| 摘要 |
An electric power assisted steering apparatus comprises an electric motor (1) operatively connected to the steering mechanism; a torque signal generator (6) adapted to produce a torque signal (Tcol) indicative of the torque carried by a portion of the steering mechanism, a column position signal generator (10) for producing a column position signal (Ncol) indicative of the angular position of the steering wheel or steering column (5) and a signal processing unit (7) adapted to receive the signals produced by the sensing means and to produce therefrom a torque demand signal representative of a torque to be applied to the steering mechanism by the motor. The signal processing unit (8) includes: • a first signal processing circuit (12) which outputs an assistance torque signal, • a second signal processing circuit (13) which in use applies an additional offset torque to at least one of the input signal and the output signal of the first processing circuit in the event that the steering wheel of the vehicle is moving back towards a centre position following a period of movement of the steering wheel away from the centre position, the additional offset torque being reduced or not being applied in the event that the steering wheel moves away from the centre position; and • torque demand signal generating circuit adapted to produce the torque demand signal (8) from the assistance torque signal. |
