System and method for inspecting surfaces using optical wavelength filtering

• US 8,405,837 B2
• Filed: 05/13/2009
• Issued: 03/26/2013
• Est. Priority Date: 06/30/2004
• Status: Active Grant

• Current Assignee: Loram Technologies Incorporated (Loram Maintenance of Way, Inc.)
• Original Assignee: Georgetown Rail Equipment Company (Loram Maintenance of Way, Inc.)
• Inventors: Nagle, John Anthony II, Villar, Christopher M., Orrell, Steven C., Aaron, Charles Wayne
• Primary Examiner(s): Geisel, Kara E
• Assistant Examiner(s): Valentin, II, Juan D
• Application Number:
  US12/465,473
• Publication Number:
  US 20090273788A1
• Time in Patent Office: 1,413 Days
• Field of Search: None
• US Class Current: 356/625
• CPC Class Codes: B61K 9/08 Measuring installations for surveying permanent way applications of measuring apparatus or devices for track building purposes E01B35/00; measuring techniques G01
• CPC Class Codes: G01C 3/08 Use of electric radiation detectors

Abstract

A system and method for daylight inspection of a surface, such as a railroad track, is disclosed. The disclosed system includes lasers, cameras, and a processor. The lasers are positioned adjacent the surface. The laser emits a beam of light across the surface at a combined intensity of at least 0.15 watts of intensity per inch of width of the surface, and the camera captures images of the surface having the beam of light emitted thereon. The camera includes a bandpass filter which passes only a band of light corresponding to a dip in solar radiation. The laser is selected to provide an emitted light beam which is more intense than the solar radiation at the dip. The processor formats the images so that they can be analyzed to determine various measurable aspects of the surface. The system and method includes one or more algorithms for determining these measurable aspects of the surface.

Claims

1. A system for inspecting a railroad track bed, the system comprising:

at least one light generator positioned adjacent the railroad track bed, the light generator adapted to project a beam of light across the railroad track bed, the beam of light having an intensity totaling at least 0.15 watts per inch of a width of the beam of light;

at least one camera positioned adjacent the railroad track bed for receiving at least a portion of the light reflected from the railroad track bed and for generating at least one image representative of a profile of at least a portion of the railroad track bed, the camera comprising a bandpass filter adapted to pass a band of the beam of light projected by the light generator, the band corresponding only to a natural intensity dip in a spectrum of ground-level solar radiation; and

at least one processor adapted to analyze the at least one image and determine one or more physical characteristics of the portion of the railroad track bed, the processor comprising an algorithm configured for determining a distance between crossties of the railroad track bed, the algorithm comprising the steps of;

(a) analyzing a first frame, one or more intermediate frames and an end frame of the at least one image, the first and end frames comprising crossties, while the one or more intermediate frames lack crossties;

(b) determining a number of the one or more intermediate frames lacking crossties;

(c) determining a known spacing between frames; and

(d) determining the distance between the crossties of the first and end frames based upon the number of the one or more intermediate frames lacking crossties and the known spacing between the frames.

2. A system as defined in claim 1, wherein an angular spread of the beam of light projected by the generator is 45 degrees.

3. A system as defined in claim 1, wherein the light generator comprises:

a center laser; and

two outer lasers located on opposites sides of the center laser, the two outer lasers each being tilted outwardly from the center laser at a 10 degree angle.

4. A system as defined in claim 1, wherein the light generator is a 808 nm laser.

5. A system as defined in claim 1, wherein the camera further comprises:

a lens;

a spacer positioned adjacent the lens; and

a charge coupled device, the bandpass filter being coupled between the charge coupled device and the spacer.

6. A system as defined in claim 1, wherein the bandpass filter is located behind a lens of the camera.

7. A system for inspecting a railroad track bed, comprising:

at least one light generator positioned adjacent the railroad track bed, the light generator adapted to project a beam of light across the railroad track bed, the beam of light having an intensity totaling at least 0.15 watts per inch of a width of the beam of light;

at least one camera positioned adjacent the railroad track bed for receiving at least a portion of the light reflected from the railroad track bed and for generating at least one image representative of a profile of at least a portion of the railroad track bed, the camera comprising a bandpass filter adapted to pass a band of the beam of light projected by the light generator, the band corresponding only to a natural intensity dip in a spectrum of ground-level solar radiation; and

at least one processor adapted to analyze the at least one image and determine one or more physical characteristics of the portion of the railroad track bed, the processor comprising an algorithm for detecting a misaligned or sunken tie plate of the railroad track bed, the algorithm comprising the steps of;

(a) analyzing a frame of the at least one image, the frame comprising a region of interest;

(b) determining whether the region of interest contains a tie plate;

(c) if a tie plate is present, determining a crosstie contour and a tie plate contour;

(d) comparing an orientation of the crosstie contour and an orientation of the tie plate contour; and

(e) determining whether the tie plate is misaligned or sunken based upon the comparison.

8. A system as defined in claim 7, wherein the light generator comprises a plurality of lasers.

9. A system as defined in claim 7, wherein the light generator is a 808 nm laser.

10. A system as defined in claim 7, wherein the camera further comprises:

a lens;

a spacer positioned adjacent the lens; and

a charge coupled device, the bandpass filter being coupled between the charge coupled device and the spacer.

