Method and apparatus of detecting a position of a movable body

• US 6,249,743 B1
• Filed: 12/01/1999
• Issued: 06/19/2001
• Est. Priority Date: 12/01/1998
• Status: Expired due to Fees

• Current Assignee: Tsubakimoto Chain Company
• Original Assignee: Tsubakimoto Chain Company
• Inventors: Ohshimo, Jun
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Beaulieu, Yonel
• Application Number:
  US09/452,742
• Time in Patent Office: 566 Days
• Field of Search: 701/200, 701/206, 701/207, 701/214, 701/28, 342/46, 342/73, 342/357.01, 342/357.08, 356/375, 356/376, 356/385
• US Class Current: 701/207
• CPC Class Codes: G01C 15/002 Active optical surveying means optical plumbing G01C15/105
• CPC Class Codes: G01S 17/06 Systems determining position data of a target
• CPC Class Codes: G01S 17/875 for determining attitude
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G05D 1/0244 using reflecting strips
• CPC Class Codes: G05D 1/0246 using a video camera in combination with image processing means
• CPC Class Codes: G05D 2201/0216 Vehicle for transporting goods in a warehouse, factory or similar

Abstract

The position of a movable body is detected by emitting a laser light in all the directions around a truck as the movable body by means of an optical unit including a laser oscillator and a CCD camera, receiving the laser light reflected by reflectors disposed at a plurality of positions in a moving area, and making comparisons between comparison data being different at each position of the truck in the moving area and reference data of the received-light data at the plurality of positions in the moving area. The comparison data is obtained from a received-light luminance distribution of the reflected laser light and an angle θ obtained by a gyrosensor relative to a reference direction.

Claims

1. A method of detecting a position of a movable body comprising the steps of:

emitting light to outside of said movable body by means of a light emitting apparatus provided with said movable body;

receiving said light, which is reflected by a plurality of reflectors provided with a moving area of said movable body, by means of a light receiving apparatus provided with said movable body for obtaining an electric output corresponding to an intensity of said received light;

comparing a received-light luminance distribution along a circumferential direction of said movable body, which is obtained from the received-light output, with reference received-light luminance distributions stored in advance in association with a plurality of positions in said moving area of said movable body; and

detecting the position of said movable body in accordance with a comparison result.

2. A method according to claim 1, wherein said reference received-light luminance distributions are given in a state in which said movable body turns towards a predetermined reference direction, said method further comprising the steps of:

detecting an angle of a moving direction of said movable body relative to said reference direction by an angle detecting means provided with said movable body;

correcting the received-light luminance distribution obtained by said light receiving apparatus into the received-light luminance distribution when the movable body turns said reference direction, by utilizing the detected angle; and

comparing the corrected received-light luminance distribution with said reference received-light luminance distributions.

3. A method according to claim 1, wherein the plurality of positions in the moving area provided with association with said reference received-light luminance distributions are respective apexes of meshes formed by polygons of the same shape that divide the moving area.

4. A method according to claim 2, wherein the plurality of positions in the moving area provided with association with said reference received-light luminance distributions are respective apexes of meshes formed by polygons of the same shape that divide the moving area.

5. A method according to claim 3, further comprising the steps of:

determining a similarity between said received-light luminance distribution and each of said reference received-light luminance distributions by said comparison;

selecting an apex having the highest similarity from the apexes of said meshes in the moving area;

selecting a plurality of polygons having said selected apex as one of apexes thereof;

selecting a polygon having the largest sum of similarities associated with the apexes of the polygon, from said selected polygons;

determining, for each side of said selected polygon, three points in a three-dimensional space having a coordinate axis which is perpendicular to a plane of moving of said movable body and which represents said similarity, corresponding to three points which are located on the plane of moving and which include two apexes at two ends of said side of said selected polygon and one apex of the mesh located opposite to said selected polygon relative to said side of said selected polygon;

determining a plane that passes through said three points in said three-dimensional space for said side of said selected polygon;

determining an intersecting point of each combination of three planes selected from the planes determined for all the sides constituting said selected polygon; and

determining the position of the movable body as an average of all the determined intersecting points.

