Collaborative robots: application benefits for manufacturers

Collaborative robotic applications, a relatively new innovation in the robotic industry, are designed to team up with a human operator to flexibly perform a wide variety of tasks.

In the initial decades of robotic applications, the technology functioned without human interaction. This was for two reasons: the flexibility of robots was limited, so humans had little reason to interact with them; and the robotic arm’s high-speed motions posed significant hazards for anyone who got too close. Despite their lack of flexibility, robotics helped lower operating costs, capital costs, labour turnover and waste while improving product quality, production work and employee safety.

Technology has advanced to the point where humans and robots can now share tasks, and this new partnership boosts flexibility for manufacturers. Today’s business and technological drivers, such as data-driven services, decreasing product lifetimes, the introduction of machine learning and the need to differentiate individual products and brands, are making flexible collaborative robot applications — where humans and robots work in tandem — an effective option for manufacturers.

Enabling collaborative robots

The robots used in collaborative applications today manage to minimise their potential for harm by limiting their power and force capabilities to levels suitable for human contact. They often employ force feedback, low-inertia servomotors, elastic actuators and collision detection technology.

Collaborative robots are more compact than conventional robots and often have lightweight frames with soft, rounded edges and minimised pinch points. They are equipped with sensors that are capable of detecting when a person has entered the collaborative workspace as well as when contact is made. Well-defined collaborative workspaces enable the robot to operate at higher speeds when people are not present within the hazard zone.

Force-torque (FT) sensors are a key component of hand-guiding mechanisms for training on new tasks. Hand-guided teaching is one of the most significant benefits of today’s collaborative robot applications because it enables the operator to prepare the robot for new applications without requiring advanced knowledge of robot programming.

To make a collaborative robot application suitable for the operator, principles for safe operation also need to be applied to the rest of the system, including the end effector and fixtures. Hazardous end effectors include any that present sharp edges or high heat, such as those used in welding applications.

Applications for collaborative robots

A collaborative application incorporates a robot designed for collaborative use that is working in close proximity with an operator. Many manufacturers introduce robots designed for collaborative applications into their facilities to take care of pick-and-place tasks, but the versatility of these robots goes far beyond those applications. Since these robots allow a significant amount of human control and authority over machinery, they can take on almost any repetitive task in manufacturing.

The flexible arm of many collaborative robots can be fitted with a wide variety of end effectors and trained on new tasks via hand-guided teaching. Source: Omron Automation Americas.

Packaging and palletising are production-line stages that can be repetitive and tedious for workers. Collaborative robot applications, in which the robots are equipped with flexible grippers and vision systems that can recognise various product types, can take care of the redundant tasks and heavy lifting while operators work on tasks that require human input.

Collaborative robotic applications can also perform processing tasks that require machine tools to act upon raw materials and works in progress. Many of these tasks require tools to traverse a precise path repeatedly. Depending on how complex the path is, it can be difficult to train the requisite number of human workers on these tasks, whereas training robots — whether through programming or hand-guided teaching — gives fast, precise and consistent results.

Machine tending is another useful application for collaborative robots. Although the process of loading parts and materials into machines is often dangerous as well as repetitive, humans currently perform most machine tending tasks. Because qualified workers are difficult to find, manufacturers are incorporating flexible robotic solutions to boost productivity while minimising hazards to workers. Robots can perform tasks such as loading materials into computer numerical control (CNC) milling machines, emptying plastic injection machines and inserting printed circuit boards (PCBs) into testing machines.

Collaborative robots and risk assessments

Although robots designed for collaborative applications may be lighter in weight and move slower than conventional robots, safety measures are still important. Features like collision detection technology and low-inertia servomotors help minimise risk, but they don’t completely remove it. Hazards must be identified through risk assessments for various applications, and appropriate training and safety measures must be implemented.

Potential risks to identify include operator conditions such as fatigue or stress, clearance around obstacles such as building structures, foreseeable contact and consequences of such contact, and other hazards associated with the work area as well as misuse or lack of operator training. Operators need to be aware of the robot’s pathways and process.

Collaborative robots are ideal for automating machine tending tasks, such as removing finished parts from CNC machines. Source: Omron Automation Americas.

While each application is unique, some guidelines help evaluate the safety of a robot while performing a given task in collaboration with a human operator. Things to consider may include:

• How long and often the operator will be inside the collaborative workspace
• The potential frequency and duration of contact between the operator and the robot
• Whether or not there is a high potential for head or neck contact (if so, the collaborative application should be reconsidered or redesigned)
• What happens during the transition into or out of the collaborative workspace
• Whether the robot might engage in unexpected starts capable of startling the operator
• If more than one operator will work with the collaborative robot or be able to access the collaborative workspace (if so, sensing devices to monitor additional individuals may need to be evaluated)
• Any potential pinch points and crushing due to additional structures in and around the workplace
• What out-of-the-ordinary events would require a manual restart
• If different levels of drive power pose varying hazard levels to the operator
• If the operator might be wearing personal protective equipment (PPE) that could get caught in clamping fixtures
• Any drive and power hazards that may exist even if the robot is not moving.
   

End-of-arm tooling (EOAT) is also a key source of potential hazard to the operator. A thorough risk assessment will include questions about EOAT including:

• Are there extreme temperatures capable of causing injury to the operator if contact is made? If so, a protective cover could be added, or the orientation of the robotic arm could be changed to restrict access to the hot area (such as a hot glue gun).
• If the part became dislodged from the EOAT, could the impact injure the operator? If so, redundant mechanisms could be added to detect and reduce the likelihood that parts might dislodge.
• If clamping forces on the EOAT or fixtures can cause an injury, can the force be reduced? Design considerations in this case might include using clamps capable of retracting if excessive force is detected.
• Can exposure to sharp edges cause cuts and abrasions? Sharp edges could be rounded or made of softer materials to reduce risk.

Conclusion

Overall, collaborative robotic applications can flexibly automate repetitive and sometimes dangerous tasks in manufacturing, including pick-and-place, packaging, processing and finishing tasks, machine tending and others. These robots are versatile and easy to train so they can take on almost any repetitive task in manufacturing. In doing so, they help reduce the risk of repetitive injuries for humans while boosting employee satisfaction.

While collaborative robots are designed with human interaction in mind, a risk assessment may still require additional reduction measures to be added. These risk assessments must consider all the ways in which the robot would interact with an operator, what aspects of the surroundings might cause clamping or entrapment, and what characteristics of the EOAT might pose a risk due to high heat, sharp edges or other hazards. If a risk assessment is performed and requisite safety measures are implemented, it will increase the overall efficiency of an application and boost performance.

*Tina Hull is a TÜV Functional Safety Expert and Product Engineer at Omron Automation Americas.

This article was first published on Control Engineering.

Top image: ©stock.adobe.com/au/zapp2photo

Originally published here.