Vehicle wheel alignment data by rotating vision sensor

• US 6,862,544 B1
• Filed: 06/09/2000
• Issued: 03/01/2005
• Est. Priority Date: 07/24/1998
• Status: Expired due to Fees

• Current Assignee: Merilab, Inc.
• Original Assignee: Merilab, Inc.
• Inventors: Merrill, M. Stanley
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): SUAREZ, FELIX E
• Application Number:
  US09/591,434
• Time in Patent Office: 1,726 Days
• Field of Search: 702/95, 702/150, 702/152, 702/153, 702/159, 701/29, 356/139
• US Class Current: 702/95
• CPC Class Codes: G01B 11/2755 using photoelectric detection means
• CPC Class Codes: G01B 2210/143 One or more cameras on each side of a vehicle in the main embodiment
• CPC Class Codes: G01B 2210/20 Vehicle in a state of translatory motion
• CPC Class Codes: H04N 7/183 for receiving images from a single remote source

Abstract

A device and method for measuring vehicle wheel alignment characteristics, and in particular measuring wheel camber and toe, uses a rotating vision sensor such as a laser sensor to map a portion of the vehicle tire and/or rim, allowing for the determination of wheel camber and toe without rotating the wheel. The sensor may be repositioned between the rear and front vehicle wheels. A separate sensor may be used for the left and the right vehicle wheels. The invention has particular utility for auditing of the alignment of vehicles in production lines. The devices and methods may also be used for more general imaging purposes.

Claims

1. A device measuring alignment characteristics of a vehicle wheel/tire, comprising:

a vision sensor having a field of vision and being capable of determining spatial coordinates of a group of pixels with the field of vision;

the field of vision being sufficiently sized to detect a portion of vehicle wheel/tire to be characterized;

means for rotating the vision sensor so that the vision sensor field of vision scribes a torus in space, whereby a collection of spatial coordinates of pixels is obtained at more than one position of the torus; and

a computer for calculating from the collection of spatial coordinates a wheel alignment characteristic of the wheel/tire selected from the group of toe, camber, and both toe and camber.

2. The device of claim 1, further comprising means for determining angular position of the vision sensor as the vision sensor is rotated.

3. The device of claim 1, including a vertical support and a blade having two ends rotatably mounted on the support, wherein the vision sensor is mounted toward one end of the blade.

4. The device of claim 3, wherein a counterweight is mounted toward the other end of the blade.

5. The device of claim 1, wherein the vision sensor comprises a laser camera.

6. The device of claim 1, wherein the means for rotating the vision sensor is capable of rotating the vision sensor at least one complete revolution.

7. The device of claim 6, wherein the means for rotating the vision sensor is capable of rotating the vision sensor a plurality of revolutions, and the vision sensor obtains pixel coordinates for each of the plurality of revolutions.

8. A method for determining alignment characteristics of vehicle wheel/tire, comprising the steps of:

positioning a vision sensor having a field of vision and capable of determining spatial coordinates of a group of pixels within the field of vision with respect to a wheel/tire to be characterized, such that at least a portion of the wheel/tire is within the sensor field of vision;

rotating the vision sensor with respect to the wheel/tire so that the vision sensor is positioned at more than one angular position with respect to the wheel/tire;

obtaining a collection of spatial coordinates of pixels at more than one angular position of the vision sensor; and

calculating from the collection of spatial coordinates a wheel alignment characteristics selected from the group of toe, camber, and both toe and camber.

9. The method of claim 8, wherein the rotating step includes rotating the vision sensor at least one complete revolution.

10. The method of claim 9, wherein the rotating step includes rotating the vision sensor more than one complete revolution.

11. The method of claim 8, wherein the step of obtaining a collection of spatial coordinates of pixels at more than one angular position of the camera is performed at about eighteen angular positions of the camera.

42. The method of claim 8, wherein the rotating step includes rotating the vision sensor less than one complete revolution.

12. A device for measuring wheel alignment of the front and rear wheel/tires of vehicle, comprising:

a vision sensor having a field of vision and capable of determining spatial coordinates of a group of points within the field of vision;

means for rotating the vision sensor so that the vision sensor field of vision scribes a torus in space means for recording a collection of spatial coordinates associated with points from more than one position of the torus;

a computer to determine a wheel alignment characteristic based upon the collection of spatial coordinates; and

a track, slidably engaged with the vision sensor to guide the vision sensor between a first position and a second position, the first position corresponding to a first wheel/tire of a vehicle to be characterized and the second position corresponding to a second wheel/tire to be characterized.

13. The device of claim 12, further comprising means for sliding the vision sensor from the first position to the second position.

14. The device of claim 13, further comprising a controller for controlling the sliding means.

15. The device of claim 14, wherein the controller causes the sliding means to slide at variable speed along the track.

16. The device of claim 15, wherein the sliding means slides at a slower speed at a position in the vicinity of the wheels than at a position further from the wheels.

17. The device of claim 16, wherein the controller determines the position of the vision sensor with respect to at least one of the wheel/tires by interpreting a collection of spatial coordinates corresponding to the wheel/tire.

18. The device of claim 12, further comprising a ramp for positioning at least one vehicle wheel/tire.

19. The device of claim 12, further comprising an additional vision sensor, means for rotating the vision sensor, and track;

whereby the vision sensor determines the characteristics of one set of a left front and rear vehicle wheel/tire set and a right front and rear vehicle wheel/tire set; and

the additional vision sensor determines the characteristics of the other set.

