Equipment and Machinery Safety, Technology and Innovation

A Closer Look at the Robotics Safety Process

Industrial robots can extend or enhance productivity at your facility, as well as perform dangerous or repetitive workplace tasks, thereby protecting the health and safety of your workers.

Robotic systems are becoming more collaborative and mobile in nature. The future of robotics involves more collaborative robots, or “co-robots,” rather than fixed industrial robots isolated from the workforce.

There now are more than 310,000 industrial robots being used in U.S. factories, according to estimates in the World Robotics 2021 Industrial Robots report.

Examples of robots in the workplace include:

  • Service robots that perform specific tasks like cleaning public spaces; delivering items in hospitals and hotels; fighting fires; and performing inspections, maintenance, and repairs in confined spaces;
  • Automated industrial vehicles like driverless forklifts and tractors and automated vehicles used to haul materials in mining that could one day be piloted for the transit of people and commercial goods delivery;
  • Unmanned aerial vehicles (UAVs or drones) that are increasingly being used to evaluate structures and worksites and may one day be used for the delivery of goods; and
  • Wearable exoskeletons and exosuits that are designed to reduce stress on some body parts and augment human workers’ physical capacity.

Industrial robots also pose hazards for those who work with and alongside such systems. Hazards for workers working with robotic systems include struck-by/caught-between, crushing and trapping, electrical, hydraulic, pneumatic, and environmental hazards.

Robotics safety standard

The current industry consensus safety standard for robot systems and applications is American National Standards Institute (ANSI)/Robotic Industries Association (RIA) R15.06-2012, Industrial Robots and Robot Systems—Safety Requirements.

While the industry standard does not use the term “hierarchy of controls,” robotics safety involves some elements of the traditional industrial hygiene hierarchy of controls. The safety standard uses a three-step process through the manufacture, integration, and operation of industrial robots.

With an emphasis on safe design, the primary responsibility for safety falls to machine manufacturers and system integrators, then finally to the employer.

Steps include:

  • Step 1: Robotics safety begins with inherently safe design measures such as the elimination or substitution of hazards or limiting human interaction.
  • Step 2: Safeguarding and complementary protective measures that include safety-related parts of the control system (SRP/CS) and protective measures such as emergency stop devices and functions, platforms and guardrails for fall protection and safe access, measures for the escape and rescue of people, and energy dissipation and isolation.
  • Step 3: Information and training for use, including awareness and warnings, along with administrative controls and personal protective equipment (PPE).

Collaborative robots

Co-robots work alongside human workers or other robots and improve worker safety, according to the Centers for Disease Control and Prevention (CDC). The CDC’s National Institute for Occupational Safety and Health (NIOSH) predicts the future of work will see more robots that work in tandem with human workers or are even worn by humans.

Robots could include remote-controlled nursing robots that might reduce the workload for workers in healthcare facilities. The use of robotics in health care also could reduce the risk of worker infection both in quarantine and in intensive care environments.

Industrial exoskeletons could assist with patient handling, potentially reducing the incidence of musculoskeletal disorders (MSDs) in the healthcare sector.

Researchers are trying to develop more intuitive interfaces to make it easier for nurses to operate robots from a distance. There is even a push to develop best practices for integrating robots into nursing education.

Other robotics researchers are looking into the potential for personalized wearable robots in manufacturing that could sense workers’ physical effort.

According to the makers of industrial exoskeletons, the devices have the potential to boost productivity and work quality while reducing the risk of work-related MSDs. Exoskeletons include back-assist, leg-assist, and shoulder-assist devices, which are powered by electric motors, hydraulics, pneumatics, or a combination of the three technologies.

Workplace applications for industrial exoskeletons also include reducing hand-transmitted vibrations in certain work tasks and aiding in materials handling in the wholesale and retail trades.

However, both the benefits and the risks of industrial exoskeletons have not been well studied, and NIOSH recently acknowledged a need for further study of robotic exoskeletons.

Existing studies usually are performed in laboratory settings and have only involved small numbers of participants. Some have had fewer than 15 participants.

Industry safety practices

Under the industry standard for collaborative robots, system integrators must perform comprehensive hazard analyses and risk assessments for each system application. Hazard analyses and risk assessments ideally will be conducted with the employer and workers participating. The company under contract to integrate systems for an employer should explain the risk assessment process to the employer’s managers, supervisors, and any workers who will work with or near the robot applications.

