| 摘要 |
<p>An electric power assisted steering system comprising a torque sensor assembly comprising an input shaft,an output shaft,a torsion bar that interconnects the input shaft and the output shaft, and a processing means which produces a torque signal indicative of the torque carried by the torsion bar, an electric motor that is connected to the output shaft,and a motor position sensor that provides a motor position signal dependent on the angular position of the motor rotor that repeats each time the motor has rotated through a known angular range. The apparatus further including processing means that generates an absolute output shaft position signal from the motor position signal by adding to the output of the motor position sensor a first term indicative of the fixed offset between the motor position sensor zero position and the zero position of the input shaft and a second term indicative of the number of turns of the motor rotor away from the zero position of the input shaft. The processing means determines the base motor position value at start up of the system by comparing the motor position signal from the position sensor with the signal from the sensor associated with the sensing means of the upper shaft to determine three candidates and during subsequent unpowered motion of the steering system rules out candidates until only one remains plausible candidate.</p> |
