FEATURE INDUSTRY 4.0/IIOT/ROBOTICS TAKING THE RISK OUT OF COBOT SOLUTIONS Prior to teaching, the robot must be
stopped before the operator enters its workspace, even if its force and speed limiting functionality has been activated. Alternatively, a safety device (e.g. an area scanner) must carry out a protective stop as soon as the operator is detected. The operator can use a simple trigger,
Peter Lange, business development manager Robotics, Omron Europe, discusses the safety aspects of collaborative robot applications and explains how to implement an effective operation
C
ollaborative robots (‘cobots’) are a key aspect of Industry 4.0 and the ‘factory
of the future’. They can be used in a range of industrial applications. Because they have various integral safety features, they can work with or near people and can adapt easily to changing needs. This means that the productivity of repetitive tasks can be increased, giving a high return on their investment. The safety features of cobots include
lightweight body, collision detection technology and minimised pinch points. However, further safety measures might still be needed for specific applications - including the end effector, the product and other equipment in the collaborative workspace (a safe space where robots and people can work together). For a cobot application to be successful, it must incorporate safety considerations based on comprehensive risk assessments. So, what are the industry safety
standards and solutions that will enable a company to gain the maximum value from cobots within a collaborative workspace? Cobots are more compact than
conventional robots and incorporate force and speed monitoring capabilities. When fitted with safety devices that detect anyone entering the collaborative workspace, they can often work at higher speeds when people aren’t present, which helps to maximise throughput. Two key safety standards that define the
safety functions and performance of a cobot are ISO 10218-1, ISO 10218-2 and ISO TS 15066. The latter sets the force and speed monitoring of the cobot based
8 SEPTEMBER 2020 | PROCESS & CONTROL
on application data, human contact area and work space hazards. There are two types of human contact: transient (non- clamping contact) and quasi-static (involving situations that can cause a body part to be clamped). Manufacturers who aren’t familiar with
the requirements of ISO TS 15066 can hire a safety assessment provider to make the calculations, take the measurements and recommend improvements to the safety of the collaborative application. ISO 10218 and ISO TS 15066 also
provide guidance on cobot teaching. Many cobots, such as Omron’s TM Series, use intuitive ‘hand guiding’ mechanisms for teaching new tasks. This avoids the need to program the specific movements of the robotic arm. The hand guiding mode monitors force and speed so that the teaching process complies with safety standards.
Designers of automated machine tooling, material handling and assembly applications should look at all of the interactions between the cobot and the human operator, along with the risks of clamping or entrapment, and the dangers from end-of- arm tooling due to high heat, sharp edges or other hazards
button or mode selection to activate teaching if safety force and speed monitoring are in operation. If not, a three-position safety enable is required. According to the safety standards, the teaching mode transition must be deliberate, mustn’t lead to any unexpected motion and mustn’t create additional hazards. The operator must be aware of surrounding equipment and possible safety issues at all times. To enhance operator safety, it’s possible to enforce limits on motion: for example, space and soft axis limits. Prior to operation, the operator must
vacate the safeguarded space. This can be verified by safety sensors or additional operator verification. Intentional mode selection is needed to re-enable the robot for operation. Cobots operate near other equipment
that could be dangerous. It’s therefore important to list and map out all additional equipment in the collaborative workspace (which must be clearly marked). Each device must be assessed for potential hazards and for safety sensors that could prevent human and equipment damage. Non-collaborative safety-rated
equipment that might need safety devices includes material handling, tooling, grippers and actuators and machines. Safety devices can usually be integrated easily into a cobot application. Several solutions can be used to
Cobots are usually considered as safe for use with people. However, they still need risk assessments throughout to ensure the safety of human operators. It’s vital for manufacturers to consider all of the potential hazards associated with hand- guided teaching, as well as possible issues when the robot is involved in an emergency stop
safeguard the collaborative workspace. In open areas and applications with low hazards, these include safety area scanners and mats. In gated or limited areas with more hazardous applications or high-speed operations, safety light curtains and safety switches can be used. In areas with active hazards or operations that could cause a hazard, operators can enable a ‘deadman’ switch, which automatically turns off if the user stops exerting pressure on it. For maximum safety in collaborative
operations, manufacturers must validate the safety of their cobot applications across all operations. There are some guidelines they can follow when evaluating the safety of a robot while performing a given task with a human operator. Some dangers, such as drive and power hazards, might still exist even if
/ PROCESS&CONTROL
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