| 摘要 |
<p>A method of calculating the position of the rotor of a motor (1) in for example an electrical power assisted steering assembly is disclosed. The method comprises the steps of measuring the output shaft (2) (i.e. steering column) position, and scaling the measured value to produce an estimated motor rotor position value. This estimated value will be relative to an arbitrary datum point, and so the method further includes steps of adding an offset value derived from low resolution measurements of rotor position obtained using Hall effect sensors provided on the motor. Offsets for compensating for backlash and (in a second embodiment) compliance can also be included. Thus, the method allows high resolution information from an output shaft sensor (e.g. a torque sensor with a position dependent output) to be combined with the low resolution output from the Hall effect sensors to produce a high resolution rotor position signal. A correction is also made to allow for 'staleness' in the Hall effect sensor output when calculating the offsets by monitoring rotor speed.</p> |
