Accidents happen, but safety assessments can help manufacturers and other robotics users minimize risks to their employees.
Even a single fatality is one too many, noted Carole Franklin, director of standards development at the Robotics Industry Association. The robotics industry is proud of its record — 30 fatalities over the past 30 years. The number of injuries is harder to extrapolate because they are lumped in with other industrial statistics, she said.
A large part of the industry’s success in this area is due to vigilance in revising safety standard R15.06 as robotics continues to evolve.
“We do have a safety standard, but sometimes some in the industry are unaware of that,” Franklin said. “It’s something we’ve been revising since the mid-1980s.”
A major revision/update to the standard — which is voluntary — is currently underway, she added. The U.S. standard follows the guidelines of ISO 20218 and similar standards in other countries. Attendees and presenters discussed the basics of the standards and best practices for safety assessments at the RIA’s International Robot Safety Conference in Detroit in October.
“It is every employer’s legal responsibility to recognize workplace hazards and to provide safe and healthful working conditions for their employees,” said Keith W. Erwin, safety instructor for the Occupational Safety and Health Administration (OSHA) Training Institute. OSHA is part of the U.S. Department of Labor.
OSHA inspections can happen at any time, without prior notifications, Erwin explained. During inspections of robotic installations, the agency concentrates on machine guarding (1910.212) and lock-out/tag-out (1910.147) systems.
OSHA requires that one or more methods of machine guarding be provided to protect the operator and other employees in the machine area from hazards such as those created by points of operation, ingoing nip points, rotating parts, flying chips, and sparks.
Robots are considered machines under OSHA guidelines, though collaborative robots do not fall under the same rules. Cobots don’t require guarding as long as they meet other requirements for safety-rated monitored stops, speed and separation monitoring, or power and force limiting.
For good robot safety, Franklin recommended that managers should not only be familiar with the standards, but they should also conduct plant-wide risk and safety assessments to see where hazards might be and determine how to minimize them. That means evaluating every cell, not just one.
“Each one is highly unique,” said Franklin, who cited wall distances, ceiling heights, and other factors that can be different from cell to cell.
Mobile robot considerations
Mobile robots add another set of safety considerations — primarily that they can approach a human, rather than the human making the approach. So RIA has a separate standard, R15.08, just for these robots.
“We’re still debating the basics of what you should be aware of,” Franklin said. “That’s why risk assessment is so important.”
With mobile robots, the robot and platform have to be considered as two individual systems, with only one being able to move at any single time, said Denise Ebenhoech, KUKA regional head of advanced robotic applications.
To protect workers, mobile robots need warning systems to indicate a change in direction or the start of movement after a stop. The alerts can be audible, visual, or a combination thereof.
The warning system must have an audible component in some high-risk areas, including those where object detection not possible, narrow spaces, and while approaching working stations, Ebenhoech added.
Cobots also require safety assessments
“No human-robot collaboration is possible without a risk assessment,” said Mark Lewandowski, robotics innovation leader at Procter & Gamble. “The overall cell must always be considered, not just the robot but also the application, tooling, grippers, system, and peripheral equipment.”
Proctor & Gamble relies on collaborative robots throughout its plants because of their flexibility compared with stationary robots that require guarding, he said. (P&G also uses these robots, depending on the application.)
When programming a cobot, the motion must be designed or limited to avoid the head and neck, and other protections may be needed, Lewandowski said.
Another risk assessment that operators need to conduct is the potential safety hazards that end effectors and payloads pose and how to minimize those hazards, observed Franklin.
Lewandowski said that safety assessments were essential for P&G as it determined how it was going to deploy various robots throughout its locations.
These types of assessments will continue to be more critical as robots continue to become more prevalent in the workplace, Franklin said.