Independently calibrated wireless structural load sensor

• US 8,024,980 B2
• Filed: 01/26/2009
• Issued: 09/27/2011
• Est. Priority Date: 01/24/2008
• Status: Expired due to Fees

• Current Assignee: Hottinger Bruel & Kjaer Incorporated
• Original Assignee: MicroStrain, Inc. (Spectris PLC)
• Inventors: Townsend, Christopher P., Churchill, David L., Arms, Steven W
• Primary Examiner(s): NOORI, MASOUD H
• Application Number:
  US12/360,111
• Publication Number:
  US 20090210173A1
• Time in Patent Office: 974 Days
• Field of Search: 73760-860
• US Class Current: 73/763
• CPC Class Codes: G01L 1/2225 the direction being perpendicular to the central axis
• CPC Class Codes: G01L 5/0004 Force transducers adapted for mounting in a bore of the force receiving structure G01L5/0009 takes precedence
• CPC Class Codes: G01L 5/1627 of strain gauges using piezoresistors G01L5/162
• CPC Class Codes: G01L 5/24 for determining value of torque or twisting moment for tightening a nut or other member which is similarly stressed

Abstract

A device includes a removable load element. The removable load element includes a pin portion and a housing portion. The pin portion extends from the housing portion. The pin portion includes a sensor. The housing portion includes an electronic circuit connected to the sensor.

Claims

1. A device, comprising a removable load bearing element, wherein said removable load bearing element includes a load sensor, a pin portion and a housing portion, wherein said pin portion extends from said housing portion, wherein said pin portion includes said load sensor, wherein said housing portion includes an electronic circuit connected to said load sensor, wherein said electronic circuit includes a device for receiving a signal derived from said load sensor, wherein said housing portion includes said device for receiving said signal, wherein said pin portion includes a first aperture, wherein said first aperture has a first inner wall, and wherein said load sensor is mounted on said first inner wall.

2. A device as recited in claim 1, wherein said housing includes a second aperture, wherein said first aperture has a first diameter, wherein said second aperture has a dimension extending in a direction parallel to said first diameter, wherein said dimension is larger than said first diameter.

3. A device as recited in claim 1, wherein said electronic circuit includes a device for processing load sensor output, wherein said housing portion includes said device for processing load sensor output.

4. A device as recited in claim 3, wherein said electronic circuit further includes a wireless transceiver and a power supply, wherein said housing portion includes said wireless transceiver and said power supply.

5. A device as recited in claim 4, wherein said power supply includes a battery.

6. A device as recited in claim 4, wherein said power supply includes an energy harvesting device.

7. A device as recited in claim 3, wherein said electronic circuit further includes a non volatile memory, wherein said non-volatile memory includes coefficients for compensating load sensor output for temperature, wherein said housing portion includes said non volatile memory.

8. A device as recited in claim 1, wherein said electronic circuit includes an orientation sensor, wherein said housing portion includes said orientation sensor.

9. A device as recited in claim 1, further comprising a first line, wherein said load sensor provides a sensor signal along said first line.

10. A device as recited in claim 9, further comprising a second line, wherein said electronic circuit provides a load sensor excitation along said second line.

11. A device as recited in claim 1, wherein said load sensor includes a strain gauge.

12. A device as recited in claim 11, wherein said load sensor includes a plurality of strain gauges.

13. A device as recited in claim 12, wherein said plurality of strain gauges are arranged to measure different kinds of loads.

14. A device as recited in claim 13, wherein said different kinds of loads include at least one from the group consisting of forces directed along orthogonal axes, moments directed about orthogonal axes, forces applied at different locations, moments about different locations.

15. A device as recited in claim 11, wherein said load sensor includes stacked strain gauges.

16. A device as recited in claim 4, wherein said electronic circuit includes a precision timekeeper, wherein said wireless transceiver is configured for wirelessly receiving a beacon that provides a periodic timing reference, wherein said wireless transceiver is connected for providing a signal derived from the beacon to said precision timekeeper for synchronizing said precision timekeeper to the beacon, wherein said wireless transceiver is connected for wirelessly transmitting data derived from said load sensor.

17. A structure as recited in claim 16, wherein said precision timekeeper is connected to provide a time stamp to data from said load sensor.

18. A device as recited in claim 16, further comprising a structure, a plurality of structural elements of the structure, and a plurality of said removable load bearing elements, wherein said structural elements are held together by said removable load bearing elements, wherein said clock synchronizing provides time synchronized data acquisition from said load sensors in said plurality of removable load bearing elements, wherein said wirelessly transmitted data from said plurality of removable load bearing elements is sufficiently time synchronized so said wirelessly transmitted data from said plurality of removable load bearing elements can be combined for calculating a load experienced by said structure.

19. A structure as recited in claim 18, further comprising a receiving unit separate from said plurality of removable load bearing elements, wherein said receiving unit includes a receiving unit transceiver and a computing device, wherein said receiving unit transceiver is configured for receiving said wirelessly transmitted data from said plurality of removable load bearing elements, wherein said computing device is connected for said combining data from said plurality of removable load bearing elements for calculating the loads experienced by the structure.

20. A structure as recited in claim 19, wherein said beacon is transmitted by said receiving unit transceiver.

21. A structure as recited in claim 16, wherein said electronic circuit includes a device for processing load sensor output, wherein said precision timekeeper is connected to said device for processing load sensor output to provide a timing reference to enable said device for processing load sensor output to schedule data collection.

22. A structure as recited in claim 16, wherein said electronic circuit includes a device for processing load sensor output, wherein said precision timekeeper is connected to said device for processing load sensor output to provide a timing reference to enable said device for processing load sensor output to schedule data transmission.