I did the experiment I wrote about in my last post. It turned out my theory only worked while driving forward. Then FreeRover could do without the steering motor. The speed difference between the two front wheels pulled the steering mechanism exactly in the right angle. But when driving backwards things didn’t turned out as I expected and hoped for. When driving backwards the steering mechanism turned the opposite way.

Why? My theory ist hat the force on each wheel has two effects. First, it makes the car move. This is shown as a green vector in the image below. As the force on the right wheel is bigger than the force on the left wheel the right wheel goes faster and the car makes a turn. This is the effect I was hoping for. Second, it makes the wheel try to rotate along it’s own steering axle (the red dot). The direction of this effect is shown by the purple vector. This effect also makes the steering mechanism rotate. As the force of the right wheel is bigger this effec

When driving forward these effects work in the same direction. When driving backward the second force workes in the opposite direction. As it easier to turn the wheel around its steering point than it is to move the car the second effect wins. As a result the steering mechanism steers the wrong way.

Is there a way to neutralise the second force? In theory there is one. If the steering axle of the wheel goes right through its centre (the red dot being at the centre of the wheel) then there is no second effect. But I think this is impossible to make.