Robust automatic steering control for look-down reference systems with front and rear sensors

This paper describes a robust control design for automatic steering of passenger cars. Previous studies [l-31 showed that' reliable automatic driving at highway speed may not be achieved under pract,ical conditions with look-down reference systems which use only one sensor at the front bumper to measure the 1at)eral displacement of the vehicle from the lane reference. An additional lateral displacement. sensor is added here at the tail bumper to solve the automatic steering control problem. The control design is performed stepwise: First, an initial controller is determined using the parameter space approach in an invariance plane. This controller is then refined to accommodate pract*ical constraints and finally optimized using the multi-objective optimization program MOPS. The performance and robustness of the final controller was verified experimentally at California PATH in a series of test runs.