Method and apparatus for producing a surface temperature map

• US 5,580,172 A
• Filed: 10/11/1994
• Issued: 12/03/1996
• Est. Priority Date: 10/11/1994
• Status: Expired due to Term

• Current Assignee: Solar Turbines Incorporated (Caterpillar Incorporated)
• Original Assignee: Solar Turbines Incorporated (Caterpillar Incorporated)
• Inventors: Smilo, Sheldon, Maden, Kenneth H., Glezer, Boris, Bhardwaj, Narender K.
• Primary Examiner(s): GUTIERREZ, DIEGO F
• Application Number:
  US08/321,369
• Time in Patent Office: 784 Days
• Field of Search: 374/137, 374/162, 354/76, 382/100, 382/165
• US Class Current: 374/137
• CPC Class Codes: G01K 11/12 using changes in colour, translucency or reflectance

Abstract

A method and apparatus are provided for producing a temperature profile of a part operating within a machine is provided. The machine is operated with the part for a predetermined period of time. The part is placed in a light box in which a camera produces an image of the part. The image is compared with a standard set of colors and the standard color most closely corresponding to each pixel of the image is selected.

Claims

1. A method for producing a temperature profile of a part operating within a machine, the part having been painted with temperature sensitive paint, comprising the steps of:

operating the machine with the part for a predetermined period of time;

placing the part in a light controlled environment;

producing an image of the part with a camera, the image including a plurality of pixels;

delivering the image to a processor;

comparing the image produced by the camera to a standard set of colors wherein said step of comparing the image with a standard set of colors includes the step of calculating a ratio of red-to-green colors corresponding to the colors present in the image, a ratio of blue-to-green colors corresponding to the colors present in the image, and a brightness level for the image and comparing the respective values for the image to the ratio of red-to-green colors, ratio of blue-to-green color, and brightness level for each of the standard colors for the temperature sensitive paint; and

selecting the standard color most closely corresponding to each pixel of the image wherein said selected colors represent the temperature profile of the part.

2. A method, as set forth in claim 1, including the step of multiplying each of the values for the ratio of red-to-green, ratio of blue-to-green, and brightness level for the image by a corresponding factor selected in response to the type of temperature sensitive paint.

3. A method, as set forth in claim 2, including the step of calibrating the image by multiplying each pixel value by a gain value and adding an offset.

4. A method, as set forth in claim 1, including the steps of:

obtaining a color template for the type of temperature sensitive paint;

placing the color template in a light box;

producing a calibration image of at least one of the colors from the color template with the camera; and

delivering the calibration image to the processor, wherein said step of selecting the standard color most closely corresponding to each pixel of the image includes the step of comparing each pixel of the image with the calibration image.

5. A method, as set forth in claim 1, including the step of displaying the temperature profile of the part in colors substantially corresponding to those in the standard set of colors.

6. A method, as set forth in claim 1, including the step of displaying the temperature profile of the part in colors substantially corresponding to the colors of the visible spectrum.

7. A method, as set forth in claim 1, including the steps of:

displaying the temperature profile of the part; and

replacing areas of the temperature profile being less than a predefined size and corresponding to a temperature being substantially different from that of the surrounding area.

8. A method for producing a temperature profile of a part operating within a machine, comprising the steps of:

operating the machine with the part for a predetermined period of time;

placing the part in a light controlled environment;

producing an image of the part with a camera, the image including a plurality of pixels;

delivering the image to a processor;

comparing the image with a standard set of colors , wherein said step of comparing the image with a standard set of colors includes the step of calculating a ratio of red-to-green colors corresponding to the colors present in the image, a ratio of blue-to-green colors corresponding to the colors present in the image, and a brightness level for the image and comparing the respective values for the image to the ratio of red-to-green colors, ratio of blue-to-green colors, and brightness level for each of the standard colors for the material of which the part is made; and

selecting the standard color most closely corresponding to each pixel of the image wherein said selected colors represent the temperature profile of the part.

9. A method, as set forth in claim 8, including the step of multiplying each of the values for the ratio of red-to-green, ratio of blue-to-green, and brightness level for the image by a factor corresponding to the material of which the part is made.

10. A method, as set forth in claim 9, including the step of calibrating the image by multiplying each pixel value by a gain value and adding an offset.

11. A method, as set forth in claim 8, including the step of displaying the temperature profile of the part in colors including at least one of red, orange, yellow, green, blue, and violet.

12. A method, as set forth in claim 8, including the steps of:

displaying the temperature profile of the part; and

replacing areas of the temperature profile being less than a predefined size and corresponding to a temperature being substantially different from that of the surrounding area.

13. An apparatus for producing a temperature profile of a part operating within a machine, comprising:

a camera for producing an image of the part;

a light box containing the part and said camera;

a processor means for receiving said image of the part from said camera, said processor means including memory means for storing data characterizing a standard set of colors, means for comparing the image with said standard set of colors; and

means for selecting the standard color most closely corresponding to each pixel of the image, wherein said selected colors represent the temperature profile of the part; and

wherein said means for comparing the image with said standard set of colors includes means for calculating;

a ratio of red-to-green 8 colors corresponding to the colors present in the image a ratio of blue-to-green 9 colors corresponding to the colors present in the image, and a brightness level for the image and comparing the respective values for the image to the ratio of red-to-green colors, ratio of blue-to-green colors and brightness level for each of the standard color for the material of which the part is made.

14. An apparatus, as set forth in claim 13, wherein said processor means further includes a means for correlating the standard color to a temperature of the temperature profile.

15. An apparatus, as set forth in claim 13, including means for displaying the temperature profile of the part in colors including at least one of red, orange, yellow, green, blue, and violet.

16. An apparatus, as set forth in claim 13, including means for displaying the temperature profile of the part;

and means for replacing areas of the temperature profile being less than a predefined size and corresponding to a temperature being substantially different from that of the surrounding area.