Biped Robot Balance Control Using ZMP Trajectory Adjustment
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Solution Overview
Problem
Conventional biped robots face stability issues when bending over to pick up objects due to difficulties in planning the trajectory of their centers of mass, leading to a risk of falling over.
Innovation Solution
A robot balance control method that uses six-axis force/torque sensors to calculate the zero moment point of the center of mass, calculates position offsets, and updates the position trajectory to adjust joint angles, ensuring stability during bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional biped robots bend over to pick up objects, then they can perform picking operations, but their stability deteriorates and they risk falling over
Solution Approach 1:
The system performs preliminary calculation of the zero moment point and center of mass trajectory before the robot executes the bending motion. By pre-planning the motion trajectory and calculating the required joint angles in advance, the system ensures stability is maintained throughout the picking operation, preventing falls while enabling the robot to bend and pick objects
2Stability of the object's composition
If the robot adjusts center of mass position and joint angles in real-time, then stability improves, but computational complexity increases
Solution Approach 1:
The system uses force/torque sensors to continuously measure the actual forces acting on the robot, compares these measurements with expected values, and adjusts the center of mass trajectory and joint angles in real-time based on this feedback. This closed-loop control maintains stability by compensating for disturbances while managing computational complexity through efficient feedback processing
3Measurement precision
If the robot uses six-axis force/torque sensors to calculate zero moment point, then control precision improves, but device complexity increases
Solution Approach 1:
The six-axis force/torque sensors are integrated into the robot's existing structure and serve multiple functions: they measure forces for zero moment point calculation, provide feedback for stability control, and enable precise trajectory tracking. By making the sensor system multi-functional, the patent achieves high measurement precision without proportionally increasing overall device complexity
Data Source
AI summary
A robot balance control method includes: obtaining force information associated with a left foot and a right foot of the robot; calculating a zero moment point of a center of mass (COM) of a body of the robot based on the force information; calculating a first position offset and a second position offset of the robot according to the zero moment point of the COM of the body; updating a position trajectory of the robot according to the first position offset and the second offset to obtain an updated position of the COM of the body; performing inverse kinematics analysis on the updated position of the COM of the body to obtain joint angles of the left leg and the right leg of the robot; and controlling the robot to move according to the joint angles.