Method and apparatus for determining the alignment of motor vehicle wheels

• US 5,724,743 A
• Filed: 10/10/1995
• Issued: 03/10/1998
• Est. Priority Date: 09/04/1992
• Status: Expired due to Term

• Current Assignee: Snap-On Technologies Incorporated (Snap-On Incorporated)
• Original Assignee: Snap-On Technologies Incorporated (Snap-On Incorporated)
• Inventors: Jackson, Bernie Fergus
• Primary Examiner(s): Fulton, Christopher W.
• Application Number:
  US08/544,378
• Time in Patent Office: 882 Days
• Field of Search: 33/288, 33/203, 33/203.18, 33/203.19, 33/203.2, 33/286, 356/155, 356/139.09, 356/152.1, 356/152.2, 356/152.3
• US Class Current: 33/288
• CPC Class Codes: G01B 11/2755 using photoelectric detection means
• CPC Class Codes: G01B 2210/12 Method or fixture for calibrating the wheel aligner
• CPC Class Codes: G01B 2210/143 One or more cameras on each side of a vehicle in the main embodiment
• CPC Class Codes: G01B 2210/26 Algorithms, instructions, databases, computerized methods and graphical user interfaces employed by a user in conjunction with the wheel aligner
• CPC Class Codes: G01B 2210/30 Reference markings, reflector, scale or other passive device

Abstract

An apparatus for determining the position and/or alignment of objects such as motor vehicle wheels, and including targets for attachment to the objects, a pair of optical sensing means such as television cameras for viewing the targets, an electronic processing means connected to the optical sensing means for processing data relating to images of the targets to determine position and/or alignment information, and a display means for displaying the position and/or alignment information. The optical sensing means view a target located on each object and form an image of each target. Electronic signals corresponding to each of the images are transferred to the electronic processing means which correlates the image signals of each of the targets with the true shape of each target. In so doing, the processing means relates the geometric characteristics and positional interrelationships of certain known elements of the target with the geometric characteristics and positional interrelationships of corresponding elements in the viewed images and calculates the position and/or alignment of the objects to which the targets are attached.

Claims

1. An apparatus for determining the alignment of motor vehicle wheels comprising:

target means including at least first and second target objects for attachment to wheels on respective first and second sides of a vehicle under inspection, each said target object including a plurality of visually perceptible, geometrically configured target elements having known geometric characteristics and positional interrelationships;

optical inspection means defining a spatial reference system and including first and second cameras respectively forming first and second viewing paths intersecting said first and second target objects when they are attached to wheels of a vehicle under inspection, each said camera being operable to inspect an image of a corresponding target object as viewed along its corresponding viewing path and to generate image information describing the geometric characteristics and positional interrelationships of the imaged target elements;

processing means for relating such image information to predetermined reference information describing the known geometric characteristics and positional interrelationships of said target elements and for determining the position and angular orientation of said first and second target objects relative to said spatial reference system and generating first and second position and orientation information commensurate therewith; and

means responsive to said first and second position and orientation information and operative to indicate the position and alignment of the wheels to which said first and second targets are attached.

2. An apparatus as recited in claim 1 wherein said means responsive includes a display means which uses said orientation information to indicate the alignment of said first and second wheels.

3. An apparatus as recited in claim 2 wherein the alignment of each said wheel is expressed in terms of caster, camber and toe measurements.

4. An apparatus as recited in claim 1 wherein said target means further includes third and fourth target objects for attachment to third and fourth wheels, respectively disposed on said first and second sides of the vehicle under inspection, said target objects each including a plurality of visually perceptible, geometrically configured target elements having known geometric characteristics and positional interrelationships, said first and second camera means being respectively operative to establish third and fourth viewing paths intersecting said third and fourth target objects, and to inspect images thereof and generate image information describing the geometric characteristics and positional relationships of the target elements of each image, said processing means being further operative to relate said image information to predetermined reference information describing the known geometric characteristics and positional interrelationships of said third and fourth target elements to determine the angular orientation of said third and fourth target elements and to generate third and fourth positions and orientation information commensurate therewith, said means responsive being further responsive to said third and fourth position and orientation information and operative to indicate the alignment of the wheels to which said third and fourth target objects are attached.

