On the optimal design of a vehicle lateral controller

An optimization approach is used to design a velocity-adaptive, lateral controller to meet requirements pertaining to lateral-position tracking accuracy, robustness, and ride comfort. The resulting nonlinear controller required full-state feedback and thus an observer, which was nonlinear with velocity, was included. The observer/controller compensator was implemented using a 16-bit microcomputer and evaluated in a laboratory study wherein vehicle lateral dynamics were simulated on an analog computer. Excellent lateral control -- close tracking |lateral-position error| < 0.024 m in curve tracking), a good insensitivity to disturbance forces and probable ride comfort -- resulted. The selected control algorithm was realized using some 5% of the available computation time. Thus the microcomputer could also be employed for other control functions and vital-function monitoring.