Device and method for the early recognition and prediction of unit damage

• US 7,039,557 B2
• Filed: 07/03/2002
• Issued: 05/02/2006
• Est. Priority Date: 09/07/2001
• Status: Expired due to Fees

• Current Assignee: Ramsle Technology Group GmbH LLC (Intellectual Ventures LLC)
• Original Assignee: Daimler Chrysler Company LLC (Stellantis NV)
• Inventors: Spiegelberg, Gernot, Schwarzhaupt, Andreas, Mayer, Christian-Michael
• Primary Examiner(s): Raymond, Edward
• Application Number:
  US10/488,860
• Publication Number:
  US 20050049835A1
• Time in Patent Office: 1,399 Days
• Field of Search: 702182-185, 702/58, 702188-189, 702/145, 714/25, 714/30, 714/39, 714/42, 714/47
• US Class Current: 702/184
• CPC Class Codes: G07C 3/00 Registering or indicating the condition or the working of machines or other apparatus, other than vehicles
• CPC Class Codes: G07C 5/00 Registering or indicating the working of vehicles
• CPC Class Codes: G07C 5/0808 Diagnosing performance data testing of vehicles G01M17/00; testing of electrical installation on vehicles G01R31/005

Abstract

In a method and apparatus for early detection and prediction of damage to assemblies in machine plants, including mobile machine plants, structure-borne sound of the machine system is sensed by a sensor, output as an acceleration signal and analyzed in a digital signal processor. For this purpose, the acceleration signal is first transformed into the frequency domain by means of a fast-Fourier transformation, and the data obtained in this manner are then transformed back into the time domain by means of cepstrum analysis, so that resonance data relating to individual shock pulses (a cepstrum) is obtained in the time domain. This cepstrum is then compared with a reference cepstrum that is selected in accordance with load signals and rotational speed signals for the present operating state in a new machine plant in a storage device. When limiting values are exceeded, the diagnostic signal (in particular information relating to the assembly which is diagnosed as damaged and its predicted remaining service life) are displayed for the user and an emergency operating mode is initiated.

Claims

1. A device for early detection and prediction of damage to assemblies in a machine plant, comprising:

at least one sensor which senses structure-borne sound in a machine plant that is being monitored, and which emits an analog measuring signal;

an analog/digital converter device coupled to receive the analog measuring signal and convert it into a digital measuring signal;

a digital signal processor, including a fast-Fourier transformation device for transforming the digital measuring signal into the frequency domain, and a cepstrum analysis device for generating a cepstrum containing resonance data relating to individual shock pulses in the time domain from the fast-Fourier-transformed digital measuring signal; and

a storage device having stored therein a reference cepstrum that is representative of a new machine plant, for each of various operating states of the machine plant that is being monitored, together with an empirical value matrix relating to damaged assemblies and assembly components and anticipated remaining service lives;

wherein,

based on rotational speed information and load information the digital signal processor reads from the storage device a reference cepstrum that is representative of a new machine plant which is being operated in a current operating state of the storage device of the machine plant that is being monitored;

the digital signal processor compares said reference cepstrum that is read from the storage device with a present cepstrum that is generated in the digital signal processor, and outputs a comparison result;

a monitoring device monitors the comparison result of the present cepstrum and associated reference cepstrum to detect instances in which limiting values are exceeded, and forwards to the digital signal processor event information indicative of said instances in which said limiting values are exceeded; and

in response to said event information provided by the monitoring device, and by referring to the empirical value matrix, the digital signal processor identifies a damaged assembly or assembly component, as well as its predicted remaining service life, and outputs to a central processor unit for further processing, a diagnostic signal, including information relating to damaged assemblies and their predicted remaining service life.

2. The device as claimed in claim 1, wherein, to determine the predicted remaining service life of a damaged assembly or assembly component, the digital signal processor also takes into account stored information regarding the history of the machine plant.

