Intelligent sensor method and apparatus for an optical wheel alignment machine

• US 5,731,870 A
• Filed: 12/04/1996
• Issued: 03/24/1998
• Est. Priority Date: 05/24/1995
• Status: Expired due to Fees

• Current Assignee: Fori Automation Incorporated (Lincoln Electric Holdings Incorporated)
• Original Assignee: Fori Automation Incorporated (Lincoln Electric Holdings Incorporated)
• Inventors: Rosen, Jack H., Bartko, Robert J.
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US08/767,116
• Time in Patent Office: 475 Days
• Field of Search: 356/139.09, 356/152.1, 356/152.2, 356/375, 33/203.16, 33/288, 348/136, 348/141
• US Class Current: 356/139.09
• 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 2210/146 Two or more cameras imaging the same area
• CPC Class Codes: G01B 2210/22 Wheels in a state of motion supported on rollers, rotating platform or other structure substantially capable of only one degree of rotational freedom
• CPC Class Codes: G01B 2210/286 Projecting a light pattern on the wheel or vehicle body
• CPC Class Codes: H04N 7/181 for receiving images from a plurality of remote sources

Abstract

A sensor method and apparatus for an optical wheel alignment machine utilizes one or more light sources, such as lasers, to project a laser line or other shaped light onto various locations about the sidewall of a tire undergoing measurement. The sensor includes a video camera or other light responsive receiver and a optical system that combines the reflected laser lines into a single image that is received by the camera. The optical system also rotates one or more of the reflected laser lines so that all of the reflected portions have the same general orientation upon entering the camera. The camera outputs a video data stream that is indicative of the image. The sensor has an electronic circuit that analyzes this video data stream in real time to determine the location in the image of a preselected feature of each of the laser lines. The circuit then outputs coordinate data indicative of the location of this feature.

Claims

1. In a sensor for use in a wheel alignment machine to measure the orientation of a tire on a vehicle, said sensor being of the type having at least one light source oriented to project shaped light onto a sidewall of the tire at a plurality of spaced locations and a light responsive receiver oriented to receive a portion of the shaped light that is reflected off the tire at a perspective angle relative to said light source, with said light responsive receiver being operable to generate electrical signals indicative of the reflected portion of the shaped light, wherein the improvement comprises:

a system of optical elements oriented relative to said light responsive receiver to provide said light responsive receiver with an optical view that includes the plurality of spaced locations of the tire, whereby portions of the shaped light that are reflected off the tire at each of the plurality of spaced locations are received by said light responsive receiver as a single image; and

an electronic circuit responsive to said electrical signals to determine the location within the image of a preselected feature of each of the reflected portions of shaped light, said circuit further being operable to generate output data representative of the locations of the preselected features.

2. A sensor as defined in claim 1, wherein said optical elements are oriented to rotate at least one reflected portion of the shaped light with respect to at least another reflected portion of the shaped light.

3. A sensor as defined in claim 2, wherein said at least one light source comprises first, second, and third lasers, each of which is oriented to project a stripe of laser light onto the sidewall at a different one of the plurality of spaced locations, whereby the shaped light at each of the plurality of spaced locations comprises a stripe of laser light.

4. A sensor as defined in claim 3, wherein said first and second lasers are oriented to project light in substantially parallel planes and said third laser is oriented to project light in a plane that is substantially perpendicular to said parallel planes.

5. A sensor as defined in claim 3, wherein:

said light responsive receiver comprises a video camera having an image receiving element that includes successive scan lines, each of which comprises a number of pixels;

said video camera is oriented to receive the reflected portions of the stripes of laser light as lines of laser light that intersect at least some of said scan lines;

said video camera is operable to generate said electrical signals as a stream of pixel data points arranged into successive lines of said pixel data points, with each of said lines of pixel data points representing one of said scan lines;

said electronic circuit includes a microprocessor and is operable to monitor said stream of pixel data points as it is received from said video camera and to interrupt said microprocessor when said electronic circuit receives a particular pixel data point representative of any of the reflected portions of the stripes of laser light; and

said microprocessor is operable in response to said interrupt to acquire a pixel count representing the position of said particular pixel data point within its associated line of pixel data points.

6. A sensor as defined in claim 1, wherein:

said light responsive receiver comprises a video camera that generates said electrical signals as a stream of pixel data points arranged into successive lines of said pixel data points, with each of said lines of pixel data points representing one row of an array of pixel data points that together represent the image;

said electronic circuit is operable to monitor said stream of pixel data points as it is received from said video camera and provide said microprocessor with an interrupt request when said electronic circuit receives a particular pixel data point representative of any of the reflected portions of the shaped light; and

said microprocessor is operable in response to said interrupt request to acquire a pixel count representing the position of said particular pixel data point within its associated line of pixel data points.

7. A sensor as defined in claim 1, wherein said optical elements include a plurality of mirrors oriented to direct the reflected portions of the shaped light into said light responsive receiver.

8. A sensor as defined in claim 1, wherein said circuit is operable to generate coordinate output data indicative of the location of a preselected feature of each of the reflected portions of shaped light.

9. In a sensor for use in a wheel alignment machine to measure the orientation of a tire on a vehicle, said sensor being of the type having at least one light source oriented to project shaped light onto a sidewall of the tire at a plurality of spaced locations and a light responsive receiver oriented to receive a portion of the shaped light that is reflected off the tire at a perspective angle relative to said light source, with said light responsive receiver being operable to generate electrical signals indicative of the reflected portion of the shaped light, wherein the improvement comprises:

an event-driven microprocessor circuit connected to receive said electrical signals from said light responsive receiver, said circuit including a microprocessor having an interrupt input;

said circuit being operable, in response to detecting in real time the presence within the image of the reflected portion of the shaped light, to generate an interrupt request on said interrupt input.

