Patent ID: 6791219
Filing Date: 2004-09-14
Classification: H02K

Abstract:
A contactless electromechanical actuator comprising:a) an electric brushless motor with a rotatable motor shaft; b) a rotable output shaft; c) first and second magnets connected for rotation with the motor shaft and output shaft, respectively; d) a geartrain (i) coupled for torque amplification from the motor shaft to the output shaft, and (ii) having a step-down ratio coupling the first magnet to the second magnet; e) magnetic field sensors (i) positioned for sensing the magnetic fields of the magnets, and (ii) providing output signals indicative of the magnetic fields sensed; f) a processor module receiving said output signals, and operative to (i) calculate the rotational angles of the magnets therefrom, and (ii) compute the angular position of the output shaft as a function of said rotational angles and the step-down ratio, wherein the rotational angle of the second magnet provides a coarse indication of the angular position of the output shaft, and the rotational angle of the first magnet divided by the gear ratio provides a refined indication of the angular position of the output shaft; and g) a motor control module responsive to the computed angular position of the output shaft to commutate the motor and control the angular position of the output shaft.