System and method for converting output of sensors to absolute angular position of a rotating member

摘要

A sensor system determines an absolute angular position of a to-be-sensed rotating member. The sensor system may include a rotor with a first magnet coupled to the rotor and a shaft having threads thereon. The sensor system may further include a sleeve with a second magnet and threads complementary to the threads of a shaft. The sleeve may be configured to travel axially along the shaft as a function of rotation of the rotor. The sensor system may also include a first transducer configured to sense orientation of the first magnet and at least one second transducer configured to sense a location of the second magnet along the shaft. Through use of the sensor system, an absolute number of turns and, consequently absolute angular position, of the rotating member can be determined.

主权项

1. A method of determining an absolute angular position of a rotating member, the method comprising:
selecting at least one sensor of a plurality of sensors to serve as an at least one selected sensor, the selecting being based on outputs of the plurality of sensors; and calculating the absolute angular position of the rotating member based on an output of the at least one selected sensor and an angular position of the rotating member, by: calculating a first difference of a first output of a first sensor among the plurality of sensors of the at least one selected sensor and a second output of a second sensor among the plurality of sensors of the at least one selected sensor; calculating a cutoff value based on a second difference of the first difference and a ratio of the angular position of the rotating member; calculating a turn number based on the cutoff value, an identifier of the at least one selected sensor, and the angular position of the rotating member; and returning an output value based on an output difference of a multiple of the turn number from the angular position of the rotating member.