When robots and machines share workspace with humans, the safety of all three is an issue. Machines and robots operating at high speeds with great force, wielding a variety of potentially dangerous tools and materials, pose great risks of injury to workers as well as damage to the robots, machinery and production output.
Reliable robot and machine safety guarding is, of course, achievable via personnel training and through the integration of special equipment. But there is much more to consider. To get deeper, up-to-date insights on the state of industrial safety today, Automation World tapped the minds of three experts: Jonathan B. Johnson (JBJ), principal application engineer at Rockwell Automation, Alex Greenberg (AG), Siemens Digital Industries Software’s director of advanced robotics simulation and Eddy Finaro (EF), product manager at Siemens.
AW: How do risk assessments for robots and industrial machinery differ?
JBJ: There are several risk assessment methodologies for industrial machinery that meet the ISO 12100 requirements for risk assessment and reduction. ISO 12100 is a general standard applicable to machine types with different levels of complexity and potential for harm. The RIA TR R15.306 risk assessment methodology for robots is a supplement to the ANSI/RIA R15.06 safety standard, which addresses hazards unique to the application of robot systems. This can include hazards associated with robot arms, end-effectors, fixtures and manual load/unload stations.
AG: The variety of industrial machines and robots is substantial and can vary greatly depending on the machine or robot model and make, manufacturing processes supported and technologies used. For example, consider these two differences between robots and machines: Machines handle a predefined set of tasks. This makes it possible to perform risk assessment and conduct design-for-safety as part of the machine design. Robots are versatile, flexible and suit a variety of tasks and applications. A robot task is programmed at the customer site, either on the shop floor or by using simulation and offline programming software. As a result, risk-assessments and safety precautions are done by the customer.
AW: What are the key safety standards and regulations that manufacturers must adhere to related to robot and machine safety?
AG: Follow industry standards like those from OSHA, ANSI and ISO to ensure safety-regulation compliance. Regularly assess risks associated with machinery and update safety protocols accordingly. Also, ensure that all personnel are trained in safety procedures and emergency responses to robot and machinery maintenance issues and failures.
JBJ: Key robot safety standards are the ISO 10218 series for industrial robots (part 1) and industrial robot applications and robot cells (part 2). These international standards have been adopted by several national standards and regulatory bodies, such ANSI and CSA — ANSI/RIA R15.06, which is a U.S. adoption of the ISO 10218 international standard, and CAN/CSA-Z434-14, which is a Canadian adoption of the ISO 10218 international standard. The standard is also approved for citation in the EUOJ (Official Journal of the European Union). As a type-C standard, this confers presumption of conformity to the Machinery Directive in Europe.
AW: How do collaborative robots (cobots) differ in terms of safety requirements compared to traditional industrial robots?
JBJ: Traditional robot safety applications do not account for robots and people to share the same workspace. Traditional safeguards are specifically designed to prevent operator access to the work area while the robot is active or limit operator interaction to specific manual modes and tasks.
Cobot applications combine the fine motor skills of a person with the power of a robot to accomplish tasks. This puts greater emphasis on the performance of the safety control system that monitors and controls robot parameters such as speed and force limits. Another important consideration is proper risk assessment of cobot applications to account for hazards related to ergonomics and human interactions with the equipment.
AG: Cobots present distinct safety requirements compared to traditional industrial robots due to their shared workspace with humans. Classic safety guards such as fences or cages provide hardware protection to both people and equipment behind a traditional industrial robot, but it does not prevent the robot from accidental crashes.
Unlike traditional robots, which operate in isolated environments protected by barriers, cobots employ advanced safety features like force and torque limiting and other sensors to detect human presence or contact. They conform to specific safety standards, e.g., ISO/TS 15066, which delineates the permissible force and pressure levels during human-robot interaction, enabling them to safely share workspaces with humans and with minimal physical separation.
AW: What are the best practices to follow when implementing robotic systems to ensure safety?
AG: A best practice is to use digital twin and 3D simulation technologies to include safety considerations and definitions as part of the initial robotic task planning. This ensures an optimal design and avoids rework on the shop floor that would balance the task optimization with safety requirements.
For example, process simulation software with robot safety management can provide a comprehensive solution that supports all capabilities, ensuring end-to-end safety in robotic operations design. Leveraging these capabilities during planning and process development helps validate safety concepts, visualize safe spaces and safety-wrapped robots, and analyze them against safety standards and rules.
JBJ: The best practice is to follow state-of-the-art industry standards such as the ISO 10218 series, which integrates safety design concepts throughout the entire life cycle of the machine design. This includes risk assessment, safety specification, system design, validation testing, installation and maintenance activities.
AW: What strategies should be employed for continuous monitoring and maintenance of robots to ensure ongoing safety?
EF: I recommend these three strategies:
- Use sensors and IoT devices on the shop floor to monitor the condition of machinery in real-time and analyze the data from these sensors to identify patterns and predict when maintenance is necessary.
- Implement vision systems and other sensors to enhance the machine’s or robot's ability to detect and avoid obstacles.
- Employ digital twin technology, simulation and advanced software for continuous monitoring and predictive maintenance to identify anomalies and schedule repairs before issues arise.
JBJ: The primary strategy has been to follow the robot manufacturers instruction handbook for guidance on manual inspection and preventative maintenance intervals. These traditional preventative maintenance strategies are still necessary, but often require shutdown of the robot cell and result in a higher likelihood of unplanned maintenance.
Additionally, predictive maintenance techniques are important to ensure ongoing safety integrity. By using control system data to monitor robot performance, common failures can be identified before they occur. For example, detecting minor deviations in robot position and repeatability can be a sign of robot joint or brake wear. Once these deviations go outside acceptable limits, appropriate maintenance measures can be taken.
AW: What are the most common challenges manufacturers face when ensuring robot and machine safety, and how can they overcome them?
JBJ: as per OSHA, human error contributes to most safety incidents in the workplace. To overcome this challenge, a proactive safety culture is necessary. This includes comprehensive safety awareness, technician training, safe work practices and safety policy enforcement.
A proactive best practice is to consider the risk assessment as a living document. With good near-miss documentation practices and ongoing risk reduction monitoring, manufacturers can stay on top of potential gaps in safety and close them before problems occur.
EF: For robots, defining the safety settings and rules for the robot controller and the PLC to make sure all safety scenarios and requirements are met, is the most common challenge manufacturers face. This is especially true when it relates to the positions and size of objects in the robotic cell. Here, again, I recommend use of digital twin and 3D simulation tools.
Listen to this Automation World podcast on industrial machinery best practice safety tips.