5. An apparatus as recited in claim 4 wherein said processing means further determines the relative positions of said first, second, third and fourth wheels.

6. An apparatus as recited in claim 1 wherein said optical inspection means further includes lighting means associated with each camera means to provide on-axis target illumination therefor.

7. An apparatus as recited in claim 6 wherein said lighting means includes an array of light-emitting diodes arrayed around the optical axis of each said corresponding camera means.

8. An apparatus as recited in claim 7 wherein said light-emitting diodes are selected to have a particular wavelength characteristic and wherein wavelength-selective filter means are used to discriminate between diode light reflected from said target objects and light emanating from other sources.

9. An apparatus as recited in claim 1 wherein each said target object includes a planar plate having said plurality of target elements formed on a surface thereof and means for attaching the plate to a wheel of a vehicle under inspection.

10. An apparatus as recited in claim 9 wherein said means for attaching orients the plane of said surface substantially normal to the rim plane of the wheel to which the target object is attached.

11. An apparatus as recited in claims 1, 4, 6 or 7, wherein said target elements are formed of retro-reflective material.

12. An apparatus as recited in claims 1 or 4 wherein said target means includes clamps for clampingly engaging the rims of wheels.

13. An apparatus as recited in claim 1 and further comprising support means for supporting said first and second cameras at a predetermined separation from each other greater than the width of a vehicle having wheels to be aligned.

14. An apparatus as recited in claim 13 wherein said support means holds said first and second cameras in fixed positions at a predetermined elevation.

15. A method of determining the relative orientation of the wheels of a vehicle comprising the steps of:

establishing a first target means on a first wheel on a first side of said vehicle and establishing a second target means on a second wheel on a second side of said vehicle, each said target means including a plurality of target elements of known geometric characteristics and positional interrelationships, said first and second target means having a predetermined positional relationship to the wheels to which they are attached;

using a first camera means having a known spatial position and directional orientation to view said first target and to form a first detected image thereof, and using a second camera means having a known spatial position and directional orientation to view said second target to form a second detected image thereof;

determining the geometric characteristics and positional interrelationships of the target elements of each of said first and second detected images;

relating the determined geometric characteristics and positional interrelationships of said first detected image to the known geometric characteristics and positional interrelationships of corresponding elements of said first target means to determine the angular orientation of said first target means;

relating the determined geometric characteristics and positional interrelationships of said second detected image to the known geometric characteristics and positional interrelationships of corresponding elements of said second target means to determine the angular orientation of said second target means; and

using said angular orientations to determine the alignment of said first and second wheels.

16. A method as recited in claim 15 and further including the step of relating the determined geometric characteristics and interrelationships of said first and second detected images to the known geometric characteristics and interrelationships of corresponding elements of said first and second target means to determine the positions of the axles of said first and second wheels.

17. An apparatus for determining the alignment of motor vehicle wheels comprising:

target means including at least a first target object having a first plurality of known geometric attributes with known spatial interrelationships, and a second target object having a second plurality of known geometric attributes with known spatial interrelationships;

first optical inspection means establishing a spatial reference system including a first viewing path intersecting said first target object when it is attached to a first wheel of a vehicle under inspection, said optical inspection means being operable to inspect a first image of said first target object as viewed along said first viewing path and to generate first image information describing the geometric attributes and interrelationships of the first image;

second optical inspection means establishing a spatial reference system including a second viewing path intersecting said second target object when it is attached to a second wheel of a vehicle under inspection, said optical inspection means being operable to inspect a second image of said second target object as viewed along said second viewing path and to generate second image information describing the geometric attributes and interrelationships of the second image;

processing means for relating said first image information to predetermined reference information describing the known geometric attributes and relationships of said first target object to determine the angular orientation of said first target object relative to said spatial reference system and to generate first orientation information commensurate therewith;

processing means for relating said second image information to predetermined reference information describing the known geometric attributes and relationships of said second target object to determine the angular orientation of said second target object relative to said spatial reference system and to generate second orientation information commensurate therewith; and

means for using said first and second orientation information to indicate the alignment of said first and second wheels.

