An electric power assisted steering system includes an upper column shaft connected to a steering wheel, a lower column shaft connected to road wheels, a torsion bar interconnecting the upper column shaft and the lower column shaft, and a processor that produces a torque signal indicative of torsion bar torque. An electric motor is connected to the lower column shaft, and a motor position sensor provides a motor position signal dependent on the angular position of the motor rotor that repeats after the motor rotates through an angular range. The processor determines a base motor position at start up by comparing the motor position signal with a signal from a sensor associated with the upper column shaft to determine three candidates and, during subsequent unpowered motion of the steering system rules out two candidates until only one plausible candidate for the base motor position remains.
Electric power assisted steering system
2019-10-15
Patent
Electronic Resource
English