Apparatus and method to enable a robot with vision to acquire, orient and transport workpieces

• US 4,305,130 A
• Filed: 05/29/1979
• Issued: 12/08/1981
• Est. Priority Date: 05/29/1979
• Status: Expired due to Term

• Current Assignee: University of Rhode Island
• Original Assignee: University of Rhode Island
• Inventors: Tella, Richard P., Birk, John R., Kelley, Robert B., Duncan, Dana L., Wilson, Laurie J.
• Primary Examiner(s): Ruggiero, Joseph F.
• Application Number:
  US06/043,197
• Time in Patent Office: 924 Days
• Field of Search: 364/107, 364/513, 364/474, 364/478, 364/559, 318/568, 318/640, 358/100, 358/101, 358/107, 358/139, 358/903, 414/730, 414/737, 414/627, 414/752, 414/267, 414/268, 414/274, 414/4, 414/5, 414/909
• US Class Current: 700/259
• CPC Class Codes: B25J 19/023 including video camera means
• CPC Class Codes: G05B 2219/40053 Pick 3-D object from pile of objects
• CPC Class Codes: G05B 2219/40583 Detect relative position or orientation between gripper and currently handled object
• CPC Class Codes: G06T 1/0014 Image feed-back for automatic industrial control, e.g. robot with camera robots B25J19/023

Abstract

A robot assembly for acquiring unorientated workpieces from a bin. A sensing system views the bin and collects data. A computer analyzes the data to determine candidate holdsites on the workpiece. The hand of the robot assembly then engages a workpiece at a selected holdsite. The workpiece is moved to a pose where the position and orientation of the workpiece are determined. After this determination, the workpiece may be disengaged, or moved to an intermediate or final goal site.

Claims

1. A robot system for acquiring unorientated unmodified workpieces from a bin which comprises:

(a) a robot assembly which includes

a hand to engage unorientated workpieces stored in the bin, at least some of the workpieces having uncertainty in three angular degrees of freedom for determining candidate holdsites and being structurally distinct from the sensing means; and

an arm secured to the hand to translate and rotate the hand;

(b) sensing means to provide data corresponding to the workpieces in the bin which data includes information based on the three angles of uncertainty and is sufficient to allow a candidate holdsite to be determined;

(c) means to store data corresponding to the relative positions of the bin, the sensing means and the robot assembly, and the data provided by the sensing means; and

(d) a computer communicating with the robot assembly, the sensing means and the means to store the data which includes

means to determine the position of the candidate holdsites; and

means to output data to the robot assembly to move the hand to engage the workpiece at the selective candidate holdsite and to remove subsequently the workpiece from the bin.

2. The system of claim 1 wherein the sensing means is a non-tactile sensor.

3. The system of claim 2 wherein the sensing means is an imaging device.

4. The system of claim 3 wherein the imaging device is a video imaging device.

5. The system of claim 4 which includes

means to move the arm through at least six axes one of which is a linear axis.

6. The system of claims 4 or 5 wherein the hand includes vacuum means to engage the workpiece.

7. The system of claim 5 wherein the video imaging device defines an optical axis, the hand is secured to the arm for movement along the linear axis and the optical axis is in parallel alignment with the linear axis.

8. The system of claim 6 wherein the vacuum means includes a flexible vacuum cup extension.

9. The system of claim 6 which includes

means to illuminate the workpieces in the bin.

10. The system of claim 1 which includes

at least one intermediate goal site, having means to engage the workpiece and wherein the means to store data includes data corresponding to the relative positions of the intermediate goal site, the robot assembly and the engaged workpiece, and the means to output data to the robot assembly includes means to move the workpiece to the intermediate goal site.

12. The system of claim 1 wherein the sensing means is a non-tactile sensor.

13. The system of claim 12 wherein the non-tactile sensor is an imaging device.

14. The system of claim 13 wherein the imaging device is a video imaging device.

16. The system of claims 14 or 15 wherein the video imaging device defines an optical axis, and which includes means to move the arm through at least six axes, one of which is a linear axis and the video imaging device is secured such that its optical axis is in parallel alignment with the linear axis.

17. The system of claim 16 which includes means to illuminate the workpiece.

18. The system of claim 17 wherein the workpiece is illuminated symmetrically about the optical axis.

20. The system of claim 10 wherein the sensing means is a first sensing means which includes

means to acquire an unoriented workpiece from a bin which means comprises second sensing means to provide data corresponding to the workpieces in the bin which data is sufficient to allow a candidate holdsite to be determined, the means to store includes data corresponding to the relative positions of the bin, the second sensing means;

and

the computer includes means to determine the position of the candidate holdsite and means to output data to the robot assembly to move the hand to engage the workpiece at the selected candidates holdsite and to move the hand to the pose.

28. The method of claims 1 or 24 which includes

illuminating the unoriented workpieces in the bin.

