System to monitor the health of a structure, sensor nodes, program product, and related methods

• US 20070118301A1
• Filed: 11/23/2005
• Published: 05/24/2007
• Est. Priority Date: 11/23/2005
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Berkcan, Ertugrul, Andarawis, Emad, Seeley, Charles, Wojnarowski, Robert, Delgado, Eladio, Gruber, Nanette, Coulter, Richard, Sealing, C.
• Granted Patent: US 7,558,701 B2
• Time in Patent Office: Days
• US Class Current: 702/33
• CPC Class Codes: G01M 5/00 Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings G01M9/00 takes precedence
• CPC Class Codes: G05B 2219/37254 Estimate wear of subsystem of machine with measures from other subsystems
• CPC Class Codes: G05B 2219/37494 Intelligent sensor, data handling incorporated in sensor
• CPC Class Codes: G05B 2219/37516 Combine results, opinions of multiple but same sensors, fuzzy logic
• CPC Class Codes: G05B 23/0221 Preprocessing measurements, e.g. data collection rate adjustment; Standardization of measurements; Time series or signal analysis, e.g. frequency analysis or wavelets; Trustworthiness of measurements; Indexes therefor; Measurements using easily measured parameters to estimate parameters difficult to measure; Virtual sensor creation; De-noising; Sensor fusion; Unconventional preprocessing inherently present in specific fault detection methods like PCA-based methods

Abstract

A system to monitor the health of a structure, health monitoring sensor nodes, program product, and associated methods are provided. The system includes an array of health monitoring sensor nodes connected to or embedded within a structure to monitor the health of the structure. Each health monitoring sensor node includes sensor elements positioned to sense parameters of the structure and to provide data related to the parameters to a health monitoring sensor node interrogator. Each health monitoring sensor node includes a processor or other means reducing raw sensor data to thereby reduce communication bandwidth requirements, and can include memory or other storage for storing the reduced data and an antenna arrangement for providing the reduced data to the health monitoring sensor node interrogator.

Claims

1. A multi-node sensor system to monitor the structural health of a structure, the system comprising:

a structure to be monitored having a body;

a plurality of separate and spaced apart health monitoring sensor nodes each connected to or embedded within the body of the structure to monitor data related to parameters of a portion of the body of the structure, each node having a sensor element positioned to sense parameters of a respective portion of the body of the structure to define sensed parameters, a processor coupled to the sensor to receive sensed parameters to define raw sensor data, and memory coupled to the processor to store operating instructions therein;

an interrogator having a transceiver positioned to request data from each of the plurality of health monitoring sensor nodes and to receive requested data therefrom; and

parameter processing program product separately stored in the memory of each of the plurality of health monitoring sensor nodes and including instructions that when executed by the respective processor performs the operations of reducing the raw sensor data to define reduced data, detecting an interrogation signal, and providing the reduced data to the interrogator.

2. The system as defined in claim 1,

wherein the parameter processing program product includes instructions to perform the operations of:

sampling sensor output from the associated sensor element to thereby form the raw sensor data,

comparing the raw sensor data to a preselected threshold value, to thereby determine if the preselected threshold value is exceeded defining a threshold crossing event,

recording each threshold crossing event responsive to determining that the threshold value is exceeded; and

wherein the reduced data includes data indicating a number of threshold crossing events.

3. The system as defined in claim 2,

wherein event recording includes incrementing an event counter.

4. The system as defined in claim 1, wherein the parameter processing program product includes instructions to perform the operations of:

sampling sensor output from the associated sensor element to thereby form the raw sensor data;

comparing the raw sensor data to a threshold value, to thereby determine if the threshold value is exceeded;

incrementing an event count responsive to determining that the threshold value is exceeded; and

adaptively resetting the threshold value to define an adaptive threshold responsive to the event count exceeding the adaptive threshold value.

