Biped robot gait control method and robot and computer readable storage medium using the same

Patent metadata

Field	Value
Publication number	US-11878426-B2
Application number	US-202117314039-A
Country	US
Kind code	B2
Filing date	May 6, 2021
Priority date	Nov 17, 2020
Publication date	Jan 23, 2024
Grant date	Jan 23, 2024

Abstract

A biped robot gait control method as well as a robot and a computer readable storage medium are provided. During the movement, the system obtains a current supporting pose of a current supporting leg of the biped robot, and calculates a relative pose between the supporting legs based on the current supporting pose and a preset ideal supporting pose of a next step. The system further calculates modified gait parameters of the next step based on the relative pose between the two supporting legs and a joint distance between left and right ankle joints in an initial state of the biped robot when standing. Finally, the system controls the next supporting leg to move according to the modified gait parameters.

First claim

What is claimed is:

1. A computer-implemented gait control method for a biped robot having two supporting legs, comprising steps of:
obtaining, by a camera on the biped robot, a current supporting pose of a current supporting leg of the two supporting legs of the biped robot in a global coordinate system, wherein the biped robot is moved according to a preset motion path in an entire environment, and a starting point of the motion path is taken as an origin of the global coordinate system;
calculating a relative pose between the two supporting legs of the biped robot based on the current supporting pose and a preset ideal supporting pose of a next step of the biped robot, wherein the relative pose between the two supporting legs is the preset ideal supporting pose of the next step with respect to the current supporting pose;
calculating one or more gait parameters of the next step of the biped robot based on the relative pose between the supporting legs and a joint distance of left and right ankle joints of the biped robot in an initial state of the biped robot; and
controlling a next supporting leg of the two supporting legs of the biped robot to move according to the one or more gait parameters of the next step.

2. The method of claim 1 , wherein the obtaining, by the camera on the biped robot, the current supporting pose of the current supporting leg of the two supporting legs of the biped robot in the global coordinate system comprises:
capturing, by the camera, an image of an environment, and calculating a pose of the camera in the global coordinate system;
obtaining a centroid pose of a centroid of the biped robot in the global coordinate system base on a coordinate conversion relationship between the camera and the centroid of the biped robot and the pose of the camera, and obtaining a supporting pose of the current supporting leg in a centroid coordinate system, wherein the centroid coordinate system is built by taking the centroid of the biped robot as an origin of the centroid coordinate system, the global coordinate system corresponds to the entire environment the biped robot being located, and the preset motion path is represented by corresponding coordinates of points in the global coordinate system; and
obtaining the current supporting pose of the current supporting leg in the global coordinate system through a coordinate system transformation based on the supporting pose and the centroid pose.

3. The method of claim 2 , wherein the centroid is a midpoint of a straight line between two hip joints of the biped robot, and the obtaining the supporting pose of the current supporting leg in the centroid coordinate system comprises:
obtaining a hip joint angle, a knee joint angle, and an ankle joint angle of the current supporting leg, wherein the hip joint angle is an included angle between a thigh of the current supporting leg and the hip joint, the knee joint angle is an included angle between the thigh and a calf of the current supporting leg, and the ankle joint angle is an included angle between the calf and a sole of the current supporting leg; and
analyzing the supporting pose of the current supporting leg in the centroid coordinate system based on the hip joint angle, the knee joint angle, the ankle joint angle, a thigh length of the current supporting leg, a calf length of the current supporting leg, and a distance between the two hip joints of the biped robot.

4. The method of claim 1 , wherein the controlling the next supporting leg of the two supporting legs of the biped robot to move according to the one or more gait parameters of the next step comprises:
performing an amplitude limiting on the one or more gait parameters of the next step based on one or more preset ideal gait parameters of the next step to obtain one or more modified gait parameters; and
controlling the next supporting leg to move according to the one or more modified gait parameters.

5. The method of claim 4 , wherein after the performing the amplitude limiting on the one or more gait parameters of the next step based on the one or more preset ideal gait parameters of the next step to obtain the one or more modified gait parameters, further comprising steps of:
determining whether a collision will occur after the next supporting leg moves according to the one or more modified gait parameters;
correcting the one or more modified gait parameters according to a pose of an object going to collide with the next supporting leg to obtain one or more second modified gait parameters, in response to the collision will occur after the next supporting leg moves according to the one or more modified gait parameters; and
controlling the next supporting leg to move according to the one or more second modified gait parameters to avoid collision.

6. The method of claim 4 , wherein the one or more gait parameters comprise a forward displacement, a lateral displacement, and a yaw angle, and the calculating the relative pose between the supporting legs of the biped robot based on the current supporting pose and the preset ideal supporting pose of the next step of the biped robot comprises:
substituting the current supporting pose and the preset ideal supporting pose of the next step into first equations to calculate the relative pose between the supporting legs, wherein the first equations are:
x 3 =( x 2 −x 1 )×cos θ 1 +( y 2 −y 1 )×sin θ 1 ;

and
θ 3 =θ 2 −θ 1 ;

where x 1 , y 1 , θ 1 represent the current supporting pose, x 1 represents a displacement in the x direction of a global coordinate system, y 1 represents a displacement in the y direction of the global coordinate system, and θ 1 represents a yaw angle; x 2 , y 2 , and θ 2 represent the preset ideal supporting pose of the next step, x 2 represents a displacement in the x direction of the global coordinate system, y 2 represents a displacement in the y direction of the global coordinate system, and θ 2 represents a yaw angle; and x 3 is a lateral displacement of the relative pose between the supporting legs, y 3 is a forward displacement of the relative pose between the supporting legs, and θ 3 is a yaw angle of the relative pose between the supporting legs.

7. The method of claim 6 , wherein the calculating the one or more gait parameters of the next step of the biped robot based on the relative pose between the supporting legs and the joint distance of the left and right ankle joints of the biped robot in the initial state of the biped robot comprises:
identifying whether the current supporting leg is a right foot of the two supporting legs;
substituting the relative pose between the supporting legs and the joint distance into second equations to calculate the one or more gait parameters of the next step in response to the current supporting leg being the right foot, wherein the second equations are:
x 4 =x 3 −α/2×sin θ 3 ;

y 4 =y 3 −α/2×(1+cos θ 3 ); and

θ 4 =θ 3 ;

where, x 4 is a lateral displacement of the one or more gait parameters of the next step, y 4 is a forward displacement of the one or more gait parameters of the next step, and θ 4 is a yaw angle of the one or more gait parameters of the next step, and α is the joint distance; and
substituting the relative pose between the supporting legs and the joint distance into third equations to calculate the one or more gait parameters of the next step in response to the current supporting leg being not the left foot, wherein the third equations are:
x 4 =x 3 −α/2×sin θ 3 ;

y 4 =y 3 −α/2×(1+cos θ 3 ); and

θ 4 =θ 3 ;

8. A robot comprising:
a processor;
a camera coupled to the processor;
a memory coupled to the processor; and
one or more computer pro

Assignees

• Ubtech Robotics Corp Ltd

Inventors

• Ma Xingxing
• Chen Chunyu
• Ge Ligang
• Wang Hongge
• Huang Mingqiang
• Zhou Jiangchen
• Liu Yizhang
• Xie Zheng
• Xiong Youjun

Classifications

• B25J9/1666 Primary

  Avoiding collision or forbidden zones · CPC title

• B25J9/162

  Mobile manipulator, movable base with manipulator arm mounted on it · CPC title

• B25J9/1653

  parameters identification, estimation, stiffness, accuracy, error analysis · CPC title

• B25J9/1664 Primary

  characterised by motion, path, trajectory planning · 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