18. An apparatus as recited in claim 17 wherein said target means further includes a third target object having a third plurality of known geometric attributes with known spatial interrelationships,

wherein said spatial reference system further includes a third viewing path intersecting said third target object when it is attached to a third wheel of the vehicle under inspection,

wherein said optical inspection means is further operative to inspect an image of said third target object as viewed along said third viewing path and to generate third image information describing the geometric attributes and interrelationships of the third target object,

wherein said processing means is further operative to relate said third image information to predetermined information describing the known geometric attributes and interrelationships of said third target object to determine the angular orientation of said third target object relative to said spatial reference system and to generate third orientation information commensurate therewith, and

wherein said means for using further uses said third orientation information to indicate the alignment of said third wheel.

19. An apparatus as recited in claim 18, wherein said processing means is further operative to determine the spatial positions of said first, second and third wheels, the said positions defining a reference plane relative to which the alignment of the wheels can be calculated.

20. An apparatus as recited in claim 17 wherein said first and second images are viewed with said first and second wheels in first positions, and wherein said optical image inspection means is further operable to inspect other images of said first and second target objects after said first and second wheels have been rotated about their axes to second positions, and to generate additional image information describing the geometric attributes and interrelationships of the first and second target objects as they appear in said other images, and wherein said processing means is further operable to relate said additional image information to said first and second image information to determine the relationships of said first and second target objects to the axes of rotation of said first and second wheels.

21. An apparatus for determining the position and orientation of an object comprising:

means defining at least one target associated with the object and having a determinable relationship to the object, each said target including a plurality of known detectable attributes having known interrelationships;

imaging means for viewing each target along a viewing path and for developing electronic signals representation of each viewed image of the target;

computational means having information stored therein defining the known attributes and interrelationships of each target, and responsive to said electronic signals, and operative to relate said electronic signals to the stored information and to determine the orientation of each target relative to its viewing path; and

means for using said determined orientation of each target to determine the position and orientation of the object.

22. An apparatus for determining the relative alignment of a plurality of components comprising:

target means including a plurality of target objects, each having a plurality of known attributes with known geometries and spatial interrelationships, each said target object being adapted for attachment to one of said components;

optical inspection means establishing a spatial reference system including a plurality of viewing paths, each of which intersect one of said target objects when the target objects are attached to said components, said optical inspection means being operable to inspect an image of each target object as viewed along its corresponding viewing path and to generate image information describing the attributes and interrelationships of each image;

processing means for relating the image information corresponding to each target object to predetermined reference information describing the known attributes and relationships of each said target object to determine the angular orientation of each said target object relative to said spatial reference system and to generate first orientation information commensurate therewith; and

indicator means for using said orientation information to indicate the alignment of each said component.

23. An apparatus as recited in claim 22 wherein said indicator means further uses said orientation information to indicate the position of each component.

24. An apparatus as recited in claim 23 wherein said optical inspection means includes video camera means and lighting means for providing on-axis illumination for said camera means.

25. An apparatus as recited in claim 24 wherein said detractable attributes are embodied as geometrical shapes formed by a body of retro-reflective material.

26. A method for determining the relative alignment of components of an object, comprising the steps of:

establishing at least one target on each component of the object such that each target has a determinable relationship to the component and wherein each target includes a plurality of known detectable attributes having known geometric characteristics and interrelationships;

viewing each target along a corresponding viewing path to form at least one detected image of each target;

determining the geometric characteristics and interrelationships of at least two attributes of each detected image;

relating the determined characteristics and interrelationships of the attributes of each detected image to the known geometric characteristics and interrelationships of corresponding attributes of a corresponding target to determine the angular orientation of each target relative to a corresponding viewing path; and

using said angular orientations and said determinable relationships to determine the relative alignment of the components of said object.