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A Hierarchical Control Strategy for a Rigid-Flexible Coupled Hexapod Bio-Robot
Kuo Yang1,2, Xinhui Liu1,2, Changyi Liu2,3
1School of Mechanical and Aerospace Engineering, Jilin University, Changchun 130025, China.
Biomimetics (Basel, Switzerland)
|December 22, 2023
Summary
This study introduces a hierarchical control strategy for legged robots, effectively managing rigid-flexible coupling. The approach reduces robot vibrations, enhancing stability for heavy-load applications.
Area of Science:
- Robotics
- Control Systems
- Mechanical Engineering
Background:
- Legged robots exhibit complex motion involving both rigid-body dynamics and elastic leg deformation, particularly under heavy loads.
- Understanding the interaction between rigid and flexible components is crucial for stable and efficient robot operation.
- Existing control strategies often overlook the significant impact of leg flexibility in heavy-duty legged robots.
Purpose of the Study:
- To propose a novel hierarchical control strategy for legged robots with rigid-flexible coupling characteristics.
- To address the challenges posed by elastic deformation in robot legs during motion, especially for heavy payloads.
- To enhance the stability and reduce vibrations in large-scale legged robots.
Main Methods:
- A hierarchical control strategy integrating leg force prediction with feedforward compensation for flexible component errors.
- Utilizing the centroid dynamics model of the rigid chassis to derive optimal drive torque based on centroid trajectories (centroid angular momentum (CAM) and centroid linear momentum (CLM)) and body trajectory.
- Implementing a sliding mode control algorithm with the flexible leg dynamic model for precise force control of hydraulic drive units.
Main Results:
- Validation on a 3.5-ton giant hexapod robot demonstrated the effectiveness of the proposed control strategy.
- The approach successfully reduced robot vibrations, indicating improved motion control and stability.
- The hierarchical strategy effectively managed the complex interactions between rigid and flexible robot components.
Conclusions:
- The proposed hierarchical control strategy is effective for robots with rigid-flexible coupling characteristics.
- This method significantly reduces vibrations in heavy-duty legged robots.
- The integration of leg force prediction, centroid dynamics, and sliding mode control offers a robust solution for advanced robot locomotion.
