用置信预测收紧约束,让未知动力学下的机器人规划更可靠
Conformal Constraint Tightening for Chance-Constrained Motion Planning with Unknown Dynamics
- 基于置信预测估计真实轨迹与模型轨迹的偏差范围
- 通过收紧规划约束,确保在真实系统上完成任务的概率达标
- 不依赖特定规划器,适合各类已有规划算法升级使用
运动规划算法为自主机器人生成控制序列,使其到达目标区域并避开危险状态。现有方法(从采样规划到深度强化学习)通常仅在理想模型或模拟器上提供任务完成保证,当真实动力学未知或难以准确建模时,该保证可能失效。本文针对具有未知动力学但有可用近似名义模型的系统,提出一种与规划器无关的约束收紧方法,使现有规划器能在真实系统上获得概率性任务完成保证。利用置信预测,在一系列规划问题上提供名义轨迹与真实轨迹偏差的概率上界,并据此收紧规划约束;证明在名义模型下求解收紧后的问题,是保证在真实系统上以指定概率完成原问题的充分条件。通过实验验证了理论保证,并展示了相较于仅依赖名义模型的规划,任务完成率显著提升。
原文摘要 · Abstract (English)
Motion planning algorithms compute control sequences that drive autonomous robots to goal regions while avoiding unsafe states. Existing methods, from sampling-based planning to deep reinforcement learning, typically provide task-completion guarantees only with respect to a nominal model or simulator, which may be invalidated when the true dynamics are unknown or difficult to model accurately. This letter addresses this limitation for systems with unknown dynamics and an available approximate nominal model, contributing a planner-agnostic constraint-tightening procedure that equips existing planners with a probabilistic task-completion guarantee on the true system. We leverage conformal prediction to provide a probabilistic bound on the nominal-to-true trajectory deviation over a distribution of planning problems. We tighten the planning constraints using that bound, and show that solving the tightened problem under the nominal model is a sufficient condition for solving the original problem on the true system with a prescribed probability. We validate the theoretical guarantees empirically and demonstrate substantially improved task completion relative to nominal-model planning.
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