As an employer, you need to confirm that the contractor performing system integrations satisfies the requirements in your contract’s statement of work (SOW).

You also must ensure that the integrator has designed and implemented safe robotic applications.

You and the employees involved in operating and maintaining systems in your facility need to understand and have a general working knowledge of any robot systems in your facility and the safety standards for robotics systems, as well as the regulations and industry standards that apply to the specific robotic applications in your facility.

System integration will include site acceptance testing (SAT) to confirm that the robotic equipment integrated into your facility’s operations performs as expected with your site’s utilities, services, machine interfaces, and environmental characteristics.

These tests should be performed by the integrator, but you need to verify the test results and ensure that site acceptance testing is performed before any initial start-up of a robot application.

Even after the system application has undergone the initial site acceptance, you have a responsibility to maintain the application in a compliant state. You can do this through periodic robot system performance testing to verify that conditions of use are unchanged from the original installation.

You also need to check the stopping-ability performance and the appropriateness of the robots’ safety distances, as well as the safety function settings to ensure they are properly set. If you prefer, you can contract with third-party testing and verification services.

However, you need to maintain records of the testing performed and results to effectively track robotic system safety. Such records also would be valuable during a safety audit.

If your company integrates robotic systems in your facility rather than contracting out the work, you need to meet all the integration and user requirements.

Safety considerations through all stages—planning and design, assembly, installation, integration, and operation—include:

  • Risk assessments performed at each stage, as system and worker safety requirements must be reevaluated at each stage.
  • Safeguarding devices, including presence-sensing devices, fixed barriers or perimeter guards that prevent system access or contact with moving parts, and interlocked barrier guards.
  • Awareness devices such as chain or rope barriers with supporting stanchions or flashing lights, signs, whistles, and horns.
  • Methods to protect the system programmer during integration, such as reducing robot speeds during programming.
  • Operator safeguards, ensuring that system operators do not have access to or are not exposed to hazards.
  • Safeguards for maintenance, repair, and troubleshooting workers. The robot should be in manual mode when maintenance, repairs, and/or troubleshooting must be performed with the power on, and maintenance workers must perform their work within the safeguarded space.
  • Written procedures for activities that must be done in specific sequences or a specific order; activities that create unique, unusual, or significant hazards; and complex jobs, tasks, or activities such as equipment replacement or overhaul.
  • Safety training for all workers who assemble, install, program, integrate, operate, maintain, or repair robots, robot systems, or robot applications.

Collaborative robot safety precautions

Collaborative robot systems use one or more safety technologies when operating in automatic mode: speed and separation monitoring (SSM), power and force limited (PFL), combined SSM/PFL, hand-guided controls (HGC), or safety-rated monitored stop (SMS).

An SSM is a protective device, such as a presence-sensing safeguarding device, integrated into the robot application to stop when worker intrusion in the safeguarded zone is detected.

With HGC, which is similar to powered-assist tools or machinery, the worker controls the motion for the collaborative portion of the task, and the robot executes a task when the worker presses a hold-to-run control.

In PFL, the power and force of the collaborative robot are limited to prevent injury to a worker. PFL capability may be part of the robot design, such as a low energy potential due to a very low payload and/or speed capability. PFL robots usually operate at lower speeds and payloads than they are physically capable of, thus not moving with enough energy to cause injury.

SSM often can be combined with PFL for collaborative applications so the system can run at a higher speed when no workers are nearby but then slow when worker contact would be permitted.

SMS is not used alone but rather in conjunction with SSM, HGC, and/or PFL. It works through the continued detection of the workers in a safeguarded space by motion sensors, for example. The robot system remains on but stops automatically when the presence of a worker is detected and holds in a monitored standstill state. Also, there’s no need for a worker to press a restart button, as it allows operations to automatically resume when there are no workers detected in the safeguarded space.

Common questions in risk reduction for collaborative robotic systems are:

  • Is the presence of a worker integral to the robotic application?
  • Do the robot and worker have to share a workstation?
  • Do the robot system and worker have to work on the same workpiece simultaneously?
  • Have task locations been identified and made known?
  • Is there safe access to the task locations?
  • Does the person need to be in physical contact with the robot while the robot system is in motion?

Robots can enhance or extend the capabilities of your workforce. However, the presence and use of robots can introduce new hazards in the workplace. With proper planning and safeguards, you can eliminate or limit the hazards to your workers.