Rotation sensing method and system

• US 8,886,471 B2
• Filed: 06/26/2008
• Issued: 11/11/2014
• Est. Priority Date: 06/26/2008
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Hainz, Simon, Hammerschmidt, Dirk, Katzmaier, Ernst
• Primary Examiner(s): BHAT, ADITYA S
• Application Number:
  US12/146,797
• Publication Number:
  US 20090326860A1
• Time in Patent Office: 2,329 Days
• Field of Search: None
• US Class Current: 702/45
• CPC Class Codes: G01D 18/00 Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00
• CPC Class Codes: G01D 18/001 Calibrating encoders
• CPC Class Codes: G01D 5/12 using electric or magnetic means G01D5/06 takes precedence
• CPC Class Codes: G01D 5/24461 by redundancy or plausibility
• CPC Class Codes: G01D 5/2448 Correction of gain, threshold, offset or phase control
• CPC Class Codes: G01D 5/24485 using other sensors
• CPC Class Codes: G01P 3/481 of pulse signals
• CPC Class Codes: G01P 3/487 delivered by rotating magnets
• CPC Class Codes: G01P 3/489 Digital circuits therefor

Abstract

A sensing system and method. A coded wheel is configured to generate a signal that varies with rotation of the coded wheel. A sensor is configured to sense the varying signal and output a corresponding signal. A correction module is configured to receive the signal output by the sensor and compare the received signal to a stored signal and detect a defect in the coded wheel in response to the comparison.

Claims

1. A method of sensing rotation of a rotatable member, comprising:

rotating a rotatable member having a coded wheel attached thereto, such that the coded wheel rotates relative to a sensor;

receiving a signal that varies with the rotation of the coded wheel;

comparing the received signal to a stored signal;

detecting a physical defect in the coded wheel in response to the comparison;

correcting the received signal in response to detecting a physical defect; and

sensing rotation of the rotatable member based on the corrected signal.

2. The method of claim 1, wherein the received signal represents a rotation of the coded wheel, and wherein the stored signal represents a previous rotation of the coded wheel.

3. The method of claim 2, further comprising:

storing the received signal; and

comparing a subsequent received signal to the stored received signal.

4. The method of claim 1, further comprising storing a plurality of received signals.

5. The method of claim 1, wherein comparing the received signal to the stored signal includes comparing at least one of zero-crossings, peaks, fixed signal levels, and signal gradients.

6. The method of claim 1, wherein comparing the received signal to the stored signal includes comparing frequencies of the received and stored signals.

7. The method of claim 1, further comprising converting the received signal to a digital signal.

8. The method of claim 7, wherein converting the received signal to a digital signal includes a zero-crossing detection process.

9. The method of claim 7, wherein converting the received signal to a digital signal includes using an analog to digital converter.

10. The method of claim 1, wherein comparing the received signal to the stored signal includes comparing analog signals.

11. The method of claim 1, wherein the coded wheel defines a plurality of teeth, and wherein the physical defect includes a defect in the teeth.

12. The method of claim 1, wherein the coded wheel includes a magnetic pattern, and wherein the physical defect includes a defect in the magnetic pattern.

13. A sensing system, comprising:

a coded wheel configured to generate a signal that varies with rotation of the coded wheel;

a sensor configured to sense the varying signal and output a corresponding signal;

a correction module configured to receive the signal output by the sensor and compare the received signal to a stored signal, detect a physical defect in the coded wheel in response to the comparison, and correct the received signal in response to detecting a defect.

14. The system of claim 13, wherein the coded wheel includes a magnetic pattern that induces a magnetic field that varies as the coded wheel rotates.

15. The system of claim 14, wherein the physical defect includes a defect in the magnetic pattern.

16. The system of claim 13, further comprising:

a magnet establishing a magnetic field; and

wherein the coded wheel defines a plurality of teeth configured to vary the established magnetic field as the coded wheel rotates.

17. The system of claim 16, wherein the physical defect includes a defect in the teeth.

18. The system of claim 13, wherein the sensor is a magnetic sensor.

19. The system of claim 13, wherein the sensor is a capacitive sensor.

20. The system of claim 13, wherein the sensor is an inductive sensor.

21. The system of claim 13, wherein the sensor is an optical sensor.

22. The system of claim 13, further comprising a memory configured to contain the stored signal.

23. The system of claim 22, wherein the memory contains a plurality of received signals.

24. The system of claim 22, wherein the correction module is configured to compare frequencies of the received and stored signals.

25. The system of claim 22, further comprising an analog-to-digital converter configured to convert the received signal to a digital signal.

26. The system of claim 25, wherein the wherein the analog-to-digital converter includes a zero-crossing detector.