Leg swing trajectories

Patent metadata

Field	Value
Publication number	US-11999423-B2
Application number	US-202217820063-A
Country	US
Kind code	B2
Filing date	Aug 16, 2022
Priority date	Aug 6, 2019
Publication date	Jun 4, 2024
Grant date	Jun 4, 2024

Abstract

A method of planning a swing trajectory for a leg of a robot includes receiving an initial position of a leg of the robot, an initial velocity of the leg, a touchdown location, and a touchdown target time. The method also includes determining a difference between the initial position and the touchdown location and separating the difference between the initial position and the touchdown location into a horizontal motion component and a vertical motion component. The method also includes selecting a horizontal motion policy and a vertical motion policy to satisfy the motion components. Each policy produces a respective trajectory as a function of the initial position, the initial velocity, the touchdown location, and the touchdown target time. The method also includes executing the selected policies to swing the leg of the robot from the initial position to the touchdown location at the touchdown target time.

First claim

What is claimed is:

1. A method comprising:
determining, by data processing hardware of a robot, a horizontal motion component and a vertical motion component of a difference between an initial position of a leg of the robot and a touchdown location for the leg;
selecting, by the data processing hardware, a horizontal motion policy from a set of horizontal motion policies, the selected horizontal motion policy having a first velocity and a first acceleration that satisfies the horizontal motion component;
selecting, by the data processing hardware, a vertical motion policy from a set of vertical motion policies, the selected vertical motion policy having a second velocity and a second acceleration that satisfies the vertical motion component; and
executing, by the data processing hardware, the selected horizontal motion policy and the selected vertical motion policy to swing the leg of the robot along a swing trajectory from the initial position of the leg to the touchdown location for the leg within a touchdown target time.

2. The method of claim 1 , wherein each horizontal motion policy of the set of horizontal motion policies produces a horizontal trajectory as a function of the initial position of the leg, an initial velocity of the leg, the touchdown location for the leg, and the touchdown target time.

3. The method of claim 2 , wherein each vertical motion policy of the set of vertical motion policies produces a vertical trajectory as a function of the initial position of the leg, the initial velocity of the leg, the touchdown location for the leg, and the touchdown target time.

4. The method of claim 1 , further comprising:
determining, by the data processing hardware, a first vertical motion policy of the set of vertical motion policies, the first vertical motion policy maximizing a vertical acceleration of the leg within a vertical acceleration limit of the leg and maximizing a vertical velocity of the leg within a vertical velocity limit of the leg, wherein selecting the horizontal motion policy from the set of horizontal motion policies comprises evaluating each horizontal motion policy of the set of horizontal motion policies with the first vertical motion policy.

5. The method of claim 1 , wherein selecting the horizontal motion policy from the set of horizontal motion policies comprises:
assigning each horizontal motion policy of the set of horizontal motion policies a tier from a plurality of tiers each comprising a tiebreaking parameter; and
selecting the horizontal motion policy from the set of horizontal motion policies based on the assigned tiers.

6. The method of claim 5 , wherein the tiebreaking parameter comprises a sum of a horizontal undesirability and a vertical undesirability.

7. The method of claim 1 , wherein selecting the vertical motion policy from the set of vertical motion policies occurs after selecting the horizontal motion policy from the set of horizontal motion policies.

8. The method of claim 1 , wherein selecting the vertical motion policy from the set of vertical motion policies comprises determining which vertical motion policy from the set of vertical motion policies is associated with a smallest acceleration and a smallest velocity that satisfies the vertical motion component.

9. The method of claim 1 , further comprising:
receiving, at the data processing hardware, an indication of a trip by the robot; and
changing, by the data processing hardware, at least one of the horizontal motion policy and the vertical motion policy based on the indication of the trip.

10. The method of claim 1 , wherein selecting the horizontal motion policy from the set of horizontal motion policies comprises:
evaluating each horizontal motion policy of the set of horizontal motion policies with a first analysis; and
evaluating a sub-set of the set of horizontal motion policies with a second analysis that is more detailed than the first analysis.

11. The method of claim 1 , further comprising:
receiving, at the data processing hardware, a touchdown target time for each of a plurality of legs of the robot;
determining, at the data processing hardware, a touchdown order of the legs based on the touchdown target time for each of the plurality of legs of the robot; and
selecting, by the data processing hardware, the horizontal motion policy and the vertical motion policy for each leg based on the touchdown order.

12. The method of claim 1 , wherein at least one horizontal motion policy of the set of horizontal motion policies comprises a lateral motion policy and a longitudinal motion policy.

13. A robot comprising:
a body;
a plurality of legs coupled to the body and configured to maneuver the robot, the plurality of legs including a leg;
data processing hardware controlling the plurality of legs; and
memory hardware in communication with the data processing hardware, the memory hardware storing instructions that when executed on the data processing hardware cause the data processing hardware to perform operations comprising:
determining a horizontal motion component and a vertical motion component of a difference between an initial position of the leg of the robot and a touchdown location for the leg;
selecting a horizontal motion policy from a set of horizontal motion policies, the selected horizontal motion policy having a first velocity and a first acceleration that satisfies the horizontal motion component;
selecting a vertical motion policy from a set of vertical motion policies, the selected vertical motion policy having a second velocity and a second acceleration that satisfies the vertical motion component; and
executing the selected horizontal motion policy and the selected vertical motion policy to swing the leg of the robot along a swing trajectory from the initial position of the leg to the touchdown location for the leg within a touchdown target time.

14. The robot of claim 13 , wherein each horizontal motion policy of the set of horizontal motion policies produces a horizontal trajectory as a function of the initial position of the leg, an initial velocity of the leg, the touchdown location for the leg, and the touchdown target time.

15. The robot of claim 14 , wherein each vertical motion policy of the set of vertical motion policies produces a vertical trajectory as a function of the initial position of the leg, the initial velocity of the leg, the touchdown location for the leg, and the touchdown target time.

16. The robot of claim 13 , wherein the operations further comprise:
determining a first vertical motion policy of the set of vertical motion policies, the first vertical motion policy maximizing a vertical acceleration of the leg within a vertical acceleration limit of the leg and maximizing a vertical velocity of the leg within a vertical velocity limit of the leg, wherein selecting the horizontal motion policy from the set of horizontal motion policies comprises evaluating each horizontal motion policy of the set of horizontal motion policies with the first vertical motion policy.

17. The robot of claim 13 , wherein selecting the horizontal motion policy from the set of horizontal motion policies comprises:
assigning each horizontal motion policy of the set of horizontal motion policies a tier from a plurality of tiers each comprising a tiebreaking parameter; and
selecting the horizontal motion policy from the set of horizontal motion policies based on the assigned tiers.

18. The robot of claim 17 , wherein the tiebreaking parameter comprises a sum of a horizontal undesirability and a v

Assignees

• Boston Dynamics Inc

Inventors

• Whitman Eric

Classifications

• B62D57/032 Primary

  with alternately or sequentially lifted supporting base and legs; with alternately or sequentially lifted feet or skid (B62D57/024 takes precedence) · CPC title

• B25J9/1666 Primary

  Avoiding collision or forbidden zones · CPC title

• B62D57/024

  specially adapted for moving on inclined or vertical surfaces (endless-track vehicles for ascending or descending stairs B62D55/075; hand-carts with provision for travelling up or down stairs B62B5/02) · CPC title

• G05B2219/39096

  Self-collision, internal collison, collision between links of one robot · CPC title

• G05B2219/45083

  Manipulators, robot · CPC title