Energy harvesting, wireless structural health monitoring system

• US 7,719,416 B2
• Filed: 09/11/2006
• Issued: 05/18/2010
• 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
• Primary Examiner(s): Crosland; Donnie L
• Application Number:
  US11/518,777
• Publication Number:
  US 20080036617A1
• Time in Patent Office: 1,345 Days
• Field of Search: 340/539.1, 340/429, 340/539.3, 340/683, 703/33, 703/42, 703/187
• US Class Current: 340/539.1
• 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 module on the structure, said sensor module including a sensor, a memory and an energy harvesting device, wherein said sensor provides data related to loading, wherein said energy harvesting device is configured to convert at least one from the group consisting of vibration of the structure and strain of the structure into electricity;

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

d. replacing said component if information derived from said data in said memory shows that said component experienced a load history indicating damaging usage.

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

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

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

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

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

7. A method 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 method as recited in claim 7, wherein said strain gauge includes a triaxial strain gauge, 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 method as recited in claim 1, wherein said sensor module further includes a processor.

11. A method as recited in claim 10, wherein said sensor module further includes a wireless communications device, wherein said processor is connected for controlling operation of said wireless communication device.

12. A method as recited in claim 10, wherein said sensor module further includes a plurality of sensors and a multiplexer, wherein said multiplexer is connected to provide data derived from said plurality of sensors to said processor.

13. A method of operating a system as recited in claim 10, further comprising using said processor to perform calculations and further comprising providing at least one communications scheme from the group consisting of a wireless communications device and a wired external connection, and further comprising transmitting results of said calculations with said at least one communications scheme.

14. A method as recited in claim 10, wherein said memory includes a volatile memory portion and a non-volatile memory portion.

15. A method as recited in claim 14, 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 method as recited in claim 10, wherein said sensor module further includes a low power time keeper, wherein said processor is capable of sleep mode, further comprising providing a periodic signal to said processor from said low power time keeper for waking said processor from said sleep mode.

17. A method of operating a system as recited in claim 16, wherein said sleep mode includes power to said processor being 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, wherein said sensor module further includes a wireless communications device, further comprising buffering data acquired in said burst mode sampling before transmitting said data with 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, wherein said sensor module further includes a wireless communications device, and further comprising transmitting data derived from said sensor with said wireless communications device, wherein all power for powering 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 IEEE 802.15.4 transceiver.

23. A method of operating a system as recited in claim 1, further comprising mounting a plurality of said sensor modules on the structure, further comprising providing a wired network, wherein said wired network connects said plurality of sensor modules.

24. A method of operating a system as recited in claim 1, wherein said sensor wirelessly communicates data 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 13, 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, wherein said sensor module further includes 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 load history indicating damaging usage includes a load exceeding a threshold.

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

34. A method as recited in claim 1, further comprising a plurality of said sensor modules, wherein each said sensor module further includes a time keeper and a two-way communications scheme, wherein each said sensor module is a member of a network, further comprising transmitting a signal for synchronizing said time keepers.

35. A method as recited in claim 34, wherein said two-way communications scheme includes two-way wireless communication.

36. A method as recited in claim 1, wherein said information includes accumulated damage.

37. A method as recited in claim 1, wherein said information shows that said component experienced fatigue.

38. A method as recited in claim 1, further comprising adjusting operation of said structure based on said information.

39. A method as recited in claim 1, wherein said sensor includes a strain gauge calibrated to provide at least one from the group consisting of load and moment.

40. A method of operating a system as recited in claim 1, wherein said using said sensor and logging data derived from said sensor for obtaining said load history indicating damaging usage includes burst mode sampling.

41. A sensing system as recited in claim 40, wherein duty cycle of said burst mode sampling is based on energy available.

42. A method of operating a system as recited in claim 33, wherein said using said sensor and logging data derived from said sensor for obtaining said load history indicating damaging usage includes burst mode sampling.

