Process for monitoring the condition of motor vehicle wheels

• US 6,959,234 B2
• Filed: 09/26/2002
• Issued: 10/25/2005
• Est. Priority Date: 09/28/2001
• Status: Expired due to Fees

• Current Assignee: Bayerische Motoren Werke AG
• Original Assignee: Bayerische Motoren Werke AG
• Inventors: Zimprich, Wolfgang, Wimmer, Markus, Vos, Serge, Jautze, Marcus
• Primary Examiner(s): ARTHUR JEANGLAUDE, GERTRUDE
• Application Number:
  US10/254,545
• Publication Number:
  US 20030093240A1
• Time in Patent Office: 1,125 Days
• Field of Search: 701/29, 340/442, 340/443, 340/444, 702/145, 702/146, 702/147, 702/148
• US Class Current: 701/29
• CPC Class Codes: B60C 23/061 by monitoring wheel speed measuring distance traversed on the ground by vehicles G01C22/00
• CPC Class Codes: B60C 23/062 Frequency spectrum analysis of wheel speed signals, e.g. using Fourier transformation
• CPC Class Codes: G01P 21/02 of speedometers
• CPC Class Codes: G01P 3/489 Digital circuits therefor

Abstract

A process and device for monitoring the state of a wheel of a motor vehicle in which an output signal of a sensor is converted into an essentially rectangular pulse signal. A respective duration of the pulse is measured; and an especially weighted average between the duration of a current value and a preceding value is determined, wherein a current value and a preceding value exhibit a time interval and/or lie a specific step size apart. A correction factor is determined from each deviation between the duration of a current value and a respective mean value. A step size of the correction method is matched to an error order of a fault. Preferably the step size with a periodic deviation of the m^th order that is to be eliminated is determined according to the formula j=1/m×n/4; for motor vehicles in particular according to the formula j=1/m×12.

Claims

1. A process for monitoring the state of a wheel of a motor vehicle, comprising the steps of:

converting an output signal (MS) generated by a sensor (S) into an essentially rectangular pulse signal (l);

measuring a respective duration of the pulses;

determining a particular weighted average between a current duration value of a current pulse and a preceding duration value of a preceding pulse, wherein the current pulse and the preceding pulse lie a specific step size apart, wherein the specific step size is the number of consecutive pulses from the current pulse to the preceding pulse; and

determining a correction factor (k_i) from each deviation between the current duration value and the particular weighted average;

wherein said step size (j) is correlated with an error order (m) of a fault and wherein the step size (j) with a periodic deviation of the m^th order (m) that is to be eliminated is determined according to the formula j=1/m×

n/4 for motor vehicles.

2. The process according to claim 1, further comprising determining the particular weighted average using at least two different step sizes (j) and (j1).

3. The process according to claim 1, wherein the correction method is carried out as a multi-step process with a series connection of the two different step sizes j=12 and j1=3 at n=48 teeth.

4. The process according to claim 1 including the step of filtering to minimize the influence of external disturbing stimuli.

5. The process according to claim 1, wherein a newly calculated current factor (k_i−

j) is filtered with an event-triggered filter according to a PT₁ structure.

6. The process according to claim 1, wherein a current factor (k₁₋

j) is calculated anew in each revolution (N) of a wheel.

7. The process according to claim 5, wherein the filter carries out the following transition function:

k_N,i=(a×

j<sub>N−

1,j</sub>+k₁)/(a+1).

8. The process according to claim 1, wherein n=48.

9. A device for monitoring the state of a wheel of a motor vehicle, said device comprising

a sensor (S), providing a first output signal to a signal converter (W) which outputs a pulse signal;

and

a downstream unit (A(ε

_i), v, p) receiving said pulse signal for determining and evaluating correction factors (k₁), in order to measure a respective duration of the pulse signal and determining a particular weighted average between a current duration value of a current pulse and a preceding duration value of a preceding pulse to provide a specific step size and determining a connection factor (ki) from each deviation between the current duration value and the particular weighted average wherein said step size is correlated to an error order (m) of a fault wherein the step size (j) with a periodic deviation of the m^th order (m) that is to be eliminated is determined according to the formula j=1/m×

n/4;

for motor vehicles.

10. The device according to claim 9, wherein at least two different step sizes (j) and (j1) are used in combination.

11. The device according to claim 9, wherein the correction method is carried out as a multi-step process with a series connection of the two different step sizes j=12 and j1=3 at n=48 teeth.

12. The device according to claim 9, wherein an influence of external disturbing stimuli is minimized by filtering.

13. The device according to claim 9, wherein a newly calculated current factor (k_i−

j) is filtered with an event-triggered filter according to a PT₁ structure.

14. The device according to claim 9, wherein a current factor (k₁₋

j) is calculated anew in each revolution (N) of a wheel.

15. The device according to claim 13, wherein the filter carries out the following transition function:

k_N,i=[a×

j<sub>N−

1j</sub>+k₁]/(a+1).

16. The device according to claim 9, wherein n=485.