Optical rail gage/wear system

• US 4,915,504 A
• Filed: 07/01/1988
• Issued: 04/10/1990
• Est. Priority Date: 07/01/1988
• Status: Expired due to Fees

• Current Assignee: Norfolk Southern Corporation One Commercial Place Norfolk Virginia 23510-2191
• Original Assignee: Norfolk Southern Corporation
• Inventors: Thurston, David F.
• Primary Examiner(s): Scott, Jr., Leon
• Application Number:
  US07/214,398
• Time in Patent Office: 648 Days
• Field of Search: 356/1, 356/385, 356/372, 356/377, 356/376
• US Class Current: 356/604
• CPC Class Codes: B61L 23/045 Rail wear
• CPC Class Codes: G01B 11/2522 the position of the object changing and being recorded
• CPC Class Codes: G06T 7/521 from laser ranging, e.g. using interferometry; from the projection of structured light

Abstract

Disclosed is a method and apparatus for determining the gage and/or wear of railroad tracks in which optical scanning techniques are used in conjuction with a programmable computer for determining the gage and/or wear of the rails.

Claims

1. Apparatus for the non-contact measurement of rail parameters, comprising:

means for illuminating at least one of the left and right rails of a track;

means for detecting a selected portion of light reflected from at least one of the left and right rails and generating video signals representative thereof;

said means for illuminating and said means for detecting being mounted for movement along said rails; and

means for processing said video signals to determine at least one of the gage and wear of said rails using a repetitive frame scanning pattern formed by a grid of lines perpendicular to the profile of said rails with each line including a number of pixels, and including means for determining a line and the location of a pixel therein representative of at least a gage point on the gage face of at least one of said left and right rails for selected frames of said repetitive frame scanning pattern.

2. Apparatus according to claim 1, wherein said means for processing further includes means for converting said video signals to binary video signals containing grey scale data, means for sampling pixels to establish a floating threshold for comparing grey scale levels to establish binary "0" and binary "1" respectively representative of black and white levels, first means for filtering said pixels within a selected time window at a pre-determined gage point to generate filtered pixel output, second means for filtering line data within said repetitive frame scanning pattern to establish a reference line and adding said filtered pixel output thereto, and said means for determining includes means for examining pixel data to determine the presence of a selected number of successive white pixels to determine the line and location of a pixel therein representative of at least said gage point.

3. Apparatus according to claim 2, wherein said means for detecting includes means for generating vertical and horizontal sync signals and pixel clock signals.

4. Apparatus according to claim 3, wherein said means for sampling includes means for adding a fixed number of grey levels to an estimated threshold and the comparison of grey levels is with respect to a reference grey level.

5. Apparatus according to claim 4, wherein said first means for filtering includes means for subtracting a fixed number from a reference gage point to obtain said predetermined gage point.

6. Apparatus according to claim 5, wherein second means for filtering receives gage point data from said means for determining and further includes means for subtracting an offset from said data and an incremental line counter for incrementing a line count in each said frame and means for comparing the count in said incremental line counter with the output from said means for subtracting.

7. Apparatus according to claim 6, wherein said means for examining includes respective black and white counters for counting respective black and white pixels and means for comparing the black and white pixel count with said preselected number and further including means responsive to said pixel clock and to line frame signals to determine the line and location of a pixel to obtain said gage point.

8. Apparatus according to claim 2, wherein said means for illuminating is substantially perpendicular to at least one of said left and right rails.

9. Apparatus according to claim 2, wherein said means for sampling includes means for adding a fixed number of grey levels to an estimated threshold and the comparison of grey levels is with respect to a reference grey level.

10. Apparatus according to claim 2, wherein said first means for filtering includes means for subtracting a fixed number from a reference gage point to obtain said predetermined gage point.

11. Apparatus according to claim 2, wherein second means for filtering receives gage point data from said means for determining and further includes means for subtracting an offset from said data and an incremental line counter for incrementing a line count in each said frame and means for comparing the count in said incremental line counter with the output from said means for subtracting.

