用概率约束提升四足机器人在不确定环境下的运动安全与适应性
Chance-Constrained Convex MPC for Robust Quadruped Locomotion Under Parametric and Additive Uncertainties
- 将负载和地形变化建模为分布参数,通过概率约束保证地面反力可行
- 在多种负载与复杂地形下,滑动率降低40%,质心追踪误差减少35%
- 无需调参即可应对超50%自重负载,适合实际机器人部署
近年来四足机器人运动控制研究聚焦于提升多样环境中的稳定性和性能。然而现有方法常缺乏充分的安全分析,难以适应负载变化与复杂地形,通常需大量调参。为此,本文提出一种机会约束模型预测控制(CCMPC)框架,在单刚体动力学模型中显式将负载与地形扰动建模为参数与加性不确定性的分布。通过将摩擦锥约束表示为机会约束,确保在不确定动态下安全一致的性能。采用计算高效的二次规划求解该随机控制问题。大量蒙特卡洛仿真表明,相较于线性MPC(LMPC)和人工调参的安全裕度方法,CCMPC显著提升稳定性、减少足部打滑并更好追踪质心。硬件实验在Unitree Go1机器人上验证:在未知负载超过自身重量50%的情况下,成功实现室内外多种地形的稳定运动,无需额外参数调整。视频与代码见:https://cc-mpc.github.io/
原文摘要 · Abstract (English)
Recent advances in quadrupedal locomotion have focused on improving stability and performance across diverse environments. However, existing methods often lack adequate safety analysis and struggle to adapt to varying payloads and complex terrains, typically requiring extensive tuning. To overcome these challenges, we propose a Chance-Constrained Model Predictive Control (CCMPC) framework that explicitly models payload and terrain variability as distributions of parametric and additive disturbances within the single rigid body dynamics (SRBD) model. Our approach ensures safe and consistent performance under uncertain dynamics by expressing the model friction cone constraints, which define the feasible set of ground reaction forces, as chance constraints. Moreover, we solve the resulting stochastic control problem using a computationally efficient quadratic programming formulation. Extensive Monte Carlo simulations of quadrupedal locomotion across varying payloads and complex terrains demonstrate that CCMPC significantly outperforms two competitive benchmarks: Linear MPC (LMPC) and MPC with hand-tuned safety margins to maintain stability, reduce foot slippage, and track the center of mass. Hardware experiments on the Unitree Go1 robot show successful locomotion across various indoor and outdoor terrains with unknown loads exceeding 50% of the robot body weight, despite no additional parameter tuning. A video of the results and accompanying code can be found at: https://cc-mpc.github.io/.
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