The Four Different Collaborative Robot Operations Explained

Collaborative robots (cobots) are assisting human workers in more ways than ever. A variety of options let the robots get their work done while ensuring human safety. Even traditional robots can become collaborative when certain safety devices are employed and they are properly integrated into a predominantly-human environment.

Collaborative Robots Help Keep Humans Safe

Cobots, which are robots meant to safely collaborate with and work closely to humans, operate in many different ways. In 2012, the ISO 10218-1 safety standard was released, classifying the four types of collaborative robot operation.

Safety Monitored Stop

Safety monitored stop pauses a robot’s motion while an operator is in the collaborative workspace. The robot maintains power but cannot move. This workspace is the shared space where a human and a robot perform tasks. While the workspace is clear of operators, the cobot works at high speeds. This results in a faster cycle time. Robots can also start back up automatically once the workspace is clear again.

Hand Guiding

Hand guiding allows a cobot to move through direct input from an operator. The cobot stays in a safety monitored stop until an operator actuates the hand guiding device through an enabling switch. These devices are often used on robots as an intelligent lift device. Such assists are easier to maneuver than traditional designs. Hand-guided cobots can also work autonomously when operators aren’t around.

Speed and Separation Monitoring

Speed and separation monitoring is often referred to as a fenceless robot system. The collaborative robot is able to move concurrently with the operator as long as they maintain a pre-determined distance apart. Often a safety-rated laser area scanner monitors this cobot application. The distance often varies based on how fast the cobot is moving.

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Power and Force Limiting by Inherent Design or Control

Limitations on power and force require a special robot that has power or force feedback built in. This system lets the cobot detect contact with a person. This is the most popular type of cobot. It requires an extensive risk assessment because the operator can remain within reach of the cobot.

Collaborative Robot Safety Standards

The ISO 10218 safety standard and the RIA ISO/TS 15066 technical specification define the safety functions and performance of a cobot.  Published in 2016 as supplemental to the guidance in ANSI/RIA R15.06, the RIA TR15.606-2016 Collaborative Robots document explains safety requirements specific to collaborative robots and robot systems and is a U.S. National Adoption of ISO/TS 15066. Under TS 15066, force and speed monitoring cobots are set based on application data, human contact area, and workspace hazards. The RIA TR15.806-2018 Guide to Testing Pressure and Force in Collaborative Robot Applications document provides guidance on determining conditions of the test measurements, measurement devices, and accurate testing methods. It also describes test methods and metrics for measuring the pressures and forces associated with quasi-static and transient contact events of collaborative applications. Both of these collaborative robot safety standards and requirements documents are available individually or as a bundle at Robotics.org.