Distance measuring apparatus and shape measuring apparatus

• US 5,929,980 A
• Filed: 02/03/1998
• Issued: 07/27/1999
• Est. Priority Date: 08/07/1995
• Status: Expired due to Fees

• Current Assignee: Komatsu Ltd.
• Original Assignee: Komatsu Ltd.
• Inventors: Ariga, Tatsuya, Yoshimi, Osamu, Yamaguchi, Hiroyoshi, Shinbo, Tetsuya
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US09/017,938
• Time in Patent Office: 539 Days
• Field of Search: 356/3.06, 356/3.07, 356/3.14, 356/376, 356/141.1, 356/139.03, 356/4.03, 382/199
• US Class Current: 356/4.03
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/026 by measuring distance between sensor and object G01B11/0608 takes precedence
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures

Abstract

A small-sized precision distance measuring apparatus. When a laser beam 1b reflected from an article is received on a photodetector array (30) through a lens array (20), the effective area of the photodetector array (30) is calculated on the basis of the output from the photodetectors, and the distance from the lens array (20) to the article 11 is calculated from the calculated area and the angle of view of the lenses constituting the lens array (20). If pixels (33a, 33b, 33c) of an image on a sensor array, corresponding to the coordinates of elements in the space (12), are determined on the basis of the positional relationship between the lenses (41a, 41b, 41c) of a lens array and photodetectors (51a, 51b, 51c) of the sensor array, the comparison of image information on the pixels (33a, 33b, 33c) can be made to determine the coordinate positions representing the profile of the article 11 from the coordinate positions of the space (12), thereby determining the distance to the article (11) and its shape. The measuring apparatus is used on a moving body, a robot or the like.

Claims

1. A distance measuring apparatus for measuring a distance from a reference plane to a laser lit position by beaming a laser beam from a laser oscillator to an article and sensing a reflected laser beam, characterized in that the apparatus comprises:

a lens array including a plurality of lenses having identical lens characteristics and disposed at uniform intervals on a plane, the lens array having a hole formed within the plane for allowing passage of the laser beam projected from the laser oscillator;

a photodetector array including a plurality of photodetectors disposed on a plane and corresponding to each lens constituting the lens array, the photodetectors in the photodetector array being disposed at a distance of a focal length of the lens from the lenses in the lens array, the photodetector array having a hole formed within the plane for allowing passage of the laser beam projected from the laser oscillator;

the laser oscillator projecting the laser beam toward the article in such a manner that a direction of the laser beam becomes perpendicular to the photodetector array and the lens array and that the laser beam passes through each of the holes formed in the photodetector array and the lens array;

the lens array, the photodetector array, and the laser oscillator being disposed in front of the article so as to be separated from the article in that order; and

calculating means for calculating an effective area on the photodetector array on the basis of an output of each photodetector in the photodetector array, when the laser beam reflected from the article is sensed by the photodetector array via the lens array, and for calculating a distance from the lens array to the article on the basis of the effective area and an angle of view of the lenses constituting the lens array.

2. The distance measuring apparatus according to claim 1 wherein the laser oscillator is disposed so that the laser beam is beamed directly to the article without passing through the photodetector array and the lens array, whereby the holes in the photodetector array and the lens array are omitted.

3. A distance measuring apparatus for measuring a distance from a reference plane to a laser lit position by beaming a laser beam from a laser oscillator to an article and sensing the reflected laser beam, characterized in that the apparatus comprises:

a lens array including a plurality of lenses having identical lens characteristics and disposed at uniform intervals on a sphere;

a photodetector array including photodetectors disposed on a sphere and corresponding to each lens constituting the lens array, the photodetectors in the photodetector array being disposed at a distance of a focal length of the lens from the corresponding lenses in the lens array;

the lens array and the photodetector array being disposed in front of the article so as to be separated from the article in that order and so that an interior of the sphere of the lens array faces an exterior of the sphere of the photodetector array; and

calculating means for calculating an effective area on the photodetector array on the basis of an output of each photodetector in the photodetector array, when the laser beam reflected is projected from the laser oscillator toward the article and the laser beam reflected from the article is detected by the photodetector array via the lens array, and for calculating a distance from the lens array to the article on the basis of this effective area and an angle of view of the lenses constituting the lens array.