6. A method according to claim 4, further comprising the steps of:

determining a similarity between said received-light luminance distribution and each of said reference received-light luminance distributions by said comparison;

selecting an apex having the highest similarity from the apexes of said meshes in the moving area;

selecting a plurality of polygons having said selected apex as one of apexes thereof;

selecting a polygon having the largest sum of similarities associated with the apexes of the polygon, from said selected polygons;

determining, for each side of said selected polygon, three points in a three-dimensional space having a coordinate axis which is perpendicular to a plane of moving of said movable body and which represents said similarity, corresponding to three points which are located on the plane of moving and which include two apexes at two ends of said side of said selected polygon and one apex of the mesh located opposite to said selected polygon relative to said side of said selected polygon;

determining a plane that passes through said three points in said three-dimensional space for said side of said selected polygon;

determining an intersecting point of each combination of three planes selected from the planes determined for all the sides constituting said selected polygon; and

determining the position of the movable body as an average of all the determined intersecting points.

7. A method according to claim 1, wherein the positions associated with said reference received-light luminance distributions are selected as comparison targets in accordance with the detected position and moving direction of said movable body.

8. A method according to claim 2, wherein the positions associated with said reference received-light luminance distributions are selected as comparison targets in accordance with the detected position and moving direction of said movable body.

9. A method according to claim 3, wherein the positions associated with said reference received-light luminance distributions are selected as comparison targets in accordance with the detected position and moving direction of said movable body.

10. A method according to claim 4, wherein the positions associated with said reference received-light luminance distributions are selected as comparison targets in accordance with the detected position and moving direction of said movable body.

11. A method according to claim 5, wherein the positions associated with said reference received-light luminance distributions are selected as comparison targets in accordance with the detected position and moving direction of said movable body.

12. A method according to claim 6, wherein the positions associated with said reference received-light luminance distributions are selected as comparison targets in accordance with the detected position and moving direction of said movable body.

13. A method according to claim 7, wherein said positions associated with said reference received-light luminance distributions and selected as comparison targets are positions contained within an ellipse with its major axis being a line segment connecting the detected position of said movable body with a point located at the maximum distance that said movable body can travel within a predetermined period of time in the moving direction.

14. A method according to claim 8, wherein said positions associated with said reference received-light luminance distributions and selected as comparison targets are positions contained within an ellipse with its major axis being a line segment connecting the detected position of said movable body with a point located at the maximum distance that said movable body can travel within a predetermined period of time in the moving direction.

15. A method according to claim 9, wherein said positions associated with said reference received-light luminance distributions and selected as comparison targets are positions contained within an ellipse with its major axis being a line segment connecting the detected position of said movable body with a point located at the maximum distance that said movable body can travel within a predetermined period of time in the moving direction.

16. A method according to claim 10, wherein said positions associated with said reference received-light luminance distributions and selected as comparison targets are positions contained within an ellipse with its major axis being a line segment connecting the detected position of said movable body with a point located at the maximum distance that said movable body can travel within a predetermined period of time in the moving direction.

17. A method according to claim 11, wherein said positions associated with said reference received-light luminance distributions and selected as comparison targets are positions contained within an ellipse with its major axis being a line segment connecting the detected position of said movable body with a point located at the maximum distance that said movable body can travel within a predetermined period of time in the moving direction.

18. A method according to claim 12, wherein said positions associated with said reference received-light luminance distributions and selected as comparison targets are positions contained within an ellipse with its major axis being a line segment connecting the detected position of said movable body with a point located at the maximum distance that said movable body can travel within a predetermined period of time in the moving direction.

19. A method according to claim 7, wherein said positions associated with said reference received-light luminance distributions and selected as comparison targets are positions contained within a fan-shaped region with its center located at the detected position of said movable body, its radius being the maximum distance that said movable body can travel within a predetermined period of time, and its central angle being a predetermined angle having the detected direction of said movable body in the middle of the angle.

20. A method according to claim 8, wherein said positions associated with said reference received-light luminance distributions and selected as comparison targets are positions contained within a fan-shaped region with its center located at the detected position of said movable body, its radius being the maximum distance that said movable body can travel within a predetermined period of time, and its central angle being a predetermined angle having the detected direction of said movable body in the middle of the angle.

