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AssigneeTRW LucasVarity Electric Steering Ltd.
InventorsRussell Wilson-Jones, Anthony Walter Burton, Andrew James Stephen Williams, John Michael Ironside
Estimating the term…
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.
A method of calculating the position at a moment in time of a rotor in a motor which is connected to an output shaft through an intermediate means for transmitting torque from the rotor to said output shaft, said intermediate means comprising a gear box, said rotor and said output shaft having gears in meshing engagement with each other in said gear box, said gear of said rotor driving said gear of said output shaft to provide torque assistance, said method comprising the steps of:
Dependencies are inferred from the claim text.