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Ensuring cobot safety

20 March 2023

Julian Ware explains why it pays to take a thorough approach to ensuring the safety of cobots when they are required to work alongside human operators.

Collaborative robots (cobots) are fast gaining a foothold in the world of industrial automation. Their ability to combine the precision, power, and endurance of robots with the dexterity and handling capabilities of humans is enabling many small- and medium-sized enterprises (SMEs) in the food sector to take the first steps to automating their operations.  

A principal motivation for automation is the ability to achieve consistent and repeatable product quality.  Automated work is completed faster, more accurately and with greater consistency in quality, which can help boost productivity and reduces costs. Cobots further expand on those benefits by overcoming the operating environment and space constraints typically faced when deploying conventional robots.  

Cobots are built to be able to work alongside humans and are typically small enough to slot into existing production lines with little or no disruption. They can also be moved between different tasks in the factory with relative ease. This is especially useful for SMEs, giving them the option of investing in just a few cobots to perform a broad range of jobs, as and when needed.  

Cobot safety
While cobots are widely presented as being safe to deploy alongside people, it is important to point out that cobots – just like industrial robots – are incomplete when deployed in isolation. Their safe usage must be considered together with the application they are installed in, along with any additional peripheral equipment and workpieces.  

Although there are characteristic differences between cobots and traditional industrial robots, the level of safety essential for both is identical.  First-time cobot users incorrectly tend to skip the requisite safety protocols because they believe cobots are inherently safe.  

Cobots are designed and built with safety functions that enable them to share workspaces with humans, but there are still additional risks beyond those directly associated with the robot manipulator. The safe deployment of the robot is core to the overall risk reduction scheme, which seeks both to reduce the severity of any hazards identified and reduce the probability of their occurrence. 

The distinguishing feature of cobots is that they are designed to accommodate human operators sharing a workspace with the cobot system, so they need properties to sufficiently reduce the risks associated with such collaborative work.  Power and force limiting (PFL), coupled with speed and separation monitoring (SSM) are the primary parameters that are regulated.  

The integrator of a cobot system is responsible for reducing risks to an acceptable level. If available, this can also be done by in-house personnel, as long as they have the necessary expertise.  

Once the risks are sufficiently reduced and validated, the integrator or safety consultant will provide a document showing this.  There is a tendency to skip this step, presuming that one has purchased a safe robot, but it is legally binding to conduct a risk assessment of the completed application and to implement risk reduction measures as appropriate. 

An essential requirement
Performing a thorough risk assessment when installing a cobot is essential. It needs to cover a range of areas that will determine its safety when operating around human workers. These include a description of the cobot application and its intended use, followed by identification of all the hazards that it may be present during programming, commissioning and operation. This is essential to give an estimation of the exposure of personnel to potential hazards. 

Documents that detail the safety-related aspects of the cobot system, the procedures followed for their correct configuration, the intended manner of working with the system as well as any limitations on use or requirements on regular adjustments or maintenance must also be produced and retained. 

Julian Ware is UK & Ireland Sales Manager at ABB Robotics.

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