Vehicle electric power assist steering system and method using H-infinity control

摘要

A steering system (10) and method (70) for controlling the steering of a vehicle having a steering assembly including a steering wheel (12), a steering column (14) connected to said steering wheel (12), and an electric motor (20) operatively engaged with the steering assembly for supplying torque assist. A steering angle sensor (32) is employed for sensing an angular position thetac of the steering column (14). The system has a torque estimator (40) for determining an estimated torque signal (Tdest), and an H-infinity controller (64) coupled in a feedback path (44) for generating a feedback signal which is combined with a feedforward signal to generate a motor control signal (U) as a function of the estimated torque. Accordingly, the present invention provides a stable and robust control system, without sacrificing steering performance and desired steering feel.