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I am hoping somebody can help me as I'm going round in circles trying to develop a driving simulator for my games programming dissertation.

I am modeling a car which is rear-wheel driven. Each wheel is modeled individually and determines the force it applies to the chassis.

I use the engine RPM to obtain a maximum engine torque value which I then multiply by the gear ratio and throttle position (between 0 and 1) to come up with the overall engine torque which I supply to each of my 2 drive wheels.

Each wheel then divides the engine torque by its radius to come up with the traction force. Rolling resistance is then subtracted from this and the result is multiplied by the direction vector and returned.

The force returned from each wheel is then summed up and aerodynamic drag is subtracted. The acceleration (force / inertia at the wheels) is calculated and then integrated for velocity.

My questions are:

1) To calculate the engine RPM and slip ratio (for braking), I need to keep track of the angular velocity of the drive wheels. However, when I attempt to integrate angular acceleration (total torque / inertia of wheel) to get this then it grows to big very quickly. What limits angular velocity, does the vehicle drag affect the wheels velocity somehow?

2) The inertia of the car wheel is: 0.5 * mass * radius^2. Is mass just the mass of the wheel or is it the mass distribution of the car on the wheel?

3) Is the engine torque applied to both wheels, or is it divided by the wheels?

Any help would be greatly appreciated. Thanks in advance

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# Homework Help: Driving simulator questions

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