again energize, attracting the contacts upward. This cycle repeats itself continuously. The constant reversal of the magnetic field induces an alternating current in the secondary of the transformer.

Safety Features
Diagonal seat belt
The diagonal seat belts are used in the design. Diagonal seat belts are used in real life cars and the purpose is to provide safety to users by protecting them from falling off their seats when there is a sudden surge in motion during the process of driving.

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Detailed Design
Assume fixed shape of the seat and backrest, Volume of seat = 0.43 * 0.43 * 0.169 = 0.0312m3 Volume of backrest = 0.29 * 0.53 * 0.136 = 0.0209m3 Volume of middle plate = 0.45 * 0.45 * 0.05 = 0.010125m3 Volume of base plate = (0.03 * 0.644 * 0.45) + (0.15 * 0.15 * 0.0848 * 3) = 0.008694 + 0.005724 = 0.014418m3
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Material choosen for seat and backrest 1) Leather Most cars use it in reality High tensile strength Resistance to tear Good heat insulation Resistance to wet and dry abrasion Density = 0.76/cc = 760kg/m3

2) Carbon Fibre - Material consisting of extremely thin fibres about 0.005-0.010mm in diameter and composed of mostly carbon atoms - Density lower than steel (Ideal for low-weight application) - High tensile strength, low weight, low thermal expansion - Strong when stretched or bent - Popular in aerospace, motorsports, civil engineering - Density = 1.78g/cc = 1780kg/m3 3) Polyurethane - Low density foam - Density = 1.05g/cc = 1050kg/m3
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Mass = Density * Volume Assuming 30% Carbon fibre, 20% Leather, 50% Polyurethane. Mass of Seat = (0.0312 * 1780 * 30/100) + (0.0312 * 760 * 20/100) + (0.0312 * 1050 * 50/100) = 16.6608 + 4.7424 + 16.38 = 37.78kg Mass of Backrest = (0.0209 * 1780 * 30/100) + (0.0209 * 760 * 20/100) + (0.0312 * 1050 * 50/100) = 11.1606 + 3.1768 + 16.318 = 30.72kg Mass of Middle Plate = 1780 * 0.010125 = 18.023kg Mass of Base Plate = 1780 * 0.014418 = 25.664kg Assume mass of person on the seat to be 80kg, Total mass of seat, backrest, middle plate and person = 37.78 + 30.72 + 18.023 + 80 = 166.523kg As the mass of the 2 side actuators and suspension are not included, we insert a safety factor of the 2. Hence total mass = 166.523 * 2 = 333.046kg
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Damping force E = Energy per stroke [Nm] m = Impact mass [kg] g = Acceleration due to gravity [m/s2] = 9.81 s = Height of fall [m] h = Damping distance [m] 24

E = (m.g.s) + (m.g.h) = 0 + (333.046 * 9.81 * 0.03) = 98.02Nm Damping Force = (Energy per stroke * correction force * 1000)/ Stroke = (98.02 * 2 *1000)/30 = 6534.36N
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Actuator Forces Assume mass of car = 2200kg speed of car = 100km/hr = 27.78m/s F1 Fact θ Time for car to stop = 3s Acceleration = 27.78/3 = 9.26m/s2 F1 = mcar * acar = 2200 * 9.26 = 20372N Let θ = 450 Fact * cosθ = F1 Fact * cos45 = 20372N Fact = 28810.36N Because there are 2 actuators, each actuator needs Fact/2 = 28810.36/2 = 14405.18N = 14.4kN

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Bottom Actuator

F2

CG y

Fd

Fact x

mg

x1 x/2

Assuming mass of car = 2200kg Speed of car = 100km/hr = 27.78m/s Time taken to reach desired speed = 5s Mass of person on seat = 80kg Acceleration = 27.78/5 = 5.556m/s2 F2 = mcar * acar = 2200 * 5.556 = 12223.2N Fact x – Fdx1 – mg(x/2) = F2y Fact(0.22) – (3267.18)(0.22) – (80)(9.81)(0.11) = (12223.3)(0.45) Fact = 28661.8N = 28.7kN

