Apparatus and procedure for locating three-dimensional objects packed in bulk for purposes of controlling a gripping terminal

• US 4,486,842 A
• Filed: 02/09/1982
• Issued: 12/04/1984
• Est. Priority Date: 02/12/1981
• Status: Expired due to Fees

• Current Assignee: Regie Nationale Des Usines
• Original Assignee: Regie Nationale Des Usines Renault (Renault)
• Inventors: Hermann, Jean-Paul
• Primary Examiner(s): Ruggiero, Joseph F.
• Assistant Examiner(s): Harkcom, Gary V.
• Application Number:
  US06/347,080
• Time in Patent Office: 1,029 Days
• Field of Search: 364/478, 364/479, 364/468, 364/469, 364/513, 364/514, 364/516, 414/730, 414/909, 358/101, 358/107, 358/903
• US Class Current: 700/259
• CPC Class Codes: G06T 1/0014 Image feed-back for automatic industrial control, e.g. robot with camera robots B25J19/023

Abstract

An apparatus and procedure for locating three-dimensional bulk-loaded objects for purposes of controlling a gripping terminal, including at least one optical projection system associated with drive mechanisms commanded by an interface connected to a central processing unit, and a light sensor such as a TV camera mounted plumb with the surface (horizontal, for example) receiving the bulk load and connected to the analysis and processing mechanisms of the central processing unit. The optical system emits a substantially planar light bundle which sweeps the surface of the bulk load under the control of the drive mechanisms to vary incrementally the angle θ made by the bundle with respect the aforementioned surface. The value of the angle, measured by a coder, is transmitted to the central processing unit which analyzes the image of the bundle trace sensed by the camera. The central processing unit selects the point whose value corresponds to a predetermined condition, such as the highest point on the surface of the bulk load. The invention finds application in automatic high-speed unloading by an industrial robot of a crate filled with three-dimensional objects loaded in bulk.

Claims

1. An apparatus for locating three-dimensional objects in a bulk load in order to control a gripping terminal for selective moving of said gripping terminal to at least one of said objects, comprising:

at least one optical projection system for producing a substantially planar light bundle;

drive means coupled to said optical projection system for sweeping said light bundle across a predetermined surface area of said bulk load, whereby an irregular light trace of said light bundle on said bulk load is produced;

a central processing unit for controlling said drive means;

light sensing means located plumb with a predetermined surface of said bulk load for sensing said irregular light trace from said light bundle reflected off said bulk load and for producing output signals indicative of said irregular light trace;

said central processing unit comprising analysis and processing means coupled to the output signals of said light sensing means for processing said output signals;

said drive means comprising means for rotating said light bundle through a predetermined angle θ

in plural predetermined increments spanning the predetermined surface area of the bulk load;

coder means for measuring the instantaneous value of said angle θ and

for communicating said instantaneous value to said central processing unit; and

said central processing unit comprising means for analyzing, for each value of the angle θ

, said irregular light trace sensed by said light sensing means and to define points (xi, yi, zi) indicative of a profile of said bulk load based on the irregular light trace for each said angle θ

, and means for selecting those of said defined points corresponding to a predetermined condition for controlling movement of the gripping terminal to the object located at the selected points based on the selected points.

2. An apparatus according to claim 1, wherein the light sensing means comprises a TV camera, comprising;

means for controlling the camera to sweep perpendicularly to the axis of rotation of the projection system; and

said analyzing means including means for recording, for each incremental angle of rotation and for each camera sweep line xi, the ordinate yi with respect to a predetermined reference plane of an intersection between the sweep of the camera and said irregular light trace sensed by said camera, said analyzing means recording parameters xi and yi for each incremental value of angular rotation θ

j.

3. An apparatus according to claim 1, wherein the light sensing means comprises a TV camera, comprising;

means for controlling the camera to sweep parallel to the axis of rotation of the projection system; and

said analyzing means comprising means for recording for each incremental angle of rotation θ

j, the ordinate yi of the first illuminated sweep line and the abscissa xi of the first illuminated point of the image of the trace, wherein xi and yi are defined with respect to a predetermined reference plane.

4. An apparatus according to claims 2 or 3, wherein said predetermined reference plane includes the axis of rotation of the optical system, and an origin on said axis is defined by a predetermined edge of the area swept by said camera.

5. An apparatus according to claim 4 wherein said central processing unit comprises:

means for computing a third-dimensional value zi for each point xi, yi based on the respective instantaneous angle θ

j measured by said coder means.

6. An apparatus according to claims 1, 2 or 3, comprising:

at least two optical projection systems arranged symmetrically with respect to said bulk load,

said drive means and said coder means including a respective drive motor and angular coder, each coupled to said central processing unit, for sweeping respective of the optical projection systems and for measuring the respective instantaneous values of the respective angles θ

j.

7. An apparatus according to claim 5, comprising:

means for controlling the gripping terminal of a robot based on the values of said coordinates (xi, yi, zi).

8. A procedure for locating three-dimensional objects in a bulk load in order to control a gripping terminal for selective moving of said gripping terminal to at least one of said objects, said procedure implemented by means of at least one optical projection system for producing a substantially planar light bundle, drive means commanded by an interface connected to a central processing unit for controlling the production of said light bundle, light sensing means mounted plumb with respect to a predetermined surface for receiving light from said light bundle reflected off said bulk load and for forming signals indicative of an image thereof, wherein said light sensing means is coupled to said central processing unit which processes the signals indicative of the reflected image, comprising:

arranging the optical system to produce a light bundle making a predetermined initial angle θ

with respect to said predetermined surface;

rotating said at least one optical projection system so as to cause the angle θ

to vary within a predetermined interval in predetermined increments θ

j in order to sweep the surface of the bulk load thereby producing an irregular light trace of said light bundle for each increment θ

j;

analyzing for each incremental value θ

j the irregular light trace reflected off said bulk load and sensed by said light sensing means to define points indicative of a profile of said bulk load; and

selecting predetermined points in the bulk load profile based on a predetermined condition as corresponding to the location of a three-dimensional object.

9. A procedure according to claim 8, wherein said analyzing step comprises:

determining, with respect to a reference, the cartesian coordinates (x, y, z) of the defined points on the surface of the bulk load on the basis of the incremental angular values θ

j and the respective coordinate (xi, yi) of the points of intersection between the sweep lines and the reflected irregular light trace sensed by said sensing means.

10. The procedure according to claim 8 or 9, wherein said selecting means comprising:

selecting by means of said central processing unit those points of the bulk load which fall into a predetermined range defined by two predetermined values.

11. A procedure according to claim 8, wherein said analyzing step comprises:

determining, with respect to a reference, the cartesian coordinates (xi, yi, zi) of the defined points on the surface of the bulk load on the basis of the incremental angular values θ

j of the coordinates (xi, yi) of the point of intersection between a sweep line of said light sensing means and a first luminous point on the reflected irregular light trace sensed by said light sensing means.

12. A procedure according to claim 11, wherein said selecting step comprises:

selecting by means of said central processing unit the highest point on the surface of the bulk load.