在未知环境扰动下,用概率约束确保机器人操作安全,避免碰撞。
Risk-Constrained Belief-Space Optimization for Safe Control under Latent Uncertainty
- 基于信念分布的动态规划,融合风险敏感优化
- 高风险规避下成功率达82%,零接触违规
- 适合需要高安全性的机械臂操作场景
许多安全关键控制系统需在传感器无法直接分辨的潜在不确定性下运行。这种不确定性来自未知物理属性、外部干扰或未观测环境结构,影响系统动力学、任务可行性与安全裕度。传统方法优化期望性能,对极端但严重后果的保护不足;鲁棒方法保守处理不确定性,未能利用其概率结构。本文针对部分可观测动力系统,其动力学、代价和安全约束依赖于一个隐变量,该变量以信念分布形式维持。提出一种风险敏感的信念空间模型预测路径积分(MPPI)控制框架,在滚动时域内对信念进行规划,并对轨迹安全裕度施加条件风险价值(CVaR)约束。所提控制器在优化风险正则化目标的同时,显式约束由隐参数变异性引发的安全违规尾部风险。证明了三个性质:(1) CVaR约束蕴含概率性安全保证;(2) 当目标中风险权重趋近于零时,控制器恢复为风险中性最优解;(3) 使用并集界论证将每时域保障扩展至重复求解下的累计安全。在视觉引导的灵巧存取任务仿真中,物体姿态不确定性超过预设侧向间隙要求,本方法在高风险规避下实现82%成功率且零接触违规,优于风险中性配置(55%)和机会约束基线(50%),后两者均产生非零外部接触力。
原文摘要 · Abstract (English)
Many safety-critical control systems must operate under latent uncertainty that sensors cannot directly resolve at decision time. Such uncertainty, arising from unknown physical properties, exogenous disturbances, or unobserved environment geometry, influences dynamics, task feasibility, and safety margins. Standard methods optimize expected performance and offer limited protection against rare but severe outcomes, while robust formulations treat uncertainty conservatively without exploiting its probabilistic structure. We consider partially observed dynamical systems whose dynamics, costs, and safety constraints depend on a latent parameter maintained as a belief distribution, and propose a risk-sensitive belief-space Model Predictive Path Integral (MPPI) control framework that plans under this belief while enforcing a Conditional Value-at-Risk (CVaR) constraint on a trajectory safety margin over the receding horizon. The resulting controller optimizes a risk-regularized performance objective while explicitly constraining the tail risk of safety violations induced by latent parameter variability. We establish three properties of the resulting risk-constrained controller: (1) the CVaR constraint implies a probabilistic safety guarantee, (2) the controller recovers the risk-neutral optimum as the risk weight in the objective tends to zero, and (3) a union-bound argument extends the per-horizon guarantee to cumulative safety over repeated solves. In physics-based simulations of a vision-guided dexterous stowing task in which a grasped object must be inserted into an occupied slot with pose uncertainty exceeding prescribed lateral clearance requirements, our method achieves 82% success with zero contact violations at high risk aversion, compared to 55% and 50% for a risk-neutral configuration and a chance-constrained baseline, both of which incur nonzero exterior contact forces.
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