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Detailed Drawings
The design of the driving simulator is created by 3-Dimensional Modelling software. Our group has chosen to use Autodesk 3D Inventor Professional to model our conceptual design and run finite element analysis. The following are detailed drawings with explanations and problems encountered while designing the driving simulator: Final Design drawing

This is the final design of the driving simulator and the chair is designed to provide 360̊ of motion to simulate real life driving experience such as acceleration, braking, steering right and left and hitting a hump. The driving simulator is powered by 5 actuators, 3 of which are used to provide motion for the entire driver’s seat while 2 smaller actuators are used to move the backrest. The following diagrams shall describe the motion in detail:

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Acceleration/ Deceleration

Finsterle Type 904

Finsterle Type 902

Backrest

From the diagram on the above left, the front actuator was extended, thus providing a backleaning position used to simulate backward G-force on the driver’s body while the vehicle is moving off. The driver’s body will be strapped tightly to the seat using a diagonal seat belt so as to ensure that the driver will experience the full motion of acceleration. During hard deceleration, the 2 rear actuators will be extended to provide a “tilt forward” motion while the vehicle is experiencing an emergency brake. The full-range of motion provided by these actuators will provide an angle (30̊) to simulate the actual driving experience. The actuators that support the driver seat is available in the market and they are made in Germany by Finsterle. The actuators that were chosen are Finsterle Hydrauliks Type 902(3 actuators supporting driver’s seat) and Finsterle Hydrauliks Type 904(2 actuators controlling motion of backrest). The arrangement of these actuators shall be explained under Part Drawings in the later section. 28

Right Turn Front View Rear View

The diagrams above illustrate the motion of the driving simulator when the car is taking a right turn. As the car turns right, the driver’s body will experience a leftward opposing force. The driving simulator is required to tilt to the left to create this leftward motion. This is motion is created by extending the REAR RIGHT actuator as shown on the “rear view” diagram above. Left Turn Front View Rear View

Similarly, a rightward motion is created by extending the REAR LEFT actuator as illustrated from the “rear view” diagram. This will allow the driver to experience the realistic force due to the swerving of the car.

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Hit Hump

The above diagram illustrates the motion of the actuators to simulate the hitting of humps during driving. This action will result in the extension of all 3 actuators by 10cm. This will create the upward thrust on the driver when the driver hits a hump forcefully.

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Part Drawings/ Isometric drawings
Final Design Isometric Drawings

The driving simulator is made up of several key components: 1) Base Plate assembly 2) Finsterle Hydrauliks (Type 902) 3) Ball Joint 4) Ball Pin 5) Center Plate Assembly 6) Suspension Lung 7) Carseat Assembly 8) Finsterle Hydrauliks (Type 904) 9) Accelerator assembly

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1) Base Plate Assembly

Raised Platform

Actuator housing

The diagrams above shows the detailed part drawings for the base plate assembly. There are 3 raised connector housings for holding the actuators in position. Notice that the 3 connector housings are arranged in a triangular pattern and this arrangement is necessary so that the car seat is able to rotate 360̊. 32

The raised platform at the front portion is designed to hold the accelerator assembly and driver’s leg space. 2) Finsterle Hydrauliks (Type 902)

Base

The Finsterle Hydrauliks Type 902 is a single action linear actuator that is readily available in the market. These actuators will be assembled in the base plate assembly by inserting the base of the actuators in the base plate connector housing. The actuators have an extended length of 578mm and has stroke of 203mm.

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3) Ball Joint

Spherical Hole

Insert actuator

Insert ball pin

The ball joint is a connector housing that connects the top of the Finsterle Type 902 to a ball pin. Notice that one end of the housing is a spherical hole for inserting the ball pin while the other end is for slotting and securing the actuator.

