Sensing method and system for correcting an input waveform from a coded wheel

• US 9,869,568 B2
• Filed: 11/11/2014
• Issued: 01/16/2018
• 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): PATIDAR, JAY M
• Application Number:
  US14/538,431
• Publication Number:
  US 20150137800A1
• Time in Patent Office: 1,162 Days
• 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 for correcting an input waveform from a coded wheel. The coded wheel is configured to generate a signal that varies with rotation of the coded wheel relative to a sensor. The sensor is configured to sense the varying signal and output a corresponding input waveform. A correction module is configured to receive the input waveform and compare the input waveform to at least one stored waveform and to correct the input waveform if a defect is detected in the coded wheel in response to the comparison.

Claims

1. A method of sensing rotation, comprising:

rotating a coded wheel to generate an input signal that varies with rotation of the coded wheel relative to a sensor;

generating with the sensor a present input waveform representative of the input signal;

comparing the present input waveform to at least one stored waveform representative of rotation of the coded wheel;

detecting an anomaly in the present input waveform representative of a defect in the coded wheel based on the comparison; and

correcting the detected anomaly in the present input waveform to provide a corrected input waveform in response to detecting an anomaly representative of a defect in the coded wheel.

2. The method of claim 1, wherein the present input waveform represents at least a portion of a present rotation of the coded wheel, and wherein the at least one stored waveform represents at least a portion of a previous rotation of the coded wheel.

3. The method of claim 1, further comprising storing a plurality of input waveforms.

4. The method of claim 2, further comprising:

storing the present input waveform as a stored waveform; and

comparing a subsequent present input waveform to the stored waveform.

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

6. The method of claim 1, wherein comparing the present input waveform to the stored input waveform includes comparing frequencies of the present input waveform and stored waveforms.

7. The method of claim 1, further comprising converting the input waveform to a digital waveform.

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

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

10. The method of claim 1, wherein comparing the present input waveform to the at least one stored waveform includes comparing analog signals.

11. 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 to generate a corresponding input waveform;

a correction module configured to receive the input waveform generated by the sensor, to compare the input waveform to at least one stored waveform, to detect a defect in the coded wheel in response to the comparison, and to correct the input waveform in response to detecting a defect to provide a corrected input waveform.

12. The system of claim 11, wherein the coded wheel includes a pattern of magnetic poles that induces a magnetic field that varies as the coded wheel rotates.

13. The system of claim 11, 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.

14. The system of claim 11, wherein the sensor is a magnetic sensor.

15. The system of claim 11, further comprising a memory configured to contain the at least one stored waveform.

16. The system of claim 15, wherein the memory contains a plurality of stored waveforms comprising previously generated input waveforms from the sensor.

17. The system of claim 15, wherein the correction module is configured to compare frequencies of the input waveform and the at least one stored waveform.

18. The system of claim 15, further comprising an analog-to-digital converter configured to convert the input waveform to a digital signal.

19. The system of claim 18, wherein the wherein the analog-to-digital converter includes a zero-crossing detector.

20. The system of claim 11, wherein the correction module is configured to detect an angular position of the defect.

21. The system of claim 12, wherein the correction module is configured to detect changes in magnetic strength of the magnetic poles.