Abstract: An apparatus for detecting an angle of rotation includes a rotatable member situated in a first plane and rotatable to be switched between a reference state and rotated states, the rotatable member being unrotated in the reference state, magnet pieces arranged on the rotatable member along a circumferential direction of the rotatable member at intervals of an angle, the magnet pieces moving along a first locus as the rotatable member is rotated, a Hall sensor lying in a second plane spaced a distance apart from the first plane and positioned along a second locus, said second locus being a projection of the first locus into the second plane, and the Hall sensor providing an output varying as the rotatable member is rotated, and a processor configured to detect an angle of rotation of the rotatable member in response to the output from the Hall sensor.

Abstract: A method of correcting an output value of a geomagnetic sensor that recursively calculates a state estimate, an estimate gain vector, and an estimate error co-variance based on the output value of the geomagnetic sensor that is acquired sequentially and corrects the output value of the geomagnetic sensor based on the value includes acquiring a kth output value of the geomagnetic sensor, calculating a kth estimate gain vector based on a k?1th estimate error co-variance and the kth output value, calculating a kth state estimate based on the calculated kth estimate gain vector and the kth output value and a k?1th state estimate, calculating the kth estimate error co-variance using the kth estimate gain vector and a k?1th estimate error co-variance, and correcting the output value of the geomagnetic sensor based on the kth state estimate, wherein k is a natural number larger than 1.

Abstract: An apparatus for detecting an angle of rotation includes a rotatable member situated in a first plane and rotatable to be switched between a reference state and rotated states, the rotatable member being unrotated in the reference state, magnet pieces arranged on the rotatable member along a circumferential direction of the rotatable member at intervals of an angle, the magnet pieces moving along a first locus as the rotatable member is rotated, a Hall sensor lying in a second plane spaced a distance apart from the first plane and positioned along a second locus, said second locus being a projection of the first locus into the second plane, and the Hall sensor providing an output varying as the rotatable member is rotated, and a processor configured to detect an angle of rotation of the rotatable member in response to the output from the Hall sensor.

Abstract: A method for calculating an angle of inclination of a magnetic field in a sensor coordination system includes measuring a magnetic field vector using a magnetometer, measuring an acceleration vector using an accelerometer, determining whether the sensor coordination system is in a moving state or a stationary state using the acceleration vector, and calculating the inclination angle of the magnetic field using the magnetic field vector and the acceleration vector, in response to the determining indicating the stationary state.

Abstract: A method of correcting an output value of a geomagnetic sensor that recursively calculates a state estimate, an estimate gain vector, and an estimate error co-variance based on the output value of the geomagnetic sensor that is acquired sequentially and corrects the output value of the geomagnetic sensor based on the value includes acquiring a kth output value of the geomagnetic sensor, calculating a kth estimate gain vector based on a k?1th estimate error co-variance and the kth output value, calculating a kth state estimate based on the calculated kth estimate gain vector and the kth output value and a k?1th state estimate, calculating the kth estimate error co-variance using the kth estimate gain vector and a k?1th estimate error co-variance, and correcting the output value of the geomagnetic sensor based on the kth state estimate, wherein k is a natural number larger than 1.