The Latest Safety Standards for Collaborative Robots
It is fascinating to see how new technology is viewed by different consumers. In the world of industrial manufacturing, Force Limited Collaborative Robots (cobots) are one of the the lighting rod topics at moment and for good reason.
End Users are intrigued because they see cobots as a way to quickly improve their bottom line by adding automation directly where it is needed without redesigning their current production lines. On the other hand, traditional robot manufacturers and integrators have a wary eye due to safety and commercial concerns. For the End User, safety is always a legitimate concern. Luckily, several of the Force Limited Robots on the market promote ease of installation and minimal advanced support requirements, as well as the elimination of Safety Cages (based on a Risk Assessment).
For the traditional robotics integrator who understands the potential complexities of making the system work and the challenges of doing a solid risk assessment, they wonder if it is worth it. Then you have the traditional robot manufacturers who have to contend with how to approach developing a new technology that could potentially cut into their existing business and threaten the relationships they have with their current channel to market.
For the automation industry, this dilemma about the closest we come to having our own reality TV show. The good news is there is a lot of solid work going into making sure the Force Limited Collaborative Robots can be used in a safe fashion. In that regard Jeff Frymanrecently gave an update about the newly released ISO Technical Specification Document at the A3 Forum.
For those you who don’t know Jeff, he has was the Director of Standards Development for the Robotic Industries Association for 17 years and during his tenure was responsible for the 1999 and 2012 editions of the ANSI/RIA R15.06 American National Standard for Industrial Robots. As Jeff aptly alludes to at the end of the summary, with each release of a safety standard or technical specification, a new round of innovation takes place to accommodate it. If you think things are exciting now in world of collaborative robots, imagine what is in store for us in the coming year.
Thanks to our friends at Robotiq who were nice enough to allow us to republish Jeff’s summary and their original article here.
A Preview of the New ISO Collaborative Robot Safety Standard
Jeff Fryman, JDF Consulting Enterprises
The highly anticipated new ISO standard on collaborative robot safety standards is not a standard. Really.
TS-15066 is not a standard. It’s a technical specification. It’s meant to eventually replace clause 5.11 of the ISO 10218-2 standard.
The objective of releasing TS-15066 is to give it life in the real world and test it against real applications, so that the specifications can mature and become finalized.
In the current standard, collaborative robots are allowed, with a few restrictions:
- They can only do pre-determined tasks.
- Protective measures must be active on the robot.
- This can only be deployed with robots designed for collaborative operation.
Human-Robot collaboration can be done by 4 different methods:
- Reduce the speed of the robot and use of a protective stop monitoring device when humans are in collaborative space (safety monitored stop).
- The robot’s motions are only possible using the direct input of the operator (hand guiding).
- The robot’s speed is limited to values low enough for the robot to stop before a human comes into contact with it under any circumstance. This scenario implies monitoring the presence of humans (speed and separation monitoring).
- By inherent design and control, the robot is limited to certain values of force and power (power and force limiting).
ISO/TS 15066 is mainly aimed at defining the latest power and force limiting method. In this context, risk assessment is paramount. “Each robot system is unique and must be assessed for risk and mitigation,” said Fryman.
Power and force-limiting robots have special considerations:
- They should be working on non-hazardous processes only.
- No sharp edges.
- Safe gripper design.
- Predicting the direction of robot movement in conjunction with the worker location and movement.
The risk assessment should encompass several elements:
- Task-based risk assessment: layout and identification of the task, system limitations, hazard identification and elimination, and risk reduction.
- Workspace requirements: a clearly defined collaborative workspace, safeguards (that can be software-based), and a 500 mm minimum space from trapping or pinch points.
- Robot operation: the robot must have a safety mode when the worker is in the collaborative space. This is where the hard math happens: there should be a dynamic definition of how much space should be kept between robot and worker.
Power and Force Limiting by Design or Control
This is the new territory. As much as we know on what amount of force or pressure is required to break a bone or cause an injury, the objective of the technical specifications is to find the threshold for no injury.
The question is: how much force is damaging? How much pressure will injure the worker? The ISO committee mandated a study to determine the onset of pain, that is, how much pressure becomes painful. The study was conducted with 100 subjects, on 29 locations on the human body.
Pressure specifications vary depending on the body part, with the temple at the lowest with 65 newtons and the 7th neck muscle at the highest with 210 newtons.
What’s next for collaborative robot safety?
Now it’s the viability test for the technical specifications. How can we meet them? How can we make sure we meet them? This will help the ISO committee finalize the specifications so they can be incorporated into the ISO 10218-2, Robots and robotic devices standard.
The next focus for the committee will be end effectors – how can we make end effectors collaborative and safe for workers?