Robot control method based on trajectory of center of mass, robot and computer-readable storage medium

Patent metadata

Field	Value
Publication number	US-12420414-B2
Application number	US-202318218604-A
Country	US
Kind code	B2
Filing date	Jul 6, 2023
Priority date	Jul 8, 2022
Publication date	Sep 23, 2025
Grant date	Sep 23, 2025

Abstract

A method for controlling a robot based on a trajectory of a center of mass (COM) of the robot includes: calculate a desired periodic trajectory of the robot in a single gait cycle based on a dynamic equation constructed according to a simplified model of the robot; correct the desired periodic trajectory according to a fed-back state of the COM of the robot; generate a desired trajectory of the COM of the robot using the corrected desired periodic trajectory; and control motion of the robot according to the desired trajectory of the COM of the robot.

First claim

What is claimed is:

1. A computer-implemented method for controlling a robot based on a trajectory of a center of mass (COM) of the robot, the method comprising:
calculating a desired periodic trajectory of the robot in a single gait cycle based on a dynamic equation constructed according to a simplified model of the robot;
correcting the desired periodic trajectory according to a fed-back state of the COM of the robot;
generating a desired trajectory of the COM of the robot using the corrected desired periodic trajectory; and
controlling motion of the robot according to the desired trajectory of the COM of the robot;
wherein the state of the COM of the robot comprises an actual position of the COM, correcting the desired periodic trajectory according to the fed-back state of the COM of the robot comprises:
calculating an error between the actual position of the COM fed back by the robot at an ending moment of a previous gait cycle and a desired position of the COM at a starting moment of a current gait cycle;
obtaining a correction term of the trajectory of the COM of the robot by cubic polynomial curve fitting based on the error and boundary conditions satisfied by the state of the COM of the robot; and
superimposing the desired periodic trajectory on the correction term to obtain the corrected desired periodic trajectory.

2. The method of claim 1 , wherein the dynamic equation is constructed by simplifying the robot into a linear inverted pendulum model, with a zero moment point of the robot consistent with a support point of the linear inverted pendulum model.

3. The method of claim 2 , wherein the dynamic equation is expressed as follows: {umlaut over (x)}=ω 2 x, ÿ=ω 2 y, where ω=√{square root over (g/z)}, x and {umlaut over (x)} are respectively a position of the COM and an acceleration of the COM of the linear inverted pendulum model in a forward direction, y and ÿ are respectively a position of the COM and an acceleration of the COM of the linear inverted pendulum model in a lateral direction, z is a height of the COM of the linear inverted pendulum model from a supporting surface, and g is acceleration of gravity.

4. The method of claim 3 , wherein the desired trajectory of the COM of the robot is expressed as follows:

x
d

(
t
)

=

-

S
2

⁢

cosh
⁡
(

ω
⁢
t

)

+

x
.

0

ω

⁢

sinh
⁡
(

ω
⁢
t

)

+

f
x

(
t
)

,

y
d

(
t
)

=

D
2

⁢

cosh
⁡
(

ω
⁢
t

)

+

y
.

0

ω

⁢

sinh
⁡
(

ω
⁢
t

)

+

f
y

(
t
)

,

represent the desired trajectories of the COM of the robot in the forward direction and the lateral direction, cos h( ) and sin h( ) represent hyperbolic cosine and sine respectively, S and D represent a step length and a step width of the robot, {dot over (x)} 0 and {dot over (y)} 0 represent speeds of the COM of the robot in the forward direction and the lateral direction at a starting moment of one gait cycle, respectively, f x (t) and f y (t) represent components of a correction term of the desired periodic trajectory in the forward direction and the lateral direction, respectively.

5. The method of claim 1 , wherein the boundary conditions satisfied by the state of the COM of the robot comprise: in the single gait cycle, correction amounts of the position of the COM at the starting moment and the ending moment are respectively the error and zero, and correction amounts of a speed of the COM at the starting moment and the ending moment are both zero.

6. The method of claim 1 , further comprising: correcting the desired periodic trajectory according to the fed-back state of the COM of the robot and task requirements received in real time to obtain the corrected desired periodic trajectory.

7. A biped robot comprising:
one or more processors; and
a memory coupled to the one or more processors, the memory storing programs that, when executed by the one or more processors of the robot, cause performance of operations comprising:
calculating a desired periodic trajectory of the robot in a single gait cycle based on a dynamic equation constructed according to a simplified model of the robot;
correcting the desired periodic trajectory according to a fed-back state of a center of mass (COM) of the robot;
generating a desired trajectory of the COM of the robot using the corrected desired periodic trajectory; and
controlling motion of the robot according to the desired trajectory of the COM of the robot;
wherein the state of the COM of the robot comprises an actual position of the COM, correcting the desired periodic trajectory according to the fed-back state of the CO

Assignees

• Ubtech Robotics Corp Ltd

Inventors

• Luo Qiuyue
• Ge Ligang
• Chen Chunyu
• Luo Xuan

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

• B25J9/1664 Primary

  characterised by motion, path, trajectory planning · CPC title