A rotation sensing apparatus includes a detected part, a sensor unit, and a rotation information calculation circuit. The sensor unit includes a first sensor disposed opposite to a first pattern portion, a second sensor disposed opposite to a second pattern portion, a third sensor disposed to be spaced apart from the first sensor in the rotation direction and opposite to the first pattern portion, and a fourth sensor disposed to be spaced apart from the second sensor in the rotation direction and opposite to the second pattern portion. The rotation information calculation circuit is configured to sense the rotation direction, in response to a differential signal, generated based on the first oscillation signal and the second oscillation signal, and an oscillation signal corresponding to maximum and minimum frequencies, from among the first oscillation signal, the second oscillation signal, the third oscillation signal, and the fourth oscillation signal.

A manufacturing error and a mounting error of a position sensor used for detection of a rotation angle of a rotary shaft are appropriately calibrated to improve detection accuracy of the rotation angle. Therefore, an angle detection device 1 includes at least a first crank angle sensor 1211 and a second crank angle sensor 1212 provided to be capable of detecting a rotation angle of a rotary shaft of a crankshaft 123, and includes: a gain corrector 4 that corrects at least any one of gains G1 and G2 of the first crank angle sensor 1211 and the second crank angle sensor 1212 such that an amplitude ya of a differential signal S41b of the first crank angle sensor 1211 is equal to an amplitude yb of a differential signal S42b of the second crank angle sensor 1212; and a phase corrector 5 that corrects at least any one of a phase αa of the differential signal S41b and a phase αb of the differential signal S42b such that the phase αa of the differential signal S41b is equal to the phase αb of the differential signal S42b.

A manufacturing error and a mounting error of a position sensor used for detection of a rotation angle of a rotary shaft are appropriately calibrated to improve detection accuracy of the rotation angle. Therefore, an angle detection device 1 includes at least a first crank angle sensor 1211 and a second crank angle sensor 1212 provided to be capable of detecting a rotation angle of a rotary shaft of a crankshaft 123, and includes: a gain corrector 4 that corrects at least any one of gains G1 and G2 of the first crank angle sensor 1211 and the second crank angle sensor 1212 such that an amplitude ya of a differential signal S41b of the first crank angle sensor 1211 is equal to an amplitude yb of a differential signal S42b of the second crank angle sensor 1212; and a phase corrector 5 that corrects at least any one of a phase αa of the differential signal S41b and a phase αb of the differential signal S42b such that the phase αa of the differential signal S41b is equal to the phase αb of the differential signal S42b.

A system may include a resistive-inductive-capacitive sensor, a driver configured to drive the resistive-inductive-capacitive sensor at a driving frequency, and a measurement circuit communicatively coupled to the resistive-inductive-capacitive sensor and configured to determine a measured change in a resonant frequency of the resistive-inductive-capacitive sensor and based on the measured change, modify the driving frequency.

A system may include a resistive-inductive-capacitive sensor, a driver configured to drive the resistive-inductive-capacitive sensor at a driving frequency, and a measurement circuit communicatively coupled to the resistive-inductive-capacitive sensor and configured to determine a measured change in a resonant frequency of the resistive-inductive-capacitive sensor and based on the measured change, modify the driving frequency.

A system and method of detecting changes in an environment of an open circuit resonator configured to generate a signal when wirelessly powered by an external oscillating magnetic field, wherein the signal varies as a function of one or more environmental factors associated with the environment about the open circuit resonator. A monitoring device receives the signal from the open circuit resonator, captures data representative of the signal, compares the captured data to data previously received from the sensor to determine changes in the data, and estimates, based on the changes in the data, changes in one or more of the environmental factors.

An apparatus with rotor input detection includes: a first reactance element disposed at a rotor configured such that at least a part of the rotor rotates around a rotation axis, and disposed at the rotor such that reactance of the first reactance element varies depending on relative rotation between a first portion of the rotor and a second portion of the rotor; and a second reactance element disposed at the rotor such that reactance of the second reactance element varies depending on a contact or a force applied to a side surface of the rotor. The first and second reactance elements are configured to detect inputs of different areas of the rotor.

A position sensing device for measuring a position, comprises a position sensing device for measuring a position; a plurality of sensors arranged to produce sense signals each being a function of an input phase representative of a position to be measured; a combiner circuit arranged to generate an error signal by combining the sense signals according to an array of weight factors; a processing block including a loop filter to filter the error signal and arranged to output a phase value representative of the position; and a feedback loop comprising a feedback signal unit arranged for receiving the output phase value and for adjusting based on the received output phase value of the array of weight factors.

A position sensing device for measuring a position, comprises a position sensing device for measuring a position; a plurality of sensors arranged to produce sense signals each being a function of an input phase representative of a position to be measured; a combiner circuit arranged to generate an error signal by combining the sense signals according to an array of weight factors; a processing block including a loop filter to filter the error signal and arranged to output a phase value representative of the position; and a feedback loop comprising a feedback signal unit arranged for receiving the output phase value and for adjusting based on the received output phase value of the array of weight factors.

A method for identifying a position of a multi-phase brushless motor includes applying a plurality of detection voltage pulses to the motor, each detection voltage pulse corresponding to a respective driving phase of the motor, measuring a time period associated with a current reaching a predetermined current limit for each applied detection voltage pulse, and identifying a driving phase associated with a shortest time period for the current to reach the predetermined current limit.