4. The distance measuring apparatus according to claim 3 wherein the calculating means calculates a direction of the article with a direction in which the article is present being a direction of a line segment connecting a spherical center of the photodetector array or the lens array to a center of the effective area of the photodetector array or the area on the lens array corresponding to the effective area.

5. A distance and shape measuring apparatus characterized in that the apparatus comprises:

an imaging lens array including a plurality of lenses disposed on a plane;

an imaging photodetector array including photodetectors disposed on a plane and having prescribed resolutions corresponding to each lens constituting the imaging lens array, the photodetectors in the photodetector array being disposed at a distance of a focal length of the lens from the corresponding lenses in the lens array;

a reproducing lens array including a plurality of lenses disposed on a plane and having lens characteristics identical to lenses constituting the imaging lens array;

a reproducing emitter array including emitters disposed on a plane and corresponding to each lens constituting the reproducing lens array and having the same size as the photodetectors constituting the imaging photodetector array, the emitters of the emitter array being disposed at a distance of a focal length of the lens from corresponding lenses in the reproducing lens array;

a reproducing sensor array including a plurality of photodetectors disposed on a plane, for sensing light passing through the reproducing lens array;

the imaging lens array, the imaging photodetector array, the reproducing emitter array, the reproducing lens array, and the reproducing sensor array being disposed in front of the article so as to be separated from the article in that order;

transferring means for transferring an output of each photodetector in the imaging photodetector array to each corresponding emitter in the reproducing emitter array and causing emission by the emitters, when the light reflected by the article passes through the imaging lens array and is sensed with the imaging photodetector array;

moving means for moving the reproducing sensor array in a direction of distance measurement for the article, when the light emitted by the reproducing emitter array passes through the reproducing lens array and is sensed with each photodetector of the reproducing sensor array; and

calculating means for calculating a distribution of an intensity of light sensed with each photodetector of the reproducing sensor array for each position to which the reproducing sensor array is moved and for calculating a distance to the article from the imaging lens array and a shape of the article on the basis of the light intensity distribution for each position.

6. The distance and shape measuring apparatus according to claim 5 wherein the imaging sensor array and the reproducing emitter array are configured with a unit plane which passes light incident from a front side and radiates from a back side, whereby the transferring means is made unnecessary.

7. The distance and shape measuring apparatus according to claim 5 wherein a reducing optical system, for reducing by a prescribed reduction ratio a reproduced image of the article reproduced with the reproducing sensor array, is disposed between the reproducing lens array and the reproducing sensor array.

8. The distance and shape measuring apparatus according to claim 5 wherein a reproduced image of the article reproduced with the reproducing sensor array is reduced by a prescribed reduction ratio, by an arrangement in which each emitter of the reproducing emitter array is reduced by the prescribed reduction ratio, while each lens of the reproducing lens array is reduced by the prescribed reduction ratio, and the transferring means is so constituted that it transfers an output of each photodetector of the imaging sensor array to each corresponding emitter of the reproducing emitter array so that an imaged image of the imaging sensor array is reduced by the prescribed reduction ratio and appears as an emission image on the reproducing emitter array.

9. A distance and shape measuring apparatus characterized in that the apparatus comprises:

an imaging lens array including a plurality of lenses disposed on a plane;

an imaging sensor array including photodetectors disposed on a plane and having a prescribed resolution and corresponding to each of the lenses constituting the imaging lens array, the photodetectors of the photodetector array being disposed at a distance of a focal length of each lens from corresponding lenses of the imaging lens array; and

calculating means for calculating pixels of an imaged image of the photodetectors corresponding to a coordinate position of each element in space on the basis of a positional relationship between the lenses in the imaging lens array and the photodetectors in the imaging photodetector array, for determining coordinate positions representing a profile of the article from among the coordinate positions in the space by comparing image information of the pixels found, and for finding a distance to and a shape of the article on the basis of the coordinate positions determined.