43. A sensing system as recited in claim 42, wherein duty cycle of burst mode sampling is based on energy available.

44. 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, wherein said sensor provides data related to loading, wherein said energy harvesting device is configured to convert at least one from the group consisting of vibration of the structure and strain of the structure into electricity;

c. acquiring data related to loading with said sensor;

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

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

f. transmitting said information with said wireless communication device; and

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

45. A method of operating a system as recited in claim 44, further comprising providing a warning if said information shows that said component is subject to damaging usage.

46. A method of operating a system as recited in claim 44, wherein said damaging usage includes a load exceeding a threshold.

47. A method of operating a system as recited in claim 44, wherein said damaging usage includes fatigue inducing cyclic loading.

48. A method of operating a system as recited in claim 44, further comprising using said information to set a time for maintaining said structure.

49. A sensing system as recited in claim 44, wherein said energy harvesting system is configured to convert at least one from the group consisting of vibration and strain of the structure into electricity.

50. 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, wherein said sensor provides data related to loading, wherein said energy harvesting device is configured to convert at least one from the group consisting of vibration of the structure and strain of the structure into electricity;

c. using said sensor and logging data derived from said sensor in said memory, wherein said memory is powered solely with electricity 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.

51. A method as recited in claim 50, further comprising replacing said component when information in said memory shows said component experienced damaging use.

52. A method as recited in claim 50, wherein said sensor provides information about load on said component.

53. A sensing system as recited in claim 50, wherein said energy harvesting system is configured to convert at least one from the group consisting of vibration and strain of the structure into electricity.

54. 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, wherein said sensor provides data related to loading, wherein said processor is connected to receive data derived from said sensor, wherein said memory is connected for storing data derived from said sensor, wherein said low power time keeper is connected to periodically provide a signal to wake said processor from a sleep mode, wherein said wireless communication device is connected for communicating data derived from said sensor, wherein said energy harvesting device is configured to convert at least one from the group consisting of vibration and strain into electricity, and wherein said energy harvesting device is connected for providing said electricity to power said processor, said memory, and said wireless communications device wherein all electricity for powering said wireless communications device is derived from said energy harvesting device, wherein said memory includes a program to track accumulated damage from repeated instances of said loading.

55. 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, wherein said sensor provides data related to loading, wherein said energy harvesting device is configured to convert at least one from the group consisting of vibration and strain into electricity;

b. providing a signal from said low power time keeper to said 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 electronic device 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;

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

g. using the data stored in memory to determine accumulated damage from repeated instances of said loading.

56. A method of operating a system as recited in claim 55, wherein power is turned off between said intervals of time.

57. A method of operating a system as recited in claim 55, 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.

58. 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 load in said structural component, wherein said second sensor is for measuring a second property related to load in said structural component, wherein said first property differs from said second property, wherein said transmitter is connected to transmit data derived from at least one from the group consisting of said first sensor and said second sensor about load in said structural component, wherein all electricity for powering said transmitter is derived from said energy harvesting device, wherein said energy harvesting device is configured to convert at least one from the group consisting of vibration of the structure and strain of the structure into electricity, and wherein said processor is connected to receive an output derived from said second sensor for testing operation of said first sensor.

59. A structure as recited in claim 58, wherein said first sensor includes a strain gauge.

60. A structure as recited in claim 58, wherein said second sensor includes a piezoelectric transducer.

61. A structure as recited in claim 60, wherein said energy harvesting device includes said piezoelectric transducer.

62. A structure as recited in claim 58, further comprising a rechargeable battery connected for recharging from said energy harvesting device.

63. A structure as recited in claim 58, wherein said structural component comprises an aircraft part.

64. A structure as recited in claim 58, wherein said structural component comprises a helicopter part.

65. A method as recited in claim 58, wherein said data includes at least one from the group consisting of strain, load, remaining life, accumulated damage, and peak data.

