Safety guidelines for collaborative robots

Safety guidelines for collaborative robots

The International Organization for Standardization (ISO) published two documents -- ISO/TS 15066 and ISO 10218 -- that set safety standards for collaborative robots or “cobots” working alongside humans.  

Traditionally, industrial robots were separated from humans to prevent workplace injuries. This has begun to change with the publication of International Organization for Standardization (ISO) ISO/TS 15066 standards for cobot systems safety in March 2016.

The guidelines provide instructions for the design and implementation of a shared workspace for humans and cobots. The ISO standards outline factors to be considered when designing collaborative robot systems, including built-in safety-related systems, and guidance on implementing collaborative techniques, such as hand guiding, power and force limiting, safety-rated monitored stopping, and speed and separation monitoring.

“ISO/TS 15066 is a comprehensive document which aims to help integrators of robotic cells conduct risk assessments when installing collaborative robots,” said Adam Sobieski, General Manager of Universal Robots Greater China.

The ISO/TS 15066 guidelines were created to support the ISO 10218 (Safety Requirements for Industrial Robots) standards. By following the two protocols, manufacturers can build a workspace where both humans and robots can work together in harmony.

“Whether or not a sensor is used depends on the risk assessment and the type of application. UR cobots have 17 safety functions certified by TÜV NORD according to EN ISO 13849,” said Sobieski.

Four methods for cobot implementation

ISO/TS 15066  lists four techniques for cobot implementation. The first is safety-rated monitored stopping. When a cobot senses a human operator is going to step into the collaborative workspace, it will stop and remain stopped until the human leaves for another station. This is helpful in situations such as when an operator sets up new fixtures or adjusts parts.

The second is hand guiding. A built-in hand guiding device allows the operator to control the direction of a cobot. It can be used, for instance, for a robot arm to pick up heavy objects. In this case, the human operator does not need to lift heavy objects manually and is able to perform other tasks.

The two methods above offer a system that can be fully stopped and manipulated while operating automatically.

Speed and separation monitoring, meanwhile, uses safety sensors to detect human presence and decrease the speed of a cobot according to the distance between a human and a cobot. When a human operator isn’t in the working zone, the cobot works at full speed; when the operator gets close, the cobot’s speed reduces; and stops completely if the operator enters the working zone.

The last technique, power and force limiting, restricts motor power and force during an application to restrict the ability of a robot to injure a human operator.

Universal Robots patented adjustable safety system allows users to adjust a range of parameters in order to reduce the risks involved with industrial robots. It includes the safety methods outlined above, such as limiting the force, speed, power or momentum of the robot, or restricting its workspace using safety boundaries in order to reduce the risk of injury.

“Over time safety will and should be an inherent factor within cobots and so be a standard which is default in all products. However, the way safety works, for example how safety sensors operate, will develop over time both short term and long term which will ultimately make cobots and the surrounding production environments even safer,” said Sobieski.



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