Energy harvesting, wireless structural health monitoring system

• US 20080036617A1
• Filed: 09/11/2006
• Published: 02/14/2008
• Est. Priority Date: 09/09/2005
• Status: Active Grant

• Current Assignee: Hottinger Bruel & Kjaer Incorporated
• Original Assignee: MicroStrain, Inc. (Spectris PLC)
• Inventors: Arms, Steven W., Hamel, Michael John, Townsend, Chris Pruyn, Churchill, David Lawrence
• Granted Patent: US 7,719,416 B2
• Time in Patent Office: Days
• US Class Current: 340/679
• CPC Class Codes: B64C 2027/002 mounted between the rotor drive and the fuselage
• CPC Class Codes: B64C 27/006 Safety devices
• 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: G07C 5/085 using electronic data carriers

Abstract

A method of maintaining a structure includes providing a structure having a component subject to failure. A sensor, a memory and an energy harvesting device are mounted on the structure. The sensor is used and data derived from the sensor logged in the memory, wherein the memory is powered solely with energy derived from the energy harvesting device. The component is replaced if information in the memory shows that the component was subject to damaging usage.

Claims

1. A method of maintaining a structure comprising,

a. providing a structure having a component subject to component failure;

b. mounting a sensor, a memory and an energy harvesting device on the structure;

c. using said sensor and logging data derived from said sensor in said memory, wherein said memory is powered solely with energy derived from said energy harvesting device; and

d. replacing said component if information in said memory shows that said component was subject to damaging usage.

2. A structure as recited in claim 1, wherein said structure comprises a vehicle.

3. A structure as recited in claim 2, wherein said vehicle comprises an aircraft.

4. A structure as recited in claim 3, wherein said aircraft comprises a helicopter.

5. A structure as recited in claim 1, wherein said component comprises a rotating part.

6. A structure as recited in claim 5, wherein said component comprises a helicopter pitch link.

7. A structure as recited in claim 1, wherein said sensor includes at least one from the group including a strain gauge and a piezoelectric transducer.

8. A structure as recited in claim 7, further comprising providing a programmable triaxial strain gauge signal conditioner with integral self calibration.

9. A method of operating a system as recited in claim 1, wherein said sensor includes at least one from the group consisting of an inertial sensing suite and a GPS.

10. A structure as recited in claim 9, further comprising providing a processor.

11. A structure as recited in claim 10, wherein said processor is connected for controlling operation of said wireless communication device.

12. A structure as recited in claim 10, further comprising providing a multiplexer connected to provide data derived from a plurality of sensors to said processor.

13. A method of operating a system as recited in claim 9, further comprising using said processor to perform calculations and further comprising transmitting results of said calculations.

14. A structure as recited in claim 1, wherein said memory includes a volatile memory portion and a non-volatile memory portion.

15. A structure as recited in claim 1, further comprising providing data directly from said sensor to said volatile memory portion and then transferring said data to said non-volatile memory.

16. A structure as recited in claim 1, further comprising providing a low power time keeper and providing a periodic signal to said processor from said low power time keeper for waking said processor from sleep mode.

17. A method of operating a system as recited in claim 16, wherein power to said processor is turned off during time between said periodic signals.

18. A method of operating a system as recited in claim 16, further comprising providing burst mode sampling data from said sensor.

19. A method of operating a system as recited in claim 18, further comprising buffering data acquired in said burst mode sampling before transmitting said data on said wireless communication device.

20. A method of operating a system as recited in claim 16, further comprising an amplifier, wherein during said waking said processor said amplifier is kept out of saturation.

21. A method of operating a system as recited in claim 1, further comprising mounting a wireless communications device to the structure and transmitting data derived from said sensor with said wireless communications device, wherein all power for operating said wireless communications device is derived from said energy harvesting device.

22. A method of operating a system as recited in claim 21, wherein said wireless communication device includes an 802.15.4 transceiver.

23. A method of operating a system as recited in claim 1, further comprising providing a wired network for connecting sensors for logging to said memory.

24. A method of operating a system as recited in claim 1, further comprising wirelessly connecting sensors for logging data to said memory.

25. A method of operating a system as recited in claim 1, further comprising connecting an actuator to said sensor module.

26. A method of operating a system as recited in claim 25, wherein said actuator is connected for providing a signal to said structure for material testing.

27. A method of operating a system as recited in claim 1, further comprising providing encryption to said information before transmitting.

28. A method of operating a system as recited in claim 1, further comprising providing a warning to said information before transmitting.

29. A method of operating a system as recited in claim 1, wherein said sensor module is one in a network of sensor modules.

30. A method of operating a system as recited in claim 29, wherein said network of sensor modules is arranged in a mesh network.

