Patent ID: 6896094
Filing Date: 2005-05-24
Classification: B62D

Abstract:
1. An electric power assist steering system for a vehicle, said steering system comprising: a steering assembly including a steering wheel connected to a steering column; an electric motor operatively engaged with said steering assembly for supplying steering torque assist; a torque detector determining a torque signal that is substantially indicative of driver torque applied to the steering assembly; a steering column sensor for sensing a steering angle of the steering column and generating a signal indicative thereof; a first H-infinity controller coupled in a feedback control loop for generating a first feedback control signal as a function of said torque signal and a first characteristic of the steering system; a second H-infinity controller coupled in the feedback control loop for generating a second feedback control signal as a function of said torque signal and a second characteristic of the steering system; and a switch for selecting one of the first and second feedback control signals as a function of the sensed steering angle.