NON CONTACT WHEEL ALIGNMENT SENSOR AND METHOD

• US 20080273194A1
• Filed: 05/01/2008
• Published: 11/06/2008
• Est. Priority Date: 05/04/2007
• Status: Active Grant

• Current Assignee: Burke E Porter Machinery Company (The Burke Porter Group), Verhaert New Products & Services NV
• Original Assignee: Burke E Porter Machinery Company (The Burke Porter Group), Verhaert New Products & Services NV
• Inventors: De Sloovere, Kris, Beghuin, Didier, Verhaert, Koen
• Granted Patent: US 7,864,309 B2
• Time in Patent Office: Days
• US Class Current: 356/139.09
• CPC Class Codes: G01B 11/25 by projecting a pattern, e.g. one or more lines, moiré fringes on the object G01B11/255 takes precedence ; image analysis for depth or shape recovery G06T7/50
• CPC Class Codes: G01B 11/2755 using photoelectric detection means
• CPC Class Codes: G01B 2210/286 Projecting a light pattern on the wheel or vehicle body
• CPC Class Codes: G06T 7/521 from laser ranging, e.g. using interferometry; from the projection of structured light

Abstract

A sensor and method of determining the orientation of an object, such as the alignment characteristics of a tire and wheel assembly mounted on a vehicle, includes projecting a plurality of light planes from a first light projector onto a tire and wheel assembly to form a plurality of generally parallel illumination lines on a tire of the tire and wheel assembly, receiving a reflected image of at least some of the illumination lines with a photo electric device reflected from the tire at an angle relative to a projecting angle of the first light projector, and determining a plane defined by spatial coordinates from a selected point located on each illumination line imaged by the photo electric device, with the plane representing the orientation of the tire and wheel assembly.

Claims

1. A method of determining alignment characteristics of a tire and wheel assembly mounted on a vehicle, said method comprising:

projecting a plurality of light planes from a first light projector onto a tire and wheel assembly to form a plurality of generally parallel illumination lines on a tire of the tire and wheel assembly;

receiving a reflected image of at least some of said illumination lines with a photo electric device, said photo electric device receiving images of said illumination lines reflected from the tire at an angle relative to a projecting angle of said first light projector; and

determining a plane defined by spatial coordinates from a selected point located on each said illumination line imaged by said photo electric device, said plane representing the orientation of the tire and wheel assembly.

2. The method of claim 1, wherein said projecting said plurality of light planes from said first light projector comprises divergently projecting said plurality of light planes from said first light projector.

3. The method of claim 1, further comprising:

projecting a single light plane from a second light projector onto the tire and wheel assembly to form a single reference illumination line on the tire of the tire and wheel assembly;

receiving a reflected image of said reference illumination line from the tire with said photo electric device; and

determining a reference distance from said reference illumination line to a noncontact wheel alignment sensor including said first and second light projectors and said photo electric device.

4. The method of claim 3, further comprising identifying which said illumination lines are imaged at said receiving step using said reference distance.

5. The method of claim 3, wherein said second light projector is angularly oriented relative to said first light projector.

6. The method of claim 1, wherein said projecting step includes projecting said plurality of light planes from said first light projector onto a reflecting device, said reflecting device directing said plurality of light planes onto the tire and wheel assembly.

7. The method of claim 1, wherein said receiving a reflected image step includes directing with a reflecting device said at least some of said illumination lines at said photo electric device.

8. The method of claim 1, wherein said projecting step comprises projecting said plurality of light planes from said light projector simultaneously onto both a first tire portion and a second tire portion, with the first tire portion being located about the wheel relative to the second tire portion.

9. The method of claim 8, wherein said receiving a reflected image step comprises receiving reflected images from both the first and the second tire portions.

10. The method of claim 1, further comprising determining a circle defined by the spatial coordinates from said selected point located on each said illumination line, said circle being concentric with the tire and wheel assembly, and determining a center point of said circle, said center point representing the center of the tire and wheel assembly.

11. The method of claim 1, further comprising repeating said receiving a reflected image step for multiple frames imaged by said photo electric device while the tire and wheel assembly is rotating.

12. The method of claim 11, further comprising repeating said determining a plane defined by spatial coordinates from a selected point located on each said illumination line imaged by said photo electric device for each frame imaged by said photo electric device.

13. The method of claim 11, wherein said determining step comprises determining a plane by averaging spatial coordinates from a selected point located on each said illumination line for each frame imaged by said photo electric device.

14. The method of claim 1, wherein said determining step comprises:

resolving three dimensional spatial coordinates for multiple points located on each said illumination line imaged by said photo electric device;

deriving a best fit curve equation for each said illumination line using the three dimensional spatial coordinates from said resolving step; and

determining said plane as a best fit tangential plane to the curve equations for each said illumination line from said deriving step, wherein the intersection of said plane with the curve equations defines said selected point located on each said illumination line.

15. The method of claim 14, wherein said determining said plane as a best fit tangential plane comprises:

determining a reference point on each said illumination line that is closest to a reference plane using the curve equations from said deriving step;

determining a first plane as a best fit plane to the reference points from each said illumination line; and

iteratively determining said plane by first determining said one selected point located on each said illumination line that is closest to a previously determined plane and then determining a new plane as a best fit plane to said selected point located on each said illumination line that is closest to the newly determined plane.

