PURPOSE: To provide an electronically controlled power steering gear capable of attaining the optimum steering characteristic in response to a vehicle traveling condition.
CONSTITUTION: This is an electronically controlled power steering gear which electronically controls the steering assist quantity of a vehicle steering mechanism. It is provided with a vehicle speed sensor 41, which detects a vehicle traveling speed V, a steering angle sensor 52, which detects the vehicle steering angle ha, and a pressure sensor 53, which detects the power steering pressure Ps, and a lateral acceleration calculation unit 54 finds a lateral acceleration Gy from the vehicle speed V and a steering angle ha while a friction coefficient calculation unit 55 finds a road surface 'μ' from the vehicle speed V, the steering angle ha and the power steering pressure Ps and, with this vehicle speed V, the lateral acceleration Gy and the road surface 'μ' as input conditions (membership functions), a fuzzy calculation unit 56 sets a target assist quantity based on a fuzzy rule.
HARAYOSHI MITSUHIKO
TANAKA TADAO
