Multi-Legged Robot Joint Torque Control With Force Priority Mapping
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Solution Overview
Problem
Conventional joint control methods for multi-legged robots, such as quadruped robots, face challenges with long calculation times and high hardware requirements when determining the torque needed for each joint during motion control, particularly in achieving a desired torso state.
Innovation Solution
A joint control method that involves creating a mapping matrix from body forces to support forces applied to the soles of supporting legs, using a processor to execute computer programs that prioritize forces and calculate desired support forces through optimization models, and then determining joint torques based on these forces and Jacobian matrices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional control method maps forces applied to torso to support forces applied to soles, then motion control is achieved, but calculation time is long and hardware requirements are high
Solution Approach 1:
The patent segments the force mapping problem into two independent parts: (1) mapping torso forces to supporting leg soles forces using a mapping matrix, and (2) mapping torso forces to swing leg soles forces separately. This segmentation allows each part to be calculated independently and efficiently, reducing overall calculation time while maintaining control accuracy.
Solution Approach 2:
The patent pre-calculates and stores the mapping matrix based on the robot's kinematic parameters and support surface geometry before actual motion control. This preliminary action enables rapid force mapping during real-time operation without requiring complex on-the-fly calculations, thus reducing calculation time during critical motion control phases.
2Reliability
If conventional control method maps forces applied to torso to support forces applied to soles, then motion control is achieved, but hardware requirements are high
Solution Approach 1:
The patent extracts the complex full-body dynamics calculation into a simplified force mapping operation using a pre-computed mapping matrix. By taking out the computationally intensive parts and replacing them with efficient matrix operations, the system achieves the same motion control accuracy with significantly reduced hardware requirements.
Solution Approach 2:
The patent changes the computational parameters from solving complex differential equations to using pre-computed mapping matrices with simpler algebraic operations. This parameter change transforms the problem from one requiring high-performance computing hardware to one that can be efficiently solved with standard processors.
3Productivity
If priority targets are used to solve optimization models, then calculation burden is reduced, but force prioritization complexity increases
Solution Approach 1:
The patent segments the force priorities into different categories (supporting legs vs. swing legs) and solves optimization models for each segment separately. This segmentation reduces the overall computational burden by breaking down a complex global optimization problem into smaller, more manageable sub-problems that can be solved faster.
Data Source
AI summary
A method for a multi-legged robot having a body and a number of legs, includes: obtaining a current pose of the body, forces applied to the body, and joint angles of each of supporting legs of the legs; creating a mapping matrix from the forces applied to the body to desired support forces applied to soles of the supporting legs; obtaining priority targets by prioritizing the forces acting in different directions, determining a weight matrix for each priority target, and creating an optimization model of the support forces for each priority target based on the mapping matrix and the weight matrices; solving the optimization model of each of the priority targets to obtain the desired support forces corresponding to each of the priority targets; and calculating joint torques of the supporting legs for joint control, based on the solved desired support forces and Jacobian matrices corresponding to the supporting legs.