Approximating Ackermann Steering Geometry with a Trapezoidal Linkage

Ackermann geometry is a theoretical model for a steering system that has zero slip. It is achieved when all four wheels of a car are perpendicular to the same turning circle center. This Demonstration uses a common approximation for Ackermann geometry: a simple three-bar linkage. The linkage is arranged in a trapezoid so that the wheel on the inside of a turn will angle more than the outside wheel.

The slider "toe" angles both the front wheels inward to allow the system to be optimized to Ackermann geometry for any turning radius.