10. The distance and shape measuring apparatus according to claim 9 wherein a plurality of cameras is provided in such a manner that the lenses constituting the imaging lens array are lenses of each camera and imaged images of the plurality of photodetectors constituting the imaging photodetector array are imaged images of the camera.

11. The distance and shape measuring apparatus according to claim 9 further comprising edge image generating means for generating an edge image for the imaged image, and wherein the calculating means, by using the edge image instead of the imaged image, finds pixels on the edge image corresponding to a coordinate position of each element in space, determines the coordinate position representing a profile of the article from among each coordinate position in the space by comparing image information of the pixels found, only in a case where the pixels found are pixels corresponding to an edge portion in the edge image, and performs calculations to find a distance to and a shape of the article on the basis of the coordinate positions determined.

12. The distance and shape measuring apparatus according to claim 9 further comprising:

edge image generating means for generating an edge image for the imaged image; and

edge resolving means for generating an edge resolving image wherein pixels corresponding to an edge portion of the edge image and a prescribed number of pixels on a periphery of the edge portion are presumed to be pixels of the edge portion, and wherein

the calculating means, by using the edge resolving image instead of the imaged image, finds pixels on the edge resolving image corresponding to a coordinate position of each element in space, determining the coordinate position representing a profile of the article from among the coordinate position of each element in the space by comparing image information of the pixels found, only in a case where the pixels found are pixels corresponding to the edge portion in the edge resolving image, and performs calculations to find a distance to and a shape of the article on the basis of the coordinate positions determined.

13. The distance and shape measuring apparatus according to claim 9 further comprising:

edge image generating means for generating an edge image for the imaged image; and

edge resolving image generating means for generating an edge resolving image wherein image information of pixels corresponding to an edge portion of the edge image is transposed with image information of corresponding pixels of a source image of the imaged image; and

wherein

the calculating means, by using the edge resolving image instead of the imaged image, finds pixels on the edge resolving image corresponding to a coordinate position of each element in space, determines a coordinate position representing a profile of the article from among coordinate positions of each element in the space by comparing image information of the pixels found, only in a case where the pixels found are pixels corresponding to the edge portion in the edge resolving image, and performs calculations to find a distance to and a shape of the article on the basis of the coordinate positions determined.

14. The distance and shape measuring apparatus according to claim 13 wherein the edge resolving image generating means presumes, as pixels of an edge portion, pixels corresponding to the edge portion of the edge resolving image and a prescribed number of pixels on a periphery of the edge portion, and generates the edge resolving image in which image information of the pixels presumed to be the edge portion is transposed with image information of corresponding pixels of a source image of the imaged image.

15. The distance and shape measuring apparatus according to claim 9 further comprising:

derivative image generating means for generating a derivative image of the imaged image;

edge image generating means for generating an edge image for the imaged image; and

edge resolving image generating means for generating an edge resolving image in which image information of pixels corresponding to the edge portion of the edge image is transposed with image information of pixels corresponding to the derivative image, and wherein

the calculating means, by using the edge resolving image instead of the imaged image, finds pixels on the edge resolving image corresponding to a coordinate position of each element in space, determines a coordinate position representing a profile of the article from among a coordinate position of each element in the space by comparing the image information of the pixels found, only in a case where the pixels found are pixels corresponding to the edge portion in the edge resolving image, and performs calculations to find a distance to and a shape of the article on the basis of the coordinate positions determined.

16. The distance and shape measuring apparatus according to claim 15 wherein the edge resolving image generating means presumes, as pixels of an edge portion, pixels corresponding to the edge portion of the edge resolving image and a prescribed number of pixels on a periphery of the edge portion, and generates the edge resolving image in which image information of the pixels presumed to be the edge portion is transposed with image information of corresponding pixels of the derivative image.