31. A method as recited in claim 1, further comprising a rechargeable battery connected for recharging from said energy harvesting device.

32. A method of operating a system as recited in claim 1, wherein said damaging usage includes a load exceeding a threshold.

33. A method of operating a system as recited in claim 1, wherein said damaging usage includes fatigue inducing cyclic loading.

34. A method of operating a structure comprising:

a. providing a structure having a component subject to component failure;

b. mounting a sensor module to said structure for measuring a parameter related to component failure, wherein said sensor module includes a sensor, a wireless communication device and an energy harvesting device;

c. acquiring data with said sensor;

d. providing information derived from said data to said wireless communication device;

e. powering said wireless communications device solely with energy derived from said energy harvesting device;

f. transmitting said information with said wireless communication device;

g. using said information to adjust operation of said structure so as to avoid damaging usage.

35. A method of operating a system as recited in claim 34, further comprising providing a warning if said information shows that said component is subject to damaging usage.

36. A method of operating a system as recited in claim 34, wherein said damaging usage includes a load exceeding a threshold.

37. A method of operating a system as recited in claim 34, wherein said damaging usage includes fatigue inducing cyclic loading.

38. A method of operating a system as recited in claim 34, further comprising using said information to set a time for maintaining said structure.

39. A method of operating a structure comprising,

a. providing a structure having a component subject to component failure;

b. mounting a sensor, a memory and an energy harvesting device on the structure;

c. using said sensor and logging data derived from said sensor in said memory, wherein said memory is powered solely with energy derived from said energy harvesting device; and

d. using information in said memory to adjust operation of said structure so as to avoid damaging usage.

40. A system comprising, a network of sensor nodes wherein each said sensor node includes a sensor, a processor, a memory, a low power time keeper, a wireless communication device and an energy harvesting device, said processor connected to receive data derived from said sensor, said memory connected for storing data derived from said sensor, said low power time keeper connected to periodically provide a signal to wake said processor from a sleep mode, said wireless communication device connected for communicating data derived from said sensor, said energy harvesting device connected for harvesting energy to power said processor, said memory, and said wireless communications device.

41. A method of operating a system comprising:

a. providing a sensor node including a sensor, a processor, a memory, a low power time keeper, a wireless communication device and an energy harvesting device;

b. providing a signal from said low power time keeper to the processor to power up said processor from a powered off or a low powered condition at predetermined intervals of time;

c. using energy derived from said energy harvesting device to provide power for operating at least one from the group consisting of said processor, said memory, and said wireless communications device;

d. providing data derived from said sensor to said processor;

e. storing data derived from said sensor in said memory; and

f. using said wireless communication device to externally communicate data derived from said sensor.

42. A method of operating a system as recited in claim 41, wherein power is turned off between said intervals of time.

43. A method of operating a system as recited in claim 41, wherein said sensor node is mounted on a structure, further comprising using data derived from said sensor to set a time for maintaining said structure.

44. A structure, comprising a wireless instrumented structural component including a first sensor, a second sensor, a processor, a transmitter, and an energy harvesting device, wherein said first sensor is for measuring a first property related to structural load in said structural component, said second sensor is for measuring a second property related to structural load in said structural component, wherein said first property differs from said second property, wherein said transmitter is connected to provide load data for said structural component, wherein all power for operating said transmitter is derived from said energy harvesting device, wherein said processor is connected to receive an output derived from said second sensor for verifying operation of said first sensor.

45. A structure as recited in claim 44, wherein said first sensor includes a strain gauge.

46. A structure as recited in claim 44, wherein said second sensor includes a piezoelectric transducer.

47. A structure as recited in claim 46, wherein said energy harvesting device includes said piezoelectric transducer.

48. A method as recited in claim 44, further comprising a rechargeable battery connected for recharging from said energy harvesting device.

49. A structure as recited in claim 44, wherein said structural component comprises an aircraft part.

50. A structure as recited in claim 44, wherein said structural component comprises a helicopter part.

51. A method of using a structure, comprising

a. providing a wireless instrumented structural component mounted to the structure, said wireless instrumented structural component including a first sensor, a second sensor, a transmitter, and an energy harvesting device, said first sensor for measuring a first property related to structural load in said structural component, said second sensor for measuring a second property related to structural load in said structural component, wherein said first property differs from said second property;

b. comparing data from said first sensor with data from said second sensor to determine that said first sensor is operating properly;

c. providing energy from said energy harvesting device wherein all power for operating said transmitter is derived from said energy harvesting device; and

d. wirelessly transmitting data about structural load in said structural component.

52. A method as recited in claim 51, wherein said first sensor comprises a strain gauge and said second sensor comprises a piezoelectric transducer.

53. A method as recited in claim 52, wherein said comparing includes a ratio of strain gauge amplitude with piezoelectric transducer amplitude.

