Method and apparatus for self-diagnosis of a sensor

• US 6,510,397 B1
• Filed: 03/13/1999
• Issued: 01/21/2003
• Est. Priority Date: 03/13/1999
• Status: Expired due to Term

• Current Assignee: Textron Innovations Incorporated (Textron Inc)
• Original Assignee: Textron Systems Corporation (Textron Inc)
• Inventors: Choe, Howard C.
• Primary Examiner(s): ASSOUAD, PATRICK J
• Application Number:
  US09/268,105
• Time in Patent Office: 1,410 Days
• Field of Search: 702/33-36, 702/56-57, 702/104, 702/108, 702/113-116, 702/122, 702/124, 702/127, 702/179, 702/180, 702/193, 702/182-185, 702/187-191, 702/195, 702/197, 702/FOR.103, 702/FOR.104, 702/FOR-123, 702/FOR-134, 702/FOR.139, 702/FOR.141, 702/FOR.155, 702/FOR.164, 702/FOR.166, 702/FOR-170, 73/10.1, 73/350.3, 73/17.3, 733/13, 733/02, 737/14, 732/92, 731/181, 340/635, 477/906
• US Class Current: 702/116
• CPC Class Codes: F16H 57/0006 Vibration-damping or noise reducing means specially adapted for gearings devices for varying tension of belts, ropes or chains with damping means F16H7/0829; toothed members with construction providing vibration damping F16H55/14; reducing vibrations or noise of the gearbox casing F16H57/028; suppression of vibrations or noise of gear selectors F16H59/0208; control of hydrostatic fluid gearing preventing or reducing vibrations or noise F16H61/4183
• CPC Class Codes: F16H 57/01 Monitoring wear or stress of gearing elements, e.g. for triggering maintenance
• CPC Class Codes: G01D 3/08 with provision for safeguarding the apparatus, e.g. against abnormal operation, against breakdown
• CPC Class Codes: G01L 19/0092 Pressure sensor associated with other sensors, e.g. for measuring acceleration or temperature G01L9/025, G01L9/045, G01L9/065, G01L9/085, G01L9/105, G01L9/125, G01L19/02, G01L19/04 take precedence; measuring two or more variable G01D21/02; temperature sensors with pressure compensation G01K1/26

Abstract

The present invention is a method and apparatus for determining whether the sensors or the used in a device monitoring system are properly functioning before rendering a determination as to a defect within the device itself. As a result, maintenance costs may be reduced while limiting the number of false indications of failure, thereby increasing the reliability of the monitoring system.

Claims

1. A method for self-diagnosing sensors for use in a device monitoring system, said method comprising the steps of:

receiving a signal from a sensor and a sensor channel representing a noise threshold;

receiving a signal from said sensor and said sensor channel when said sensor is energized to obtain a sensed value; and

,

determining whether said sensor is operational based on whether said sensed value exceeds said noise threshold.

2. A method according to claim 1 wherein said step of receiving a signal from a sensor and a sensor channel representing a noise threshold comprises the step of receiving a signal from a sensor and a sensor channel when a sensor is de-energized.

3. A method according to claim 1 wherein said step of receiving a signal from a sensor and a sensor channel comprises the step of accessing a stored noise threshold signal.

4. A method according to claim 1 further comprising the steps of:

receiving signals from a plurality of sensors and sensor channels when said sensors are de-energized; and

,

receiving signals from said plurality of sensors and said sensor channels when said sensors are energized.

5. A method according to claim 4 further comprising the steps of:

generating, for each sensor, sensor status values based on said determination;

comparing said values to each other; and

,

determining a malfunctioning sensor based on said comparison of said values.

6. A method according to claim 5 further comprising the step of:

performing a statistical analysis to determine a malfunctioning sensor when more than one sensor is determined to be malfunctioning.

7. A method according to claim 6 wherein said statistical analysis comprises one of a mean-time-to-failure analysis and a statistical trending analysis.