10. A sensor as defined in claim 9, further comprising a system of optical elements oriented relative to said light responsive receiver to provide said light responsive receiver with an optical view that includes the plurality of spaced locations of the tire, whereby portions of the shaped light that are reflected off the tire at each of the plurality of spaced locations are received by said light responsive receiver as a single image.

11. A sensor as defined in claim 10, wherein:

said at least one light source comprises a plurality of lasers, each of which is oriented to project a stripe of laser light onto the sidewall at a different one of the plurality of spaced locations with the stripes of laser light extending radially with respect to the tire, whereby the portion of the shaped light reflected from each of the plurality of spaced locations comprises a stripe of laser light;

one of said lasers being oriented to project a first stripe of laser light in a first plane and another of said lasers being oriented to project a second stripe of laser light in a second plane that forms an angle with said first plane; and

said optical elements are oriented to cause rotation of the reflected portion of the first stripe of laser light relative to the reflected portion of the second stripe of laser light such that the reflected portions of the first and second stripes of laser light enter said light responsive receiver having the same orientation.

12. A sensor as defined in claim 9, wherein said interrupt input is a dedicated interrupt request line.

13. A sensor as defined in claim 9, wherein said circuit is operable to generate coordinate output data indicative of the location of a preselected feature of each of the reflected portions of shaped light.

14. In an optical sensor for generating data indicative of a spatial attribute of an object, said sensor being of the type having at least one light source oriented to project shaped light onto the object at a plurality of spaced locations and a light responsive receiver oriented to receive a portion of the shaped light that is reflected off the object at a perspective angle relative to said light source, with said light responsive receiver being operable to generate electrical signals indicative of the reflected portion of the shaped light, wherein the improvement comprises:

an event-driven microprocessor circuit connected to receive said electrical signals from said light responsive receiver, said circuit including a microprocessor having an interrupt input;

said circuit being operable, in response to detecting in real time the presence within the image of the reflected portion of the shaped light, to generate an interrupt request on said interrupt input.

15. A sensor as defined in claim 14, further comprising a system of optical elements oriented relative to said light responsive receiver to provide said light responsive receiver with an optical view that includes the plurality of spaced locations of the object, whereby portions of the shaped light that are reflected off the object at each of the plurality of spaced locations are received by said light responsive receiver as a single image.

16. In an optical sensor for generating data indicative of a spatial attribute of an object, said sensor being of the type having at least one light source oriented to project shaped light onto the object at a plurality of spaced locations and a light responsive receiver oriented to receive a portion of the shaped light that is reflected off the object at a perspective angle relative to said light source, with said light responsive receiver being operable to generate electrical signals indicative of the reflected portion of the shaped light, wherein the improvement comprises:

a system of optical elements oriented relative to said light responsive receiver to provide said light responsive receiver with an optical view that includes the plurality of spaced locations of the object, whereby portions of the shaped light that are reflected off the object at each of the plurality of spaced locations are received by said light responsive receiver as a single image; and

an electronic circuit responsive to said electrical signals to determine the location within the image of a preselected feature of each of the reflected portions of shaped light, said circuit further being operable to generate output data representative of the locations of the preselected features.

17. A sensor as defined in claim 16, wherein said optical elements are oriented to rotate at least one reflected portion of the shaped light with respect to at least another reflected portion of the shaped light.

18. A sensor as defined in claim 17, wherein said at least one light source comprises a plurality of lasers, each of which is oriented to project a stripe of laser light onto the object at a different one of the plurality of spaced locations, whereby the shaped light at each of the plurality of spaced locations comprises a stripe of laser light.

19. A sensor as defined in claim 18, wherein:

said light responsive receiver comprises a video camera having an image receiving element that includes successive scan lines, each of which comprises a number of pixels;

said video camera is oriented to receive the reflected portions of the stripes of laser light as lines of laser light that intersect at least some of said scan lines;

said video camera is operable to generate said electrical signals as a stream of pixel data points arranged into successive lines of said pixel data points, with each of said lines of pixel data points representing one of said scan lines;

said electronic circuit includes a microprocessor and is operable to monitor said stream of pixel data points as it is received from said video camera and to interrupt said microprocessor when said electronic circuit receives a particular pixel data point representative of any of the reflected portions of the stripes of laser light; and

said microprocessor is operable in response to said interrupt to acquire a pixel count representing the position of said particular pixel data point within its associated line of pixel data points.

20. A sensor as defined in claim 16, wherein:

said light responsive receiver comprises a video camera that generates said electrical signals as a stream of pixel data points arranged into successive lines of said pixel data points, with each of said lines of pixel data points representing one row of an array of pixel data points that together represent the image;

said electronic circuit is operable to monitor said stream of pixel data points as it is received from said video camera and provide said microprocessor with an interrupt request when said electronic circuit receives a particular pixel data point representative of any of the reflected portions of the shaped light; and

said microprocessor is operable in response to said interrupt request to acquire a pixel count representing the position of said particular pixel data point within its associated line of pixel data points.

21. A sensor as defined in claim 16, wherein said optical elements include a plurality of mirrors oriented to direct the reflected portions of the shaped light into said light responsive receiver.

22. A sensor as defined in claim 16, wherein said circuit is operable to generate coordinate output data indicative of the location of a preselected feature of each of the reflected portions of shaped light.