Method for measuring a three-dimensional position of an object

• US 4,846,576 A
• Filed: 05/20/1986
• Issued: 07/11/1989
• Est. Priority Date: 05/20/1985
• Status: Expired due to Term

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Hanahara, Keishi, Maruyama, Tsugito, Kanda, Shinji
• Primary Examiner(s): Rosenberger, Richard A.
• Application Number:
  US06/864,846
• Time in Patent Office: 1,148 Days
• Field of Search: 356/354, 356/355, 356/356, 356/375, 356/376, 356/1, 356/162.17, 356/169, 356/433, 396/376, 396/1, 396/375, 396/376
• US Class Current: 356/604
• CPC Class Codes: G01B 11/00 Measuring arrangements characterised by the use of optical techniques
• CPC Class Codes: G01B 11/005 coordinate measuring machines
• CPC Class Codes: G01S 17/46 Indirect determination of position data
• CPC Class Codes: G01S 7/4814 of transmitters alone
• CPC Class Codes: G01S 7/491 Details of non-pulse systems

Abstract

A method for measuring a three-dimensional position of an object with a single camera and a multislit light, i.e., a source of multiplanar light beams. A surface of the object is irradiated with multislit lights, i.e., multiplanar light beams, having a plurality of slit light faces and also irradiated with a single standard slit light having a slit light face identical to one of the plurality of slit light faces of the multislit lights. A plurality of slit light photo images corresponding to a plurality of slit light projected images and a standard slit light photo image corresponding to a slit light projected image formed on the object are obtained. One of the slit light photo images which corresponds to the standard slit light photo image is specified and made to correspond, to compute a three-dimensional position of the object in a predetermined coordinate.

Claims

1. A method for measuring a three-dimensional position of an object, comprising the steps of:

irradiating the surface of the object with a multiplanar light beam comprising a plurality of planar light beams which exist in respective planes having a predetermined relative relationship and defining parallel luminance lines in a plane including the surface of the object and corresponding to a predetermined coordinate direction thereby to produce a corresponding plurality of planar light beam projected images of the surface of the object;

irradiating the surface of the object with a single standard planar light beam which exists in a plane common to one of the planes of the multiplanar light beam and produces a corresponding luminance line on the surface of the object thereby to produce a corresponding, single standard planar light beam projected image of the surface of the object;

obtaining a plurality of planar light beam photo images corresponding to the plurality of planar light beam projected images;

obtaining a single standard planar light beam photo image corresponding to the single standard planar light beam projected image;

identifying a specific one of the plurality of planar light beam photo images which corresponds to the single standard planar light beam photo image;

determining the correspondence between the plural planar light beam photo images and the respective planes of the plural planar light beams of the multiplanar light beam on the basis of the relative positions of the identified, specific planar light beam photo image and the remaining planar light beam photo images of the plurality thereof formed by the multiplanar light beam; and

computing the three-dimensional position of the object in the predetermined coordinate on the basis of the relative positions of the respective, plural planar light beam photo images and the respective planes thereof, as determined theretofore to correspond to the respective planar light beam photo images.

2. A method as set forth in claim 1, wherein the object is linear, the coordinates of the standard planar light beam photo image on the object and the plural planar photo images on the object are extracted by AND operations of the center line photo image on the object and the standard planar light beam photo image, and of the center line photo image on the object and the plural planar light beam photo images.

3. A method as recited in claim 2, wherein said identifying a specific one of the plurality of planar light beam photo images which corresponds to the single standard planar light beam photo image, comprises the steps of:

(a) averaging the coordinates of the single standard planar light beam photo image on the object;

(b) determining the distance and direction of the single standard planar light beam photo image on the object to each of the plurality of planar light beam photo images on the object; and

(c) rearranging and classifying the coordinates of the plurality of planar light beam images on the object based upon said determining in step (b).

4. A method as set forth in claim 1, wherein said object is solid, the coordinates of the standard planar light beam photo image on the object and the plural planar light beam photo images on the object are extracted by AND operations of the configuration line photo image on the object and the standard planar light beam photo image, and of the configuration photo image on the object and the plural planar light beam photo images.

5. A method as recited in claim 4, wherein said identifying a specific one of the plurality of planar light beam photo images which corresponds to the single standard planar light beam photo image, comprises the steps of:

(a) averaging the coordinates of the single standard planar light beam photo image on the object;

(b) determining the distance and direction of the single standard planar light beam photo image on the object to each of the plurality of planar light beam photo images on the object; and

(c) rearranging and classifying the coordinates of the plurality of planar light beam images on the object based upon said determining in step (b).

6. A method as recited in claim 1, further comprising:

obtaining the correspondence between the respective planar light beam photo images and the corresponding planes of the planar light beams of the multiplanar light beam for the condition that no interchange has occurred between the plurality of planar light beam photo images.

7. A method as recited in claim 1, further comprising:

irradiating the surface of the object with a multiplanar light beam produced by a multiplanar light source;

arranging a single standard planar light source relative to the multiplanar light source such that the plane of the single standard planar light beam is identical to a selected one of the planes of the planar light beams of the multiplanar light beam; and

irradiating the surface of the object with the single standard planar light beam from the single standard light beam source, as thus arranged relative to the multiplanar light beam source.

