Tire and suspension warning and monitoring system

• US 20030006893A1
• Filed: 07/06/2001
• Published: 01/09/2003
• Est. Priority Date: 07/06/2001
• Status: Active Grant

• Current Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Magiawala, Kiran R., Brown, Kenneth L., Chilcott, Kelley D., Dunbridge, Barry, McIver, George W.
• Granted Patent: US 6,759,952 B2
• Time in Patent Office: Days
• US Class Current: 340/444
• CPC Class Codes: G01M 17/02 Tyres
• CPC Class Codes: G01M 17/04 Suspension or damping
• CPC Class Codes: Y10T 152/10009 Emergency

Abstract

A tire and suspension monitoring and warning system consisting of a set of multi-function sensors that monitor and warn of a failure mode. The system monitors and warns for tire imbalance, tire tread wear, and shock absorbers for a tire attached to a vehicle. The monitoring and warning system includes one axial, radial, and lateral acceleration measurement of the wheel to provide acceleration signal sample power. For tire imbalance, signal sample power in the second harmonic of the tire rotational frequency is compared to that of the first harmonic. For tire tread wear, average signal sample power within a second frequency range is compared to a previously stored baseline value. For shock absorber performance, a sum of all frequency components in a second predetermined frequency range is compared to a baseline value.

Claims

1. A method for tire and suspension warning and monitoring system for monitoring tire imbalance of a tire attached to a vehicle wheel comprising:

sensing at least one acceleration of the wheel to provide acceleration signals;

collecting a predetermined number of acceleration signal samples;

transforming and normalizing the samples;

computing a rotational frequency of the wheel from the normalized samples;

computing a second harmonic frequency of the rotational frequency of the wheel;

summing frequency components around the second harmonic frequency;

comparing summed frequency components with a previously stored baseline value; and

outputting a signal indicative of the comparison result.

2. The method of claim 1, wherein sensing at least one acceleration of the wheel comprises sensing at least one of radial, axial, and longitudinal acceleration of the wheel.

3. The method of claim 1, wherein sensing at least one acceleration of the wheel comprises sensing a radial acceleration of the wheel.

4. The method of claim 1, wherein transforming the samples comprises performing a Fast Fourier Transform (FFT) of the samples.

5. The method of claim 1, wherein transforming the samples comprises performing a Fast Fourier Transform (FFT) of the samples in the frequency range 0 to 50 Hz.

6. The method of claim 1, wherein transforming samples comprises performing a Fast Fourier Transform (FFT) of the samples to determine tire balance for all speeds based on a wheel speed weighting function.

7. The method of claim 1, further comprising low pass filtering the computed second harmonic frequency of the wheel prior to comparing the components with the previously stored baseline value.

8. The method of claim 1, wherein the previously stored baseline value corresponds to an averaged sample value obtained with a new tire.

9. An apparatus for tire and suspension warning and monitoring system for monitoring tire imbalance of a tire attached to a vehicle wheel, the apparatus comprising:

a sensor for sensing at least one acceleration of the wheel and for providing acceleration signals corresponding thereto;

a collector for collecting a predetermined number of acceleration signals samples;

a transformer and normalizer for transforming and normalizing the samples within a first predetermined frequency range;

a first calculator for calculating a rotational frequency of the wheel from the transformed and normalized samples;

a second calculator for calculating a second harmonic frequency of the wheel from the calculated rotational frequency of the wheel;

a comparator for comparing the second harmonic frequency with a previously stored baseline value; and

an output circuit for outputting a signal indicative of the comparison results of the comparator.

10. The apparatus of claim 9, wherein said sensor senses at least one of radial, axial, and longitudinal acceleration of the wheel.

11. The apparatus of claim 9, wherein said sensor senses a radial acceleration of the wheel.

12. The apparatus of claim 9, wherein said transformer performs a Fast Fourier Transform (EFT) of the samples.

13. The method of claim 9, wherein said transforming the samples comprises performing a Fast Fourier Transform (FFT) of the samples in the frequency range 0 to 50 Hz.

14. The apparatus of claim 9, further comprising a low pass filter for low pass filtering the calculated second harmonic frequency prior to inputting it to said comparator.

15. The apparatus of claim 9, wherein said signal output by said output circuit comprises a signal proportional to a difference between the second harmonic frequency and the previously stored baseline value.

16. The apparatus of claim 9, wherein the previously stored baseline value corresponds to an averaged sample value obtained with a properly balanced wheel.

18. The method of claim 17, wherein sensing at least one acceleration of the wheel comprises sensing at least one of radial, axial, and longitudinal acceleration of the wheel.

19. The method of claim 17, wherein sensing at least one acceleration of the wheel comprises sensing an axial acceleration of the wheel.

20. The method of claim 17, wherein transforming the samples comprises performing a Fast Fourier Transform (FFT) of the samples.

21. The method of claim 17, wherein the first frequency range is from 0 to 50 Hz range

22. The method of claim 17, wherein the second predetermined frequency range is from 30 to 50 Hz range.

23. The method of claim 17, further comprising low pass filtering the averaged samples prior to comparing them with the previously stored baseline value.

24. The method of claim 17, wherein outputting a signal indicative of the comparison result comprises outputting a signal proportional to a difference between the averaged samples and the previously stored baseline value.

