Planning a Grasp, for Use by a Robotic grasper to Pick Up a Complex Object, Based on Object, Grasper, and Grasper Approach Data

• US 20140163729A1
• Filed: 12/06/2013
• Published: 06/12/2014
• Est. Priority Date: 12/07/2012
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Shi, Jianying, Koonjul, Gurdayal Singh
• Granted Patent: US 9,399,291 B2
• Time in Patent Office: Days
• US Class Current: 700/245
• CPC Class Codes: B25J 9/1612 characterised by the hand, wrist, grip control
• CPC Class Codes: G05B 2219/39466 Hand, gripper, end effector of manipulator
• CPC Class Codes: G05B 2219/39486 Fingered hand, multifingered hand
• CPC Class Codes: G05B 2219/39505 Control of gripping, grasping, contacting force, force distribution
• CPC Class Codes: Y10S 901/31 Gripping jaw

Abstract

A system, for planning a grasp for implementation by a grasping device having multiple grasping members, comprising a processor and a computer-readable storage device having stored thereon computer-executable instructions that, when executed by the processor, cause the processor to perform multiple operations. The operations include generating, for each of the multiple grasping members, multiple planar polygon representations of a three-dimensional object model. The operations also include transforming a planar polygon, of the multiple polygons generated, to a frame of a link of multiple links of a subject member of the multiple grasping members, forming a transformed polygon, being a cross-section of the object model taken along a member-curling plane of the subject member. The operations further include sweeping, in iterations associated respectively with each link of the subject member, the link from a fully-open position for the link to a point at which the link contacts the transformed planar polygon.

Claims

1. A system, for planning a grasp for implementation by a grasping device having multiple grasping members, comprising:

a processor; and

a computer-readable storage device having stored thereon computer-executable instructions that, when executed by the processor, cause the processor to perform operations comprising;

generating, for each of the multiple grasping members, multiple planar polygon representations of a three-dimensional object model;

transforming a planar polygon, of the multiple polygons generated, to a frame of a link of multiple links of a subject member of the multiple grasping members, forming a transformed polygon, wherein the transformed polygon is a cross-section of the object model taken along a member-curling plane of the subject member; and

sweeping the link from a fully-open position for the link to a point at which the link contacts the transformed planar polygon.

2. The system of claim 1, wherein the operations further comprise performing iterations, including at least the generating, transforming, and sweeping operations, with respect to each the multiple links of the subject member to determine a grasping pose for the links of the member.

3. The system of claim 1, wherein the operations further comprise:

determining, based on the sweeping operation, an angle θ

(i) for a subject link (i) of the plurality of links; and

comparing the angle θ

(i) determined to a pre-set lower-limit angle θ

<sub>lower—

limit</sub>(i) for the subject link (i) and a preset upper-limit angle θ

<sub>upper—

limit</sub>(i), including determining whether the determined angle θ

(i) is between the lower limit θ

<sub>lower—

limit</sub>(i) and the upper limit θ

<sub>upper—

limit</sub>(i).

4. The system of claim 3, wherein the operations further comprise determining, responsive to determining that the determined angle θ

(i) is not between the lower limit θ

<sub>lower—

limit</sub>(i) and the upper limit θ

<sub>upper—

limit</sub>(i), whether θ

(i) is greater than θ

<sub>upper—

limit</sub>(i).

5. The system of claim 4, wherein the subject member is represented by (k), and the operations further comprise:

determining, if the determined angle θ

(i) is greater than the upper limit θ

<sub>upper—

limit</sub>(i), that the subject member (k) would not, at the subject link (i), establish a valid grasp contact with the object model based on the determined link angle θ

(i); and

setting as the link (i) angle, for use in subsequent grasp planning, in one or more next iterations, with respect to upper links (i+1, . . . , N_e(k)), the link (i) lower limit θ

<sub>lower—

limit</sub>(i).

6. The system of claim 4, wherein:

the subject member is represented by (k); and

the operations further comprise determining, if the angle θ

(i) is not greater than θ

<sub>upper—

limit</sub>(i), whether the subject link (i) is a first link N_s(k) of the subject member (k).

