This paper presents a safety-critical approach to the coordinated control of cooperative robots locomoting in the presence of fixed (holonomic) constraints. To this end, we leverage control barrier functions (CBFs) to ensure the safe cooperation of the robots while maintaining a desired formation and avoiding obstacles. The top-level planner generates a set of feasible trajectories, accounting for both kinematic constraints between the robots and physical constraints of the environment. This planner leverages CBFs to ensure safety-critical coordination control, i.e., guarantee safety of the collaborative robots during locomotion. The middle-level trajectory planner incorporates interconnected single rigid body (SRB) dynamics to generate optimal ground reaction forces (GRFs) to track the safety-ensured trajectories from the top-level planner while addressing the interconnection dynamics between agents. Distributed low-level controllers generate whole-body motion to follow the prescribed optimal GRFs while ensuring the friction cone condition at each end of the stance legs. The effectiveness of the approach is demonstrated through numerical simulations and experimentally on a pair of quadrupedal robots.

翻译：本文提出了一种针对协作机器人在存在固定（完整）约束条件下运动协调的安全关键型方法。为此，我们利用控制障碍函数（CBFs）确保机器人安全协作，同时维持期望队形并规避障碍物。顶层规划器生成一组可行轨迹，同时考虑机器人之间的运动学约束及环境的物理约束。该规划器利用控制障碍函数确保安全关键型协调控制，即在运动过程中保障协作机器人的安全性。中层轨迹规划器整合了互联单刚体（SRB）动力学，通过生成最优地面反作用力（GRFs）来跟踪顶层规划器输出的安全轨迹，同时处理智能体之间的互联动力学。分布式底层控制器生成全身运动以跟踪预设的最优地面反作用力，并确保支撑腿末端的摩擦锥条件。通过数值仿真与双四足机器人实验验证了该方法的有效性。