To make them safer to operate around humans, cobots are designed to exert a controlled amount of force that will not cause injury in the event of a collision with a person. For that reason, cobots are limited in the weights and speeds they can handle. Most collaborative robots on the market today have weight capacities between 6 and 10 kg. FANUC offers a 35-kg capacity cobot.
The International Organization for Standardization (ISO) and American National Standards Institute (ANSI) break down collaborative safety features for robots into the following four types:
- Power and Force Limiting—This type of robot can work alongside humans without any additional safety devices.
- Hand Guiding—This type of cobot can be used to read forces applied on the robot tool. This application is used for hand guiding or path teaching and can only be used while the robot is performing a particular function. For other functions, it will need to have safeguarding in place.
- Safety-Rated Monitored Stop—All movement stops when a human has entered a predetermined safety zone.
- Speed and Separation Monitoring—Movement slows as a human enters a predetermined safety zone and eventually stops if the human gets too close. It does not need a worker to give the go-ahead to resume movement.
“Danger, Will Robinson!”
Do not confuse cobots with industrial robots that are integrated with control systems designed to slow down or stop if a person gets too close. Industrial high-speed robots can handle full payload and full movement, and they will go back to full speed as soon as the person moves away. They do not meet the Robotic Industries Association (RIA) code requirements for collaborative robots.