Collaborative robots (cobots) are robots that are designed to collaborate with humans in an open workspace. In contrast to industrial robots in an enclosed environment, cobots need additional mechanisms to assure humans’ safety in collaborations. It is especially true when a cobot is used in manufacturing environment; since the workload or moving mass is usually large enough to hurt human when a contact occurs. In this article, we are interested in understanding the existing studies on cobots, and especially, the safety requirements, and the methods and challenges of safety assurance. The state of the art of safety assurance of cobots is discussed at the aspects of key functional requirements (FRs), collaboration variants, standardizations, and safety mechanisms. The identified technological bottlenecks are (1) acquiring, processing, and fusing diversified data for risk classification, (2) effectively updating the control to avoid any interference in a real-time mode, (3) developing new technologies for the improvement of HMI performances, especially, workloads and speeds, and (4) reducing the overall cost of safety assurance features. To promote cobots in manufacturing applications, the future researches are expected for (1) the systematic theory and methods to design and build cobots with the integration of ergonomic structures, sensing, real-time controls, and human-robot interfaces, (2) intuitive programming, task-driven programming, and skill-based programming which incorporate the risk management and the evaluations of biomechanical load and stopping distance, and (3) advanced instrumentations and algorithms for effective sensing, processing, and fusing of diversified data, and machine learning for high-level complexity and uncertainty. The needs of the safety assurance of integrated robotic systems are specially discussed with two development examples.

协作机器人（cobot）是旨在在开放的工作空间中与人类协作的机器人。与封闭环境中的工业机器人相比，协作机器人需要其他机制来确保协作中人员的安全。在制造环境中使用协作机器人时尤其如此。因为工作量或移动质量通常足够大，以至于在发生接触时伤人。在本文中，我们有兴趣了解有关协作机器人的现有研究，尤其是安全要求以及安全保证的方法和挑战。在关键功能需求（FR），协作变体，标准化和安全机制等方面讨论了协作机器人安全保证的最新技术。识别出的技术瓶颈是（1）获取，处理和融合各种数据以进行风险分类；（2）有效地更新控制以避免实时模式下的任何干扰；（3）开发新技术以改善HMI性能，尤其是工作量和速度，以及（4）降低安全保障功能的总体成本。为了促进协作机器人在制造业的应用，未来的研究有望（1）结合人体工学结构，传感，实时控制和人机界面的系统化理论和方法来设计和制造协作机器人；（2）直观编程，任务驱动的编程和基于技能的编程，它们结合了风险管理以及对生物力学载荷和停止距离的评估，（3）先进的仪器和算法，用于有效地感测，处理和融合各种数据，以及机器学习，以实现高度的复杂性和不确定性。通过两个开发示例专门讨论了集成机器人系统的安全保证需求。