What are Cobots? – Basics and explanation

The topic “Cobot” is very current at the moment, so I want to describe the meaning as well as the possibilities of Cobots.

As so often, Cobot is a compound word of collaboration, i.e. jointly networked working together and robots. A Cobot is a robot that can work together with humans – and this without barriers.

Classical industrial robots are much too fast and too strong to work with humans. Industrial robots work at speeds of up to 8 m/second and can move loads over 1000 kg. In the case of direct contact “human – robot” there is a high risk of injury or even death. Cobots are therefore structured differently or bring along special functionalities. The mechanical construction is usually not so massive but rather lightweight. In addition, the possible speeds and the payloads are in the low weight range. Classically, the payloads for Cobots are in the range of less than 16 kg and slower than 4 m/s. For collaborative work with humans, the speed must be further reduced. How far this speed can be reduced is described under safety regulations.

In addition, Cobots are monitored to stop in case of collision or touching. Some models are monitored by the current consumption of the drives (electric motors), others have internal force-torque sensors installed. To be able to use these sensors for safety shutdown, they are redundant (two channels).

Even if you use a Cobot, you must have it checked for safety and carry out the necessary tests. This includes an overall CE of the system. This includes biometric measurements and the necessary risk assessment for collaborative applications. This results in the maximum speed as well as requirements for additional protective devices. If the forces become too high and thus dangerous for people, either the speed can be reduced or the danger zones can be additionally protected with a so-called Air Skin. This is a padded sensor cover which distributes the forces better and allows the Cobot to be switched off more quickly.

Often the question comes up: “Why all this effort if I use a Cobot, it is already safe?

However, the robot usually has other attachments such as cable carriers, camera, gripper where the geometries can lead to higher forces than on the robot arm itself. In addition, there are all parts that the robot transports. At the latest when the Cobot transports a knife, glass pipettes or similar in the gripper it becomes clear that the entire system including all parts to be handled must be considered. You have to question whether the application is still collaborative!

This is one of the main reasons why most Cobot applications do not collaborate with humans. The effort to consider all the parts that are handled is daunting. In addition, when new tasks are performed with new parts, these checks have to be extended. In addition, the speed of the Cobot can be set to a very low level without additional protective devices to generate secure collaboration. This often means that the required cycle times cannot be implemented.

Very important for the human-robot-collaboration thought: Make the MRK area as small as possible and only as big as absolutely necessary!

For many people, a Cobot is just a robot arm with a small footprint and no protective fences. If this is the real issue, it can be solved by using additional safety technology. Usually security scanners are used to monitor the environment of the Cobot. If a human gets closer to the Cobot, first the working speed can be reduced and then the Cobot is stopped if it gets further away. These areas have to be marked on the floor. If a person leaves this zone the Cobot will continue to run normally.

Another solution is the airskin mentioned above. Another advantage of this solution is that the Cobot only stops when touched – not every time someone (even by accident) walks through the sensor area.