Subject:
Steering error:
The Ackermann principle ensures that when steering, one wheel turns further than the other wheel. For more information, see the pages Ackermann principle and toe-out on turns.
When reading through the referenced pages, it becomes clear that the left front wheel and the right front wheel each have a different steering angle. So a steering error almost always occurs. The steering error means that the two steered angles are not equal to each other and therefore one wheel has more slip than the other. There is only one situation in which no steering error occurs. This is when steering with a small steering angle, up to approx. 10 degrees (see image).
On the X-axis in the image you can see the steered angle, and on the Y-axis the steering error. At the left corner (so at X = 0) the car is driving straight ahead. The line under “Small steering angle” runs positively along the X-axis. This line indicates that the steering error up to a maximum of 10 degrees of steering is 0. So with a maximum of 10 degrees of steering there is no steering error. No slip then occurs in the front wheels. This is intentionally designed this way, because when driving at high speeds (e.g. on the motorway) the steering angle is often around 10 degrees. At high speed, at a maximum of 10 degrees of steering, the front wheels have no slip, and therefore maximum grip. When steering further, the steering error becomes much greater. In principle this is not a problem, because this usually happens in the city, at lower speeds. At lower speeds the steering error has less influence than at higher speed.
