Gait control method, biped robot, and computer-readable storage medium

Patent metadata

Field	Value
Publication number	US-12226903-B2
Application number	US-202217732568-A
Country	US
Kind code	B2
Filing date	Apr 29, 2022
Priority date	Sep 2, 2021
Publication date	Feb 18, 2025
Grant date	Feb 18, 2025

Abstract

A method for controlling gait of a biped robot includes: collecting a lateral center of mass (CoM) speed and a lateral CoM position of the biped robot when the biped robot walks in place; calculating phase variables of virtual constraints corresponding to the CoM of the biped robot in a first phase and a second phase according to the lateral CoM speed and the lateral CoM position; constructing motion trajectory calculation equations for the biped robot based on the phase variables corresponding to the first phase and the second phase, respectively; and finding inverse solutions for joints of the biped robot using the motion trajectory calculation equations to obtain joint angles corresponding to each of the joints of the biped robot to realize gait control.

First claim

What is claimed is:

1. A computer-implemented method for controlling gait of a biped robot, comprising:
collecting a lateral center of mass (CoM) speed and a lateral CoM position of the biped robot when the biped robot walks in place, wherein the lateral CoM speed is a speed of the CoM of the biped robot in a left-right oscillating direction, and the lateral CoM position is a position of the CoM of the biped robot in the left-right oscillating direction;
calculating phase variables of virtual constraints corresponding to the CoM of the biped robot in a first phase and a second phase according to the lateral CoM speed and the lateral CoM position, wherein the first phase represents a phase in which the CoM of the biped robot moves from a position farthest from a support leg of the biped robot to a closest position, and the second phase represents a phase in which the CoM of the biped robot moves from the closest position from the support leg to the position farthest from the support leg;
constructing motion trajectory calculation equations for the biped robot based on the phase variables corresponding to the first phase and the second phase, respectively; and
finding inverse solutions for joints of the biped robot using the motion trajectory calculation equations to obtain joint angles corresponding to each of the joints of the biped robot to realize gait control;
wherein calculating phase variables of virtual constraints corresponding to the CoM of the biped robot in the first phase and the second phase according to the lateral CoM speed and the lateral CoM position, comprises:
determining whether the lateral CoM speed is less than a threshold:
in response to the lateral CoM speed being less than the threshold, acquiring an initial speed of the CoM of the biped robot, and calculating a first phase variable corresponding to the first phase according to the initial speed and the lateral CoM speed;
in response to the lateral CoM speed not being less than the threshold, acquiring a step width of the biped robot and an initial position of the CoM, and calculating a second phase variable corresponding to the second phase according to the step width, the initial position and the lateral CoM position:

wherein calculating the second phase variable corresponding to the second phase according to the step width, the initial position and the lateral CoM position, comprises:
acquiring a desired speed of the CoM and an actual speed of the CoM of the biped robot at a termination moment of each step; and
calculating the second phase variable according to the step width, the initial position, the lateral CoM position, the desired speed of the CoM, and the actual speed of the CoM; and

wherein calculating the second phase variable according to the step width, the initial position, the lateral CoM position, the desired speed of the CoM, and the actual speed of the CoM, comprises:
calculating a speed feedback term according to the following equation:

δ
⁢
l

=

kp
×

(

y
.

d

-

y
.

a

)

,

 where represents the speed feedback term, kp represents a preset coefficient, {dot over (y)} d represents the desired speed of the CoM, and represents the actual speed of the CoM; and
calculating the second phase variable according to the following equation:

ϕ
2

=

-
y

+

y
cl

-

(

D
2

+

δ
⁢
l

)

+

y
cl

,

 where ϕ 2 represents the second phase variable, D represents the step width, y represents the lateral CoM position, and y el represents the initial position.

2. The method of claim 1 , wherein constructing the motion trajectory calculation equations for the biped robot based on the phase variables corresponding to the first phase and the second phase, comprises:
retrieving boundary conditions satisfied by motion trajectories of the biped robot in the first phase and the second phase; and
constructing the motion trajectory calculation equations corresponding to the first phase and the second phase, respectively, according to the boundary conditions and the phase variables, using the first phase and the second phase as a pairing benchmark.

3. The method of claim 2 , wherein constructing the motion trajectory calculation equations corresponding to the first phase and the second phase, respectively, according to the boundary conditions and the phase variables, using the first phase and the second phase as a pairing benchmark, comprises:
in response to the lateral CoM speed being less than the threshold, according to the boundary condition satisfied by the motion trajectory of the first phase and the first phase variable, solving a polynomial of the motion trajectory of the first phase to obtain the motion trajectory calculation equation corresponding to the first phase, where the boundary condition satisfied by the motion trajectory of the first phase is expressed as follows:

z
s
d

(
0
)

=
0

,

z
s
d

(
1
)

=

h
1

,

z
.

1
d

(
0
)

=

Assignees

• Ubtech Robotics Corp Ltd

Inventors

• Luo Qiuyue
• Ge Ligang
• Liu Yizhang
• Chen Chunyu
• Bai Jie

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

• B25J13/088

  with position, velocity or acceleration sensors · CPC title

• B25J9/1664

  characterised by motion, path, trajectory planning · CPC title

• B25J9/163 Primary

  learning, adaptive, model based, rule based expert control · CPC title

• G05D1/0212 Primary

  with means for defining a desired trajectory (involving a plurality of land vehicles G05D1/0287) · CPC title