8. A method as recited in claim 1, further comprising;

providing a multiplanar light beam source producing a plurality of planar light beams and having a selected planar light beam, out of the plurality thereof, of higher luminance than the remainder of the plurality of the planar light beams; and

performing the step of irradiating the surface of the object with a multiplanar light beam by utilizing the plurality of planar light beams of the source, including the light beam of higher luminance than the remainder thereof; and

performing the step of irradiating the surface of the object with a single standard planar light beam by irradiating the object with the multiplanar light beam source having a planar light beam of higher luminance and utilizing only the planar light beam of higher luminance as the single standard planar light beam.

9. A method as recited in claim 8, further comprising:

performing the step of obtaining a plurality of planar light beam photo images by selective binary processing at a high level thereby to obtain parallel light beam photo images corresponding to all of the plurality of planar light beam projected images; and

performing the step of obtaining a standard planar light beam photo image by low level binary processing thereby to obtain as the standard planar light beam photo image the photo image corresponding to and produced by the high luminance planar light beam.

10. A method as recited in claim 11, further comprising:

providing a source of a multiplanar light beam;

performing the step of irradiating the surface of the object with a multiplanar light beam by utilizing the multiplanar light beam source; and

performing the step of irradiating the surface of the object with a single standard planar light beam by blocking all but a selected one of the planar light beams of the source thereof and irradiating the surface of the object with the selected planar light beam.

11. A method as recited in claim 1, further comprising:

performing the steps of irradiating the surface of the object with a multiplanar light beam and with a single standard planar light beam in individual time periods of selected succession.

12. A method as recited in claim 1, wherein said irradiating the surface of the object with a multiplanar light beam is performed by a single light source having a single light beam.

13. A method as recited in claim 1, wherein said obtaining a plurality of planar light beam photo images is performed by a single camera.

14. A device for emitting multiplanar light beams comprising:

means for generating a single wavelength, parallel light beam defining an optical axis;

first and second diffraction gratings positioned in the path of the parallel light beam with the respective gratings thereof in mutually perpendicular relationship and both transverse to the optical axis, the first grating receiving the parallel light beam and producing a linear array of optical spots parallel to the direction of diffraction of the second diffraction grating;

a cylindrical lens having a longitudinal axis and positioned along the optical axis with the longitudinal axis thereof parallel to the direction of diffraction of one of the diffraction gratings;

the said one of the diffraction gratings having a first, diffraction grating portion and a second, non-grating diffraction portion in contiguous edge-to-edge relationship and positioned on the optical axis such that the optical spots of the diffracted light beam produced by the first diffraction grating are incident in part on the diffraction grating portion and in part on the non-diffraction grating portion of the second diffraction grating, the non-diffraction grating portion transmitting the part of the optical spots of the diffracted beam incident thereon directly therethrough and without diffraction thereof.

15. A device as recited in claim 14, wherein:

the second diffraction grading is positioned with the contiguous edge of the diffraction grating portion thereof on the optical axis thereby to produce plural, parallel planar light beams having a central planar light beam of higher luminance than the remainder thereof for use as a standard single planar light beam.

16. A device as recited in claim 15, wherein:

the second diffraction grating has a direction of diffraction parallel to the longitudinal axis of the cylindrical lens; and

the first and second diffraction gratings and the cylindrical lens are positioned at successive first, second and third positions, respectively, along the optical axis from the generating means.

17. A device as recited in claim 15, wherein:

the second diffraction grating has a direction of diffraction parallel to the longitudinal axis of the cylindrical lens; and

the cylindrical lens and the first and second diffraction gratings are respectively positioned at successive, first, second, and third positions, respectively, along the optical axis from the generating means.

19. A device as recited in claim 17, wherein:

the second diffraction grating has a direction of diffraction parallel to the longitudinal axis of the cylindrical lens; and

the cylindrical lens is positioned in the path of the light beam in front of the second diffraction grating.

20. A device as recited in claim 19, wherein:

the second diffraction grating has a direction of diffraction parallel to the longitudinal axis of the cylindrical end; and

the cylindrical lens, the first and second diffraction gratings, and the shutter are positioned at successive first, second, third and fourth positions, respectively, along the optical access from the generating means.

21. A device as recited in claim 16, wherein:

the second diffraction grating has a direction of diffraction parallel to the longitudinal axis of the cylindrical lens; and

the cylindrical lens, the second diffraction grating, the shutter, and the first diffraction grating are positioned at successive, first, second, third and fourth positions, respectively, along the optical axis from the generating means.

18. A device for emitting multiplanar light beams comprising:

means for generating a single wavelength, parallel light beam defining an optical axis;

first and second diffraction gratings positioned in the path of the parallel light beam with the respective gratings thereof in mutually perpendicular relationship and both transverse to the optical axis;

a cylindrical lens having a longitudinal axis and positioned in the path of the parallel light beam and with the longitudinal axis thereof parallel to the direction of diffraction of one of the diffraction gratings;

the second diffraction grating having a first, grating portion and a second, non-grating portion in contiguous, edge-to-edge relationship and with the contiguous edge of the diffraction grating portion thereof positioned on the optical axis;

the lens and the first and second diffraction gratings being positioned in a selected succession along the optical axis and together forming, from the light beam generated from the generating means, a plurality of parallel light beams; and

a shutter positioned on the optical axis, operable selectively between a partially closed, selective light beam blocking position and an open, light beam transmitting and non-blocking position, the light beam passing through the shutter means in its open position and the device thereby emitting plural parallel planar light beams and the light beam being selectively blocked by the shutter means in its blocking position and the device thereby emitting a single planar light beam for use as a standard single planar light beam.