25. The method of claim 17, wherein transforming the samples comprises performing a Discrete Fourier Transform (DFT) of the samples.

26. The method of claim 17, wherein the previously stored baseline value corresponds to an averaged sample value obtained with a new tire.

28. The apparatus of claim 27, wherein said sensor senses at least one of radial, axial, and longitudinal acceleration of the wheel.

29. The apparatus of claim 27, wherein said sensor senses an axial acceleration of the wheel.

30. The apparatus of claim 27, wherein said transformer performs a Fast Fourier Transform (FFT) of the samples.

31. The apparatus of claim 27, wherein the first predetermined frequency range is from 0 to 50 Hz.

32. The apparatus of claim 27, wherein the second predetermined frequency range is from 30 to 50 Hz.

33. The apparatus of claim 27, wherein the second predetermined frequency range is a tire tread shell lateral frequency.

34. The apparatus of claim 27, further comprising a low pass filter for low pass filtering the averaged samples prior to inputting them to said comparator.

35. The apparatus of claim 27, wherein said signal output by said output circuit comprises a signal proportional to a difference between the averaged samples and the previously stored baseline value.

36. The apparatus of claim 27, wherein the previously stored baseline value corresponds to an averaged sample value obtained with a new time.

38. The method of claim 37, wherein sensing at least one acceleration of the wheel comprises sensing at least one of radial, axial, and longitudinal acceleration of the wheel.

39. The method of claim 37, wherein sensing at least one acceleration of the wheel comprises sensing a radial acceleration of the wheel.

40. The method of claim 37, wherein transforming the samples comprises performing a Fast Fourier Transform (FFT) of the samples.

41. The method of claim 37, wherein the first predetermined frequency range is from 0 to 50 Hz.

42. The method of claim 37, wherein the second predetermined frequency range is from 18 to 22 Hz.

43. The method of claim 37, wherein the second predetermined frequency range is a vehicle unsprung mass resonance frequency.

44. The method of claim 37, further comprising low pass filtering the summed samples prior to comparing them with the previously stored baseline value.

45. The method of claim 37, wherein outputting a signal indicative of the comparison result comprises outputting a signal proportional to a difference between the summed samples and the previously stored baseline value.

47. The apparatus of claim 46, wherein said sensor senses at least one of radial, axial, and longitudinal acceleration of the wheel.

48. The apparatus of claim 46, wherein said sensor senses a radial acceleration of the wheel.

49. The apparatus of claim 46, wherein said transformer performs a Fast Fourier Transform (FFT) of the samples.

50. The apparatus of claim 46, wherein the first predetermined frequency range is from 0 to 50 Hz.

51. The apparatus of claim 46, wherein the second predetermined frequency range is from 18 to 22 Hz.

52. The apparatus of claim 46, wherein the second predetermined frequency range is a vehicle unsprung mass resonance frequency.

53. The apparatus of claim 46, further comprising a low pass filter for low pass filtering the summed samples prior to inputting them to said comparator.

54. The apparatus of claim 46, wherein said signal output by said output circuit comprises a signal proportional to a difference between the summed samples and the previously stored baseline value.

55. The apparatus of claim 46, wherein the previously stored baseline value corresponds to a summed sample value obtained with a new shock absorber.

17. A method for tire and suspension warning and monitoring system for monitoring tire tread wear of a tire attached to a vehicle wheel, the method comprising:

sensing at least one acceleration of the wheel to provide acceleration signals;

collecting a predetermined number of acceleration signal samples;

transforming and normalizing the samples within a first predetermined frequency range;

averaging the transformed and normalized samples within a second predetermined frequency range;

comparing the averaged samples with a previously stored baseline value; and

outputting a signal indicative of the comparison result.

27. An apparatus for tire and suspension monitoring and warning system for monitoring tire tread wear of a tire attached to a vehicle wheel, the apparatus comprising:

a sensor for sensing at least one acceleration of the wheel and for providing acceleration signals corresponding thereto;

a collector for collecting a predetermined number of acceleration signals samples;

a transformer and normalizer for transforming and normalizing the samples within a first predetermined frequency range;

an averager for averaging the transformed and normalized samples within a second predetermined frequency range;

a comparator for comparing the averaged samples with a previously stored baseline value; and

an output circuit for outputting a signal indicative of the comparison results of the comparator.

37. A tire and suspension warning and monitoring system for monitoring shock absorber performance of a shock absorber attached to a vehicle wheel, the method comprising:

sensing at least one acceleration of the wheel to provide acceleration signals;

collecting a predetermined number of acceleration signal samples;

transforming and normalizing the collected samples within a first predetermined frequency range;

summing the transformed and normalized samples within a second predetermined frequency range;

comparing the summed samples with a previously stored baseline value; and

outputting a signal indicative of the comparison result.

46. An apparatus for a tire and suspension warning and monitoring system for monitoring shock absorber performance of a shock absorber attached to a vehicle wheel, the apparatus comprising:

a sensor for sensing at least one acceleration of the wheel and for providing acceleration signals corresponding thereto;

a collector for collecting a predetermined number of acceleration signals samples;

a transformer and normalizer for transforming and normalizing the samples within a first predetermined frequency range;

a summer for summing the transformed and normalized samples within a second predetermined frequency range;

a comparator for comparing the summed samples with a previously stored baseline value; and

an output circuit for outputting a signal indicative of the comparison results of the comparator.