Vehicle electric power assist steering system and method using velocity based torque estimation

摘要

A steering system (10) and method (70) for controlling the steering of a vehicle having a steering wheel (12), a steering column (14)connected to the steering wheel (12), and an electric motor (20) operatively engaged with the steering column (14) for supplying torque assist. A velocity detector is employed for detecting an angular velocity {dot over (theta)}m of the electric motor (20). The system has a torque estimator (40) for determining an estimated torque signal Tdest as a function of the detected motor velocity {dot over (theta)}m, and a motor controller (30) for generating a motor control signal (U) as a function of the estimated torque. Accordingly, the present invention reduces the complexity and cost of the electric power assist steering system by eliminating the need for a conventional pinion torque sensor, without sacrificing vehicle steering performance.