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    Collaborative Robots

    9 Feb 2022, 3:26 PM
    Person working with a collaborative robot

    What are collaborative robots?

    Collaborative robots are low-cost automation solutions that are intended for direct human to robot interaction within a space without guarding. They can learn multiple tasks through demonstration and reinforcement learning to help assist humans.

    Using mobile technology, machine vision, cognitive computing and anti-collision technology they can fulfil various roles without injuring people near them. All cobots are designed to minimise or stop injuries from occurring in the off chance that there is collision between the cobot and human.

    Cobots are intended to augment a human workers capability and act like an extra set of hands. Some service robots can be considered cobots as they are intended to work alongside humans.

     

    There are 4 different types of cobots:

    • Coexistence collaboration – Where a human and cobot work alongside each other without fencing but do not share a workspace.

    • Sequential Collaboration – Where a human and cobot work in a shared workspace but they do not work on the same part at the same time.

    • Cooperation Collaboration – Where a human and cobot work in a shared workspace and work on the same part at the same time.

    • Responsive Collaboration – Where the cobot responds in real time to the movement of a human.

     

    A Brief History of Cobots

    The first ancestor cobot was invented in 1996 by J. Edward Colgate and Michael Peshkin, lecturers at Northwestern University in the USA. It was an invention that resulted from a 1994 General Motors initiative to find way to make robots safe enough to work with people.

    Its name then was the Intelligent Assist Device and could move in a non-caged environment and help humans in assembly operations. Then they did not have an internal source of motion power for safety reasons.

    The first cobot was installed in 2008 by Universal Robots at a facility that supplied technological plastics and rubber. The robot used was a UR5 to automate the process of machine tending CNC machines.

     

    What makes collaborative robots safe to work with humans?

    The ISO/TS156 regulation introduced in 2006 made all cobots follow it to make cobots meet certain safety norms. This ISO mandates that cobots require at least 1 safety feature like force limiting or speed monitoring.

    Risk assessments must also be carried out by the integrator or manufacturer of the cobot. In this risk assessment they must consider the entire collaborative environment, every possible job the cobot may do, every possible contact situation between the human and robot and evaluate how the operator will interact with the cobot. After the risk assessment it completed it must be shared with the operators who will be near or working with the cobot so that they are aware of the risks and how to avoid them.

    Force monitoring enables a robot to sense its force and torque outputs in each joint and stay within its safety limits. If it does breach its limits, it will stop moving immediately.

    Speed monitoring requires the cobot cell to be equipped with sensors to detect when a person enters its workspace. The absence or presence of a person determines how fast a cobot is allowed to move. It will not move so fast that it would cause injury if a collision did occur.

    Hand guiding can be done by operators to teach a new movement or task to the cobot. For this to be done safely the cobot must be stopped before the operator enters its workspace. Also, to enter the teaching mode, it must be by a deliberate set of actions that cannot be accidental. The operator must also be aware of the surrounding equipment and the cobots safety limits while guiding it.

     

    What are the advantages of collaborative robots?

    • Cobots can be programmed within 30 minutes as it is very easy to do and they have user friendly software. Mobile apps can also be used. The cobot can also be manually set up and the process then saved in its software.

    • They can be installed within 30 minutes.

    • They are more consistent and accurate than humans and have accuracies of 0.1mm. They never deviate from the actions that they were programmed to do and the tasks are always done with the same force, speed and tension.

    • Cobots can be used in a range of different departments as they are incredibly flexible and adding new tasks for them to do is simple. This flexibility enables them to be hired temporarily when needed like during peak times.

    • As they are much cheaper than traditional industrial robots, they have a much faster ROI.

    • They help to increase productivity and improve process optimisation as errors are minimised. This can also lead to more profits and employees having more time to do other tasks that are more fulfilling.

    • They are available to small and midsized companies because of their low cost which enables them to compete with larger businesses.

     

    What are the disadvantages of cobots?

    • Although they are designed to work with or alongside humans, this depends on the task. They may require to be placed in a cell behind guarding for safety purposes which will increase the price of implementing a cobot system.
    • Their work speed is limited depending on what is in its workspace and what task it is carrying out. To make the area safe when people are in or near it the robot may have to slow down its actions or even stop.
    • By teaching the cobots by hand it transfers over human errors and makes them have non-optimal movements.
    • Cobots also have limited reach and payload due to their size. Their payload capability is normally around the 10kg range however some have been manufactured to have payloads up to 35kg. Traditional industrial robots can lift up to 2 tonnes.
    • Compared to traditional industrial robots they are not as powerful or as accurate due to their closeness working with humans.
    • Before being implemented they must have a thorough risk assessment produced.
    • They cannot work by themselves and always need human assistance or supervision.

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