8. A method according to claim 1 further comprising the steps of:

receiving a plurality of signals from a sensor and a sensor channel during a single operating state, with said single operating state defining a state when said sensor is one of energized and de-energized; and

,

generating an average value of said plurality of signals.

19. A method according to claim 1 wherein said determining step comprises the step of determining whether said sensor is in an open circuit condition.

20. A method according to claim 1 wherein said determining step comprises the step of determining whether said sensor is in a short circuit condition.

9. A self-diagnostic system for diagnosing a sensor for use in a device monitoring system, said diagnostic system comprising a processing unit for receiving a signal from a sensor and a sensor channel representing a noise threshold, receiving a signal from said sensor and said sensor channel when said sensor is energized to obtain a sensed value, and determining whether said sensor is operational based on whether said sensed value exceeds said noise threshold.

10. A self-diagnostic system according to claim 9 wherein said noise threshold is determined based on a signal from said sensor and said sensor channel when a sensor is de-energized.

11. A self-diagnostic system according to claim 9 wherein said noise threshold signal is stored in memory.

12. A self-diagnostic system according to claim 9 wherein said processing unit further receives signals from a plurality of sensors when said sensors are de-energized and receives signals from said plurality of sensors during when said sensors are energized.

13. A self-diagnostic system according to claim 9 wherein said processing unit further generates, for each sensor, sensor status values based on said determination, compares said values to each other and determines a malfunctioning sensor based on said comparison of said values.

14. A self-diagnostic system according to claim 13 wherein said processing unit further performs a statistical analysis to determine a malfunctioning sensor when more than one sensor is determined to be malfunctioning.

15. A self-diagnostic system according to claim 14 wherein said statistical analysis comprises one of a mean-time-to-failure analysis and a statistical trending analysis.

16. A self-diagnostic system according to claim 9 wherein said processing unit further receives a plurality of signals from a sensor and a sensor channel during a single operating state, with said single operating state defining a state when said sensor is one of energized and de-energized and said processing unit is energized, and generates an average value of said plurality of signals.

17. A self-diagnostic system according to claim 9 in combination with said device monitoring system.

18. A self-diagnostic system according to claim 17 further comprising a plurality of sensors.

21. A self-diagnostic system according to claim 9 wherein said processing unit further determines whether said sensor is in an open circuit condition.

22. A self-diagnostic system according to claim 9 wherein said processing unit further determines whether said sensor is in a short circuit condition.

23. A method for self-diagnosing sensors for use in a device monitoring system, said method comprising the steps of:

generating, for each sensor, sensor status values;

comparing said values to each other;

determining a malfunctioning sensor based on said comparison of said values; and

performing a statistical analysis to determine a malfunctioning sensor when more than one sensor is initially determined to be malfunctioning.

24. A method according to claim 23 wherein said statistical analysis comprises one of a mean-time-to-failure analysis and a statistical trending analysis.

25. A self-diagnostic system for diagnosing a sensor for use in a device monitoring system, said self-diagnostic system comprising a processing unit for generating, for each sensor, sensor status values, for comparing said values to each other and for determining a malfunctioning sensor based on said comparison of said values;

wherein said processing unit further performs a statistical analysis to determine a malfunctioning sensor when more than one sensor is initially determined to be malfunctioning.

26. A self-diagnostic system according to claim 25 wherein said statistical analysis comprises one of a mean-time-to-failure analysis and a statistical trending analysis.

27. A monitoring system for a gearbox comprising:

a sensor for sensing gearbox operating conditions;

a processing unit for receiving sensed operating conditions of the gearbox and for determining a condition of the gearbox, said processing unit comprising a self-diagnostic routine for diagnosing said sensor, said routine causing said processing unit to receive a signal from said sensor through a sensor channel to obtain a noise threshold when the sensor is de-energized, causing said processing unit to receive a signal from said sensor through said sensor channel when said sensor is energized to obtain a sensed value, and causing said processing unit to determine whether said sensor is operational based on whether said sensed value exceeds or is close to said noise threshold.