One way of ensuring operator's safety during human-robot collaboration is through Speed and Separation Monitoring (SSM), as defined in ISO standard ISO/TS 15066. In general, it is impossible to avoid all human-robot collisions: consider for instance the case when the robot does not move at all, a human operator can still collide with it by hitting it of her own voluntary motion. In the SSM framework, it is possible however to minimize harm by requiring this: \emph{if} a collision ever occurs, then the robot must be in a \emph{stationary state} (all links have zero velocity) at the time instant of the collision. In this paper, we propose a time-optimal control policy based on Time-Optimal Path Parameterization (TOPP) to guarantee such a behavior. Specifically, we show that: for any robot motion that is strictly faster than the motion recommended by our policy, there exists a human motion that results in a collision with the robot in a non-stationary state. Correlatively, we show, in simulation, that our policy is strictly less conservative than state-of-the-art safe robot control methods. Additionally, we propose a parallelization method to reduce the computation time of our pre-computation phase (down to 0.5 sec, practically), which enables the whole pipeline (including the pre-computation) to be executed at runtime, nearly in real-time. Finally, we demonstrate the application of our method in a scenario: time-optimal, safe control of a 6-dof industrial robot.

翻译：确保人机协作中操作员安全的一种方法是遵循ISO标准ISO/TS 15066中定义的速度与分离监控（SSM）。一般而言，完全避免人机碰撞是不可能的：例如，即使机器人完全不移动，操作员也可能因自身主动运动而与机器人发生碰撞。然而，在SSM框架内，可通过以下要求最大限度减少伤害：如果发生碰撞，则机器人在碰撞瞬间必须处于静止状态（所有关节连杆速度为零）。本文提出一种基于时间最优路径参数化（TOPP）的时间最优控制策略以实现该行为保障。具体而言，我们证明：任何严格快于本策略推荐速度的机器人运动，都会存在某种人类运动导致机器人在非静止状态下发生碰撞。研究还通过仿真表明，本策略的保守性显著低于现有最先进的安全机器人控制方法。此外，我们提出一种并行化方法将预计算阶段的耗时缩短至实际可用的0.5秒，使得整个流程（含预计算）可在运行时近乎实时执行。最后，我们在六自由度工业机器人的场景中展示了本方法的时间最优安全控制应用。