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 magnetic position detection device includes two magnetic scales 1a, 1b on which N and S magnetic poles are disposed alternately, magnetism sensing element groups 2a, 2b for measuring variation in magnetic fields formed respectively by the magnetic scales 1a, 1b, and a position calculation device 3 for calculating absolute positions of magnetism sensing elements 21 on the magnetic scales 1a, 1b from output values output by the magnetism sensing elements 21, wherein a difference between the respective numbers of magnetic poles on the magnetic scales 1a, 1b is 2, and the magnetism sensing elements 21 are disposed such that arrangement intervals between the magnetism sensing elements 21 of the respective magnetism sensing element groups 2a, 2b each take a value obtained by dividing a length of one magnetic pole equally by the number of magnetism sensing elements 21.

A magnetism detecting element detects a leakage magnetism from a scale, on which a magnetic signal with a constant period is recorded, and a relative position between the scale and the magnetism detecting element is detected. The magnetism detecting elements are arranged, along a detection direction of the magnetic signal relative to the scale, in a pattern with a pitch of 1/2n (n is a prime number of 3 or more) of a wavelength λ′ of a signal output by the element. Furthermore, as the pattern for cancelling m odd-order harmonics, the m-th power of 2 magnetism detecting elements are arranged within a range in which a pitch distance L of the magnetism detecting element farthest in the detection direction is expressed by L=(λ′/2)×(1/3+1/5+1/7+ . . . 1/(2m+1)).

An electronic absolute position encoder includes a scale extending along a measuring axis direction (MA) and including a signal modulating scale pattern defining a corresponding absolute range R along MA, a detector including sensing elements arranged along MA and configured to provide detector signals which respond to the signal modulating scale pattern, and a signal processing configuration that determines an absolute position of the detector along the scale based on the detector signals. The signal modulating scale pattern includes a coarse periodic pattern component as a function of position along the scale having a spatial wavelength λ.sub.C, wherein n*λ.sub.C=R and n is an integer, and a fine periodic pattern component as a function of position along the scale having a spatial wavelength λ.sub.F, wherein (mn+1)*λ.sub.F=R and m is an integer that is at least two. The wavelengths λ.sub.C and λ.sub.C may be widely separated.

Aspects of this disclosure relate to a magnetic sensor system for measuring any desired combination of measuring torque, rotation angle, and turn count of a shaft. The shaft may include two portions connected by a torsion element. The system can measure rotation angle using a magnetic target coupled to the shaft that produces a magnetic field that varies as a function of rotation angle. The system can measure torque applied to the shaft by measuring the difference in rotation angles between the two portions of the shaft and factoring in a torsion coefficient. The system can track a turn count of the shaft using a multi-turn sensor. The magnetic sensor system may be part of an electric power assisted steering (EPAS) system.

Disclosed is a method for counting events occurring during a period T carried out by a mechanical counter including two toothed wheels with the same pitch, the occurrence of an event causing the rotation of each wheel by an angle corresponding to the pitch of the teeth thereof, the method including: counting or calculating, for each wheel at the end of T, the difference in the number of teeth between the initial and final position thereof, the step being at least partially carried out either by an optical unit, requiring the presence on each wheel of at least one marker, or by a unit for measuring the angular displacement of each wheel and associated calculation unit; and calculating the number of occurred events N in accordance with the difference between the values counted or measured and in accordance with the number of teeth of the wheels.

An absolute position detecting device and method are provided. The absolute position detecting device utilizes the incremental magnetization on a magnetic encoding ruler with two different pole widths, such that elliptical Lissajous curves may be obtained by magnetoresistive sensors. The absolute position may be obtained by determining the region of the signals on the ellipses read by the magnetoresistive sensors.

A position sensor system is arranged for determining a position of a sensor device movable along a predefined path relative to a magnetic source. The system includes the magnetic source and the sensor device. The magnetic source has a first plurality of magnetic pole pairs arranged along a first track and a second plurality of magnetic pole pairs arranged along a second track, centrelines of the tracks are spaced apart by a predefined track distance. The sensor device is configured for measuring at least two orthogonal magnetic field components at a first sensor location, and at least two second orthogonal magnetic field components at a second sensor location. The first and second sensor location are spaced apart by a predefined sensor distance smaller than the predefined track distance, in a direction transverse to the tracks.

A position sensing arrangement for sensing the position of a revolute joint of an articulated structure. The position sensing arrangement comprises a disc and a magnetic sensor assembly. The disc comprises a first magnetic ring with m magnetic pole pairs, and a second magnetic ring with n magnetic pole pairs, where m and n are co-prime, and a mounting arrangement by which the disc is mountable to a magnetisation jig during manufacture and the articulated structure during operation, the mounting arrangement permitting the disc to be mounted to the magnetisation jig and articulated structure in a single orientation only. The magnetic sensor assembly comprises a first magnetic sensor array for detecting the magnetic pole pairs of the first magnetic ring, and a second magnetic sensor array for detecting the magnetic pole pairs of the second magnetic ring.

A method for calibrating a position measurement system includes receiving measurement data from the position measurement system and determining that the measurement data includes periodic distortion data. The position measurement system includes a nonius track and a master track. The method also includes modifying the measurement data by decomposing the periodic distortion data into periodic components and removing the periodic components from the measurement data.