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4) Ballpin

Slot into center plate assembly

Slot into BallJoint

The ball pin above is a connecting pin that is slotted into the ball joint and to the center plate assembly. The ball joint is slotted into the spherical hole in the ball joint while the other end will be slotted into the center plate assembly.

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5) Centerplate Assembly Top View Bottom View

Insert suspension lung

Swinging bracket for slotting ballpin

The centerplate assembly is the portion that houses the ballpin and the suspension lung. The 3 swinging brackets are slotted in with the 3 ball pins. There are 4 circular indented housings for slotting in the suspension lungs.

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6) Suspension Lung

Compound Rubber

The suspension lung in the diagram above is an compact air bellow suspension. The center portion is a fabric reinforced compound rubber. This device is a single acting suspension and is pressurized to provide damping effect while driving.

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7) Carseat Assembly

Adjustable backrest

For inserting into suspensiong lung

The carseat assembly above was fitted with an adjustable backrest so as to provide forwardacting motion when the vehicle is slowing down. The bottom of the backrest was drilled for slotting in the suspension lung as aforementioned. The backrest is designed to hold the driver comfortably. The “bucket” design wraps the driver’s body comfortably and snugly in the seat and prevents unnecessary sliding.

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8) Finsterle Hydrauliks Type 904

This actuator is connected between the sides of the driver’s seat and the backrest to move the backrest. This actuator creates the backward/ forward G-force that the driver experiences while stopping and accelerating.

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9) Accelerator Assembly

The accelerating assembly is mated onto the raised platform on the baseplate assembly. The part is designed to fit to the body posture of drivers. This assembly is added on so that we can have a rough gauge of the leg space required for a typical driver.

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Finite Element Analysis (Ball Joint)
Material(s)
Name Carbon Fibre Mass Density General Ultimate Tensile Strength Young's Modulus Stress Poisson's Ratio Shear Modulus Part Name(s) Ball Joint

1.78 g/cm^3 5650 MPa 125 GPa 0.34 ul 30 GPa

The table above shows the mechanical properties of carbon fiber. Carbon fibre was chosen for the ball joint due to its high ultimate tensile strength. The picture below shows the bottom section of the ball joint. Within the cylindrical intrusion, we will be running Finite Element Testing on the PIN that will be secured to the linear actuator. This joint is critical as any breakage will cause the driver to topple over and cause injuries. Therefore, it is critical to conduct stress analysis on this part.

Stress analysis to be done on this pin

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Pressure:1
Load Type Pressure Magnitude 4.220 MPa Pin slotted into 10mm diameter hole on the top section of actuator

Selected Face(s)

Pressure load of 4.22Mpa applied on the highlighted section of the pin

As the pin is fully in contact with the actuator pin slot, a pressure load was selected and applied on, we will be able to obtain the pressure load. A safety factor of 2.5 is considered due to the possibility of the driver jumping onto the seat.

onto the pin. The pressure input is 4.220Mpa which is derived from the weight (80kg) of the driver and factoring in a safety factor of 2.5. By obtaining the area of the pin that the pressure is applied

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Fixed Constraint:1
Constraint Type Fixed Constraint
Selected Face(s)

Highlighted surfaces selected as fixed constraints

The walls of the cylindrical intrusion for slotting in the top section of the actuator were selected as fixed constraints.

The von Mises stress is used to predict yielding of materials under any loading condition from results of simple uniaxial tensile tests.

Von Mises Stress

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Max. Tensile stress of 2.033Mpa observed at the end sections of the pin

The test revealed a maximum stress of 2.033Mpa along the grains of the carbon fiber material. Majority section of the pin has an average tensile stress of 1.6Mpa. The test showed that the yield conditions of the pin is satisfactory and will be able to sustain the weight of a 80kg driver who jumps onto the simulator. Hence, it is concluded that no amendments are needed to improve the strength this part.