66. A method as recited in claim 58, wherein said data includes a ratio of strain amplitude to piezoelectric amplitude.

67. A method of using a structure, comprising

a. providing a wireless instrumented structural component mounted to the structure, wherein said wireless instrumented structural component includes a first sensor, a second sensor, a transmitter, and an energy harvesting device, wherein said first sensor is for measuring a first property related to load in said structural component, wherein said second sensor is for measuring a second property related to load in said structural component, wherein said first property differs from said second property, and wherein said energy harvesting device is configured to convert at least one from the group consisting of vibration of the structure and strain of the structure into electricity;

b. comparing data from said first sensor with data from said second sensor to test operation of said first sensor;

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

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

68. A method as recited in claim 67, wherein said first sensor comprises a strain gauge and said second sensor comprises a piezoelectric transducer.

69. A method as recited in claim 68, wherein said comparing includes a ratio of strain gauge amplitude with piezoelectric transducer amplitude.

70. A method as recited in claim 68, wherein said strain gauge amplitude is a peak to peak amplitude and wherein said piezoelectric transducer amplitude is a peak to peak amplitude.

71. A method as recited in claim 68, further comprising providing a moisture sensor, further comprising using output of said moisture sensor to provide a check of said strain gauge data.

72. A method as recited in claim 67, further comprising providing an energy storage device connected for storing energy from said energy harvesting device.

73. A method as recited in claim 67, further comprising measuring charge on said energy storage device.

74. A method as recited in claim 67, further comprising detecting a problem with said energy harvesting device from said charge on said energy storage device.

75. A method as recited in claim 67, wherein said second sensor includes said energy harvesting device.

76. A method as recited in claim 67, further comprising providing a receiving device for receiving said data, and further comprising providing a plurality of said wireless instrumented structural components mounted to the structure, wherein said receiving device receives data from said plurality of said wireless instrumented structural components mounted to the structure.

77. A method as recited in claim 76, further comprising determining usage of the structure from said received data.

78. A method as recited in claim 76, wherein said receiving device is located on the structure.

79. A method as recited in claim 67, further comprising providing a rechargeable battery and charging said rechargeable battery with said energy harvesting device.

80. 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 loading of the structure, said memory for logging data derived from said sensor;

c. providing an energy harvesting device on the structure, wherein said energy harvesting device is configured to convert at least one from the group consisting of vibration of the structure and strain of the structure into electricity, wherein said energy harvesting device is connected to provide all power for powering logging data;

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

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

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

81. A method as recited in claim 80, further comprising providing maintenance based on said estimated time.

82. A method as recited in claim 80, 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.

83. A method as recited in claim 80, further comprising instrumenting said structure with a plurality of said sensors.

84. A method as recited in claim 80, wherein said sensor includes a strain sensor.

85. A method as recited in claim 84, wherein said mathematical model includes empirical data relating strain and cycles to failure.

86. A method as recited in claim 84, wherein said mathematical model includes an algorithm relating strain in one location to strain in another location.

87. A method as recited in claim 84, wherein said mathematical model relates strain to load.

88. A method as recited in claim 87, wherein said mathematical model includes an algorithm relating load in one location to load in another location.

89. A method as recited in claim 80, further comprising a wireless transmitter connected for transmitting at least one from the group consisting of said data and said information.

90. A method as recited in claim 89, wherein said data includes strain.

91. A method as recited in claim 90, wherein said data includes time when a data point was logged.

92. A method as recited in claim 89, wherein said information includes peaks and valleys of cycles of strain.

93. 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 instrumented 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, wherein said sensor provides data related to loading, wherein said energy harvesting device is configured to convert at least one from the group consisting of vibration of the structure and strain of the structure into electricity;

b. installing said instrumented component in the structure; and

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

94. A method as recited in claim 93, wherein said packaging provides environmental protection.

95. A method as recited in claim 93, wherein said packaging provides shielding from electromagnetic field.

96. A method as recited in claim 95, wherein said packaging provides an environmental protection material, further comprising an antenna extending outside said shielding and inside said environmental protection material.

97. 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, wherein said energy harvesting device is configured to convert at least one from the group consisting of vibration of the structure and strain of the structure into electricity;

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;

d. automatically adjusting sampling rate to log data at a rate depending on amount of energy harvested by said energy harvesting device.

98. A method as recited in claim 97, wherein said rate depends on magnitude of strain experienced by the structure.