21. A method according to claim 9, wherein said positions associated with said reference received-light luminance distributions and selected as comparison targets are positions contained within a fan-shaped region with its center located at the detected position of said movable body, its radius being the maximum distance that said movable body can travel within a predetermined period of time, and its central angle being a predetermined angle having the detected direction of said movable body in the middle of the angle.

22. A method according to claim 10, wherein said positions associated with said reference received-light luminance distributions and selected as comparison targets are positions contained within a fan-shaped region with its center located at the detected position of said movable body, its radius being the maximum distance that said movable body can travel within a predetermined period of time, and its central angle being a predetermined angle having the detected direction of said movable body in the middle of the angle.

23. A method according to claim 11, wherein said positions associated with said reference received-light luminance distributions and selected as comparison targets are positions contained within a fan-shaped region with its center located at the detected position of said movable body, its radius being the maximum distance that said movable body can travel within a predetermined period of time, and its central angle being a predetermined angle having the detected direction of said movable body in the middle of the angle.

24. A method according to claim 12, wherein said positions associated with said reference received-light luminance distributions and selected as comparison targets are positions contained within a fan-shaped region with its center located at the detected position of said movable body, its radius being the maximum distance that said movable body can travel within a predetermined period of time, and its central angle being a predetermined angle having the detected direction of said movable body in the middle of the angle.

25. An apparatus for detecting a position of a movable body comprising:

a light emitting apparatus provided with said movable body;

a light receiving apparatus provided with said movable body for obtaining an electric output corresponding to an intensity of received light;

a storage medium; and

a controller for calculating a position of said movable body in accordance with the output obtained by receiving, by means of said light receiving apparatus, the light emitted from said light emitting apparatus and reflected by a plurality of reflectors disposed at appropriate positions in a moving area of said movable body,

wherein said controller is coupled to said storage medium and capable of performing the operations of;

reading, from said storage medium, reference received-light luminance distributions at a plurality of positions in said moving area of said movable body; and

comparing a received-light luminance distribution obtained by said light receiving apparatus, with said reference received-light luminance distributions to calculate the position of said movable body.

26. An apparatus according to claim 25, wherein said light emitting apparatus comprises a light source unit and an irradiating unit for reflecting and rotating the light emitted by said light source unit to irradiate the light in all directions around the movable body.

27. An apparatus according to claim 25, wherein said light emitting apparatus comprises a light source unit and an irradiating unit for simultaneously irradiating the light emitted by said light source unit in all directions around the movable body.

28. An apparatus according to claim 25, wherein said light receiving apparatus comprises a reflector for reflecting the light from around the movable body, a condensing unit for rotating said reflector to condense the light from all directions around the movable body into an annular light, and a light receiving unit for receiving the light condensed by said condensing unit.

29. An apparatus according to claim 26, wherein said light receiving apparatus comprises a reflector for reflecting the light from around the movable body, a condensing unit for rotating said reflector to condense the light from all directions around the movable body into an annular light, and a light receiving unit for receiving the light condensed by said condensing unit.

30. An apparatus according to claim 27, wherein said light receiving apparatus comprises a reflector for reflecting the light from around the movable body, a condensing unit for rotating said reflector to condense the light from all directions around the movable body into an annular light, and a light receiving unit for receiving the light condensed by said condensing unit.

31. An apparatus according to claim 25, wherein said light receiving apparatus comprises a condensing unit for condensing the light from all directions around the movable body simultaneously into an annular light, and a light receiving unit for receiving the light condensed by said condensing unit.

32. An apparatus according to claim 26, wherein said light receiving apparatus comprises a condensing unit for condensing the light from all directions around the movable body simultaneously into an annular light, and a light receiving unit for receiving the light condensed by said condensing unit.

33. An apparatus according to claim 27, wherein said light receiving apparatus comprises a condensing unit for condensing the light from all directions around the movable body simultaneously into an annular light, and a light receiving unit for receiving the light condensed by said condensing unit.