An increasing number of jobs once performed by humans are now performed by robots. Most incidents of injury occur during activities such as maintenance, programming, and adjustments of robots. To avoid such incidents, employers should consider the following fundamental areas for safety improvements.
Employers need to be sure that adequate clearance distances are established.
One of the most important features of a robotic workstation is a safety fence, at least six feet in height, with an electrical interlocking gate. It should not be possible to access the robotic workstation when the gate is closed. This will prevent unauthorized entry into the range of the robot’s moving parts. When the gate is opened, the operation of the robot should stop.
Deliberate manual action should be required to restart the robot’s automatic operation. In addition, employers should:
- avoid free-standing steel posts—these create “pinch points” where an unsuspecting worker can become trapped between the post and the robot’s arm;
- consider limit switches and fixed stops located near an axis of rotation or translation;
- provide barriers between the robotic equipment and the object if freestanding objects in the robot’s proximity cannot be avoided; and
- be aware that safety rails, chains, ropes, and floor markings, although useful as a cautionary reminder, do not provide adequate perimeter guarding.
Another important feature of a safe robotic workstation is a presence sensing device. Presence sensing devices include light curtain installations, pressure floor mats, and ultrasonic sensors on the robot’s arm. When a presence is sensed by the device, the robot is triggered to either operate at a greatly reduced speed or halt motion entirely. The ideal design includes more than one presence sensing device.
Extensive safety training should be provided for all employees who are expected to have any possible contact with the robot system.
Workers must be familiar with all working aspects of the robot, including the full range of motion, known hazards, programming information, locations of emergency stop buttons and power sources, and the importance of safety barriers.
Training should also include procedures for freeing a colleague who becomes caught. It is important to emphasize that just because a robot is stopped does not mean it will remain stopped, and just because a robot is a repeating a motion does not mean it will continue to repeat only that motion.
Newly trained employees should be closely supervised until they adjust to the robot.
Training requirements do not, however, only apply to newly hired, inexperienced employees. Experienced robot programmers and operators should also receive refresher training courses that allow them to stay up to date with technological advancements and remind them of the concern for safety. Supervisors should receive the same robotics training as other employees and operate under the assumption that no one is permitted to enter the robotic workstation without first reducing the speed of the robot or halting its movement.
Source: Epstein Becker & Green, P.CThis article was written with contributions from Theresa E. Thompson, Summer Associate.