5. The system as defined in claim 4, wherein the reduced data includes at least one of the following:

data indicating a number of threshold crossings;

data indicating a number of threshold crossings for each respective threshold value;

data indicating a final state of the adaptive threshold; and

data indicating a time history of the adaptive threshold.

6. The system as defined in claim 4, wherein the threshold value is a first threshold value, and wherein the instructions to perform the operation of adaptively resetting the threshold includes:

resetting the first threshold value responsive to the event count exceeding a first preselected value to form a second threshold value; and

resetting the second threshold value responsive to the event count exceeding the second threshold value to form a third threshold value.

7. The system as defined in claim 4,

wherein the parameter processing program product includes instructions to perform the operation of forming a trend of a number of threshold crossing events over time;

and

wherein the reduced data includes data indicating the trend of the number of threshold crossing events.

8. The system as defined in claim 1,

wherein the parameter processing program product includes instructions to perform the operations of:

sampling sensor output from each of the plurality of sensor elements to thereby form the raw sensor data, and

iteratively comparing the raw sensor data to prior trend data describing a prior trend in the raw sensor data, to thereby determine a current trend in the raw sensor data; and

wherein the reduced data includes a description of the current trend in the raw sensor data.

9. The system as defined in claim 1,

wherein the parameter processing program product includes instructions to perform the operations of:

sampling sensor output from the associated sensor element to thereby form the raw sensor data for the respective node,

iteratively comparing the raw sensor data to prior trend data describing a prior trend in the raw sensor data, to thereby determine a current trend in the raw sensor data, and

fitting a descriptive curve to the current trend in the raw sensor data to thereby describe the current trend in the raw sensor data; and

wherein the reduced data includes parameters describing the fitted curve.

10. The system as defined in claim 9, wherein the parameter processing program product includes instructions to perform the operation of receiving from the interrogator the prior trend data describing at least a portion of the prior trend in the raw sensor data.

13. The method as defined in claim 11, wherein the method further comprises the steps of:

sampling sensor output by the health monitoring sensor node from an associated sensor element to thereby form the raw sensor data;

iteratively comparing the raw sensor data by the health monitoring sensor node to a threshold value, to thereby determine if the threshold value is exceeded;

incrementing an event count by the health monitoring sensor node responsive to determining that the threshold value is exceeded; and

adaptively resetting the threshold value by the health monitoring sensor node to define an adaptive threshold responsive to the respective event count exceeding the adaptive threshold value.

14. The method as defined in claim 13, wherein the reduced data includes at least one of the following:

data indicating a number of threshold crossings;

data indicating a number of threshold crossings for each respective threshold value;

data indicating a final state of the adaptive threshold; and

data indicating a time history of the adaptive threshold.

15. The method as defined in claim 13, wherein the threshold value is a first threshold value, and wherein the method includes adaptively resetting the threshold by the health monitoring sensor node which further includes the steps of:

resetting the first threshold value responsive to the event count exceeding a first preselected value to form a second threshold value; and

resetting the second threshold value responsive to the event count exceeding the second threshold value to form a third threshold value.

16. The method as defined in claim 13, wherein the threshold value is a first threshold value, and wherein the method includes adaptively resetting the threshold value by the health monitoring sensor node which further includes the steps of:

resetting the first threshold value responsive to the raw sensor data not reaching the first threshold value for a first time period to form a second threshold value; and

resetting the second threshold value responsive to the raw sensor data not reaching the second threshold value for a second time period to form a third threshold value.

17. The method as defined in claim 13,

wherein the method further includes the step of forming over time a trend of a number of threshold crossing events by the health monitoring sensor node;

and

wherein the reduced data includes data indicating the trend of the number of threshold crossing events.

11. A method to monitor the structural health of a structure, the method comprising the steps of:

positioning a health monitoring sensor node on or within a body of a structure to be monitored;

sensing parameters of the body of the structure by the health monitoring sensor node to define sensed parameters;

processing the sensed parameters by the health monitoring sensor node to define raw sensor data;

reducing the raw sensor data by the health monitoring sensor node to define reduced data to thereby reduce data transmission bandwidth requirements;

receiving by the health monitoring sensor node an interrogation signal from an interrogator; and

providing to the interrogator the reduced data responsive to receiving the interrogation signal.

