Control system for electrical power steering uses speed, position and torque measurements on wheel to determine applied assistance torque

摘要

The electrical steering power assistance system uses a kinetic term, based on steering wheel speed information, and a potential term, Ep, based on steering wheel torque and position information. A following torque (Cs) and a damping torque (Cf) are determined, to reduce the oscillating movement after releasing the steering wheel. The system for providing electrical power assistance for vehicle steering includes determining the torque (C) exerted by the driver on the steering wheel (3), and the angular position (theta) and the speed (omega) of the steering wheel. A kinetic term, Ec, is determined as a function of the steering wheel speed information, and a potential term, Ep, is determined as a function of the torque and position information, this potential term being null when the torque on the steering wheel is null. A weighting coefficient Kp = Ec / (Ec + Ep) is determined. At each instant a following torque (Cs) and a damping torque (Cf) are determined, the latter being to reduce the pendular movement after releasing the steering wheel. The damping torque (Cf) is dependent on the speed of the steering wheel (omega). A power assistance torque reference (Ca) is applied to an electric motor, in order to deliver an assisting torque, the reference being the difference Cs - Kp.Cf.