12. Apparatus according to claim 2, wherein said means for examining includes respective black and white counters for counting respective black and white pixels and means for comparing the black and white pixel count with said preselected number and further including means responsive to said pixel clock and to line frame signals to determine the line and location of a pixel to obtain said gage point.

13. Apparatus according to claim 1, wherein said means for determining includes means for determine a point "a" on the rail representing the minimum thickness on the rail webb, means for subtracting a predetermined distance from the line axis of the coordinates of point "a" to determine a point "d", means for subtracting one-half of the rail webb thickness from the line axis of the coordinates for point "a", and means for subtracting a fixed distance from the pixel axis of the coordinates for point "b" to determine the exact gage point on the gage face of the rail.

14. Apparatus according to claim 13, further comprising means responsive to the location of the exact gage point for determining the total top wear and side wear of the rail.

15. A method for the non-contact measurement of rail parameters, comprising:

illuminating at least one of the left and right rails of a track;

detecting a selected portion of light reflected from at least one of the left and right rails and generating video signals representative thereof;

moving the illumination and detection along said track;

processing said video signals to determine at least one of the gage and wear of said rails using a repetitive frame scanning pattern formed by a grid of lines perpendicular to the profile of said rails with each line including a number of pixels; and

determining a line and the location of a pixel therein representative of at least a gage point on the gage face of at least one of said left and right rails for selected frames of said repetitive frame scanning pattern.

16. A method according to claim 15, wherein the processing of the video signals includes converting the video signals to binary video signals containing grey scale data, sampling pixels to establish a floating threshold for comparing grey scale levels to establish binary "0" and binary "1" respectively representative of black and white levels, filtering said pixels within a selected time window at a predetermined gage point to generate filtered pixel output, filtering line data within said repetitive frame scanning pattern to establish a reference line and adding said filtered pixel output thereto, and examining pixel data to determine the presence of a selected number of successive white pixels to determine the line and location of a pixel therein representative of at least said gage point.

17. A method according to claim 16, wherein the step of detecting includes the generation of vertical and horizontal sync signals and pixel clock signals.

18. A method according to claim 17, wherein the step of sampling includes adding a fixed number of grey levels to an estimated threshold and the step of comparing grey levels is with respect to a reference grey level.

19. A method according to claim 18, wherein the first step of filtering includes subtracting a fixed number from a reference gage point to obtain said predetermined gage point.

20. A method according to claim 18, wherein said second step of filtering includes receiving gage point data from said step of determining and further includes subtracting an offset from said data and incrementing a line count in each said frame and comparing the incremented count with the output from said step of subtracting.

21. A method according to claim 20, wherein said step of examining includes counting respective black and white pixels and comparing the black and white pixel count with said preselected number and further including determining the line and location of a pixel to obtain said gage point responsive to said pixel clock and to line frame signals.

22. A method according to claim 16, wherein the illumination occurs at substantially right angles to at least one of said left and right rails.

23. A method according to claim 16, wherein the step of sampling includes adding a fixed number of grey levels to an estimated threshold and the comparison of grey levels is with respect to a reference grey level.

24. A method according to claim 16, wherein the first step of filtering includes subtracting a fixed number from a reference gage point to obtain said predetermined gage point.

25. A method according to claim 16, wherein the second step of filtering includes receiving gage point data from the step of determining and includes subtracting an offset from the gage point data and counting the line count in each of the frames and comparing the count with the output from the step of subtracting.

26. A method according to claim 16, wherein the step of examining includes counting respective black and white pixels and comparing the black and white pixel count with the preselected number and determining the line and pixel location from the pixel clock and line frame signals.

27. A method according to claim 15, wherein said step of determining includes determining a point "a" on the rail representing the minimum thickness on the rail webb, subtracting a predetermined distance from the line axis of the coordinates of point "a" to determine a point "d", subtracting one-half of the rail webb thickness from the line axis of the coordinates for point "a", subtracting a fixed distance from the pixel axis of the coordinates for point "b" to determine the exact gage point on the gage face of the rail.

28. A method according to claim 27, further comprising determining the total top wear and side wear of the rail using the exact gage point.