Leg collision avoidance in a robotic device

• US 9,446,518 B1
• Filed: 11/11/2014
• Issued: 09/20/2016
• Est. Priority Date: 11/11/2014
• Status: Active Grant

• Current Assignee: Boston Dynamics, Inc. (SoftBank Group Corp.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Blankespoor, Kevin
• Primary Examiner(s): Tran, Dalena
• Assistant Examiner(s): Peche, Jorge
• Application Number:
  US14/538,777
• Time in Patent Office: 679 Days
• Field of Search: 700/245, 700/247, 700/253, 700/255, 901/1, 901/28, 901/29, 901/46
• US Class Current: 1/1
• CPC Class Codes: B25J 9/1666 Avoiding collision or forbidden zones
• CPC Class Codes: B25J 9/1676 Avoiding collision or forbidden zones
• CPC Class Codes: B62D 57/00 Vehicles characterised by having other propulsion or other ground- engaging means than wheels or endless track, alone or in addition to wheels or endless track sledges B62B; motor sledges B62M
• CPC Class Codes: G05B 2219/39096 Self-collision, internal collison, collision between links of one robot
• CPC Class Codes: Y10S 901/01 Mobile robot
• CPC Class Codes: Y10S 901/02 Arm motion controller
• CPC Class Codes: Y10S 901/28 Joint

Abstract

An example implementation for avoiding leg collisions may involve a biped robot reducing a three-dimensional system to a two-dimensional projection of the biped robot'"'"'s feet. An example biped robot may determine a touchdown location for a swing foot. The biped robot may determine lateral positions of the touchdown location and the swing foot, each relative to a stance foot. Based on one or more of the determined lateral positions of the touchdown location and the swing foot, each relative to the stance foot, the biped robot may determine an intermediate swing point for the swing foot that is not on a line defined by the swing foot and the touchdown location. The biped robot may further cause the swing foot to move to the intermediate swing point, and then cause the swing foot to move to the touchdown location.

Claims

1. A method comprising:

determining a touchdown location for a swing foot of a biped robot, the biped robot having a stance foot, wherein the swing foot and stance foot are each coupled to a body of the biped robot, and wherein the stance foot comprises a footprint;

determining lateral, medial, posterior, and anterior sides of the stance foot to be outwardly offset from the footprint, wherein the lateral, medial, posterior, and anterior sides of the foot define an expanded footprint of the stance foot;

determining a lateral position of the touchdown location relative to the stance foot;

determining a lateral position of the swing foot relative to the stance foot;

based on one or more of the determined lateral positions of the touchdown location and the swing foot, each relative to the stance foot, determining an intermediate swing point for the swing foot, wherein the intermediate swing point is not on a line defined by the swing foot and the touchdown location, and wherein determining (i) the lateral position of the touchdown location relative to the stance foot, (ii) the lateral position of the swing foot relative to the stance foot and (iii) the intermediate swing point for the swing foot are each based on the expanded footprint of the stance foot;

causing, by the biped robot, the swing foot to move to the intermediate swing point; and

after causing the swing foot to move to the intermediate swing point, causing the swing foot to move to the touchdown location.

2. The method of claim 1, wherein determining the lateral position of the touchdown location relative to the stance foot comprises determining that the touchdown location is laterally outside of the medial side of the stance foot, and wherein the intermediate swing point is medial to the medial side of the stance foot and anterior to the anterior side of the stance foot.

3. The method of claim 1, wherein determining the lateral position of the swing foot relative to the stance foot comprises determining that the swing foot is laterally outside of the medial side of the stance foot, and wherein the intermediate swing point is medial to the medial side of the stance foot and posterior to the posterior side of the stance foot.

4. The method of claim 3, wherein the intermediate swing point is a first intermediate swing point, and wherein determining the lateral position of the touchdown location relative to the stance foot comprises determining that the touchdown location is laterally outside of the medial side of the stance foot, the method further comprising:

determining a second intermediate swing point, wherein the second intermediate swing point is medial to the medial side of the stance foot and anterior to the anterior side of the stance foot; and

after causing the swing foot to move to the first intermediate swing point, causing the swing foot to move to the second intermediate swing point.

5. The method of claim 1, wherein the operations of determining (i) the lateral position of the touchdown location relative to the stance foot and (ii) the lateral position of the swing foot relative to the stance foot are each repeated a frequency within the range of 1-10,000 Hz until the robot detects an indication to stop repeating the operation.

6. The method of claim 5, wherein the stance foot comprises an anterior side, the method further comprising:

determining a forward position of the swing foot relative to the stance foot, wherein the indication to stop repeating the operations comprises an indication that the determined forward position of the swing foot is anterior to the anterior side of the stance foot.

