New Safety Standards for Collaborative Robots

The Robotic Industries Association has a vision that “every robot integrator and user in the nation (or even, the world!) is aware of our robot safety standard, has a copy, understands it and uses that knowledge to keep people safe around robots.” These standards also need to keep up with industrial robots as they evolve to move around the factory floor and collaborate with their human operators. New RIA standards allow for greater flexibility in robot operations while still keeping humans safe.

New standards will address human-robot collaboration within shared workspaces. (Image courtesy of RIA and Clarissa Carvalho, Robot Safety Webinar.)

What Is a Standard?

Rather than regulations created by a federal body with which industries are required to comply, like OSHA standards, the RIA develops voluntary industry consensus standards. Carole Franklin, RIA director of Standards Development, used a USB stick design to illustrate this. Whether it’s the size of a thumbnail, shaped like Yoda, or attached to heated slippers, the prong of a USB stick can be inserted into the same type of socket all around the world. Voluntary industry consensus standards codify research and expert opinions into normative and informative guidelines recognized as best practice for a particular area of design, manufacturing or safety.

RIA works with the International Organization for Standardization (ISO) to ensure that there is little difference between standards across the world. For instance, the safeguarding standards for the United States and Canada are virtually identical except for the distance a particular barrier must be placed from the floor. If a robotics company expands from the United States into Canada, the factory design will require only a small alteration in barrier height in order to ensure standard compliance.

How Do the Standards Apply?

The RIA is careful to define the difference between robot, robot system and robot cell when writing standards. An industrial robot must fit all parts of the following definition, which is the same in both RIA standard 15.06 and ISO standard 10218-1, 2:2011: “automatically controlled, reprogrammable multipurpose manipulator, programmable in three or more axes, which can be either fixed in place or mobile for use in industrial automation applications.”

A device that operates in only two axes does not fall under the definition of an industrial robot, and the RIA standards do not apply to such a device.

Illustration of a robot and robot system as they are defined in the RIA standards. Not shown is a robot cell, which refers to the workspace and physical safeguards around a fixed robot. (Image courtesy of RIA and Clarissa Carvalho, Robot Safety Webinar.)

Functional Safety and Cobots

Current updates to RIA’s standards focus on mobile and collaborative robots, or cobots. Cobots necessitate a departure from the traditional robot safety paradigm’s focus on separating workers from the robot system.

Above, a factory worker in a traditional robot cell. Labels 3 and 4 indicate the interlocked rear guard and fixed guards, respectively. 5 and 6 indicate the safety scanner and robotic axis limiters. These safeguards are part of a safety paradigm that separates human workers from robots, making it less than ideal for collaboration. (Image courtesy of RIA and Clarissa Carvalho, Robot Safety Webinar.)

Cobots that work with humans directly and mobile robots that move around a factory floor independently will rely less on physical safeguards to keep humans safe and more on inherently safe measures. These measures are properties of the robot itself that make it less likely to cause harm and can include automation of routine procedures in the place of manual controls. This way, physical human contact with the robot is not required while it is performing a task, but it is not necessarily fixed to one spot on the factory floor.

Collaborative robot systems involve sharing the workspace with humans. Safety features such as physical safeguards or pressure sensors that automatically shut off the robot cannot be used without interfering with the robot’s function. Can this man safely approach the robot? (Image courtesy of RIA and Clarissa Carvalho, Robot Safety Webinar.)

Incorporating “Inherently Safe” Design

When humans and robots share a physical work environment, the robots must have intrinsic properties that make them safe around humans. This concept of “inherently safe” does not mean that the robot is 100 percent safe around humans. Standards for cobots that have inherently safe features still require that the robots undergo a full risk assessment before being put into operation on the factory floor.

Robots with rounded edges and padding are considered “inherently safe” since they are less likely to bruise humans who accidentally bump into them. (Image courtesy of RIA and Clarissa Carvalho, Robot Safety Webinar.)

ISO Technical Standard 15066:2016 and RIA Technical Report 15.606-2016 detail the requirements and information surrounding safe collaborative robots. The content is roughly the same in both documents, but TS 15066 is normative (detailing the steps required for conformance to the standard) while TS 15.606 is informative (providing information and methods that can be used for standard compliance). Both describe the four collaborative techniques used to reduce risks to human workers: safety-rated monitor stops, hand guiding, speed and separation monitoring, and power force limiting (PFL) systems.

“It is important to realize that… when we use the word collaborative robots, or cobots, we are almost always referring to a power and force limiting robot,” Franklin said. “It is important to realize that the other three types of collaboration can be implemented using a robot that is not a PFL robot.”

ISO TS 15066 and RIA TR 15.606 should be used in conjunction with RIA TR R15.806-2018, which describes a method for testing forces exerted by a pressure force limiting system. Some physical safeguards may be required if a risk assessment reveals a need for them. Sensor systems are required for standard compliance for speed and separation monitoring. For PFL systems and safety-rated monitor stops, safeguarding is a requirement for high-speed and high-risk operations.

Upcoming Changes

ISO standard 10218-2011, which covers safety requirements for industrial robots and robot systems, is slated for an update in mid-to-late 2021. The corresponding United States standard, R15.06-2012, is a direct adoption of ISO 10218-2011 and will likely be completed and published in the last half of 2022.

U.S. Standard R15.08, which concerns safety around mobile robots, is currently under development. Part 1, Guidance for Manufacturers, will likely be ready for ballot at the end of 2019.