Method for controlling legged robot, robot and computer-readable storage medium

Patent metadata

Field	Value
Publication number	US-12138803-B2
Application number	US-202218089588-A
Country	US
Kind code	B2
Filing date	Dec 28, 2022
Priority date	Jul 26, 2021
Publication date	Nov 12, 2024
Grant date	Nov 12, 2024

Abstract

A method for controlling a legged robot includes: in response to detection of a collision event associated with a foot of a swing leg of the biped robot, terminating a trajectory component planning of the swing leg in a collision direction; calculating a position offset in the collision direction according to an external force that is received by the foot of the swing leg in the collision direction and obtained in real time, based on a foot dragging control mode, and determining a replanned trajectory component in the collision direction based on the position offset; and controlling the swing leg to move based on the replanned trajectory component in the collision direction and a desired trajectory component of the swing leg in a non-collision direction.

First claim

What is claimed is:

1. A computer-implemented method for controlling a legged robot, comprising:
in response to detection of a collision event associated with a foot of a swing leg of the biped robot, terminating a trajectory component planning of the swing leg in a collision direction, wherein the trajectory component planning in the collision direction comprises a trajectory component in a forward direction and a trajectory component in a lateral movement direction of a single-leg motion planning trajectory of the robot;
calculating a position offset in the collision direction according to an external force that is received by the foot of the swing leg in the collision direction and obtained in real time, based on a foot dragging control mode, and determining a replanned trajectory component in the collision direction based on the position offset; and
controlling the swing leg to move based on the replanned trajectory component in the collision direction and a desired trajectory component of the swing leg in a non-collision direction.

2. The method of claim 1 , wherein calculating the position offset in the collision direction comprises:
performing integral transformation on the foot dragging control mode to obtain a position offset calculation equation, wherein the position offset calculation equation is configured to calculate the position offset in a direction of a corresponding trajectory component according to the external force received by the foot of the swing leg in the direction of the corresponding trajectory component.

3. The method of claim 2 , wherein the foot dragging control mode is expressed as follows: b({dot over (X)} r −{dot over (X)} m )=F, where {dot over (X)} r and {dot over (X)} m respectively represent a reference speed and a measured actual speed of the robot; b is a preset parameter; F is the external force received by the foot of the swing leg; the position offset calculation equation is as follows: ΔX=F·t 0 /b, where ΔX represents the position offset; t 0 represents a program control cycle for the robot.

4. The method of claim 1 , wherein when the trajectory component planning in the collision direction is the trajectory component in a forward direction and/or the trajectory component in a lateral movement direction, the position offset in the collision direction comprises a position offset in the forward direction and/or a position offset in the lateral movement direction; replanned trajectory components of the swing leg in the forward direction and the lateral movement direction are as follows: X x1 (t) =X x1 (t-1) +ΔX x and X y1 (t) =X y1 (t-1) +ΔX y , where X x1 (t) and X x1 (t-1) represent positions of the swing leg at time t−1 and time t in the forward direction, respectively; X y1 (t) and X y1 (t-1) represent positions of the swing leg at time t−1 and time t in the lateral movement direction, respectively; ΔX x and ΔX y represent the position offsets calculated in real time in the forward direction and the lateral movement direction, respectively.

5. The method of claim 1 , wherein the foot of the robot is provided with a force sensor, and directions along an X axis, a Y axis and a Z axis in a coordinate system of the force sensor correspond to the forward direction, the lateral movement direction and a lifting direction respectively; the detection of the collision event associated with the foot of the swing leg comprises:
when the robot is in a swing phase, detecting the external force received by the foot of the swing leg in the directions along the X axis, the Y axis and the Z axis using the force sensor; and
in response to the external force received by the foot of the swing leg in the direction along the X axis or the Y axis being greater than or equal to a preset threshold, determining that the collision event associated with the foot of the swing leg is detected.

6. The method of claim 5 , further comprising:
in response to the external force received by the foot of the swing leg in the direction along the X axis or the Y axis being less than the preset threshold, controlling the swing leg to move according to a desired motion planning trajectory of the swing leg.

7. The method of claim 6 , where the desired motion planning trajectory of the swing leg is expressed as follows:

X

x
2

=

l
x

2

-

l
x

2

⁢

cos
⁡
(

π
⁢
t
/
T

)

;

X

y
2

=

l
y

2

-

l
y

2

⁢

cos
⁡
(

π
⁢
t
/
T

)

;

X

z
2

=

At
3

+

Bt
2

+
Ct
+
D

Assignees

• Ubtech Robotics Corp Ltd

Inventors

• Chen Chunyu
• Liu Yizhang
• Ge Ligang
• Bai Jie
• Zhou Jiangchen
• Luo Qiuyue
• Xiong Youjun

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

• B25J13/085

  Force or torque sensors (B25J13/082, B25J13/084 take precedence) · CPC title

• B25J9/1676

  Avoiding collision or forbidden zones · CPC title

• G05B2219/39082

  Collision, real time collision avoidance · CPC title

• B25J9/1666 Primary

  Avoiding collision or forbidden zones · CPC title