12. The method as defined in claim 11,

wherein the method further includes the steps of:

iteratively sampling sensor output by the health monitoring sensor node from an associated sensor element to thereby form the raw sensor data,

iteratively comparing the raw sensor data by the health monitoring sensor node to a threshold value, to thereby determine if the threshold value is exceeded defining a threshold crossing event,

incrementing an event counter by the health monitoring sensor node responsive to determining that the threshold value is exceeded to thereby record the number of threshold crossing events; and

wherein the reduced data includes data indicating the number of threshold crossing events.

18. The method as defined in claim 11,

wherein the method further comprises the steps of:

sampling sensor output by the health monitoring sensor node from an associated sensor element to thereby form the raw sensor data, and

comparing the raw sensor data to prior trend data in the raw sensor data by the health monitoring sensor node to thereby determine a current trend in the raw sensor data; and

wherein the reduced data includes a description of the current trend in the raw sensor data.

19. The method as defined in claim 11,

wherein the method further comprises the steps of:

sampling sensor output by the health monitoring sensor node from an associated sensor element to thereby form the raw sensor data,

comparing the raw sensor data to prior trend data describing a prior trend in the raw sensor data by the health monitoring sensor node, to thereby determine a current trend in the raw sensor data, and

fitting a descriptive curve to the current trend in the raw sensor data by the health monitoring sensor node to thereby describe the current trend in the raw sensor data; and

wherein the reduced data includes parameters describing the fitted curve.

20. The method as defined in claim 11, wherein the method further comprises the step of:

sampling sensor output by the health monitoring sensor node from an associated sensor element to thereby form the raw sensor data;

comparing the raw sensor data to a threshold value, to thereby determine if the threshold value is exceeded; and

recording a description of the raw sensor data responsive to determining that the threshold value is exceeded.

21. A method to monitor the structural health of a structure, the method comprising the steps of:

positioning a health monitoring sensor node including a sensor element on or within a body of a structure to be monitored;

sampling sensor output by the health monitoring sensor node from the associated sensor element to thereby form raw sensor data;

comparing a value of the raw sensor data to a threshold value by the health monitoring sensor node, to thereby determine if the threshold value is exceeded;

incrementing an event count by the health monitoring sensor node responsive to determining that the threshold value is exceeded;

adaptively resetting by the health monitoring sensor node the threshold value to define an adaptive threshold responsive to the event count exceeding at least one predetermined value;

receiving by the health monitoring sensor node an interrogation signal from an interrogator; and

providing to the interrogator responsive to receiving the interrogation signal, one of the following forms of reduced raw sensor data;

data indicating a number of threshold crossings, data indicating a number of threshold crossings for each respective threshold value, data indicating a final state of the adaptive threshold, and data indicating a time history of the adaptive threshold, the reduced raw sensor data having a reduced transmission bandwidth requirement.

22. A method to monitor the structural health of a structure, the method comprising the steps of:

positioning a health monitoring sensor node on or within a body of a structure to be monitored, each node including a sensor element;

sampling sensor output by the health monitoring sensor node from the associated sensor element to thereby form raw sensor data;

iteratively comparing by the health monitoring sensor node the raw sensor data to prior trend data describing a prior trend in the raw sensor data, to thereby determine a current trend in the raw sensor data;

receiving by the health monitoring sensor node an interrogation signal from an interrogator; and

providing to the interrogator by the health monitoring sensor node indicia of the current trend responsive to the interrogation signal, the indicia of the current trend providing a reduced data transmission bandwidth requirement.

23. The method as defined in claim 22,

wherein the method further includes the step of fitting a descriptive curve to the current trend in the raw sensor data;

and

wherein the step of providing to the interrogator indicia of the current trend includes providing to the interrogator parameters describing the fitted curve.