Since they are different by design, specific safety standards have been developed for cobots. The International Organization for Standardization Technical Specification (ISO/TS) 15066 specifies safety requirements for industrial cobots and their work environments. It supplements the requirements and guidance on cobot operation in ISO 10218‑1 and ISO 10218‑2. This article briefly reviews the requirements of ISO/TS 15066 and how they fit in with ISO 10218- 1 and 10218-2. It then considers the complexities of collaboration, including how the collaborative workspace is defined. It examines factors related to robot safety, like safety features built into cobots, and what external safety functions are needed, along with exemplary devices like proximity sensors, light curtains, and safety contact mats. It closes with a brief review of a few applications specific to cobot safety considerations. There are several key safety standards for industrial robots and cobots. ISO/TS 15066 details safety requirements for industrial cobot systems and the work environment and was written to build on and supplement the limited requirements in previous standards like the ISO 10218 series. ISO 10218-1 focuses on general robots and robotic devices, while ISO 10218-2
focuses on robot systems and integration. American National Standards Institute/Robotics Industry Association (ANSI/RIA) R15.06 is a national adoption of ISO 10218-1 and ISO 10218-2.
Common protective features integrated into cobots include contact detection systems based on torque measurements at every joint that monitor for unexpected impacts, obstructions, or excessive forces or torque. There should also be automatic braking systems and manual brake releases for moving the arm without power. Unexpected contact with the person by the cobot is a particular concern. The standards dictate that contact should be prevented anywhere on a person's head. In addition, the standard splits the body into 29 specific areas and details limitations for two types of contact: ■ Transient contact is a moving, dynamic event where the cobot hits a person. Limitations are based on location, inertia, and relative speed. ■ Quasi-static contact occurs when a body part is trapped between the cobot and a surface. Limitations are based on pressure and force related to crushing and clamping effects. The specification provides guidance, not absolute limits, based on application considerations. It also states that the guidance is informative and reflects current best practices since collaboration between people and robots is a new field, and research is ongoing.
Complexities of collaboration
Before getting into the details of cobot safety, it's helpful to define collaboration. Collaboration in robotics is complex and includes three factors: ■ A cobot is a "robot designed for direct interaction with a human within a defined collaborative workspace," according to ANSI/ RIA R15.06. ■ A collaborative operation is a "state in which a purposely designed robot system and an operator work within a collaborative workspace," according to ISO/TS 15066. ■ Finally, a collaborative workspace is the "workspace within the safeguarded space where the robot and a human can perform tasks simultaneously during production operation," according to ANSI/RIA R15.06. It comes down to the definition of the collaborative workspace "within the safeguarded space." The safeguarded space includes a layer of safety protection in addition to the standard safety functions included in the cobot.
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