29. The method of claims 1 or 24 which includes

removing the workpiece from the bin.

11. A robot system for determining the pose of an engaged unmodified workpiece which comprises:

(a) a robot assembly which includes a hand to engage a workpiece and an arm to translate and rotate the hand;

(b) sensing means to provide data corresponding to the position and orientation of the workpiece in six degrees of freedom, three of translation and three angles, the workpiece being structurally distinct from the sensing means;

(c) means to store the data corresponding to the relative positions of the robot assembly and the sensing means, and the data provided by the sensing means; and

(d) a computer communicating with the robot assembly, the sensing means and the means to store, which includes means to determine the pose of the workpiece and means to output data to the robot assembly to control movement of the workpiece.

15. The system of claim 11 wherein the hand includes vacuum means to engage the workpiece.

19. The system of claim 11 which includes at least one intermediate goal site having means to engage the workpieces, the means to store includes data relative to the position of the goal site, the robot assembly and the workpiece;

and means to output data to move the workpiece to the goal site.

21. A method of acquiring unoriented unmodified workpieces from a bin, the workpieces being structurally distinct from a sensing means which collects data, at least some of the pieces having uncertainty in three angular degrees of freedom for determining candidate holdsites which includes:

(a) collecting data about candidate holdsites by a sensing system, the data including information based on three angles of uncertainty;

(b) locating a candidate holdsite relative to the hand of a robot assembly, the robot assembly including an arm to translate and rotate the hand;

(c) moving the hand to engage the selected holdsite; and

(d) engaging the workpiece.

22. The method of claim 21 which includes

collecting the data with a non-tactile sensor.

23. The method of claim 22 which includes

collecting the data with an imaging device.

24. The method of claim 23 which includes

collecting the data with a video imaging device.

25. The method of claim 24 which includes

establishing at least one candidate holdsite from the collected data.

26. The method of claim 25 which includes selecting a candidate holdsite for engagement by the hand.

27. The method of claim 24 which includes

matching the collected data with a model of holdsite data, the model corresponding to a desired candidate holdsite.

30. The method of claim 24 wherein the video imaging device defines an optical axis and which includes

moving the hand along a linear axis parallel to the optical axis to engage the workpiece.

31. The method of claim 24 wherein the collecting of the data includes

creating images of the workpieces in the bin;

setting all pixels whose brightness is below a threshold to zero, the rest to one;

defining solid regions which relate to the dimensions of the hand; and

selecting one of said defined regions as the candidate holdsite.

32. The method of claim 24 which includes moving the engaged workpiece to an intermediate goal site;

and

releasing the workpiece at the intermediate goal site from the hand; and

engaging the workpiece at the goal site.

33. A method of determining the pose of a workpiece which includes:

(a) engaging an unmodified workpiece with the hand of a robot assembly, the robot assembly including an arm to translate and rotate the hand;

(b) moving the workpiece relative to a presentation pose;

(c) collecting data about the pose of the workpiece by a sensing system in six degrees of freedom, three of translation and three angles, the workpiece being structurally distinct from the sensing system; and

(d) establishing the position and orientation of the workpiece from the collected data.

34. The method of claim 33 wherein the pose is established by:

storing features of the workpiece image in a plurality of orientations during an instruction phase; and

comparing the features of the image of the workpiece when it is moved to the presentation pose with the features of the stored workpiece images established during the instruction phase.

35. The method of claim 33 wherein the pose is established by:

identifying spatial locations of workpiece features from a plurality of views of the workpiece in the presentation pose; and

comparing these features with a structural model of the workpiece.

36. The method of claim 33 wherein the pose is established by:

comparing the centroid of the workpiece with the axis having the minimum moment of inertia.

37. The method of claim 33 wherein the data collection includes

collecting the data with a non-tactile sensor.

38. The method of claim 37 wherein the non-tactile sensor is an imaging device.

39. The method of claim 38 wherein the non-tactile sensor is a video imaging device.

40. The method of claims 33 or 39 which includes engaging the workpiece in a fixed manner.

41. The method of claims 33 or 39 which includes:

moving the workpiece from the presentation pose to a final goal site.

42. The method of claim 41 which includes:

releasing the workpiece at the final goal site.

43. The method of claims 33 or 39 which includes:

moving the workpiece from the presentation pose to an intermediate goal site;

releasing the workpiece at the intermediate goal site; and

engaging the workpiece at the intermediate goal site.

44. The method of claim 43 which includes:

moving the workpiece from the intermediate goal site to a final goal site.

45. The method of claims 33 or 39 which includes

acquiring an unorientated workpiece from a bin by collecting data about candidate holdsites,

locating a candidate holdsite relative to the hand,

moving the hand to engage the selected holdsite,

engaging the workpiece, and

moving the hand to the presentation pose.