论文标题

在混乱的环境中,机器人操纵器的安全 - 关键 - 最佳控制

Safety-Critical Optimal Control for Robotic Manipulators in A Cluttered Environment

论文作者

Ding, Xuda, Wang, Han, Ren, Yi, Zheng, Yu, Chen, Cailian, He, Jianping

论文摘要

为机器人操纵器设计关键的安全控制是具有挑战性的,尤其是在混乱的环境中。首先,由于复杂的碰撞环境和非平凡的动态,机械手的实际轨迹可能会偏离计划中的轨迹,从而导致碰撞。其次,由于碰撞网格之间的显式距离函数尚不清楚,因此很难获得操纵器的可行空间。通过分析安全集合与受控不变集之间的关系,本文提出了一种数据驱动的控制屏障函数(CBF)构建方法,该方法从距离样本中提取CBF。具体而言,CBF保证了用于考虑系统动力学的受控属性。数据驱动的方法示例距离函数并确定安全集。然后,通过基于方案的Square(SOS)程序总和来合成CBF。与大多数基于线性化的方法不同,我们的方法保留了无近似计划的可行计划空间的体积,这有助于在混乱的环境中找到解决方案。控制法是通过实时求解基于CBF的二次程序的,该程序可作为所需基于计划的控制器的安全过滤器。此外,我们的方法通过可靠的概率结果保证了安全性。我们的方法在真实和虚拟杂物环境中的7-DOF操纵器上得到了验证。实验表明,操纵器能够执行障碍物之间的间隙为毫米的任务。

Designing safety-critical control for robotic manipulators is challenging, especially in a cluttered environment. First, the actual trajectory of a manipulator might deviate from the planned one due to the complex collision environments and non-trivial dynamics, leading to collision; Second, the feasible space for the manipulator is hard to obtain since the explicit distance functions between collision meshes are unknown. By analyzing the relationship between the safe set and the controlled invariant set, this paper proposes a data-driven control barrier function (CBF) construction method, which extracts CBF from distance samples. Specifically, the CBF guarantees the controlled invariant property for considering the system dynamics. The data-driven method samples the distance function and determines the safe set. Then, the CBF is synthesized based on the safe set by a scenario-based sum of square (SOS) program. Unlike most existing linearization based approaches, our method reserves the volume of the feasible space for planning without approximation, which helps find a solution in a cluttered environment. The control law is obtained by solving a CBF-based quadratic program in real time, which works as a safe filter for the desired planning-based controller. Moreover, our method guarantees safety with the proven probabilistic result. Our method is validated on a 7-DOF manipulator in both real and virtual cluttered environments. The experiments show that the manipulator is able to execute tasks where the clearance between obstacles is in millimeters.

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