Abnormality detector for motor assisted steering apparatus

摘要

A motor assisted steering apparatus has its wheels oriented with respect to a car body in response to a combination of a steering force which is supplied by a manual operation and a driving force developed by an electric motor which is energized in accordance with the steering force. The existence of an abnormality is annunciated when the relationship between the manual steering force and the operational condition of the motor deviates from a predetermined relationship. For example, the existence of an abnormality is annunciated when the motor is energized even though a steering wheel is not substantially operated, when the motor is energized for rotation in a direction which causes the wheels to be turned to the left even though the steering wheel is turned to the right or vice versa. The existence of such abnormality is detected by monitoring the manual steering force and the operational condition of the motor, without requiring any addition of sensors which have no direct connection with the operation of the apparatus.