11. A system as defined in claim 7, wherein the bandpass filter is located behind a lens of the camera.

12. A method for inspecting a railroad track bed, the method comprising the steps of:

(a) illuminating a light across the span of the railroad track bed, the light totaling a combined intensity of at least 0.15 watts per inch of a width of the light;

(b) receiving at least a portion of the light reflected from the railroad track bed using one or more cameras, the one or more cameras comprising a bandpass filter adapted to pass only a band of the reflected light, the band corresponding only to a natural intensity dip in a spectrum of ground-level solar radiation;

(c) generating at least one image representative of a profile of at least a portion of the railroad track bed;

(d) analyzing the at least one image;

(e) determining one or more physical characteristics of the portion of the railroad track bed;

(f) outputting the determined physical characteristics of the portion of the railroad track bed;

(g) determining a distance between crossties of the railroad track bed by the steps of;

(h) analyzing a first frame, one or more intermediate frames and an end frame of the at least one image, the first and end frames comprising crossties while the one or more intermediate frames lack crossties;

(i) determining a number of the one or more intermediate frames lacking crossties;

(j) determining a known spacing between frames; and

(k) determining the distance between the crossties of the first and end frames based upon the number of the one or more intermediate frames lacking crossties and the known spacing between the frames.

13. A method as defined in claim 12, wherein step (a) comprises the step of projecting a plurality of beams of light to form the light illuminated across the surface, the plurality of beams of light each having an angular spread of 45 degrees.

14. A method as defined in claim 13, wherein the plurality of beams of light comprise a center beam and two outer beams on opposite sides of the center beam, step (a) further comprising the step of projecting the two outer beams outwardly from the center beam at a 10 degree angle.

15. A method as defined in claim 12, wherein the light illuminated across the span of the surface is created using 808 nm lasers.

16. A method for inspecting a railroad track bed, comprising the steps of:

(a) illuminating a light across the span of the railroad track bed, the light totaling a combined intensity of at least 0.15 watts per inch of a width of the light;

(b) receiving at least a portion of the light reflected from the railroad track bed using one or more cameras, the one or more cameras comprising a bandpass filter adapted to pass only a band of the reflected light, the band corresponding only to a natural intensity dip in a spectrum of ground-level solar radiation;

(c) generating at least one image representative of a profile of at least a portion of the railroad track bed;

(d) analyzing the at least one image;

(e) determining one or more physical characteristics of the portion of the railroad track bed;

(f) detecting a misaligned or sunken tie plate of the railroad track bed, the step of detecting comprising the steps of;

(g) analyzing a frame of the at least one image, the frame comprising a region of interest;

(h) determining whether the region of interest contains a tie plate;

(i) if a tie plate is present, determining a crosstie contour and a tie plate contour;

(j) comparing an orientation of the crosstie contour and an orientation of the tie plate contour; and

(k) determining whether the tie plate is misaligned or sunken based upon the comparison.

17. A method as defined in claim 16, wherein step (a) comprises the step of projecting a plurality of beams of light to form the light illuminated across the railroad track bed.

18. A method as defined in claim 16, wherein the light illuminated across the span of the railroad track bed is created using 808 nm lasers.

19. A method for inspecting a railroad track bed, the method comprising the steps of:

(a) projecting a light onto the railroad track bed, the light having an intensity of at least 0.15 watts per inch of a width of the light;

(b) receiving at least a portion of the light reflected from the railroad track bed into a receiver;

(c) utilizing a bandpass filter of the receiver to pass a band of the reflected light which corresponds only to a natural intensity dip in a spectrum of ground-level solar radiation, wherein the reflected light is adapted to be more intense than the solar radiation at the dip;

(d) utilizing the passed band of the reflected light to generate one or more images representative of a profile of at least a portion of the railroad track bed;

(e) determining one or more characteristics of the portion of the railroad track bed;

(f) outputting the determined characteristics of the portion of the railroad track bed;

(g) determining a distance between crossties of the railroad track bed by the steps of;

(h) analyzing a first frame, one or more intermediate frames and an end frame of the one or more images, the first and end frames comprising crossties while the one or more intermediate frames lack crossties;

(i) determining a number of the one or more intermediate frames lacking crossties;

(j) determining a known spacing between frames; and

(k) determining the distance between the crossties of the first and end frames based upon the number of the one or more intermediate frames lacking crossties and the known spacing between the frames.

20. A method as defined in claim 19, wherein step (a) further comprises the step of projecting a plurality of beams of light to form the light projected onto the surface, the plurality of beams of light each having an angular spread of 45 degrees.

21. A method as defined in claim 20, wherein the plurality of beams of light comprise a center beam and two outer beams on opposite sides of the center beam, step (a) further comprising the step of projecting the two outer beams outwardly from the center beam at a 10 degree angle.

22. A method for inspecting a railroad track bed, comprising the steps of:

(a) projecting a light onto the railroad track bed, the light having an intensity of at least 0.15 watts per inch of a width of the light;

(b) receiving at least a portion of the light reflected from the railroad track bed into a receiver;

(c) utilizing a bandpass filter of the receiver to pass a band of the reflected light which corresponds only to a natural intensity dip in a spectrum of ground-level solar radiation, wherein the reflected light is adapted to be more intense than the solar radiation at the dip;

(d) utilizing the passed band of the reflected light to generate one or more images representative of a profile of at least a portion of the railroad track bed;

(e) determining one or more characteristics of the portion of the railroad track bed;

(f) outputting the determined characteristics of the portion of the railroad track bed;

(g) detecting a misaligned or sunken tie plate of the railroad track bed, the step of detecting comprising the steps of;

(h) analyzing a frame of one or more images, the frame comprising a region of interest;

(i) determining whether the region of interest contains a tie plate;

(j) if a tie plate is present, determining a crosstie contour and a tie plate contour;

(k) comparing an orientation of the crosstie contour and an orientation of the tie plate contour; and

(l) determining whether the tie plate is misaligned or sunken based upon the comparison.

23. A method as defined in claim 22, wherein step (a) further comprises the step of projecting a plurality of beams of light to form the light projected onto the surface.