Control method for robot, computer-readable storage medium and robot

Patent metadata

Field	Value
Publication number	US-12076860-B2
Application number	US-202117561609-A
Country	US
Kind code	B2
Filing date	Dec 23, 2021
Priority date	Dec 24, 2020
Publication date	Sep 3, 2024
Grant date	Sep 3, 2024

Abstract

A control method for a robot includes: determining a desired zero moment point (ZMP) of the robot; obtaining a position of a left foot and a position of a right foot of the robot, and calculating desired support forces of the left foot and the right foot according to the desired ZMP, the positions of the left foot and the right foot; obtaining measured support forces of the left foot and the right foot, and calculating an amount of change in length of the left leg and an amount of change in length of the right leg according to the desired support forces of the left foot and the right foot, the measured support forces of the left foot and the right foot; and controlling the robot to walk according to the amount of change in length of the left leg and the right leg.

First claim

What is claimed is:

1. A computer-implemented control method for a robot, comprising:
determining a desired zero moment point (ZMP) of the robot;
obtaining a position of a left foot and a position of a right foot of the robot, and calculating a desired support force of the left foot and a desired support force of the right foot according to the desired ZMP, the position of the left foot and the position of the right foot;
obtaining a measured support force of the left foot and a measured support force of the right foot, and calculating an amount of change in length of the left leg and an amount of change in length of the right leg according to the desired support force of the left foot, the desired support force of the right foot, the measured support force of the left foot, and the measured support force of the right foot, wherein the left leg and the right leg are equivalent to a spring model, the length of the left leg and the length of the right leg are adjusted based on the spring model, the change in the length of the left leg comprises elongation and shortening in the length of the left leg equivalent to the spring model, and the change in the length of the right leg comprises elongation and shortening in the length of the right leg equivalent to the spring model; and
controlling the robot to walk according to the amount of change in length of the left leg and the amount of change in length of the right leg;
wherein calculating the desired support force of the left foot and the desired support force of the right foot comprises:
calculating a support force distribution coefficient according to the desired ZMP, the position of the left foot, and the position of the right foot; and
calculating the desired support force of the left foot and the desired support force of the right foot according to the supporting force distribution coefficient and a mass of the robot;
wherein the support force distribution coefficient is calculated according to the following equation:

K
f

=



p
y

-

p
lf





p
lf

-

p
rf



,

where p y represents the desired ZMP, p lf represents the position of the left foot, p rf represents the position of the right foot, and K f represents the support force distribution coefficient.

2. The method of claim 1 , wherein calculating the amount of change in length of the left leg and the amount of change in length of the right leg comprises:
calculating a first difference between the measured support force of the left foot and the measured support force of the right foot;
calculating a second difference between the desired support force of the left foot and the desired support force of the right foot;
calculating a third difference between the first difference and the second difference;
calculating a total amount of change in leg length of the robot according to the third difference; and
calculating the amount of change in length of the left leg and the amount of change in length of the right leg according to the total amount of change in leg length of the robot.

3. The method of claim 1 , wherein the desired support force of the left foot and the desired support force of the right foot are calculated according to the following equations: f rd =K f Mg, and f ld =(1−K f )Mg, where K f represents the support force distribution coefficient, M represents the mass of the robot, g represents acceleration due to gravity, f ld represents the desired support force of the left foot, and f rd represents the support force of the right foot.

4. The method of claim 1 , wherein determining the desired ZMP of the robot comprises:
obtaining a center-of-mass planning position and a center-of-mass planning speed of the robot, and calculating a planned capture point of the robot according to the center-of-mass planning position and the center-of-mass planning speed;
obtaining a center-of-mass measured position and a center-of-mass measured speed of the robot, and calculating a measured capture point of the robot according to the center-of-mass measured position and the center-of-mass measured speed; and
calculating the desired ZMP of the robot according to the planned capture point of the robot and the measured capture point of the robot.

5. The method of claim 4 , wherein the desired ZMP of the robot is calculated according to the following equation:
p y =K cp control ξ plan +(1−K cp control )ξ measure , where ξ plan represents the planned capture point, ξ measure represents the measured capture point, K cp control represents a preset controller parameter, and p y represents the desired ZMP of the robot;
wherein

K

cp
control

=

1

1
-

e

ω
⁢
dT

,

 where ω represents a natural frequency of a linear inverted pendulum model, dT represents a time required for ξ measure to track ξ plan , and e is a natural constant.

6. A robot comprising:
one or more processors;
a memory; and
one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs comprises:
instructions for determining a desired zero moment point (ZMP) of the robot;
instructions for obtaining a position of a left foot and a position of a right foot of the robot, and calculating a desired support force of the left foot and a desired support force of the right foot according to the desired ZMP, the position of the left foot and the position of the right foot;
instructions for obtaining a measured support force of the left foot and a measured support force of the right foot, and calculating an amount of change in length of the left leg and an amount of change in length of the right leg according to the desired support force of the left foot, the desired support force of the right foot, the measured support force of the left foot and the measured support force of the right foot, wherein the left leg and the right leg are equivalent to a spring model, the length of the left leg and the length of the right leg are adjusted based on the spring model, the change in the length of the left leg comprises elongation and shortening in the length of the left leg equivalent to the spring model, and the change in the length of the right l

Assignees

• Ubtech Robotics Corp Ltd

Inventors

• Ge Ligang
• Liu Yizhang
• Chen Chunyu
• Xie Zheng
• Xiong Youjun

Classifications

• B25J9/1633

  compliant, force, torque control, e.g. combined with position control · CPC title

• B62D57/032

  with alternately or sequentially lifted supporting base and legs; with alternately or sequentially lifted feet or skid (B62D57/024 takes precedence) · CPC title

• B25J9/1602 Primary

  characterised by the control system, structure, architecture · CPC title

• B62D57/024 Primary

  specially adapted for moving on inclined or vertical surfaces (endless-track vehicles for ascending or descending stairs B62D55/075; hand-carts with provision for travelling up or down stairs B62B5/02) · CPC title