Handling gait disturbances with asynchronous timing

Patent metadata

Field	Value
Publication number	US-11654569-B2
Application number	US-202017129996-A
Country	US
Kind code	B2
Filing date	Dec 22, 2020
Priority date	Aug 25, 2014
Publication date	May 23, 2023
Grant date	May 23, 2023

Abstract

An example method may include i) detecting a disturbance to a gait of a robot, where the gait includes a swing state and a step down state, the swing state including a target swing trajectory for a foot of the robot, and where the target swing trajectory includes a beginning and an end; and ii) based on the detected disturbance, causing the foot of the robot to enter the step down state before the foot reaches the end of the target swing trajectory.

First claim

What is claimed is:

1. A computer-implemented method when executed by data processing hardware of a quadruped robot causes the data processing hardware to perform operations comprising:
identifying an estimated swing time for a swing phase of a gait pattern, the swing phase comprising:
a swing forward state when a respective foot of the quadruped robot has a forward velocity along a swing trajectory; and
a step down state when the respective foot of the quadruped robot approaches a ground surface from a swing height of the swing trajectory;

determining whether a first foot of a first leg of the quadruped robot executing the swing phase contacts the ground surface earlier than expected based on the estimated swing time for the first leg; and
when the first foot of the first leg of the quadruped robot executing the swing phase contacts the ground surface earlier than expected based on the estimated swing time for the first leg:
determining that a second foot of a second leg of the quadruped robot is still executing the swing phase for the estimated swing time for the second leg; and
when the second leg completes the swing phase in the estimated swing time and the second foot contacts the ground surface:
transitioning control of a pair of contralateral legs of the quadruped robot from a stance phase to the swing phase; and
lifting each foot of the pair of contralateral legs of the quadruped robot to execute the swing phase of the gait pattern for the pair of contralateral legs.

2. The method of claim 1 , further comprising executing ground reaction force control for the first foot and the second foot of the quadruped robot when the second leg completes the swing phase in the estimated swing time and the second foot contacts the ground surface.

3. The method of claim 1 , wherein when the first foot of the first leg of the quadruped robot contacts uneven terrain causes the first foot of the first leg of the quadruped robot executing the swing phase to contact the ground surface earlier than expected based on the estimated swing time for the first leg.

4. The method of claim 1 , wherein the gait pattern causes the first leg and the second leg to have initially synchronized swing phases.

5. The method of claim 1 , wherein the gait pattern corresponds to a trotting gait.

6. The method of claim 1 , wherein (i) transitioning control of the pair of contralateral legs of the quadruped robot from the stance phase to the swing phase and (ii) lifting each foot of the pair of contralateral legs of the quadruped robot to execute the swing phase of the gait pattern for the pair of contralateral legs synchronizes the swing phase of the pair of contralateral legs.

7. The method of claim 1 , further comprising receiving an indication of a disturbance at the first leg while the first leg of the quadruped robot is executing the swing phase.

8. The method of claim 1 , wherein the first leg and the second leg comprise a second pair of contralateral legs of the quadruped robot.

9. The method of claim 1 , wherein determining whether the first foot of the first leg of the quadruped robot executing the swing phase contacts the ground surface earlier than expected based on the estimated swing time for the first leg comprises determining that the first foot contacts the ground surface at a touchdown location that diverges from a desired touchdown location associated with the estimated swing time.

10. The method of claim 1 , further comprising:
prior to lifting each foot of the pair of contralateral legs of the quadruped robot to execute the swing phase of the gait pattern, for each foot of the pair of contralateral legs of the quadruped robot:
determining a stance velocity of the respective foot with respect to a body of the quadruped robot; and
generating a lift-off velocity for the respective foot equal to a current forward velocity of the quadruped robot,

wherein lifting each foot of the pair of contralateral legs of the quadruped robot to execute the swing phase of the gait pattern occurs by applying the lift-off velocity using one or more actuators configured to control motion for the pair of contralateral legs of the quadruped robot.

11. A quadruped robot comprising:
a first pair of contralateral legs comprising a first leg having a first foot associated with a first leg and a second leg having a second foot associated with the second leg;
a second pair of contralateral legs comprising a third leg having a third foot associated with the third leg and a fourth leg having a fourth foot associated with the fourth leg; and
a control system comprising a processor and memory in communication with the processor, the memory storing program instructions that, when executed by the processor, cause the processor to perform operations comprising:
identifying an estimated swing time for a swing phase of a gait pattern, the swing phase comprising:
a swing forward state when a respective foot of the quadruped robot has a forward velocity along a swing trajectory; and
a step down state when the respective foot of the quadruped robot approaches a ground surface from a swing height of the swing trajectory;

determining whether the first foot of the first leg of the quadruped robot executing the swing phase contacts the ground surface earlier than expected based on the estimated swing time for the first leg; and
when the first foot of the first leg of the quadruped robot executing the swing phase contacts the ground surface earlier than expected based on the estimated swing time for the first leg:
determining that the second foot of the second leg of the quadruped robot is still executing the swing phase for the estimated swing time for the second leg; and
when the second leg completes the swing phase in the estimated swing time and the second foot contacts the ground surface:
transitioning control of the second pair of contralateral legs of the quadruped robot from a stance phase to the swing phase; and
lifting each foot of the second pair of contralateral legs of the quadruped robot to execute the swing phase of the gait pattern for the second pair of contralateral legs.

12. The quadruped robot of claim 11 , wherein the operations further comprise executing ground reaction force control for the first foot and the second foot of the quadruped robot when the second leg completes the swing phase in the estimated swing time and the second foot contacts the ground surface.

13. The quadruped robot of claim 11 , wherein when the first foot of the first leg of the quadruped robot contacts uneven terrain causes the first foot of the first leg of the quadruped robot executing the swing phase to contact the ground surface earlier than expected based on the estimated swing time for the first leg.

14. The quadruped robot of claim 11 , wherein the gait pattern causes the first leg and the second leg to have initially synchronized swing phases.

15. The quadruped robot of claim 11 , wherein the gait pattern corresponds to a trotting gait.

16. The quadruped robot of claim 11 , wherein (i) transitioning control of the second pair of contralateral legs of the quadruped robot from the stance phase to the swing phase and (ii) lifting each foot of the second pair of contralateral legs of the quadruped robot to execute the swing phase of the gait pattern for the second pair of contralateral legs synchronizes the swing phase of the second pair of contralateral legs.

17. The quadruped robot of claim 11 , wherein the operations further comprise receiving an indication disturbance at the first leg while the first l

Assignees

• Boston Dynamics Inc

Inventors

• Blankespoor Kevin
• Stephens Benjamin
• Da Silva Marco

Classifications

• B25J9/16

  Program controls (total factory control, i.e. centrally controlling a plurality of machines, G05B19/418) · CPC title

• B25J9/1679

  characterised by the tasks executed · CPC title

• 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

• Y10S901/49

  Protective device · CPC title

• Y10S901/46

  Sensing device · CPC title