Method and apparatus for calculating a correction factor for an angular measuring system

Patent metadata

Field	Value
Publication number	US-10161762-B2
Application number	US-201514854430-A
Country	US
Kind code	B2
Filing date	Sep 15, 2015
Priority date	Sep 29, 2014
Publication date	Dec 25, 2018
Grant date	Dec 25, 2018

Abstract

A method for computing a correction factor (KF) for an angular measuring system (10) comprising a measurement of a first output value (W1) in a first measuring position (20) and a measurement of a second output value (W2) in a second measuring position (30). An actual value (DI) is formed from the difference between the first output value (W1) and the second output value (W2), and a target value (DS) is formed from the difference of target values (S1, S2) in the first measuring position (20) and in the second measuring position (30). The correction factor (KF) is computed from the ratio of the target value (DS) to the actual value (DI).

First claim

What is claimed is:

1. A method for calculating a correction factor for an angular measuring system comprising:
measuring, using a magnetic field sensor, the first orthogonal components of a magnetic field at a first measuring position of an axle;
calculating, using a computing unit, a first output value of a first angle of the first measuring position from the acrctan2 function of the measured first orthogonal components;
measuring, using the magnetic field sensor, the second orthogonal components of a magnetic field at a second measuring position of the axle;
calculating, using the computing unit, a second output value of a second angle of the second measuring position from the acrctan2 function of the measured second orthogonal components;
forming an actual value from the difference between the first output value and the second output value;
computing, in the computing unit, a first target value of the first measuring position from one of the first orthogonal components in the first measuring position;
computing, in the computing unit, a second target value of the second measuring position from one of the second orthogonal components in the second measuring position;
forming a difference target value from the difference of the first target value and the second target value in the first measuring position and in the second measuring position;
calculating the correction factor from the ratio of the difference target value to the actual value.

2. The method according to claim 1 , wherein the angular difference between the first measuring position and the second measuring position is less than 50°.

3. The method according to claim 1 , wherein at least one of the first measuring position or the second measuring position has an angular value and where the sine value or the cosine value of the angular value is substantially amounts 0 or 1.

4. The method according to claim 1 , further comprising measuring of further output values in further ones of the measuring positions and use of the further output values for the computation of the correction factor.

5. An apparatus for calibrating an angular measuring system, comprising:
a magnetic field sensor for measuring the first orthogonal components of a magnetic field at a first measuring position and for measuring the second orthogonal components of a magnetic field at a second measuring position;
a computing unit for calculating a first output value of a first angle of the first measuring position from the acrctan2 function of the measured first orthogonal components, for calculating a second output value of a second angle of the second measuring position from the acrctan2 function of the measured second orthogonal components, and for calculating a correction factor from a ratio between an actual value and a difference target value, wherein the actual value is formed from a difference between the measured first output value and the measured second output value, and the difference target value is formed from a difference of a first target value and a second target value in the first measuring position and in the second measuring position, wherein first target value of the first measuring position is computed, in the computing unit, from one of the first orthogonal components in the first measuring position and the second target value of the second measuring position is computed, in the computing unit, from one of the second orthogonal components in the second measuring position.

6. The apparatus according to claim 5 , wherein the sensor is a Hall sensor.

7. The apparatus according to claim 5 , wherein the angular distance between the first sensor position and the second sensor position is less than 50°.

8. The apparatus according to claim 5 , wherein at least one of the first measuring position or the second measuring position has an angular value and where the sine value or the cosine value of the angular value is substantially 0 or 1.

9. The apparatus according to claim 5 , having a plurality of further measuring positions for measuring a multiplicity of different output values.

Assignees

• Micronas Gmbh
• Tdk Micronas Gmbh

Inventors

• Bondar Yan

Classifications

• G01C25/005 Primary

  initial alignment, calibration or starting-up of inertial devices · CPC title