16. The method of claim 1, wherein said projecting a plurality of light planes from said first light projector onto the tire and wheel assembly forms approximately fifteen generally parallel illumination lines on the tire, and wherein said receiving a reflected image of at least some of said illumination lines with a photo electric device comprises receiving a reflected image of approximately ten to twelve of said illumination lines.

17. The method of claim 1, further comprising:

projecting a plurality of light planes from another light projector onto the tire and wheel assembly to form a plurality of generally parallel second illumination lines on the tire, said illumination lines from said first light projector being spaced from said second illumination lines from said another light projector;

wherein said receiving a reflected image of said at least some of said illumination lines with a photo electric device comprises receiving a reflected image of at least one said illumination line formed by said first light projector and receiving a reflected image of at least one said second illumination line formed by said another light projector.

18. The method of claim 1, further comprising monitoring temperature during said projecting and said receiving steps, and further comprises compensating for temperature during said determining step.

19. A method of determining alignment characteristics of a tire and wheel assembly mounted on a vehicle, said method comprising:

providing a first noncontact wheel alignment sensor and a second noncontact wheel alignment sensor, said first sensor being positioned at a location spaced from said second sensor adjacent a wheel of a tire and wheel assembly, each said sensor including a multiline light projector and a camera device;

projecting a plurality of light planes from said multiline light projector of said first sensor onto the tire and wheel assembly to form a plurality of generally parallel illumination lines on a first tire portion;

receiving a reflected image of at least some of said illumination lines from said first tire portion with said camera device of said first sensor, the images being reflected from said first tire portion toward said camera device at an angularly offset orientation relative to said multiline light projector of said first sensor;

projecting a plurality of light planes from said multiline light projector of said second sensor onto the tire and wheel assembly to form a plurality of generally parallel illumination lines on a second tire portion;

receiving a reflected image of at least some of said illumination lines from said second tire portion with said camera device of said second sensor, the images being reflected from the second tire portion toward said camera device at an angularly offset orientation relative to said multiline light projector of said second sensor;

determining a plane defined by spatial coordinates from a selected point located on each said illumination line imaged by said camera devices of said first and second sensors, said plane representing the orientation of the tire and wheel assembly.

20. The method of claim 19, wherein said multiline light projectors of said first and second sensors divergently project said plurality of light planes.

21. The method of claim 19, wherein said first sensor includes a single line reference projector and said second sensor includes a single line reference projector, and wherein said method further comprises:

projecting a single light plane from said single line reference projector of said first sensor onto the tire and wheel assembly to form a single reference illumination line on the first tire portion, and projecting a single light plane from said single line reference projector of said second sensor onto the tire and wheel assembly to form a single reference illumination line on the second tire portion;

receiving a reflected image of said single reference illumination line from the first tire portion with said camera device of said first sensor, and receiving a reflected image of said single reference illumination line from the second tire portion with said camera device of said second sensor; and

determining a reference distance from said single reference illumination line on the first tire portion to said first sensor, and determining a reference distance from said single reference illumination line on the second tire portion to said second sensor.

22. The method of claim 19, further comprising repeating said receiving a reflected image of said at least some of said illumination lines from said first tire portion with said camera device of said first sensor and repeating said receiving a reflected image of at least some of said illumination lines from said second tire portion with said camera device of said second sensor while the tire and wheel assembly is rotating.

23. A noncontact wheel alignment sensor for determining alignment characteristics of a tire and wheel assembly mounted on a vehicle, said sensor comprising:

a first multiline light projector that projects a plurality of light planes onto the tire and wheel assembly to form generally parallel illumination lines on the tire;

a camera device that receives reflected images of at least some of said illumination lines reflected from the tire at an offset angle relative to a projecting angle of said first multiline light projector; and

a processor that determines a plane defined by spatial coordinates from a selected point located on each said illumination line imaged by said camera device, said plane representing the orientation of the tire and wheel assembly.

24. The noncontact wheel alignment sensor of claim 23, wherein said first multiline light projector divergently projects said plurality of light planes.

25. The noncontact wheel alignment sensor of claim 23, further comprising a single line reference light projector that projects a single light plane onto the tire and wheel assembly to form a reference illumination line on the tire.

26. The noncontact wheel alignment sensor of claim 25, wherein said single line reference light projector is oriented to project at an angle offset from said first multiline light projector.

27. The noncontact wheel aligmnent sensor of claim 23, further comprising a second multiline light projector that projects a second plurality of light planes onto the tire and wheel assembly to form a second set of generally parallel illumination lines on the tire.

28. The noncontact wheel alignment sensor of claim 27, wherein said illumination lines formed by said first multiline light projector are spaced on the tire from said second set of generally parallel illumination lines formed by said second multiline light projector.

29. The noncontact wheel alignment sensor of claim 23, further including a first reflecting device, said plurality of light planes from said first multiline light projector being reflected by said first reflecting device onto the tire and wheel assembly.

30. The noncontact wheel alignment sensor of claim 23, further including a second reflecting device, said camera device receiving images of said at least some of said illumination lines reflected by said second reflecting device.