# US 2023/0264358 A1 · Handling gait disturbances with asynchronous timing

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- Number: US 2023/0264358 A1
- Document ID: US20230264358A1
- Status: Published application
- Kind: A1
- Application number: 18/299,645
- Filed: 2023-04-12
- Published: 2023-08-24
- Earliest claimed: 2014-08-25
- Assignees: Boston Dynamics, Inc.
- Applicants: Boston Dynamics, Inc.
- Inventors: Kevin Blankespoor; Benjamin Stephens; Marco da Silva
- Web page: https://patentgrep.com/patent/US20230264358A1

## CPC

- B25J 9/1692: {Calibration of manipulator}
- B25J 9/1628: {characterised by the control loop}
- B62D 57/032: with alternately or sequentially lifted supporting base and legs; with alternately or sequentially lifted feet or skid (B62D57/024 takes precedence)
- B25J 9/16: Program controls (total factory control, i.e. centrally controlling a plurality of machines, G05B19/418)
- B25J 9/1679: {characterised by the tasks executed}
- Y10S 901/01: Mobile robot
- Y10S 901/46: Sensing device
- Y10S 901/49: Protective device
- B25J: MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES ({manipulators specially adapted for use in surgery A61B34/70; manipulators used in cleaning hollow articles B08B9/04}; manipulators associated with rolling mills B21B39/20; manipulators associated with forging machines B21J13/10; {manipulators associated with picking-up and placing mechanisms B23P19/007}; means for holding wheels or parts thereof B60B30/00; {vehicles with ground-engaging propulsion means, e.g. walking members B62D57/02, B62D57/032; devices for picking-up and depositing articles or materials between conveyors B65G47/90, B65G47/91; manipulators with gripping or holding means for transferring packages B65H67/065}; cranes B66C; {manipulators used in the protection or supervision of pipe-line installations F17D5/00; walking equipment adapted for nuclear steam-generators F22B37/006}; manipulators specially adapted for, or associated with, nuclear reactors G21C; {apparatus used for handling wafers during manufacture or treatment of semiconductor H10P72/50})
- B62D: MOTOR VEHICLES; TRAILERS (steering, or guiding on a desired track, of agricultural machines or implements A01B69/00; wheels, castors, axles, increasing wheel adhesion B60B; vehicle tyres, tyre inflation or tyre changing B60C; connections between vehicles of a train or the like B60D; vehicles for use on rail and road, amphibious or convertible vehicles B60F; suspension arrangements B60G; heating, cooling, ventilating or other air treating devices B60H; windows, windscreens, non-fixed roofs, doors or similar devices, protective coverings for vehicles not in use B60J; propulsion plant arrangements, auxiliary drives, transmissions, controls, instrumentation or dashboards B60K; electric equipment or propulsion of electrically-propelled vehicles B60L; power supply for electrically-propelled vehicles B60M; passenger accommodation not otherwise provided for B60N; adaptations for load transportation or to carry special loads or objects B60P; arrangement of signalling or lighting devices, the mounting or supporting thereof or circuits therefor, for vehicles in general B60Q; vehicles, vehicle fittings or vehicle parts not otherwise provided for B60R; servicing, cleaning, repairing, supporting, lifting, or manoeuvring, not otherwise provided for, B60S; brake arrangements, brake control systems or parts thereof B60T; air-cushion vehicles B60V; motor-cycles, accessories therefor B62J, B62K; testing of vehicles G01M)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## 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.

## Claims

### Claim 1

A computer-implemented method when executed by data processing hardware of a quadruped robot causes the data processing hardware to perform operations comprising:
determining whether a first foot of a first leg of the quadruped robot contacts a ground surface earlier than expected based on an estimated swing time for the first leg; and
determining that a second foot of a second leg of the quadruped robot contacts the ground surface after determining that the first foot contacts the ground surface earlier than expected; and
based on determining that the first foot contacts the ground surface earlier than expected and the second foot contacts the ground surface, transitioning control of third and fourth legs of the quadruped robot from a stance phase to a swing phase.

### Claim 2 (depends on 1)

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 contacts the ground surface.

### Claim 3 (depends on 1)

The method of claim 1, wherein uneven terrain causes the first foot to contact the ground surface earlier than expected.

### Claim 4 (depends on 1)

The method of claim 1, wherein the data processing hardware instructs the first to fourth legs to traverse in a gait pattern causing the first leg and the second leg to have initially synchronized swing phases.

### Claim 5 (depends on 4)

The method of claim 4, wherein the gait pattern corresponds to a trotting gait.

### Claim 6 (depends on 1)

The method of claim 1, further comprising, upon transitioning control of the third and fourth legs of the quadruped robot from the stance phase to the swing phase, lifting each foot of the third and fourth legs of the quadruped robot to execute the swing phase.

### Claim 7 (depends on 6)

The method of claim 6,
further comprising, prior to lifting each foot of the third and fourth legs of the quadruped robot to execute the swing phase, for each foot of the third and fourth legs of the quadruped robot, 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 third and fourth legs of the quadruped robot to execute the swing phase occurs by applying the lift-off velocity using one or more actuators configured to control motion for the third and fourth legs of the quadruped robot.

### Claim 8 (depends on 1)

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

### Claim 9 (depends on 1)

The method of claim 1, wherein determining whether the first foot of the first leg of the quadruped robot contacts the ground surface earlier than expected 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.

### Claim 10

A quadruped robot comprising:
a first pair of 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 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:
determining whether the first foot of the first leg of the quadruped robot contacts the ground surface earlier than expected based on an estimated swing time for the first leg,
determining that the second foot of the second leg of the quadruped robot contacts the ground surface after determining that the first foot of the first leg contacts the ground surface earlier than expected, and
based on determining that the first foot contacts the ground surface earlier than expected and the second foot contacts the ground surface, transitioning control of the second pair of legs of the quadruped robot from a stance phase to a swing phase.

### Claim 11 (depends on 10)

The quadruped robot of claim 10, 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 foot contacts the ground surface.

### Claim 12 (depends on 10)

The quadruped robot of claim 10, wherein uneven terrain causes the first foot to contact the ground surface earlier than expected.

### Claim 13 (depends on 10)

The quadruped robot of claim 10, wherein the programming instructions include instructions on a gait pattern causing the first leg and the second leg to have initially synchronized swing phases.

### Claim 14 (depends on 13)

The quadruped robot of claim 13, wherein the gait pattern corresponds to a trotting gait.

### Claim 15 (depends on 10)

The quadruped robot of claim 10, wherein, upon transitioning control of the second pair of legs of the quadruped robot from the stance phase to the swing phase, lifting each foot of the second pair of legs of the quadruped robot to execute the swing phase.

### Claim 16 (depends on 10)

The quadruped robot of claim 10, wherein determining whether the first foot of the first leg of the quadruped robot contacts the ground surface earlier than expected 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.

### Claim 17 (depends on 16)

The quadruped robot of claim 16, wherein the operations further comprise:
prior to lifting each foot of the second pair of legs of the quadruped robot to execute the swing phase, for each foot of the second pair of 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 second pair of legs of the quadruped robot to execute the swing phase occurs by applying the lift-off velocity using one or more actuators configured to control motion for the second pair of legs of the quadruped robot.

### Claim 18 (depends on 11)

The quadruped robot of claim 11, wherein transitioning control of the second pair of legs of the quadruped robot from the stance phase to the swing phase comprises ceasing execution of ground reaction force control for the third foot and the fourth foot of the quadruped robot.