How can I calculate the torque that is needed to keep the steering wheel at the same steering angle during turning at given speed?
A car with Ackermann steering geometry weights 1000 kg. It is going though a curve - the steering angle is constant 5 degrees. Car's velocity is 10 m/s. Steering ratio is 15:1 (15 degrees on steering wheel means 1 degree of actual steering angle). What torque do I need to apply to the steering wheel to hold those constant 5 degrees on steering?
I need to know the torque because I want to robotize steering of a passenger vehicle and since torque will be applied by human driver's hands I need to supply such torque by an electric motor (probably a stepper with a required "holding torque" specification).
I know the torque could probably somehow measured on the steering wheel (with a torque wrench) with power steering off but it would be nice to be able to at least roughly calculate it. I actually need to know all torques for all car's normal operation scenarios (turning when standing still, when turning in speed, when going through a curve etc.).
I may have forgotten few parameters for the example. Say car's width is 1.5m (tire to tire) and distance between front and read axle is 2m.