An encoder comprises first and second sensors which reads first and second tracks, the first and second sensors being arranged in a radial direction to face each other, and a processor which generates a first position signal based on first and second periodic signals based on a signal obtained by reading the first and second tracks by the first sensor, and generates a second position signal based on third and fourth periodic signals based on a signal obtained by reading the first and second tracks by the second sensor, wherein the processor generates an absolute position signal indicating an absolute position of at least one of the scale, the first sensor, or the second sensor based on the first and second position signals and the first and third periodic signals.

A rotation angle detection device includes a correction-object driven gear that is a driven gear meshing with a main driving gear, a first sensor that is configured to generate an electrical signal based on rotation of the correction-object driven gear, and an electronic control unit that computes a driven-side rotation angle based on the electrical signal. The electronic control unit is configured to store a correction angle used to correct the driven-side rotation angle when computing the driven-side rotation angle. The correction angle is a predetermined deviation in a predetermined angle domain obtained as an average value in which deviations of the number equal to the integer and corresponding to a same relative rotation angle is averaged, so as to be deviation in an angle domain of 0 to 360 degrees.

A method of correcting a position reading from a position sensing arrangement. The position sensing arrangement is suitable for sensing the position of a revolute joint of an articulated structure, and comprises a disc having a magnetic ring with magnetic pole pairs and a magnetic sensor assembly comprising a magnetic sensor array for detecting the magnetic pole pairs of the magnetic ring. The method comprises: for each pole pair of the magnetic ring, taking a calibration pole pair position reading with the magnetic sensor array, and generating a pole pair correcting function by comparing the calibration pole pair position reading with a model pole pair position reading; averaging the pole pair correcting functions of the pole pairs of the magnetic ring to generate an average pole pair correcting function for the magnetic ring; taking a position reading with the magnetic sensor array, the position reading comprising a plurality of pole pair position readings; and generating a corrected position reading by deducting the average pole pair correcting function from each pole pair position reading.

A magnetic sensor assembly for detecting angular positions of a camera module, includes: a housing; a rotation member configured to rotate together with the camera module; a magnet member that is configured to rotate with the rotation member on at least a portion of the housing, the magnet member includes a first multi-pole magnetized magnet that has a first number of pole pairs alternately disposed along a first circumference on the rotation member, and further includes a second multi-pole magnetized magnet that has a second number of pole pairs alternately disposed along a second circumference on the rotation member; a hall sensor configured to detect a change of magnetic field generated from the first multi-pole magnetized magnet and the second multi-pole magnetized magnet; and a processor configured to estimate an initial position of the rotation member and a rotational angle from the initial position using the detected magnetic field.

In some embodiments, a method can include receiving, by an angle sensor, a first periodic angle signal indicative of an angle of a first magnetic field associated with a first track of a target; receiving, by the angle sensor, a second periodic angle signal indicative of an angle of a second magnetic field associated with a second track of the target; generating an uncorrected absolute angle signal indicative of an absolute angle of the target based on the first and second periodic angle signals; determining an estimated error associated with the uncorrected absolute angle signal based on the first periodic angle signal and the second periodic signal; subtracting the estimated error from the uncorrected absolute angle to generate a corrected absolute angle signal; and providing the corrected absolute angle signal as output of the angle sensor.

The invention relates to a method for identifying a fault (96) in an angle sensor (24) which is designed to determine the angular position (18) of a shaft (14) based on an angular position difference (56) between a first output gear (32), which is driven by the shaft (14), and a second output gear (34), which is driven by the shaft (14), the output gears differing in respect of their diameter (34, 36), said method comprising: determining a reference value (18, 52) for the angular position (18) of the shaft (14) based on the angular position (42) of the first output gear (32), determining a comparison value (18′, 52′) for the angular position (18) of the shaft (14) based on the angular position (46) of the second output gear (34) and a transmission ratio (90) between the first output gear (32) and the second output gear (34), and identifying the fault (96) when a comparison (93, 94) of the reference value (18, 52) and the comparison value (18′, 52′) satisfies a predetermined condition (95).

The present invention provides an apparatus for sensing rotor location, the apparatus comprising: a central shaft; a magnet coupled to the central shaft; a sensor portion is disposed correspond to the magnet; wherein the sensor portion comprising a substrate, a first group including a first Hall sensor and a third Hall sensor disposed on the substrate, and a second group including a second Hall sensor and a fourth Hall sensor, the first Hall sensor and the third Hall sensor are arranged to overlap in a radial direction about the central shaft and the second Hall sensor and the fourth Hall sensor are arranged to overlap in a radial direction about the central shaft.

A method of correcting a position reading from a position sensing arrangement. The position sensing arrangement is suitable for sensing the position of a revolute joint of an articulated structure, and comprises a disc having a magnetic ring with magnetic pole pairs and a magnetic sensor assembly comprising a magnetic sensor array for detecting the magnetic pole pairs of the magnetic ring. The method comprises: for each pole pair of the magnetic ring, taking a calibration pole pair position reading with the magnetic sensor array, and generating a pole pair correcting function by comparing the calibration pole pair position reading with a model pole pair position reading; averaging the pole pair correcting functions of the pole pairs of the magnetic ring to generate an average pole pair correcting function for the magnetic ring; taking a position reading with the magnetic sensor array, the position reading comprising a plurality of pole pair position readings; and generating a corrected position reading by deducting the average pole pair correcting function from each pole pair position reading.

There is provided a displacement measuring device that minimize unnecessary power consumption and improves power efficiency.

A displacement measuring device includes a main scale and a detection head that is provided in such a manner as to be relatively displaceable to the main scale and outputs a periodic signal having a phase to be changed according to relative displacement to the main scale.

The detection head outputs, as the periodic signal, a coarse scale signal having a coarse period and a fine scale signal having a fine period. A coarse phase detector calculates, from two pieces of phase information acquired from the coarse scale signal, the average phase of the coarse scale signal. A fine phase detector calculates, from four pieces of phase information acquired from the fine scale signal, the average phase of the fine scale signal. The coarse phase detector calculates the average phase of the coarse scale signal from the two pieces of phase information and, then, stops operating without the completion of the operation of the fine phase detector.

There is provided a position detection device to suppress an influence of a signal distortion due to a processing error, an assembly error of a sensor, or the like. The position detection device includes: a waveform correction unit that corrects waveforms of a first signal and a second signal, the first signal being detected from a first track provided on a moving body and having a scale of predetermined cycles, and the second signal being detected from a second track provided on the moving body and having a scale of cycles less than the predetermined cycles; and a position calculation unit that calculates a position of the moving body on the basis of the corrected first signal and second signal.