The Ackerman vehicle is a single-steer wheel vehicle (steer) with one (or a pair) of steering wheels that can only steer but not provide power, and one (or a pair) of drive wheels that can only provide power but cannot steer. If there is a pair of steering wheels, they must use a trapezoidal steering mechanism, which can be equivalent to a single steering wheel. If there is a pair of drive wheels, they must be connected through a differential (or have an equivalent mechanism) and be equivalent to a single drive wheel. The origin of the robot base coordinate system of the rear-wheel driven single-steer vehicle type is located on the (equivalent) drive wheel, and the x-axis of the robot base coordinate system is perpendicular to the drive wheel axle, as shown in the figure below:

At the same time, it is required that the (equivalent) steering wheel must not fall on the wheel axle of the (equivalent) drive wheel, that is, b≠0.