Detecting sensor error

Patent metadata

Field	Value
Publication number	US-2016245677-A1
Application number	US-201615048883-A
Country	US
Kind code	A1
Filing date	Feb 19, 2016
Priority date	Feb 20, 2015
Publication date	Aug 25, 2016
Grant date	—

Abstract

Sensor error detection with an additional channel is disclosed herein. First and second magnetic sensing elements can be disposed at angles relative to each other. In some embodiments, the first and second magnetic sensing elements can be magnetoresistive sensing elements, such as anisotropic magnetoresistance (AMR) sensing elements. Sensor data from first and second channels, respectively, having the first and second sensing elements, can be obtained. Third channel can receive a signal from the first sensing element and a signal from the second sensing element, and sensor data from the third channel can be obtained. Expected third channel data can be determined and compared to the obtained third channel data to indicate error.

First claim

What is claimed is:

1 . An apparatus for detecting sensor error, the apparatus comprising:
a first channel comprising a first magnetic sensing element, the first channel configured to provide first channel data; a second channel comprising a second magnetic sensing element, the second channel configured to provide second channel data; a third channel configured to receive a first signal from the first sensing element and a second signal from the second sensing element, the third channel configured to provide third channel data; and a processor configured to:
receive first channel data from the first channel, second channel data from the second channel, and the third channel data;
compute expected third channel data from the first channel data and the second channel data; and
detect sensor error based at least partly on a comparison of the expected third channel data with the third channel data.

2 . The apparatus of claim 1 , wherein:
the second sensing element is oriented at a first non-zero angle relative to the first sensing element, and the third channel is configured to receive the first signal from the first magnetic sensing element and the second signal from the second magnetic sensing element.

3 . The apparatus of claim 2 , wherein the processor is further configured to:
determine an angle and a radius based at least partly on the first channel data and the second channel data; and compute the expected third channel data based at least partly on the angle and the radius.

4 . The apparatus of claim 2 , wherein each of the first and second magnetic sensing elements comprises a magnetoresistance sensor.

5 . The apparatus of claim 2 , wherein the first angle is approximately 45 degrees.

6 . The apparatus of claim 1 , wherein each of the first, second, and third channels further comprises an amplifier and a sampling circuit.

7 . The apparatus of claim 1 , wherein the first sensing element comprises a first full bridge and the second sensing element comprises a second full bridge, and wherein the first signal is an output from a half-bridge of the first full bridge and the second signal is an output from a half-bridge of the second full bridge.

8 . The apparatus of claim 1 , wherein the first sensing element comprises a first full bridge and the second sensing element comprises a second full bridge, and wherein the first sensing channel is configured to process two half bridge outputs of the first full bridge and the second sensing channel is configured to process two half bridge outputs of the second full bridge.

9 . The apparatus of claim 1 , wherein the first and second sensing elements are collocated.

10 . The apparatus of claim 1 , wherein each of the first and second elements is configured to provide a differential output.

11 . The apparatus of claim 1 , wherein the apparatus is configured to provide an error flag responsive to the detected error satisfying a threshold.

12 . An electronic power assisted steering system comprising the apparatus of claim 1 .

13 . A method for detecting sensor error, the method comprising:
receiving first sensor data from a first channel and second sensor data from a second channel; determining an angle and a radius based at least partly on the first sensor data and the second sensor data; computing the expected third sensor data based at least partly on the angle and the radius; and detecting sensor error based at least partly on a comparison of the expected third sensor data with the third sensor data, wherein the first channel includes a first magnetic sensing element, wherein the second channel includes a second magnetic sensing element, the second magnetic sensing element oriented at a first angle relative to the first sensing element, wherein the third channel is configured to receive a first signal from the first magnetic sensing element and a second signal from the second magnetic sensing element.

14 . The method of claim 13 , wherein determining the angle comprises computing the angle using an arctan function.

15 . The method of claim 13 , further comprising providing an error flag responsive to the detected error satisfying a threshold.

16 . The method of claim 13 , wherein each of the first and second magnetic sensing elements comprises an anisotropic magnetoresistance (AMR) sensor.

17 . The method of claim 13 , wherein the first angle is approximately 45 degrees.

18 . An apparatus for detecting sensor error, the apparatus comprising:
a first channel comprising a first magnetic sensing element comprising a first full bridge having two half bridge outputs; a second channel comprising a second magnetic sensing element comprising a second full bridge having two half bridge outputs; a third channel configured to receive a first signal from one of the half bridge outputs of the first full bridge and a second signal from one of the half bridge outputs of the second full bridge; and a processor configured to:
receive first channel data from the first channel, second channel data from the second channel, and third channel data from the third channel;
compute a first value from two of the first channel data, second channel data, and third channel data and compute a second value from another two of the first channel data, second channel data, and third channel data; and
detect sensor error based at least partly on a comparison of the first value with the second value.

19 . The apparatus of claim 18 , further comprising differential amplifiers, wherein each of the differential amplifiers are configured to receive a signal from the first full bridge and a signal from the second full bridge, and wherein each of the differential amplifiers are configured to receive different combinations of signals from the first and second full bridges, wherein the processor is in communication with the differential amplifiers, and wherein the first channel data, second channel data, and third channel data are associated with outputs of the differential amplifiers.

20 . The apparatus of claim 18 , wherein the first value is a first magnetic angle and the second value is a second magnetic angle.

Assignees

• Analog Devices Global
• Sensitec Gmbh

Inventors

• Cosgrave Gavin Patrick
• Schmitt Jochen
• O'Keeffe Dermot G

Classifications

• B62D5/049 Primary

  detecting sensor failures · CPC title

• G01D5/24461 Primary

  by redundancy or plausibility · CPC title

• G01D18/00 Primary

  Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00 · CPC title

• G01R35/00

  Testing or calibrating of apparatus covered by the other groups of this subclass · CPC title

• G01D5/145

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