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Finite Element Analysis (Center plate assembly)
Material(s)
Name Carbon Fibre Mass Density General Ultimate Tensile Strength Young's Modulus Stress Poisson's Ratio Shear Modulus Part Name(s) Centre plate Assembly

1.78 g/cm^3 5650 MPa 125 GPa 0.34 ul 30 GPa

Air bellows suspension to be fitted onto center plate assembly

Circular intrusion fitting for 4 suspension air bellows

The center plate assembly was chosen for the second part of the Finite Element Analysis. This part was designed to join 3 actuators and 4 air suspension bellows together. It is critical this assembly is designed to be able to sustain high impact loads caused by the extension of the actuators and the damping force of the suspensions. Carbon fiber was selected to construct this part due to its high tensile strength and lightweight properties.

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Pressure:1

Load Type Pressure Magnitude 0.520 MPa
Selected Face(s)

Pressure load of 0.52Mpa applied on the highlighted surfaces

The circular surfaces highlighted above were selected for FEM and a uniform pressure load of 0.520Mpa was applied on this surfaces. The pressure load was derived from the weight of the onto the seat.

driver and this includes a safety factor of 2.5 so as to factor in the possibility of the driver jumping

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Fixed Constraint:1
Constraint Type Fixed Constraint
Selected Face(s)

Highlighted surfaces selected as fixed constraints

To simulate the application of pressure load on the cylindrical fittings, the surrounding surfaces of the center plate assembly were selected as fixed constraints.

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Von Mises Stress

Critical zones observed at rims of cylindrical fitting

The diagram above shows the mesh view of the center plate assembly. The maximum tensile stress observed was 1.654Mpa and this was mainly found to be on the rims of the cylindrical intrusion. The center plate assembly is designed to sustain a high impact pressure load of 0.52Mpa on the fittings and no amendments have to be made to increase the strength of the assembly.

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Cost Estimation

Material Cost
Item No 1 2 3 4 Description Qty Price/Unit Total Cost (S$) 2145.25 29.30 49.05 271.50

Carbon Fibre Leather Polyurethane

71.5084kg 7.9192kg 32.698kg

$30/kg $3.70/kg $1.50/kg $90.50/pc

5 6 7 8 9 10

Finsterle Hydraulic 3 pcs Cylinder Type 902 (HZD0OOR-ST) Hydraulic Cylinder 2 pcs Finsterle Type 904 Hinge (Hinge 3’’) 2 pcs Ball Joints Air Suspension 3pcs 4pcs

$67.50/pc $4.85/pc $31.00/pc $54.25/pc $12.00/pc $1.80/pc

135.00 9.70 93.00 217.00 12.00 1.80 $ 2963.60

Seat Adjusting 1pc Mechanism Seat Belt 1pc

Total Material Cost

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Cost Estimating Spreadsheet for Product Cost Center Hours to Comp lete 4 Wage Rate ($) Factory Overhea d Rate ($) 12.00 Direct Labour Hours Direct Labour Cost ($) 78.00 Factory Overhea d Cost ($) 72.00 Material Cost ($) Total Factory Cost ($) 150.00

Manufact uring Engineeri ng CC21

Process 13.00 6 Planning 2 Tooling Design CNC Tapes Machine CNC 24 10.00 8.00 24 Shop Machining CC22 EDM Wire Cut Assembly Assembly 4 9.00 7.00 14 & Test 5 Welding CC23 5 Test QC Inspection 5 12.00 11.00 8 Division Calibratio CC40 n 3 Random Test Total Factory Cost Contingency Allowance 10% of Factory Cost New Total Factory Cost Corporate Labour Cost Based on Direct Labour Cost at 120% Total Cost Profit Margin 10% of Selling Price Selling Price

240.00

192.00

2963.60

3395.6

126.00

98.00

224.00

96.00

88.00

184.00

3953.60 395.36 4348.96 648.00 4996.96 555.22 5552.18

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Conclusion
The driving simulator was successfully designed with the stringent criteria in mind. It was a daunting task but we managed to complete it and meet the objectives that were first highlighted.

