让四足机器人在人类操控下安全避障,能自适应学习操作者意图。
Teleoperator-Aware and Safety-Critical Adaptive Nonlinear MPC for Shared Autonomy in Obstacle Avoidance of Legged Robots
- 用噪声理性的玻尔兹曼模型在线学习人类操作意图
- 10Hz CBF-NMPC确保安全集不变,60Hz跟踪参考轨迹
- 适合需要人机协同避障的机器人应用
在杂乱环境中实现人与自主四足机器人安全有效的协作是共享自主的核心挑战,尤其针对遥操作场景。传统共享控制方法依赖固定融合策略,无法捕捉腿部运动特性,可能危及安全。本文提出一种面向遥操作者的、安全关键的自适应非线性模型预测控制(ANMPC)框架,用于四足机器人避障任务。该框架采用固定仲裁权重,但通过噪声理性玻尔兹曼模型建模人类输入,并基于观测操纵杆指令使用投影梯度下降法在线更新参数。安全性通过将控制屏障函数(CBF)约束嵌入计算高效的非线性MPC中实现,确保在人类行为不确定下安全集的前向不变性。控制架构分层:高层(10 Hz)CBF-ANMPC生成融合的人机速度参考;中层(60 Hz)动力学感知非线性MPC利用简化刚体(SRB)模型跟踪参考;底层(500 Hz)非线性全构型控制器通过二次规划实现完整动力学跟踪。在Unitree Go2四足机器人上开展的大量数值仿真与硬件实验,以及用户研究验证了该框架,展示了实时避障能力、人类意图参数的在线学习以及安全的人机协作效果。
原文摘要 · Abstract (English)
Ensuring safe and effective collaboration between humans and autonomous legged robots is a fundamental challenge in shared autonomy, particularly for teleoperated systems navigating cluttered environments. Conventional shared-control approaches often rely on fixed blending strategies that fail to capture the dynamics of legged locomotion and may compromise safety. This paper presents a teleoperator-aware, safety-critical, adaptive nonlinear model predictive control (ANMPC) framework for shared autonomy of quadrupedal robots in obstacle-avoidance tasks. The framework employs a fixed arbitration weight between human and robot actions but enhances this scheme by modeling the human input with a noisily rational Boltzmann model, whose parameters are adapted online using a projected gradient descent (PGD) law from observed joystick commands. Safety is enforced through control barrier function (CBF) constraints integrated into a computationally efficient NMPC, ensuring forward invariance of safe sets despite uncertainty in human behavior. The control architecture is hierarchical: a high-level CBF-based ANMPC (10 Hz) generates blended human-robot velocity references, a mid-level dynamics-aware NMPC (60 Hz) enforces reduced-order single rigid body (SRB) dynamics to track these references, and a low-level nonlinear whole-body controller (500 Hz) imposes the full-order dynamics via quadratic programming to track the mid-level trajectories. Extensive numerical and hardware experiments, together with a user study, on a Unitree Go2 quadrupedal robot validate the framework, demonstrating real-time obstacle avoidance, online learning of human intent parameters, and safe teleoperator collaboration.
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