CONTROLLER FOR ELECTRIC POWER STEERING DEVICE

摘要

A controller for an electric power steering device effectively reduces torque steer caused by a brake-drive power difference between left and right wheels and also effectively reduces behavior deterioration of a vehicle. The reduction is made by controlling steering assist torque. Basic assist torque (Tab) is calculated (S20-40) based on steering torque (Ts) and a vehicle speed (V), torque steer-reducing torque (Tts) promoting steering in the direction to cancel torque steer caused by a brake-drive power difference between the left and right wheels is calculated (S50), and behavior deterioration-reducing torque (Tvs) promoting steering in the direction to reduce an over steer state or an under steer state of the vehicle is calculated (S80). When the magnitude of the torque steer-reducing torque (Tts) is less than a standard value (Ttso), a target assist torque (Ta) is calculated based on the sum of Tab, Tts, and Tvs, and when the magnitude of the torque steer-reducing torque (Tts) is equal to or greater than the standard value (Ttso), the target assist torque (Ta) is calculated based on the sum of Tab and Tts.