We first started our research on existing simulator models and this aided in our brainstorming for our design. Our finalised design was chosen using the Matrix Evaluation table to identify the best design for our project. We aimed to achieve a simple but effective and safe design for the user therefore we paid less emphasis on the looks of our design. Using our knowledge from previously learnt subjects (such as MP2001, MP2011, MP2002 etc) and library/internet materials, we were able to calculate the forces and stresses within our system. The calculated values were then used to search for our components available from the catalogues found from the design lab.

To design a driving simulator from scratch was a big achievement to our group and this was an enjoyable and fruitful experience. This would provide us with a good indication of the possible expectations that are in store for us in our future as engineers.

This was not the only achievement as we learned the importance of working as a team and completing the tasks allocated within the specified time. To achieve a good working environment, we must constantly communicate with each other to ensure that we have everyone’s consensus before carrying out the tasks and also ensuring no one sidetracks or overlap each other’s work.

During our designing phase, we encountered a few problems that was challenging for us. The first obstacle was we couldn’t come up with a good design that is able to do the functions that we require. It was not easy to visualize the whether the structure we design was feasible. Therefore we had to work with the Working Model program to assist us in that area. Unfortunately, since we only had a brief introduction during our second year lab, we were not familiar with its limitations and functions.

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The calculations were also not simple and due to the fact we were using our knowledge based on our previous years of study, we could hardly remember what has to be calculated in our design. When drawing out our final design of our product, we also encountered problems such as different parts unable to fit and drawing out the actuators.

Due to these problems and the limited time constrains, we had limitations to our design. The main one being that we cannot actually test our mechanisms to see as this would require us to build out our wheelchair.

The FEM analysis did however prove to be a useful application as it gave us an idea as to whether our design would be able to withstand the forces it would be subjected to eventually. Fortunately our design had no problems in the analysis. We also had a tough time sourcing for prices of materials that we needed in the manufacturing of our product and this made cost estimation an extremely tedious task. Nonetheless we persevered and finally managed to carve out a rough estimate for the cost of the simulator. It has to be noted however that this cost is only for the seat and mechanical parts of the driving simulator.

All in all, this 13 week design project was a challenging but enriching experience and we are glad we were given the opportunity to do it.

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References http://www.faac.com/literature/military-sims-USMC-ODS_1008.pdf ftp://ftp.forum8.co.jp/forum8lib/pdf/ITS-America2009.pdf http://www.eureka.be/showcasePDF?prjId=1493 http://www.kevaeng.com/pdffiles/SAE%20760810.pdf http://www.gyroxus.com/ http://www.carsim.com/products/carsim/index.php http://www.x-simulator.de/forum/tronic-s-full-motion-car-racing-simulator-using-x-simt471.html http://www.nads-sc.uiowa.edu/ http://www.cxcsimulations.com/products/mps2/features.html http://www.nads-sc.uiowa.edu/ http://www.cxcsimulations.com/products/mps2/features.html http://www.carsim.com/products/carsim/index.php http://www.zentechnologies.com/zen_driving_training_simulator.html http://www.freepatentsonline.com/6283757.pdf http://www.freepatentsonline.com/7033177.pdf http://www.freepatentsonline.com/3967387.pdf http://www.freepatentsonline.com/5511852.pdf Machine Elements in Mechanical Design R L Mott, Prentice - Hall Inc Anthony E. Armenakas. (Seat Design)

Advanced mechanics of materials and applied elasticity Structural mechanics Harlow: Pearson/Prentice Hall, 2003 Magnetic actuators and sensors John R. Brauer.

Kinematics, dynamics, and design of machinery Mechanics of materials Gere, James M

K.J. Waldron, G.L. Kinzel

Design of machinery: an introduction to the synthesis and analysis of mechanisms and machines Norton, Robert L. Electromechanical sensors and actuators Busch-Vishniac, Ilene J.

Mechanical tribology: materials, characterization, and applications Totten, George E. Materials and processes in manufacturing 9th ed. DeGarmo, E. Paul (Ernest Paul)

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