Robot vision system

• US 4,611,292 A
• Filed: 09/29/1983
• Issued: 09/09/1986
• Est. Priority Date: 10/06/1982
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ninomiya, Takanori, Nakagawa, Yasuo
• Primary Examiner(s): Krass, Errol A.
• Assistant Examiner(s): Dixon, Joseph L.
• Application Number:
  US06/537,095
• Time in Patent Office: 1,076 Days
• Field of Search: 364/559, 364/513, 356/376, 356/12, 356/13, 358/96, 358/101, 358/88, 358/89, 358/90, 358/93, 358/101, 358/107, 382/8, 382/46, 382/48
• US Class Current: 702/153
• CPC Class Codes: B25J 19/023 including video camera means
• CPC Class Codes: G01B 11/00 Measuring arrangements characterised by the use of optical techniques
• CPC Class Codes: G01S 17/06 Systems determining position data of a target
• CPC Class Codes: G06T 1/0014 Image feed-back for automatic industrial control, e.g. robot with camera robots B25J19/023

Abstract

A method and an apparatus for detecting the position and posture of an object (5, 9, 10) are characterized by two planar light beams (3a, 3b) alternately projected on the object (5, 9, 10) to be handled and intersection lines (A, B) formed between the two planar light beams (3a, 3b) and the object (5, 9, 10) which are imaged by a single image pickup device (2) positioned between the two planar light beams (3a, 3b).

A bright line occurring at a junction between an edge of the object and an intersection line is separated, extracted and transformed into an actual coordinate in a three dimensional coordinate system (x, y, z) by referring to corresponding relationships between the actual coordinate system (x, y, z) and a scanning coordinate system (i, j) so that the position and posture of the object (5, 9, 10) are detected in three dimensions.

Claims

1. An apparatus for detecting the position and posture of an object, comprising:

means having first and second optical axes for alternatively projecting two intersecting planar light beams coplanar with respective ones of said first and second axes, upon an object with the planes of said light beams intersecting along a first line, said first line of intersection being pointed toward the object;

image sensor means positioned between the planar light beams, for forming two-dimensional images from intersections of said planar light beams and said object;

means coupled to said forming means, for extracting scanning coordinates of said intersections; and

means coupled to said extracting means, for computing three dimensional actual coordinates from said scanning coordinates whereby the position and posture of said object is described by said actual coordinates.

2. The apparatus of claim 1, wherein said image sensor means has a single image pickup device for forming the two-dimensional images.

3. The apparatus of claim 2, further comprising:

means for transmitting said three dimensional actual coordinates to a controller of a device supporting said apparatus.

4. The apparatus of claim 1, wherein said image sensor means exhibits a third optical axis obliquely oriented toward said first line.

5. The apparatus of claim 4, wherein said third optical axis is positioned on a plane equally dividing an angle included between the planar light beams.

6. The apparatus of claim 5, wherein said image sensor means includes an areal solid-state image sensor.

7. The apparatus of claim 6, wherein said projecting means has a plurality of light emitting diodes.

8. The apparatus of claim 4, wherein said first, second and third optic axes lie on a single plane.

9. The apparatus of claim 1, wherein a straight line formed by the intesection of said planar light beams is in co-axial alignment with an axis of rotation of a rotatable member of the device.

10. The apparatus of claim 9, wherein said two intersecting planar light beams intersect orthogonally.

11. The apparatus of claim 10, wherein said image sensor means has a detection portion having an optical axis positioned on a plane equally dividing an angle included between the planar light beams.

12. The apparatus of claim 11, wherein said image sensor means includes an areal solid-state image sensor.

13. The apparatus of claim 9, wherein said first, second and third optic axes lie on a single plane.

14. An apparatus for detecting the position and posture of an object, comprising:

a first light source having a first optical axis, to project a first planar light beam coplanar with the first optical axis toward an object;

a second light source having a second optical axis, to project toward said object a second planar light beam coplanar with the second optical axis, with the planes of said first and second light beams intersecting along a first line, said first line being pointed toward the object;

an image pickup device positioned between the planes of said light beams to form in a two dimensional coordinate system images of intersection lines projected upon said object by said light beams;

means for alternately energizing said first and second light sources;

a light segment extracting circuit coupled to said pickup device to scan said images and detect scanning coordinates of edges of said object along the intersection lines;

a memory device to store corresponding relationships between said two dimensional coordinate system and a three dimensional actual coordinate system; and

a computing device using the corresponding relationships to determine from said scanning coordinates actual coordinates of said edges in said three dimsnsional coordinate system and thereby provide an indication of the position and posture of said object in said three dimensional coordinate system.

15. The apparatus of claim 14, wherein said scanning coordinates are provided to said computing device solely by said single light segment extracting circuit.

16. The apparatus of claim 15, further comprising

means for transmitting said actual coordinates to a controller of a device supporting said apparatus.

17. The apparatus of claim 14, wherein said image pickup device exhibits a third optical axis obliquely oriented toward said first line.

18. The apparatus of claim 17, wherein said third optical axis is positioned on a plane equally dividing an angle included between said first planar light beam and said second planar light beam.

19. The apparatus of claim 18, wherein said image pickup device has an areal solid-state image sensor.

20. The apparatus of claim 19, wherein said first and second light sources contain a plurality of light emitting diodes generating said first and second planar light beams.

21. The apparatus of claim 14, wherein said first line comprises a straight line formed by the intersection of the planes of said first planar light beam and said second planar light beam, in co-axial alignment with an axis of rotation of a rotatable member of the device.

22. The apparatus of claim 21, wherein said first planar light beam and said second planar light beam intersect orthogonally.

23. The apparatus of claim 22, wherein said image pickup device has a third optical axis positioned on a plane equally dividing an angle included between said first planar light beam and said second planar light beam.

24. The apparatus of claim 23, wherein said image pickup device has an areal solid-state image sensor.

25. The apparatus of claim 21, wherein said image pickup device exhibits a third optical axis and said first, second and third optical axes lie on a single plane.

26. The apparatus of claim 14, wherein said image pickup device exhibits a third optical axis and said first, second and third optical axes lie on a single plane.

27. A method of detecting the position and posture of an object, comprising the steps of:

alternately projecting toward an object a first planar light beam having a first optical axis and a second planar light beam having a second otpical axis and intersecting the plane of said first light beam along a first line;

pointing said first line toward the object;

producing in a two dimensional coordinate system images of intersection lines formed on said object by said light beams with a photo-sensitive device exhibiting a third optical axis obliquely oriented toward said first line;

extracting sets of scanning coordinates of edges of said object from said images of said intersection lines; and

computing in a three dimensional coordinate system actual coordinates of said object from the sets of said scanning coordinates by using corresponding relationships between said two dimensional and three dimensional coordinate systems.

28. The method of claim 27, wherein said images are produced by a single photo-responsive device.

29. The method of claim 28, further comprising:

storing the corresponding relationships in a memory; and

reading said corresponding relationships from said memory while computing said actual coordinates.

30. The method of claim 29, wherein said step of projecting includes a step of alternately energizing a first light source which projects the first planar light beam and a second light source which projects the second planar light beam.

31. The method of claim 29, wherein said step of computing includes:

a step of computing an approximate central position of the object and an inclination of the object in an x-direction;

a step of computing an approximate central position of the object and an inclination of the object in a y-direction; and

a step of computing a central position of the object and a distance from the apparatus to the central position of the object by using the approximate central positions and the inclination of the object.

32. The method of claim 27, further comprised of placing said first, second and third optical axes in a single plane.