I'm trying to develop a car driving game using a steering wheel.I am recieving two signals indicating the position and torque from the steering wheel.I want to know how the power steering feature depends on these two signals.what impact the torque signal has on the wheel's turning control.Does the torque decide the angle of turning or the speed of turning.what does the torque signal indicate. I would also like to know how the power steering feature depends on the vehicle speed.Does the sensitivity of the power steering change with vehicle speed .If so how ?

I assume by torque you mean the 2 back wheel's torque (or 4wd or whatever) as given by the gas pedal and by position you mean the angle of the steering wheel.

It's a matter of friction really, and if you want a realistic power steer you need to look into dynamic and static friction. Power steer is what happens when your wheels start going in dynamic friction.

However, if you are aiming for arcadey power-steering, then the speed of the turn and the speed of the car decide how hard the power-steer is, and you can regain control only by turning the steering wheel such that the car's front wheels line up with the direction the car is moving. This makes turn sharply into the direction of the movement and you can easily get into another powersteer in the opposite direction if you don't compensate right away.

Hope that answers your question.