Method and apparatus for monitoring a machine bearing on-vehicle

1. A method for monitoring a machine bearing that is disposed on a rotatable member of a vehicle, the method comprising:

monitoring, via an on-vehicle microphone, an acoustic signal and monitoring, via a position sensor, a rotational speed of the rotatable member associated with the machine bearing;

capturing the acoustic signal when the rotational speed of the rotatable member is at a steady-state condition;

executing, via a controller, a time-frequency analysis of the acoustic signal to determine a sound spectrum;

transforming the sound spectrum to a residual spectrum;

extracting a first feature from the residual spectrum, wherein the first feature is within a first frequency band;

extracting a second feature from the residual spectrum, wherein the second feature is within a second frequency band;

determining a state of health associated with the machine bearing based upon the first and second features; and

communicating, via the controller, the state of health of the machine bearing to a second controller.

2. The method of claim 1 , further comprising capturing the acoustic signal for a preset window of time when the rotational speed is at the steady-state condition.

3. The method of claim 1 , wherein the first frequency band includes a harmonic frequency of the rotational speed of the rotatable member.

4. The method of claim 1 , wherein the second frequency band includes a harmonic frequency of the rotational speed of the rotatable member.

5. The method of claim 1 , wherein transforming the sound spectrum to the residual spectrum comprises determining a moving average for the sound spectrum, and subtracting the moving average from the sound spectrum to determine the residual spectrum.

6. The method of claim 1 , further comprising:

capturing the acoustic signal when the rotational speed of the rotatable member is at the steady-state condition and is within a first speed range;

extracting first and second features from a first residual spectrum associated with the acoustic signal when the rotational speed is within the first speed range;

capturing the acoustic signal when the rotational speed of the rotatable member is at the steady-state condition and is within a second speed range;

extracting third and fourth features from a second residual spectrum associated with the acoustic signal when the rotational speed is within the second speed range; and

detecting a fault associated with the machine bearing based upon the first, second, third and fourth features.

7. The method of claim 1 , wherein determining the state of health associated with the machine bearing based upon the first and second features comprises:

detecting a fault or degradation associated with the machine bearing based upon the first and second features; and

communicating, via the controller, the fault or the degradation associated with the machine bearing to a second controller.

8. A method for monitoring a machine bearing that is disposed on a rotatable member of a vehicle, the method comprising:

monitoring, via a plurality of microphones, a plurality of acoustic signals proximal to the machine bearing and monitoring, via a position sensor, a rotational speed of the rotatable member associated with the machine bearing;

capturing the plurality of acoustic signals when the rotational speed of the rotatable member is at a steady-state condition;

for each of the acoustic signals monitored by the plurality of microphones:

executing, via a controller, a time-frequency analysis of each of the acoustic signals to determine a corresponding sound spectrum;

transforming each of the corresponding sound spectrums to a corresponding residual spectrum;

extracting, for each residual spectrum, a first feature, wherein the first feature is associated with a first frequency band;

extracting, for each residual spectrum, a second feature, wherein the second feature is associated with a second frequency band;

detecting a fault associated with the machine bearing based upon the first features and the second features; and

communicating, via the controller, the fault associated with the machine bearing to a second controller.

9. The method of claim 8 , further comprising capturing the plurality of acoustic signals for a preset window of time when the rotational speed is at the steady-state condition.

10. The method of claim 8 , wherein the first frequency band includes a harmonic frequency of the rotational speed of the rotatable member.

11. The method of claim 8 , wherein the second frequency band includes a harmonic frequency of the rotational speed of the rotatable member.

12. The method of claim 8 , wherein transforming each of the sound spectrums to a respective residual spectrum comprises determining a moving average for the respective sound spectrum, and subtracting the moving average from the respective sound spectrum to determine the respective residual spectrum.

13. A device, including:

a machine bearing disposed on a rotatable member;

a microphone disposed proximal to the machine bearing;

a rotational position sensor disposed to monitor the rotatable member; and

a controller, in communication with the rotational position sensor and the microphone, the controller including an instruction set, the instruction set executable to:

monitor, via the microphone, an acoustic signal,

monitor, via the rotational position sensor, a rotational speed of the rotatable member,

capture the acoustic signal when the rotational speed of the rotatable member is at a steady-state condition;

execute a time-frequency analysis of the acoustic signal to determine a sound spectrum,

transform the sound spectrum to a residual spectrum,

extract a first feature from the residual spectrum, wherein the first feature is within a first frequency band,

extract a second feature from the residual spectrum, wherein the second feature is within associated with a second frequency band, and

detect a fault associated with the machine bearing based upon the first and second features.

14. The device of claim 13 , further comprising the instruction set executable to communicate the fault associated with the machine bearing to a second controller.

15. The device of claim 14 , wherein the second controller is disposed remote from the device.

16. The device of claim 13 , further comprising the controller configured to:

capture the acoustic signal for a preset window of time when the rotational speed is at the steady-state condition; and

execute a time-frequency analysis of the acoustic signal that is captured when the rotational speed is at the steady-state condition to determine the sound spectrum.

17. The device of claim 13 , wherein the first and second frequency bands are harmonic frequencies of the rotational speed of the rotatable member.

18. The device of claim 13 , wherein the instruction set executable to transform the sound spectrum to the residual spectrum comprises the instruction set executable to determine a moving average for the sound spectrum, and subtract the moving average from the sound spectrum to determine the residual spectrum.