Method and device for normalizing temperature variations

• US 7,758,239 B2
• Filed: 12/17/2004
• Issued: 07/20/2010
• Est. Priority Date: 08/27/2002
• Status: Active Grant

• Current Assignee: Fluke Corporation (Fortive Corp.)
• Original Assignee: Fluke Corporation (Fortive Corp.)
• Inventors: Ignatowicz, Steven
• Primary Examiner(s): VERBITSKY, GAIL KAPLAN
• Application Number:
  US11/016,414
• Publication Number:
  US 20050111520A1
• Time in Patent Office: 2,041 Days
• Field of Search: 374/4, 374/45, 374/57, 374/121, 374/137, 374/139, 374/1, 374/2, 374/129, 374/5, 374/E13.001, 374/110, 374/112, 374/43, 374/100, 374/141, 374/160, 266/274
• US Class Current: 374/139
• CPC Class Codes: F23M 11/04 Means for supervising combustion, e.g. windows
• CPC Class Codes: F23M 5/00 Casings; Linings; Walls
• 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: G01J 5/0022 for sensing the radiation of moving bodies
• CPC Class Codes: G01J 5/004 by molten metals
• CPC Class Codes: G01J 5/02 Constructional details
• CPC Class Codes: G01J 5/025 Interfacing a pyrometer to an external device or network; User interface
• CPC Class Codes: G01J 5/026 Control of working procedures of a pyrometer, other than calibration; Bandwidth calculation; Gain control

Abstract

A method of sensing the temperature of a heated object includes obtaining past temperature data relating to the heated object, capturing a thermal image of the heated object, obtaining a reference temperature of the heated object, and calculating a normalized hotspot temperature.

Claims

1. A method of sensing the temperature of a heated object associated with a heat source and having at least a first portion and a second portion, wherein the first portion is less affected by the heat source than the second portion, comprising:

obtaining past temperature data relating to the heated object and associated with past temperature measurements;

capturing a thermal image of the heated object;

obtaining a reference temperature of the heated object based on the captured thermal image, wherein the reference temperature is associated with the first portion of the heated object; and

calculating a normalized hotspot temperature based on at least the obtained past temperature data, the captured thermal image, and the reference temperature to compensate for environmental factors associated with the heated object, wherein

the heated object is a molten metal vehicle, and wherein the first portion of the heated object is less affected by a molten metal than the second portion of the heated object, wherein the second portion is in contact with the molten metal.

2. The method of claim 1, wherein the past temperature data includes at least one of a past hotspot temperature and a past reference temperature.

3. The method of claim 1, further including obtaining a hotspot temperature of the heated object.

4. The method of claim 3, wherein calculating the normalized hotspot temperature further includes comparing the hotspot temperature to the past temperature data.

5. The method of claim 1, wherein calculating the normalized hotspot temperature further includes comparing the reference temperature to the past temperature data.

6. The method of claim 1, wherein the heat source is not associated with the acts of capturing the thermal image of the heated object or obtaining the reference temperature of the heated object.

7. The method of claim 1, wherein obtaining past temperature data relating to the heated object includes averaging a plurality of past temperature measurements of the heated object.

8. The method of claim 1, further comprising developing a thermal fingerprint of the heated object, including:

generating a plurality of individual pixels based on the captured thermal image;

comparing each of the plurality of individual pixels to a threshold value; and

generating a binary value for each of the plurality of individual pixels according to whether the pixel is above or below the threshold value.

9. A system for sensing the temperature of a heated object, comprising:

at least one thermal imager;

a memory storing past temperature data associated with the heated object; and

a controller communicably coupled to the thermal imager and to the memory, the controller being adapted to receive thermal image data associated with the heated object from the thermal imager and the past temperature data from the memory, obtain current temperature data from the thermal image, and calculate a normalized hotspot temperature from the current temperature data and the past temperature data to compensate for environmental factors associated with the heated object, wherein

the past temperature data includes at least one of a past hotspot temperature and a past reference temperature, and wherein

the past reference temperature is obtained from a portion of the heated object less affected by a molten metal than a portion of the heated object that is in contact with the molten metal.

10. The system of claim 9, wherein the controller is programmed to calculate the normalized hotspot temperature by comparing the past hotspot temperature and the past reference temperature to the current temperature data.

11. A system for sensing the temperature of a heated object, comprising:

at least one thermal imager;

a memory storing past temperature data associated with the heated object; and

a controller communicably coupled to the thermal imager and to the memory, the controller being adapted to receive thermal image data associated with the heated object from the thermal imager and the past temperature data from the memory, obtain current temperature data from the thermal image, and calculate a normalized hotspot temperature from the current temperature data and the past temperature data to compensate for environmental factors associated with the heated object, wherein

the current temperature data includes at least one of a hotspot temperature and a reference temperature, and wherein

the reference temperature is obtained from a portion of the heated object less affected by a molten metal than a portion of the heated object that is in contact with the molten metal.

12. The system of claim 11, wherein the controller is programmed to calculate the normalized hotspot temperature by comparing the hotspot temperature and the reference temperature to the past temperature data.