thumbnail group

Connect With Us:

ME Channels / Advanced Manufacturing Now

Ria Addresses Safety of Humans In Cobot System

Bob Doyle
 By Bob Doyle
Director of Communications
Robotic Industries Association
The Robotic Industries Association (RIA) recently delivered the first solid step toward ensuring the safety of human workers in a collaborative robot system. The technical specification (TS) document ISO /TS 15066 provides supplemental and supporting information to the industrial robot safety standards ISO 10218-1 and ISO 10218-2, from 2011. The technical specification applies to how closely humans work with the collaborative robot system.
At least with regard to the new TS, collaborative robots refer to a robot system, rather than a particular type of robot. With a collaborative robot, or cobot, application, humans and robots can simultaneously occupy the same workspace while the system is in automatic mode. Of course, safeguards and a risk assessment—from the robot system safety standard ISO 10218-1 and -2:2011—are still required. For now, the industrial collaborative workspace will most likely be a small defined space with familiar fencing or other safeguards surrounding the rest of the robot.
TS 15066 is important because it facilitates combining the unique strengths of humans, such as creative problem solving, with those of robot systems, such as power and precision in repetitive tasks. The combo opens the potential for a dramatic increase in productivity both in industry and throughout the overall economy.
When implemented according to the guidelines in TS 15066, the collaborative robot system might use “power and force limiting” and/or “speed and separation monitoring.”
Power and force limiting constrains the power and force of the robot’s motion to levels that have been shown not to cause pain to a human if contact were to occur. TS 15066 provides data on pain threshold levels, allowing us to know where to set those limits on the power and force of the robot’s movement. Until TS 15066, there had been no studies with data about power or forces that resulted in pain that could serve as a guide in designing power and force-limited robot systems.
Speed and separation monitoring makes the robot aware of the human presence and takes action to maintain a safe distance or shut down if the safe distance cannot be maintained. In this scenario, when a human takes a step toward a robot, the robot might move an equal distance backward. You can think of this as the robot system “dancing” with the person.
Traditionally, humans have been safeguarded from the hazards of a robot system by guards, fences and protective devices that served to keep the human apart from the machinery or to stop the machinery before any contact could be made. 
The ISO group that produced TS 15066 has been working on the topic of collaborative robot systems since at least 2010. ISO 10218 covered the paradigm shift in general terms. TS 15066 helped robot designers come up with scenarios in which people and robots can work together more closely.
TS 15066 provides safety requirements specifically to suppliers and integrators of collaborative industrial robot systems.
For the design of cobot systems, TS 15066 provides key information, such as guidance on maximum allowable speeds and minimum protective distances, as well as the formula for determining the protective separation distance. It also provides data to help determine threshold limit values for power and force limiting to avoid pain or discomfort on the part of the human operator.
While power and force limiting and speed and separation monitoring are happening with existing technologies, the future is likely to bring breakthroughs related to protective devices with tighter integration, such as when motion controls for the cobot are integrated with a protective device that detects intrusion and presence in the shared workspace.
Companies are going to great lengths to create cobots they believe can coexist with humans without barriers. And while RIA believes that could be commonplace in the future, this document is essential to protect humans until the smart manufacturing industry reaches that point. 

Published Date : 4/27/2016

Editor's Picks

Advanced Manufacturing Media - SME
U.S. Office  |  One SME Drive, Dearborn, MI 48128  |  Customer Care: 800.733.4763  |  313.425.3000
Canadian Office  |  7100 Woodbine Avenue, Suite 312, Markham, ON, L3R 5J2  888.322.7333
Tooling U  |   3615 Superior Avenue East, Building 44, 6th Floor, Cleveland, OH 44114  |  866.706.8665