🤖 AI Summary
This work addresses the challenges of error accumulation and poor interpretability in long-horizon locomotion of quadrupedal robots, which often arise from the absence of physically informed inductive biases in learned dynamics models. To this end, the authors propose embedding a Lagrangian neural network within a reinforcement learning and model predictive control (MPC) framework to construct a dynamics model that adheres to physical principles. They further design an inverse-dynamics-based infinite-horizon MPC formulation to enhance computational efficiency. The resulting approach achieves a favorable balance among dynamical consistency, real-time planning performance, and task execution. Experimental validation on the Unitree Go1 platform demonstrates that, compared to unstructured neural dynamics models, the proposed method yields higher sample efficiency, significantly reduced long-horizon tracking errors, and a fourfold improvement in real-time planning speed.
📝 Abstract
State of the art quadrupedal locomotion approaches integrate Model Predictive Control (MPC) with Reinforcement Learning (RL), enabling complex motion capabilities with planning and terrain adaptive behaviors. However, they often face compounding errors over long horizons and have limited interpretability due to the absence of physical inductive biases. We address these issues by integrating Lagrangian Neural Networks (LNNs) into an RL MPC framework, enabling physically consistent dynamics learning. At deployment, our inverse dynamics infinite horizon MPC scheme avoids costly matrix inversions, improving computational efficiency by up to 4x with minimal loss of task performance. We validate our framework through multiple ablations of the proposed LNN and its variants. We show improved sample efficiency, reduced long-horizon error, and faster real time planning compared to unstructured neural dynamics. Lastly, we also test our framework on the Unitree Go1 robot to show real world viability.