7. A biped robot comprising:

a body;

a swing foot coupled to the body;

a stance foot coupled to the body;

a processor;

a non-transitory computer readable medium; and

program instructions stored on the non-transitory computer readable medium that, when executed by the processor, cause the biped robot to perform operations comprising;

determining a touchdown location for the swing foot of the biped robot, wherein the stance foot comprises a footprint;

determining lateral, medial, posterior, and anterior sides of the stance foot to be outwardly offset from the footprint, wherein the lateral, medial, posterior, and anterior sides of the foot define an expanded footprint of the stance foot;

determining a lateral position of the touchdown location relative to the stance foot;

determining a lateral position of the swing foot relative to the stance foot;

based on one or more of the determined lateral positions of the touchdown location and the swing foot, each relative to the stance foot, determining an intermediate swing point for the swing foot, wherein the intermediate swing point is not on a line defined by the swing foot and the touchdown location, and wherein determining (i) the lateral position of the touchdown location relative to the stance foot, (ii) the lateral position of the swing foot relative to the stance foot and (iii) the intermediate swing point for the swing foot are each based on the expanded footprint of the stance foot;

causing the swing foot to move to the intermediate swing point; and

after

causing the swing foot to move to the intermediate swing point, causing the swing foot to move to the touchdown location.

8. The biped robot of claim 7, wherein determining the lateral position of the touchdown location relative to the stance foot comprises determining that the touchdown location is laterally outside of the medial side of the stance foot, and wherein the intermediate swing point is medial to the medial side of the stance foot and anterior to the anterior side of the stance foot.

9. The biped robot of claim 7, wherein determining the lateral position of the swing foot relative to the stance foot comprises determining that the swing foot is laterally outside of the medial side of the stance foot, and wherein the intermediate swing point is medial to the medial side of the stance foot and posterior to the posterior side of the stance foot.

10. The biped robot of claim 9, wherein the intermediate swing point is a first intermediate swing point, wherein determining the lateral position of the touchdown location relative to the stance foot comprises determining that the touchdown location is laterally outside of the medial side of the stance foot, and wherein the program instructions, when executed by the processor, further cause the biped robot to perform operations comprising:

determining a second intermediate swing point, wherein the second intermediate swing point is medial to the medial side of the stance foot and anterior to the anterior side of the stance foot; and

after causing the swing foot to move to the first intermediate swing point, causing the swing foot to move to the second intermediate swing point.

11. The biped robot of claim 7, wherein the program instructions, when executed by the processor, further cause the operations of determining (i) the lateral position of the touchdown location relative to the stance foot and (ii) the lateral position of the swing foot relative to the stance foot to be each repeated at a frequency within the range of 1-10,000 Hz until the robot detects an indication to stop repeating the operations.

12. The biped robot of claim 11, wherein the program instructions, when executed by the processor, further cause the biped robot to perform functions comprising:

determining a forward position of the swing foot relative to the stance foot, wherein the indication to stop repeating the operations comprises an indication that the determined forward position of the swing foot is anterior to the anterior side of the stance foot.

13. An article of manufacture including a non-transitory computer-readable medium, having stored thereon program instructions that, upon execution by a processor, cause a biped robot to perform operations comprising:

determining a touchdown location for a swing foot of the biped robot, the biped robot having a stance foot, wherein the swing foot and stance foot are each coupled to a body of the biped robot, and wherein the stance foot comprises a footprint;

determining lateral, medial, posterior, and anterior sides of the stance foot to be outwardly offset from the footprint, wherein the lateral, medial, posterior, and anterior sides of the foot define an expanded footprint of the stance foot;

determining a lateral position of the touchdown location relative to the stance foot;

determining a lateral position of the swing foot relative to the stance foot;

based on one or more of the determined lateral positions of the touchdown location and the swing foot, each relative to the stance foot, determining an intermediate swing point for the swing foot, wherein the intermediate swing point is not on a line defined by the swing foot and the touchdown location, and wherein determining (i) the lateral position of the touchdown location relative to the stance foot, (ii) the lateral position of the swing foot relative to the stance foot and (iii) the intermediate swing point for the swing foot are each based on the expanded footprint of the stance foot;

causing the swing foot to move to the intermediate swing point; and

after

causing the swing foot to move to the intermediate swing point, causing the swing foot to move to the touchdown location.

14. The article of manufacture of claim 13, wherein determining the lateral position of the touchdown location relative to the stance foot comprises determining that the touchdown location is laterally outside of the medial side of the stance foot, and wherein the intermediate swing point is medial to the medial side of the stance foot and anterior to the anterior side of the stance foot.

15. The article of manufacture of claim 13, wherein determining the lateral position of the swing foot relative to the stance foot comprises determining that the swing foot is laterally outside of the medial side of the stance foot, and wherein the intermediate swing point is medial to the medial side of the stance foot and posterior to the posterior side of the stance foot.

16. The article of manufacture of claim 15, wherein the intermediate swing point is a first intermediate swing point, and wherein determining the lateral position of the touchdown location relative to the stance foot comprises determining that the touchdown location is laterally outside of the medial side of the stance foot, the operations further comprising:

determining a second intermediate swing point, wherein the second intermediate swing point is medial to the medial side of the stance foot and anterior to the anterior side of the stance foot; and

after causing the swing foot to move to the first intermediate swing point, causing the swing foot to move to the second intermediate swing point.

17. The article of manufacture of claim 13, wherein the operations of determining (i) the lateral position of the touchdown location relative to the stance foot and (ii) the lateral position of the swing foot relative to the stance foot are each repeated a frequency within the range of 1-10,000 Hz until the robot detects an indication to stop repeating the operation.

18. The article of manufacture of claim 17, wherein the stance foot comprises an anterior side, the operations further comprising:

determining a forward position of the swing foot relative to the stance foot, wherein the indication to stop repeating the operations comprises an indication that the determined forward position of the swing foot is anterior to the anterior side of the stance foot.