Infrared assessment system

• US 5,775,806 A
• Filed: 09/12/1996
• Issued: 07/07/1998
• Est. Priority Date: 09/12/1996
• Status: Expired due to Fees

• Current Assignee: Government of The United States As Represented By The U.S. Air Force (Government of the United States of America)
• Original Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Inventors: Allred, Lloyd G.
• Primary Examiner(s): BENNETT, GEORGE B
• Application Number:
  US08/712,920
• Time in Patent Office: 663 Days
• Field of Search: 374/4, 374/5, 374/43, 374/57, 374/120, 374/121, 374/124, 374/129, 374/137, 250/330, 250/341.8, 250/342, 250/358.1, 356/237, 348/129, 364/507, 364/552, 364/557
• US Class Current: 374/124
• CPC Class Codes: G01J 2005/0077 Imaging
• CPC Class Codes: G01J 5/0003 for sensing the radiant heat transfer of samples, e.g. emittance meter
• CPC Class Codes: G01R 31/309 of printed or hybrid circuits or circuit substrates

Abstract

A process and system for determining the integrity of an object by analyzing its dynamic heat properties is disclosed. A properly functioning reference object is heated and an infrared camera is positioned above the object. A digital computer collects the infrared images of the object and analyzes its dynamic heat properties. Only heat changes within predefined regions of the object are analyzed and the data is reduced to a peak temperature across each region for a given time. This data is stored and used for future reference. Next, a test object is sampled in the same manner. The reference and test object data is then compared by employing a complex neural network. The neural network uses confidence estimates and historical data on similar reference and test objects to determine the integrity of the object. Thermal images of objects under test are graphically displayed on a video screen. Out-of-profile regions are indicated on the thermal image by displaying the region'"'"'s actual heating rate and a range of acceptable heating rates.

Claims

1. A process for analyzing an object to determine its functional status, comprising:

scanning a reference object with an infrared detector to measure infrared radiation emitted from the reference object and determining its heating rate thereby;

scanning a test object with an infrared detector to measure infrared radiation emitted from the test object and determining its heating rate thereby;

comparing the reference and test object heating rates to determine if the test object is functioning within specified tolerances;

graphically displaying a thermal image generated from the infrared detector; and

identifying the test object if it exceeds specified tolerances.

2. The process defined by claim 1, wherein only infrared radiation within defined regions on the reference object is analyzed.

3. The process defined by claim 2, further comprising a step of reducing infrared data to a peak temperature value for each defined region of the reference object by comparing two adjacent pixel temperature values within a region, only accepting a pixel temperature value as accurate if it has an equally high temperature as an adjacent pixel, and using accepted pixel temperature values to determine the peak temperature within each defined region.

4. The process defined by claim 1, wherein only infrared radiation within defined regions on the test object is analyzed.

5. The process defined by claim 4, further comprising a step of reducing the infrared data to a peak temperature value for each defined region of the test object by comparing two adjacent pixel temperature values within a region, only accepting a pixel temperature value as accurate if it has an equally high temperature as an adjacent pixel, and using accepted pixel temperature values to determine the peak temperature within each defined region.

6. The process defined by claim 1, wherein a graphic display is used to visually compare two objects simultaneously.

7. The process defined by claim 1, wherein any part of a reference object is visually assessed by zooming into that part of the graphic image.

8. The process defined by claim 1, wherein any part of a test object is visually assessed by zooming into that part of the graphic image.

9. The process defined by claim 1, wherein comparison of reference and test object heating rates is accomplished by generating a confidence estimate that a test object is within specified tolerances by dividing test objects into classes and analyzing the likelihood that a test object in a particular class will fail based on data measured from prior scanning of reference and test objects.

10. A system for analyzing an object to determine its functional status, comprising:

means for scanning a reference object with an infrared detector to measure infrared radiation emitted from the reference object and determining its heating rate thereby;

means for scanning a test object with an infrared detector to measure infrared radiation emitted from the test object and determining its heating rate thereby;

means for comparing the reference and test object heating rates to determine if the test object is functioning within specified tolerances;

means for graphically displaying a thermal image generated from the infrared detector; and

means for identifying the test object if it exceeds specified tolerances.

11. The system defined by claim 10, wherein only infrared radiation within defined regions on the reference object is analyzed.

12. The system defined by claim 11, further comprising a means for reducing infrared data to a peak temperature value for each defined region of the reference object by comparing two adjacent pixel temperature values within a region, only accepting a pixel temperature value as accurate if it has an equally high temperature as an adjacent pixel, and using accepted pixel temperature values to determine the peak temperature within each defined region.

13. The system defined by claim 10, wherein only infrared radiation within defined regions on the test object is analyzed.

14. The system defined by claim 13, further comprising a means for reducing the infrared data to a peak temperature value for each defined region of the test object by comparing two adjacent pixel temperature values within a region, only accepting a pixel temperature value as accurate if it has an equally high temperature as an adjacent pixel, and using accepted pixel temperature values to determine the peak temperature within each defined region.

15. The system defined by claim 10, wherein a graphic display is used to visually compare two objects simultaneously.

16. The system defined by claim 10, wherein any part of a reference object is visually assessed by zooming into that part of the graphic image.

17. The system defined by claim 10, wherein any part of a test object is visually assessed by zooming into that part of the graphic image.

18. The system defined by claim 10, wherein comparison of reference and test object heating rates is accomplished by generating a confidence estimate that a test object is within specified tolerances by dividing test objects into classes and analyzing the likelihood that a test object in a particular class will fail based on data measured from prior scanning of reference and test objects.