In the early decades , robotic applications operated without human intervention. This was for two reasons: robots had limited dexterity, so human interaction was unnecessary; and the high-speed movements of robotic arms posed a danger to anyone near them. Despite this lack of dexterity, robotics could reduce operating costs, capital costs, labor turnover, and waste, while simultaneously improving product quality, productivity, and employee safety.
With the advancement of robotics, humans and robots can now collaborate on tasks, and this new partnership enhances the flexibility of manufacturing production lines. Today's business models and technological drivers, such as data-driven services, shorter product cycles, the introduction of machine learning, and the need to differentiate products and brands, are making flexible collaborative robot applications (humans and robots working together) an effective option for manufacturers.
Using robots in collaborative work
Currently, robots used in collaborative applications attempt to minimize potential harm by limiting their force to a level suitable for human contact. They typically employ force feedback, low-inertia servo motors, elastic actuators, and collision detection technology.
Collaborative robots are more compact than conventional robots and typically feature a lightweight frame with soft, rounded edges and minimal contraction points. They are equipped with sensors capable of detecting when an operator enters the collaborative work area and when contact will occur. Within a well-defined collaborative work area, robots in hazardous areas can operate at higher speeds if no one is present.
Force-torque (FT) sensors are a key component of manually guided mechanisms used to guide new tasks. Manually guided instruction is one of the greatest advantages of collaborative robot applications today because it allows operators to prepare robots for new applications without requiring advanced robot programming knowledge.
For collaborative robot applications to be suitable for operators, safe operating principles must also be applied to the rest of the system, including end effectors and fasteners. Some end effectors are relatively dangerous, including those with sharp edges or high temperatures, such as those used in welding applications.
In collaborative applications, specially designed robots can work closely with operators to complete tasks more efficiently. Many manufacturing companies have introduced robots specifically designed for collaborative applications into their factory facilities to handle simple pick-and-place tasks; however, the versatility of these robots extends beyond pick-and-place applications. Because these robots allow for a significant amount of human control and authorization, they can accomplish many repetitive manufacturing tasks.
On the production line, packaging and palletizing can be repetitive and tedious for workers. Collaborative robot systems equipped with flexible grippers and vision systems that can recognize various product types can handle redundant tasks and heavy workloads, allowing operators to perform tasks that require manual input.
Collaborative robots can also be used to perform tasks involving the handling of raw materials. Many of these tasks require tools to repeatedly traverse precise paths. Given the complexity of these paths, it can be difficult to train the required number of workers for the task, while collaborative robots trained through programming or manual guidance can provide fast, accurate, and consistent results.
Machine maintenance is another useful application for collaborative robots. Although loading parts and materials into machines is often a repetitive and hazardous task, most machine maintenance work is currently still done manually. Because qualified workers are difficult to find, manufacturers are adopting flexible robotic solutions to increase productivity while minimizing harm to workers. Robots can load materials into CNC milling machines, empty injection molding machines, or insert printed circuit boards (PCBs) into testing machines, among other things.
Safety awareness and risk assessment
While robots designed for collaborative applications may be lighter and slower than conventional robots, safety measures remain crucial. Features such as collision detection technology and low-inertia servo motors help minimize, but do not eliminate, risks. Risks must be identified through risk assessments tailored to various applications, and appropriate training and safety measures must be implemented.
Potential risks that need to be identified include operator condition (e.g., fatigue or stress), clearances around obstacles (e.g., building structures), foreseeable contact and the consequences of such contact, other hazards associated with the work area, and situations such as misuse or lack of operator training. Operators also need to understand the paths and processes the robot will traverse.
Developing guidelines helps operators assess the safety of robots performing a given task in various applications. These should include:
●When and how frequently do operators enter the collaborative work area?
● What is the potential frequency and duration of contact between operators and robots?
●Is there a high likelihood of contact with the head or neck (if so, collaborative applications should be reconsidered or redesigned)?
●Work scenarios when transitioning to or from a collaborative workspace?
●Is it possible for the robot to be accidentally activated, shocking the operators?
● Are there multiple operators working with the collaborative robot or having access to the collaborative work area (if so, it may be necessary to evaluate sensing devices for monitoring other personnel)?
● Could other structures in the workplace or surrounding space cause pinching and crushing injuries?
●Which abnormal events require manual restart?
●Do different levels of drive power pose different levels of danger to operators?
●Are operators wearing personal protective equipment (PPE) that could get caught in clamps?
● Are there any drive and power-related hazards when the robot is not moving?
Although human-robot interaction is considered during the design phase of collaborative robots, additional mitigation measures may still be necessary after a risk assessment. These risk assessments must consider all ways in which the robot interacts with the operator, which aspects of the surrounding environment might cause clamping or entrapment, and which features of the end effector tool (EOAT) might pose a risk due to high temperatures, sharp edges, or other hazards.
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