Patent ID: 6651771
Filing Date: 2003-11-25
Classification: B62D

Abstract:
A method of controlling an electric power assist steering system having a steering assembly including a steering wheel connected to a steering column for a vehicle, said method comprising the steps of:providing a first H-infinity controller in a feedback loop and configured according to a first characteristic of the steering system; providing a second H-infinity controller in the feedback loop and configured according to a second characteristic of the steering system; determining a torque signal that is substantially indicative of driver torque applied to the steering wheel; processing the torque signal with the first H-infinity controller and generating a first feedback signal; processing the torque signal with the second H-infinity controller and providing a second feedback signal; measuring a steering angle position of the steering system and generating a steering angle signal indicative thereof; selecting one of the first and second feedback signals as a function of the measured steering angle signal; generating a motor control signal as a function of the selected feedback signal; and applying said motor control signal to an electric motor to generate a controlled amount of steering torque assist.