Wheel speed sensor with support for indirect tire pressure monitoring

• US 8,868,290 B2
• Filed: 01/04/2013
• Issued: 10/21/2014
• Est. Priority Date: 01/04/2013
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Hammerschmidt, Dirk
• Primary Examiner(s): Trammell, James
• Assistant Examiner(s): Sweeney, Brian P
• Application Number:
  US13/734,320
• Publication Number:
  US 20140195104A1
• Time in Patent Office: 655 Days
• Field of Search: 701/32.7, 731/462, 731/465, 340/442
• US Class Current: 701/32.7
• CPC Class Codes: B60C 23/062 Frequency spectrum analysis of wheel speed signals, e.g. using Fourier transformation

Abstract

The present disclosure relate to an indirect tire pressure monitoring system (TPMS). In some embodiments, the indirect TPMS has magnetic field sensor that detects a modulated magnetic field indicative of one or more resonance parameters of an automobile tire. The magnetic field sensor generates a modulated sensor signal based upon the modulated magnetic field. An analog-to-digital converter (ADC) converts the modulated sensor signal to a digital sensor signal, which is provided to a digital signal processing unit that perform analysis of the digital sensor signal to determine the one or more resonance parameters. A communication interface transmit data corresponding to the one or more resonance parameters to an electronic control unit (ECU).

Claims

1. An indirect tire pressure monitoring system (TPMS), having a sensor housing comprising:

a magnetic field sensor configured to detect a modulated magnetic field indicative of one or more resonance parameters of an automobile tire and to generate a modulated sensor signal based upon the modulated magnetic field;

an analog-to-digital converter (ADC) configured to convert the modulated sensor signal to a digital sensor signal;

a digital signal processing unit configured to receive the digital sensor signal and to perform analysis of the digital sensor signal to determine the one or more resonance parameters; and

a communication interface configured to transmit data corresponding to the one or more resonance parameters to an electronic control unit (ECU).

2. The indirect TPMS of claim 1, wherein a sensor housing comprises the magnetic field sensor, the ADC, the digital signal processing unit, and the communication interface.

3. The indirect TPMS of claim 2, wherein the digital signal processing unit comprises:

a demodulation element configured to demodulate the modulated sensor signal to generate a demodulated signal having a reduced bandwidth relative to the digital sensor signal; and

a spectral analysis element configured to receive the demodulated signal, and from the demodulated signal to determine the one or more resonance parameters.

4. The indirect TPMS of claim 3, wherein the digital signal processing unit comprises a time frequency transform unit configured to perform a time to frequency transformation of the demodulated signal to generate a spectral density of the demodulated signal.

5. The indirect TPMS of claim 4, wherein the time frequency transform unit comprises a fast Fourier transform calculation unit.

6. The indirect TPMS of claim 4, further comprising:

a decimation filter disposed within the sensor housing at a location downstream of the demodulation element and upstream of the time frequency transform unit, wherein the decimation filter is configured reduce a sampling frequency of the demodulated signal.

7. The indirect TPMS of claim 4, further comprising:

a frequency identifier disposed within the sensor housing at a location downstream of the time frequency transform unit and configured to determine frequency peaks in the spectral density corresponding to the one or more resonance parameters.

8. The indirect TPMS of claim 3, wherein the digital signal processing unit comprises a phase-locked loop configured to receive the digital sensor signal, to lock onto a frequency of the digital sensor signal that represents the wheel speed, and to provide an output signal that controls the locked oscillator and represents the wheel speed.

9. The indirect TPMS of claim 3, further comprising:

a bandpass filter disposed within the sensor housing at a location upstream of the demodulation element.

10. The indirect TPMS of claim 1, wherein the one or more resonance parameters comprise a resonance frequency or a q-factor of a resonance.

11. An indirect tire pressure monitoring system (TPMS), comprising:

a magnetic field sensor configured to generate a modulated sensor signal corresponding to a measured magnetic field indicative of one or more resonance parameters of an automobile tire; and

an analog-to-digital converter (ADC) configured to sample the modulated sensor signal and to provide a digital signal, based upon the samples, to a demodulation element configured generate a demodulated signal having a lower frequency than the modulated sensor signal;

a spectral analysis element configured to receive the demodulated sensor signal and to perform analysis of the sensor signal to determine the one or more resonance parameters; and

a communication interface configured to transmit data corresponding to the one or more resonance parameters to an electronic control unit (ECU).

12. The indirect TPMS of claim 11, wherein the spectral analysis element comprises a time frequency transform unit configured to perform a time to frequency transformation of the demodulated signal to generate a spectral density of the demodulated signal.

13. The indirect TPMS of claim 12, further comprising:

a decimation filter disposed at a location downstream of the demodulation element and upstream of the time frequency transform unit, wherein the decimation filter is configured to reduce a sampling rate of the demodulated signal.

14. The indirect TPMS of claim 11, wherein the spectral analysis element comprises a phase-locked loop configured to receive the digital sensor signal, to lock onto a frequency of the digital sensor signal that represents the wheel speed, and to provide an output signal that controls the locked oscillator and represents the wheel speed.

15. The indirect TPMS of claim 11, further comprising:

a bandpass filter disposed at a location upstream of the demodulation element.

16. The indirect TPMS of claim 11, further comprising:

a frequency identifier disposed within the sensor housing at a location downstream of the FFT calculation unit and configured to determine frequency peaks in the spectral density corresponding to a wheel speed and to one or more resonance frequencies.

17. The indirect TPMS of claim 11, wherein the communication interface is configured to transmit or compress and transmit a low frequency part of a spectral density of the demodulated signal to the ECU without detection frequency peaks in the spectral density.

18. A method of measuring a tire pressure, comprising:

receiving a modulated sensor signal from a magnetic field sensor disposed within a sensor housing configured to detect a modulated magnetic field indicative of a wheel speed and one or more resonance frequencies of an automobile tire;

converting, using an analog to digital converter disposed within a sensor housing, the modulated sensor signal to a digital sensor signal;

performing analysis, using a digital signal processing unit disposed within a sensor housing, of the digital sensor signal to determine the one or more resonance parameters; and

transmitting data, using a communication interface disposed within a sensor housing, corresponding to the one or more resonance parameters to an electronic control unit (ECU).

19. The method of claim 18, wherein performing analysis of the digital sensor signal comprises:

demodulating the received digital sensor signal to generate a demodulated signal having a reduced bandwidth relative to the digital sensor signal; and

performing spectral analysis of the demodulated signal to determine the one or more resonance parameters.

20. The method of claim 19, further comprising:

filtering the digital sensor signal prior to demodulating the received digital sensor signal.

21. The method of claim 19, further comprising:

decimating the demodulated signal prior to reduce a sampling rate of the demodulated signal.

22. The method of claim 18, wherein performing spectral analysis of the digital signal comprises performing a time to frequency transformation of the demodulated signal to generate a spectral density of the demodulated signal.

23. The method of claim 18, further comprising:

identifying frequency peaks in the spectral density corresponding to a wheel speed and to one or more resonance frequencies.

24. The method of claim 18, further comprising:

transmitting or compressing and transmitting a low frequency part of a spectral density of the demodulated signal without detection of frequency peaks in the spectral density.