54. A method as recited in claim 51, wherein said strain gauge amplitude is a peak to peak amplitude and wherein said piezoelectric transducer amplitude is a peak to peak amplitude.

55. A method as recited in claim 51, further comprising providing a moisture sensor, further comprising using output of said moisture sensor to provide a check of said strain gauge data.

56. A method as recited in claim 51, further comprising providing an energy storage device connected for storing energy from said energy harvesting device.

57. A method as recited in claim 51, further comprising measuring charge on said energy storage device.

58. A method as recited in claim 51, further comprising detecting a problem with said energy harvesting device from said charge on said energy storage device.

59. A method as recited in claim 51, wherein said second sensor includes said energy harvesting device.

60. A method as recited in claim 51, further comprising providing a receiving device for receiving said data, wherein said receiving device receives data from a plurality of said wireless instrumented structural components mounted to the structure.

61. A method as recited in claim 60, further comprising determining usage of the structure from said received data.

62. A method as recited in claim 60, wherein said receiving device is located on the structure.

63. A method as recited in claim 51, further comprising providing a rechargeable battery, and charging said rechargeable battery with said energy harvesting device.

64. A sensing device, comprising an inertial sensor and a GPS, said inertial sensor integrated with said GPS wherein all power for operation of said inertial sensor is provided from energy harvesting.

65. A sensing device as recited in claim 64 wherein said inertial sensor includes a microprocessor, wherein said processor uses data from said GPS to correct data from said inertial sensor.

66. A sensing system comprising a base station, a first plurality of sensors, and a second plurality of sensors, wherein said first plurality of sensors are connected to said base station on a wired network and wherein said second plurality of sensors are connected to said base station on a wireless network.

67. A sensing system as recited in claim 66, wherein said wired network includes a CAN bus.

68. A sensing system as recited in claim 66, wherein said wireless network includes an 802.15.4 network.

69. A method of estimating time before failure of a component of a structure, comprising:

a. providing the structure having the component;

b. instrumenting said structure with a sensor and a memory, said sensor to measure a parameter related to the structure, said memory for logging data derived from said sensor;

c. providing an energy harvesting device on the structure, said energy harvesting device connected to provide all power for powering logging data;

d. providing a model of the component subject to failure;

e. entering information derived from said data into said model; and

f. using said model and said information to estimate a parameter related to time before failure of said component.

70. A method as recited in claim 69, further comprising providing maintenance based on said estimated time.

71. A method as recited in claim 69, wherein said parameter related to the structure includes a parameter related to input load experienced by the structure and wherein said using said mathematical model involves estimating a parameter related to time before structural component fatigue.

72. A method as recited in claim 69, further comprising instrumenting said structure with a plurality of said sensors.

73. A method as recited in claim 69, further comprising instrumenting said structure with a plurality of said sensors.

74. A method as recited in claim 69, wherein said sensor includes a strain sensor.

75. A method as recited in claim 74, wherein said model includes empirical data relating strain and cycles to failure.

76. A method as recited in claim 74, wherein said model includes an algorithm relating strain in one location to strain in another location.

77. A method as recited in claim 74, wherein said model relates strain to load.

78. A method as recited in claim 77, wherein said model includes an algorithm relating load in one location to load in another location.

79. A method as recited in claim 69, further comprising a wireless transmitter connected for transmitting at least one from the group consisting of said data and said information.

80. A method as recited in claim 79, wherein said data includes strain.

81. A method as recited in claim 80, wherein said data includes time when a data point was logged.

82. A method as recited in claim 79, wherein said information includes peaks and valleys of cycles of strain.

83. A method of collecting information about a structure, comprising:

a. providing an instrumented component including a sensor, a memory, and an energy harvesting device, wherein said component is an integral part of a structure when installed in the structure, wherein said instrumented component includes packaging to protect said sensor, said memory, and said energy harvesting device;

b. installing said component in the structure; and

c. using energy derived from said energy harvesting device to provide power for logging data in said memory.

84. A method as recited in claim 83, wherein said packaging provides environmental protection.

85. A method as recited in claim 83, wherein said packaging provides shielding from electromagnetic field.

86. A method as recited in claim 85, further comprising an antenna extending outside said shielding and inside said environmental protection.

87. A method of maintaining a structure comprising,

a. providing a structure having a component subject to component failure;

b. mounting a sensor, a memory and an energy harvesting device on the structure;

c. using said sensor and logging data derived from said sensor in said memory, wherein said memory is powered solely with energy derived from said energy harvesting device; and

d. logging data at a rate depending on amount of energy harvested by said energy harvesting device.

88. A method as recited in claim 87, wherein said rate depends on magnitude of strain experienced by the structure.