17. The distance and shape measuring apparatus according to claim 9 comprising:

first dividing means for setting a space surrounding the article and for dividing the space into a plurality of elements;

wherein

the calculating means finds pixels in the imaged image corresponding to coordinate positions of each element of the space divided with the first means for dividing, determines coordinate positions representing a profile of the article from among each of the coordinate positions in the space by comparing the image information of the pixels determined, and finds a distance to and a shape of the article on the basis of the determined coordinate positions;

determining means for determining whether the article is present in which area of the space on the basis of results of calculations in progress by the calculating means;

second dividing means for dividing into a further plurality of elements those elements divided by the first dividing means, for an area, in which the article is present, of the space where it is determined that the article is present; and

wherein

the calculating means finds pixels in the imaged image corresponding to coordinate positions of each element of the area where the article is present and which is divided by the second dividing means, determines coordinate positions representing a profile of the article from among each of the coordinate positions of the area where the article is present by comparing the image information of the pixels found, and finds a distance to and a shape of the article on the basis of the coordinate positions determined.

18. The distance and shape measuring apparatus according to claim 9 wherein the distance and shape measuring apparatus is mounted on a moving body and used to measure the distance to and shape of an article present in front of and in the path of the moving body;

wherein the apparatus comprises;

dividing means for setting a space so as to enclose the article in front of the moving body, along the path before the moving body and for dividing the space into a plurality of elements so that a number of divided elements per a uniform area increases in relation to the nearness of a distance from the moving body; and

wherein

the calculating means finds pixels in the imaged image corresponding to coordinate positions of each element of the space divided by the dividing means, determines coordinate positions representing a profile of the article from among the coordinate positions of each element of the space by comparing image information of the pixels determined, and finds a distance to and a shape of the article on the basis of the coordinate positions determined.

19. The distance and shape measuring apparatus according to claim 9 wherein the dividing means divides a central portion of a cross section, perpendicular to the direction of the moving body in the space, so that the number of divided elements per uniform area becomes high compared to a peripheral portion of the cross section, when the forward path of the moving body is a straight path.

20. The distance and shape measuring apparatus according to claim 9 wherein the dividing means divides a peripheral portion of a cross section, perpendicular to the direction of the moving body in the space, so that the number of divided elements per uniform area becomes high compared to a central portion of the cross section, when the forward path of the moving body is a curved path.

21. The distance and shape measuring apparatus according to claim 11 wherein flat portion distance measuring device for measuring a distance to a flat portion of a surface of the article, is disposed other than the distance and shape measuring apparatus, for measuring a distance to each position of the surface of the article on the basis of results of measuring the distance to the edge portion of the surface of the article, attained with the distance and shape measuring apparatus, and results of measuring the distance to the flat portion of the surface of the article, attained with the flat portion distance measuring apparatus.

22. The distance and shape measuring apparatus according to claim 21 wherein the flat portion distance measuring apparatus is a laser radar for scanning space in three dimensions.

23. The distance and shape measuring apparatus according to claim 10 wherein:

at least two modules, in which the plurality of cameras is disposed so that cameras are separated from each other by a prescribed distance between cameras, are disposed in such a manner that a distance from a camera of one module to a camera of an adjacent module is a distance greater or equal to the prescribed distance between cameras;

plurality of modules are selected from among the two or more modules, so that a distance to one module or between two modules farthest apart becomes less than or equal to the prescribed distance between modules, when a distance from the module to the article is less than or equal to a prescribed distance between module and article;

plurality of modules are selected from among the two or more modules, so that a distance between the two modules farthest apart becomes greater than the prescribed distance between modules, when the distance from the modules to the article is greater than the prescribed distance between module and article; and

a distance to and a shape of the article are measured by using the cameras installed in the selected modules.