Center of Mass Trajectory Generation for Humanoid Robot Stability
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Solution Overview
Problem
Humanoid robots face instability and potential falls when increasing walking speed due to divergent gait and untracked center of mass, as step length increases and stability is compromised.
Innovation Solution
A method for generating a center of mass (CoM) trajectory that alternately tracks the poses of a robot's feet using pose tracking vectors and activation functions, ensuring stable CoM positioning and attitude control through linear and spherical interpolation, implemented in a processor-controlled system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the walking speed of the robot is increased, then the productivity is improved, but the stability of the robot deteriorates due to divergent gait and untracked center of mass
Solution Approach 1:
The patent implements feedback control by continuously tracking the center of mass position relative to the feet and adjusting the gait parameters accordingly. The controller monitors the actual center of mass trajectory and compares it with the desired trajectory, then modifies the step length and timing to maintain stability during high-speed walking.
Solution Approach 2:
The patent employs dynamic adjustment of gait parameters including step length, step frequency, and center of mass trajectory based on real-time walking conditions. The system transitions from static gait patterns to dynamically adaptive patterns that optimize both speed and stability during locomotion.
2Productivity
If the step length of the robot is increased to increase walking speed, then the productivity is improved, but the center of mass tracking capability deteriorates
Solution Approach 1:
The patent dynamically changes multiple parameters including step length, step frequency, swing phase duration, and stance phase duration to maintain optimal center of mass tracking. By adjusting these parameters in coordination rather than independently, the system achieves both longer steps for speed and accurate center of mass control.
Solution Approach 2:
The patent calculates and plans the center of mass trajectory in advance based on the desired step length and walking speed, then executes the pre-planned trajectory adjustments during the gait cycle to ensure accurate tracking throughout the motion.
3Productivity
If the step length is increased to improve walking speed, then the productivity is improved, but the gait stability deteriorates causing divergent gait
Solution Approach 1:
The system continuously monitors gait parameters and center of mass position, providing real-time feedback to adjust step length and timing. This feedback mechanism prevents the accumulation of errors that lead to divergent gait, allowing sustained high-speed walking with maintained stability.
Solution Approach 2:
The robot's control system automatically adjusts its own gait parameters to maintain stability during high-speed walking, without external intervention. The system self-corrects deviations in real-time, enabling autonomous stable locomotion at increased speeds.
Data Source
AI summary
A method for generating a center of mass (CoM) trajectory includes determining an actual pose of a center of mass (CoM), a pose of a left foot, and a pose of a right pose of a robot; determining a first pose tracking vector of the robot according to the actual pose of the CoM and the pose of the left foot, and determining a second pose tracking vector of the robot according to the actual pose of the CoM and the pose of the right foot; and controlling a desired pose of the CoM of the robot to alternately track the pose of the left foot and the pose of the right foot, according to the first pose tracking vector and the second pose tracking vector, so as to generate a desired CoM trajectory of the robot.