A Nonlinear MPC and Hybrid Whole-body Control Framework for Optimizing Agile Motions in Quadruped Robots
摘要
In recent years, quadruped robots have made remarkable progress in dynamic mobility. However, most existing methods are still limited to specific motion patterns and lack a unified framework capable of flexibly adapting to predefined trajectories and gaits. To overcome these limitations, we propose a novel control framework that integrates nonlinear model predictive control (NMPC) with a hybrid whole-body control (WBC) strategy. NMPC is used to optimize complex gaits and highly nonlinear trajectories in real time through a switching cost and constraint mechanism. The hybrid WBC combines task prioritization with weight-based coordination, enabling concurrent execution of multiple motion tasks. We validate the proposed framework through simulations and real-world experiments on a quadruped robot. The system successfully executes a range of agile behaviors, including upright walking, handstands, and diagonal stepping. These behaviors are smooth and have a strong robustness against disturbances and delays. Our approach demonstrates, for the first time, that a unified NMPC-WBC controller can enable real-time execution of diverse and highly dynamic quadruped motions. The framework presents a significant step forward in achieving animal-level agility in legged robotic systems.