7. The system of claim 6, wherein the operations further comprise:

determining, in response to determining that the subject link (i) is not the first link N_s(k) of the member (k), that an angle previously set for a prior link should be changed;

adjusting a previously-set angle θ

(i−

1) of the immediately-preceding link (i−

1), including lowering the previously-set angle θ

(i−

1); and

repeating, with respect to the subject link (i), after adjusting the previously-set angle θ

(i−

1), and using the angle as adjusted for θ

(i−

1), at least the generating, transforming, sweeping, and comparing operations.

8. The system of claim 6, wherein the operations further comprise:

determining, in response to determining that the subject link (i) is a first link of the subject member (k), that the subject member (k) would contact the object model at an angle that would not allow a proper grasp of the object model using the subject link,

initiating obtaining of new approach data; and

repeating, using the new approach data, at least the generating, transforming, sweeping, and comparing operations.

9. The system of claim 3, wherein the operations further comprise determining, in response to determining that the determined angle θ

(i) is between the lower limit θ

<sub>lower—

limit</sub>(i) and the upper limit θ

<sub>upper—

limit</sub>(i), whether contact with the object model occurred on the link.

10. The system of claim 9, wherein the operations further comprise:

determining, in response to determining that contact with the object model occurred on the subject link, that the contact determined is a valid grasp contact on the subject link; and

setting the determined angle θ

(i) as the angle for the link (i), and setting the contact data as a valid contact, for use in one or more subsequent iterations including performing again at least the generating, transforming, sweeping, and comparing operations in connection with at least one higher link.

11. The system of claim 10, wherein the operations further comprise determining, responsive to determining that the determined contact is a valid grasp contact on the subject link, etc., whether the subject link (i) is a last link N_e(k) on the member (k).

12. The system of claim 11, wherein the operations further comprise performing, responsive to determining that the subject link (i) is not the last link N_e(k) on the member (k), again at least the generating, transforming, sweeping, and comparing operations in connection with a next link (i+1), with the pose of the subject link (i) set as a consideration.

13. The system of claim 11, wherein the operations further comprise determining, in response to determining that the subject link (i) is the last link N_e(k) on the subject member (k), whether a valid contact was set for all links coupled to the current link.

14. The system of claim 13, wherein the operations further comprise determining, responsive to determining that a valid contact was set for all links, that processing is complete regarding the subject member (k).

15. The system of claim 14, wherein the operations further comprise initiating, responsive to determining that the processing is complete for the subject member (k), performance of processing with respect to at least one other members of the device.

16. The system of claim 13, wherein the operations further comprise determining, responsive to determining that a valid contact was not set for all links coupled to the subject link, in previous iterations, whether a contact length l_c is greater than half of a link length l_i.

17. The system of claim 5, wherein the operations further comprise determining, responsive to determining that the member would not, at the subject link, establish a valid grasp contact with the object model whether the subject link (i) is the last link N_e(k) on the subject member (k).

18. The system of claim 9, wherein the operations further comprise, responsive to determining that the determined angle θ

(i) is between the lower limit θ

<sub>lower—

limit</sub>(i) and the upper limit θ

<sub>upper—

limit</sub>(i);

determining that a valid feasible grasp contact exists on the subject link; and

setting the angle θ

(i) determined as a set angle for the link (i), for use in any subsequent processing, such as in any next iteration in connection with any higher links, with a pose set for the present link (i) as a consideration.

19. A method, for planning a grasp for implementation by a grasping device, comprising:

generating, by a system having using a processor, in connection with each of the multiple grasping members, multiple planar polygon representations of a three-dimensional object model;

transforming, by the system, a planar polygon, of the multiple polygons generated, to a frame of a link of multiple links of a subject member of the multiple grasping members, forming a transformed polygon, wherein the transformed polygon is a cross-section of the object model taken along a member-curling plane of the subject member; and

sweeping, by the system, the link from a fully-open position for the link to a point at which the link contacts the transformed planar polygon.

20. A computer-readable storage device having stored thereon computer-executable instructions that, when executed by a processor, cause the processor to perform operations, for planning a grasp for implementation by a grasping device, comprising:

generating, for each of the multiple grasping members, multiple planar polygon representations of a three-dimensional object model;

transforming a planar polygon, of the multiple polygons generated, to a frame of a link of multiple links of a subject member of the multiple grasping members, forming a transformed polygon, wherein the transformed polygon is a cross-section of the object model taken along a member-curling plane of the subject member; and

sweeping the link from a fully-open position for the link to a point at which the link contacts the transformed planar polygon.