3. The device as claimed in claim 1, wherein the central processor unit displays the information contained in the diagnostic signal, relating to damaged assemblies and their predicted remaining service lives, on a display device or transmits said information by telemetry to a corresponding workshop or a machine plant operator.

4. The device as claimed in claim 1, wherein, in response to diagnostic signal for assemblies which are diagnosed as damaged, the central processor unit implements an emergency operating mode to prevent or reduce further damage to the damaged assembly and to ensure further availability of the machine plant.

5. The device as claimed in claim 4, wherein, if further possibilities for an emergency operating mode are present, the central processor unit displays such possibilities to a user for selection, so that the user can select an emergency operating mode in accordance with an alternative which suits him best.

6. The device as claimed in claim 1, wherein the machine plant is one of a drive train, a drive train component and a steering system.

7. The device as claimed in claim 6, wherein, when damage to the transmission is diagnosed in the emergency operating mode, a gear speed corresponding to such damage is jumped over, or the power or speed is reduced.

8. The device as claimed in claim 6, wherein, when a defect is diagnosed in a retarder as a drive train component in the emergency operating mode, the retarder is switched off, and a brake system assumes its function.

9. The device as claimed in claim 6, wherein, when a defect is diagnosed in a brake as a drive train component in the emergency operating mode, the function of the brake is taken over by a retarder.

10. The device as claimed in claim 1, wherein a wavelet analysis device is used to detect a damaged assembly.

11. A method for early detection and prediction of damage to assemblies in a machine plant, said method comprising:

sensing structure-borne sound from a machine plant that is being monitored, and issuing an analog measuring signal that is indicative thereof;

converting the analog measuring signal into a digital measuring signal;

transforming the digital measuring signal into the frequency domain, using a fast-Fourier transformation;

generating a present cepstrum containing resonance data relating to individual shock pulses in the time domain, by means of cepstrum analysis, based on a result of said fast-Fourier transformation;

based on rotational speed information and load information, a digital signal processor reading from a storage device a reference cepstrum that is representative of a new machine plant that is being operated in a current operating state of the machine plant that is being monitored;

the digital signal processor comparing said reference cepstrum that is read from the storage device with the present cepstrum, and outputting a comparison result;

monitoring said comparison result, to detect instances in which limiting values are exceeded; and

providing to the digital signal processor event information indicative of said instances in which said limiting values are exceed;

based on said event information, and by reference to an empirical value matrix, determining a damaged assembly or assembly component, as well as its predicted remaining service life; and

generating a diagnostic signaling that contains information relating to damaged assemblies and their predicted remaining service lives, and providing said diagnostic signal to a central processor unit for further processing.

12. The method as claimed in claim 11, stored information relating to history of the machine plant is also taken into account in determining the predicted remaining service life of a damaged assembly or assembly component.

13. The method as claimed in claim 11, further comprising at least one of:

displaying information contained in the diagnostic signal relating to damaged assemblies and their predicted remaining service life or a user; and

transmitting said information by telemetry to a corresponding workshop or a machine plant operator.

14. The method as claimed in claim 11, further comprising:

implementing an emergency operating mode in response to the diagnostic signal for assemblies which are diagnosed as damaged, to prevent or reduce further damage to the assembly which is diagnosed as damaged, and to ensure further availability of the machine plant.

15. The method as claimed in claim 14, further comprising:

if a plurality of possibilities are available for an emergency operating mode, said plurality selection are displayed for a user, so that the user can select a most desired an emergency operating mode.

16. The method as claimed in claim 14, wherein, if the damaged machine plant is a drive train, a gear speed corresponding to damage to the gearbox is jumped over, or the engine power or engine speed is reduced, as an emergency operating mode.

17. The method as claimed in claim 14, wherein, if the machine system is a drive train, a retarder is switched off and a brake system assumes its function as an emergency operating mode if a defect is diagnosed in the retarder.

18. The method as claimed in claim 14, wherein, if the machine system is a drive train, the function of a brake is assumed by a retarder in the emergency operating mode if a defect is diagnosed in the brake as drive train component.