20. A method for measuring wheel alignment of the front and rear wheel/tires of vehicle, comprising the steps of:

positioning a vision sensor with respect to one of the front and rear wheel/tires, the sensor having a field of vision and being capable of determining spatial coordinates of a group of pixels within the field of vision, the vision sensor being engaged with means for rotating the vision sensor so that the vision sensor field of vision scribes a torus in space, whereby a collection of spatial coordinates of pixels is obtained at more than one position of the torus;

calculating from the collection of spatial coordinates a wheel alignment characteristics selected from the group of toe, camber, and both toe and camber for the one of the front and rear wheel/tires;

sliding the vision sensor along a track from a first position corresponding to the one of the vehicle front and rear wheel/tires to a second position corresponding to the other of the vehicle front and rear wheel/tires; and

calculating from the collection of spatial coordinates a wheel alignment characteristic selected from the group of toe, camber and both toe and camber for the other of the front and rear wheel/tires.

21. A wheel alignment system comprising:

a vision sensor having a field of vision and being capable of determining spatial coordinates of a group of pixels within the field of vision, the field of vision being sufficiently sized to detect a portion of vehicle wheel/tire to be characterized;

means for rotating the vision sensor so that the vision sensor field of vision scribes a torus in space;

means for recording a collection of spatial coordinates associated with points from more than one position of the torus;

a computer to calculate a wheel alignment characteristic of the wheel/tire based upon the collection of spatial coordinates; and

an additional wheel alignment device (60) to characterize the wheel/tire in a conventional manner.

22. The wheel alignment system of claim 21, further comprising a plurality of vision sensors and associated means for rotating the plurality, and a corresponding plurality of additional wheel alignment devices (60) to characterize a plurality of wheel/tires in a conventional manner.

23. An apparatus comprising:

a vision sensor capable of determining spatial coordinates of a group of points with its field of vision, the field of vision being sufficiently sized to contain a portion of a wheel/tire to be characterized;

a motor to rotate the vision sensor through a plurality of angular positions with respect to the wheel/tire so that the fields of vision associated with each of the plurality of angular positions together form at least a portion of a torus in Euclidean space;

a positional recorder to collect spatial coordinates of a plurality of points from more than one position of the torus; and

a computer to determine one or more characteristics of the wheel/tire based upon the collected spatial coordinates.

24. The apparatus of claim 23, wherein a characteristic of the one or more characteristics of the wheel/tire comprises an alignment characteristic of the wheel/tire.

25. The apparatus of claim 23, wherein a characteristic of the one or more characteristics of the wheel/tire comprises wheel/tire toe.

26. The apparatus of claim 23, wherein a characteristic of the one or more characteristics of the wheel/tire comprises wheel/tire camber.

27. The apparatus of claim 23, wherein a characteristic of the one or more characteristics of the wheel/tire indicates whether the wheel/tire has any irregularities in its sidewall.

28. A method comprising:

obtaining spatial coordinates of a plurality of points on a wheel/tire to be characterized by positioning a vision sensor at a plurality of angular offsets relative to the wheel/tire, each of the plurality of points corresponding to a different one of the plurality of angular offsets; and

determining one or more characteristics of the wheel/tire by performing statistical computation based upon the spatial coordinates of the plurality of points.

29. The method of claim 28, wherein the plurality of points lie on a sidewall of the wheel/tire.

30. The method of claim 28, wherein the plurality of points lie on a rim of the wheel/tire.

31. The method of claim 28, further comprising rotating the wheel/tire during said obtaining spatial coordinates.

32. The method of claim 28, further comprising rotating the vision sensor during said obtaining spatial coordinates.

33. The method of claim 32, wherein said rotating the vision sensor during said obtaining spatial coordinates comprises rotating the vision sensor in a circular arc.

34. The method of claim 32, wherein said rotating the vision sensor during said obtaining spatial coordinates comprises rotating the vision sensor in a non-circular arc.

35. The method of claim 32, wherein said rotating the vision sensor during said obtaining spatial coordinates comprises a combination of linear translation and curvilinear rotation of the vision sensor.

36. The method of claim 32, wherein said determining one or more characteristics is unaffected by the wheel/tire having negligible runout.

37. The method of claim 32, further comprising positioning the vision sensor with respect to a second wheel/tire.

38. The method of claim 32, wherein said positioning is based upon provided wheelbase dimensions.

39. The method of claim 37, wherein said positioning is based upon locating the rim of the second wheel/tire using computer vision techniques.

40. The method of claim 28, further comprising measuring and recording an angular position of the vision sensor relative to the wheel/tire as a function of time along with those of the spatial coordinates corresponding to the angular position.

41. A method for determining alignment characteristics of vehicle wheel/tire, the method comprising the steps of:

a step for positioning a vision sensor with respect to a wheel/tire to be characterized such that at least a portion of the wheel/tire is within a field of vision of the vision sensor, the vision sensor capable of determining spatial coordinates of a group of points within the field of vision;

a step for rotating the vision sensor through a plurality of angular positions with respect to the wheel/tire;

a step for obtaining a collection of spatial coordinates of points associated with each of the plurality of angular positions; and

a step for calculating one or more wheel alignment characteristics of the wheel/tire based upon the collection of spatial coordinates.