Multi-format, binary code symbol for non-linear strain measurement

• US 8,347,727 B2
• Filed: 08/16/2007
• Issued: 01/08/2013
• Est. Priority Date: 08/17/2006
• Status: Active Grant

• Current Assignee: GE Infrastructure Technology, LLC (General Electric Company)
• Original Assignee: Direct Measurements, Inc.
• Inventors: Hovis, Gregory, Ranson, William, Vachon, Reginald
• Primary Examiner(s): Noori, Max
• Application Number:
  US12/311,052
• Publication Number:
  US 20090312961A1
• Time in Patent Office: 1,972 Days
• Field of Search: 737/60, 737/77, 738/00
• US Class Current: 73/777
• CPC Class Codes: G01B 11/165 by means of a grating deformed by the object
• CPC Class Codes: G01L 1/24 by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
• CPC Class Codes: G06K 19/06037 multi-dimensional coding

Abstract

A binary code symbol for non-linear strain measurement that can be constructed in any geometric shape having a solid, continuous perimeter containing straight line segments. The symbol includes finder cells to “orient” the symbol in order to associate strain measurements with physical dimensions; and contains encoded data in “data regions” and/or “utility regions.” The data and utility regions can be distinct and separate, combined, exclusive (i.e. data regions and no utility regions, or utility regions and no data regions), or omitted. The data “density” can be varied depending upon the application, by varying the number of distinct data or utility cells present in the data regions or utility regions.

Claims

1. A target for association with an object for which at least one of strain and fatigue damage is to be measured, the target incorporating a binary code symbol for perimeter-based, non-linear strain measurement using discrete or analog deformation analysis methods, the binary code symbol emitting a detectable physical quantity and including:

an outer perimeter constructed of line segments,

orienting means for determining the orientation of the binary code symbol, in order to associate strain measurements with physical dimensions, wherein the orienting means is bounded at least in part by the outer perimeter, and

inner and outer quiet regions for distinguishing the orienting means from its background.

2. The target of claim 1, wherein the orienting means of the binary code symbol comprises at least one distinct feature.

3. The target of claim 2, wherein the at least one distinct feature of the binary code symbol is a finder cell.

4. The target of claim 1, wherein the orienting means of the binary code symbol comprises at least two distinct features to provide redundancy and to enable robust algorithms to determine symbol orientation.

5. The target of claim 1, wherein the binary code symbol further includes an inner perimeter constructed of line segments.

6. The target of claim 5, wherein the inner perimeter of the binary code symbol is an enlargement of the outer perimeter having a fractional scale factor greater than 0 and less than 1.

7. The target of claim 5, wherein the inner and outer perimeters of the binary code symbol are concentric.

8. The target of claim 5, wherein the inner and outer perimeters of the binary code symbol have different shapes.

9. The target of claim 1, wherein the outer perimeter of the binary code symbol is a polygon.

10. The target of claim 1, wherein the binary code symbol further includes at least one data region containing encoded data region data, wherein the at least one data region is bounded at least in part by the outer perimeter, and wherein the inner and outer quiet regions further distinguish the at least one data region from its background.

11. The target of claim 10, wherein the binary code symbol further includes an inner perimeter constructed of line segments, wherein the at least one data region is bounded at least in part by the inner perimeter.

12. The target of claim 10, wherein the at least one data region of the binary code symbol comprises a plurality of data cells, and the encoded data region data is encoded in the data cells.

13. The target of claim 12, wherein the density of the data region data of the binary code symbol is determined by one of the number and width of the data cells.

14. The target of claim 12, wherein the at least one data region of the binary code symbol contains multiple rows of data cells.

15. The target of claim 10, wherein the binary code symbol further includes at least one utility region containing encoded utility data, wherein the at least one utility region is bounded at least in part by the outer perimeter, and wherein the inner and outer quiet regions of the binary code symbol further distinguish the at least one utility region from its background.

16. The target of claim 15, wherein the binary code symbol further includes an inner perimeter constructed of line segments, wherein the at least one utility region of the binary code symbol is bounded at least in part by the inner perimeter.

17. The target of claim 15, wherein the at least one utility region of the binary code symbol comprise a plurality of utility cells with alternating appearance, and the utility data is encoded in the utility cells.

18. The target of claim 17, wherein the density of the utility data is determined by one of the number and width of utility cells.

19. The target of claim 15, wherein the at least one utility region of the binary code symbol contains multiple rows of utility cells.

20. The target of claim 19, wherein the multiple rows of encoded utility data store at least one of auxiliary information and codes.

21. The target of claim 15, wherein the at least one data region and the at least one utility region of the binary code symbol are distinct and separate.

22. The target of claim 15, wherein the at least one data region and the at least one utility region of the binary code symbol are combined.

23. The target of claim 22, wherein the combined data and utility regions encode one of all data region data, all utility data, and a combination of data region data and utility data.

24. A non-linear strain gage comprising:

the target in accordance with claim 1, associated with an object for which at least one of strain and fatigue damage is to be measured,

sensor means for pre-processing the detectable physical quantity emitted by the target and output data representing the physical quantity, the sensor means being compatible with the detectable physical quantity; and

a computer including;

means for analyzing the data output by the sensor means to define the binary code symbol; and

means for measuring the strain on the object directly based on the pre-processed and analyzed data.

25. A method of measuring strain on an object directly, using the non-linear strain gage in accordance with claim 24, comprising the steps of:

associating the target with an object in such a way that deformation of the binary code symbol and deformation under load of the object bear a one-to-one relationship;

identifying the changes in the binary code symbol as a function of time and change in the load applied to the object, using the computer; and

translating the changes in the binary code symbol into a direct measurement of strain, using the computer.