Position sensor system and method

Patent metadata

Field	Value
Publication number	US-12339138-B2
Application number	US-202418654250-A
Country	US
Kind code	B2
Filing date	May 3, 2024
Priority date	Dec 23, 2020
Publication date	Jun 24, 2025
Grant date	Jun 24, 2025

Abstract

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.

First claim

The invention claimed is:

1. A method of forming two pairs of quadrature signals comprising the steps of:
providing a magnetic source comprising a first plurality of magnetic pole pairs arranged along a first track having a first periodicity, and comprising a second plurality of magnetic pole pairs arranged along a second track having a second periodicity different from the first periodicity;
measuring by a first plurality of magnetic sensors a first magnetic field signal, and a second magnetic field signal which is phase shifted relative to the first magnetic field signal;
measuring by a second plurality of magnetic sensors a third magnetic field signal, and a fourth magnetic field signal which is phase shifted relative to the third magnetic field signal, the second plurality of magnetic sensors being spaced from the first plurality of magnetic sensors by a predefined distance (ds);
forming a first pair of quadrature signals using a set of linear or polynomial equations of at least two of the measured magnetic field signals and a first set of coefficients;
forming a second pair of quadrature signals using a set of linear or polynomial equations of at least two of the measured magnetic field signals and a second set of coefficients, the second pair different from the first pair.

2. A method according to claim 1 ,
wherein the first set of coefficients is a first predefined set of coefficients; and
wherein the second set of coefficients is a second predefined set of coefficients.

3. A method according to claim 1 ,
wherein each of the first set of coefficients and the second set of coefficients is determined during a calibration procedure; and
wherein the first set of coefficients and the second set of coefficients are stored in a non-volatile memory of a sensor device during said calibration procedure.

4. A method according to claim 1 ,
wherein the first pair of quadrature signals is formed using said set of linear equations of at least one of the magnetic field signals measured by the first plurality of magnetic sensors, and at least at least one of the magnetic field signals measured by the second plurality of magnetic sensors;
and wherein the second pair of quadrature signals is formed using said set of linear equations of at least one of the magnetic field signals measured by the first plurality of magnetic sensors, and at least at least one of the magnetic field signals measured by the second plurality of magnetic sensors.

5. A method of determining an absolute linear or an angular position, comprising the steps of:
forming two pairs of quadrature signals according to claim 1 ;
determining a first angle based on a first ratio of the two signals of the first pair of quadrature signals;
determining a second angle based on a second ratio of the two signals of the second pair of quadrature signals;
determining an absolute position based on the first angle and the second angle.

6. The method of claim 5 ,
wherein the first angle is determined as an arctangent function of said first ratio, or as a modified arctangent function of said first ratio;
and wherein the second angle is determined as an arctangent function of said second ratio, or as a modified arctangent function of said second ratio.

7. A sensor device comprising:
a first plurality of magnetic sensors configured for measuring a first magnetic field component and a second magnetic field component of a first magnetic field generated by a first plurality of magnetic pole pairs arranged along a first track having a first periodicity;
a second plurality of magnetic sensors configured for providing a third magnetic field component and a fourth magnetic field component of a second magnetic field generated by a second plurality of magnetic pole pairs arranged along a second track having a second periodicity, the second plurality of magnetic sensors being spaced from the first plurality of magnetic sensors by a predefined distance (ds);
a processing circuit configured for:
forming a first pair of quadrature signals using a first set of linear or polynomial equations of at least two of the measured first, second, third or fourth magnetic field components with a first set of coefficients; and for
forming a second pair of quadrature signals using a second set of linear or polynomial equations of at least two of the measured first, second, third or fourth magnetic field components with a second set of coefficients, the second pair different from the first pair.

8. A sensor device according to claim 7 ,
wherein the first set of coefficients is a first predefined set of coefficients; and
wherein the second set of coefficients is a second predefined set of coefficients.

9. A sensor device according to claim 7 ,
wherein each of the first set of coefficients and the second set of coefficients is determined during a calibration procedure;
and wherein the sensor device further comprises a non-volatile memory;
and wherein the first set of coefficients and the second set of coefficients are stored in a non-volatile memory of a sensor device during said calibration procedure, and are retrieved from the non-volatile memory during normal operation.

10. A sensor device according to claim 7 ,
wherein the processing circuit is configured for forming the first pair of quadrature signals using said set of linear equations of at least one of the magnetic field signals measured by the first plurality of magnetic sensors, and at least at least one of the magnetic field signals measured by the second plurality of magnetic sensors;
and wherein the processing circuit is configured for forming the second pair of quadrature signals using said set of linear equations of at least one of the magnetic field signals measured by the first plurality of magnetic sensors, and at least at least one of the magnetic field signals measured by the second plurality of magnetic sensors.

11. A sensor device according to claim 7 ,
wherein the processing circuit is further configured for:
determining a first angle based on a first ratio of the two signals of the first pair of quadrature signals;
determining a second angle based on a second ratio of the two signals of the second pair of quadrature signals;
determining an absolute position based on the first angle and the second angle.

12. A sensor device according to claim 7 ,
wherein the processing circuit is configured for determining the first angle as an arctangent function of said first ratio, or as a modified arctangent function of said second ratio;
and wherein the processing circuit is configured for determining the second angle as an arctangent function of said second ratio, or as a modified arctangent function of said second ratio.

13. A position sensor system comprising:
a magnetic source comprising a first plurality of magnetic pole pairs arranged along a first track having a first periodicity, and comprising a second plurality of magnetic pole pairs arranged along a second track having a second periodicity different from the first periodicity;
a sensor device comprising:
a first plurality of magnetic sensors for measuring a first magnetic field signal and a second magnetic field signal which is phase shifted relative to the first magnetic field signal;
a second plurality of magnetic sensors for measuring a third magnetic field signal and a fourth magnetic field signal which is phase shifted relative to the third magnetic field signal, the second plurality of magnetic sensors being spaced from the first plurality of magnetic sensors by a predefined distance (ds);
a processing circuit configured for forming a first pair of quadrature signals

Assignees

• Melexis Tech Sa

Inventors

• Schott Christian
• Close Gael
• Brajon Bruno

Classifications

• G01R33/091

  Constructional adaptation of the sensor to specific applications · CPC title

• G01D5/244

  influencing characteristics of pulses or pulse trains; generating pulses or pulse trains · CPC title

• G01D5/24438

  Special design of the sensing element or scale · CPC title

• G01D5/2452

  incorporating two or more tracks having an (n, n+1, ...) relationship · CPC title

• G01D5/145 Primary

  influenced by the relative movement between the Hall device and magnetic fields (see G01R33/06) · CPC title