Are cobots inherently safe?

08 June 2019

Nigel Smith comments on some common misconceptions about collaborative robot safety.

Results from the Global Robotics Report 2019 identified that 79% of automation distributors do not believe their customers understand the safety requirements of installing a collaborative robot. As one of the fastest growing sectors of the robot market, this lack of knowledge could be dangerous. 

Collaborative robots, often referred to as cobots, have been heavily marketed as unguarded and easy to integrate machines that can work seamlessly alongside human workers. However, this does not necessarily make these machines exempt from the safety regulations associated with regular industrial robots. 

Standards for cobot safety
While there are significant differences between cobots and their industrial counterparts, the industry does not acknowledge cobots as a separate entity. As far as safety is concerned, cobots are subject to the same stringent regulations as traditional robot variations such as SCARA, six-axis and Cartesian models. 

Robots for use in manufacturing are subject to two distinct standards, ISO 10218-1:2011 Robots and Robotic Devices - Safety Requirements for Industrial Robots and ISO 10218-2:2011 - Part 2: Robot Systems and Integration. At present, there is no comprehensive standard that has been exclusively developed for the safety collaborative robots, but there is plenty of guidance available. 

Cobot end users should adhere to the most relevant published guidance contained in the ISO 10218 standards, a report entitled ‘Collision and Injury Criteria When Working with Collaborative Robots’. 

Additionally, a technical specification released in February 2016 – ISO/TS 15066 ¬– provided safety guidelines for the use of robots in collaborative applications and this determines guidelines for force limitation, maximum allowable robot power and speed.

Risk assessment
There is plenty of literature available on the safety requirements of collaborative robots, but the problem is that this information is often overlooked. Due to the way cobots have been marketed, many plant managers mistakenly assume that all cobots are automatically safe for use alongside their employees. After all, they are ‘collaborative’. However, this misconception simply is not true.

Deploying a cobot safely requires a comprehensive risk assessment. This should consider the risks that may occur while the robot is in operation, performing the tasks required of it, as well as the potential risks when the cobot is between tasks.

Unlike traditional variations, cobots are often lightweight and portable. Therefore, they are ideal to be used for various tasks within a factory. Used in such applications, the plant manager must assess how the safety may be compromised when the cobot is in transit. For example, being moved from one section of the production line to another. In addition, an assessment is required for every separate activity and task the cobot will perform. 

Taking packaging applications as an example – A risk assessment may find that, in order to operate at full speed and meet palletising KPIs, fencing around the cobot is required to maintain worker safety.  Albeit standard practice with traditional industrial robots, fencing usually isn’t considered when purchasing a cobot. Therefore, these additional safety features often are not budgeted for.

To cobot, or not?
Motivation for most automation investments is to increase productivity and output. Therefore, reducing a cobots operating speed in order to remove safety fencing does not make sense from a business or manufacturing perspective. What’s more, physically separating the robot from human workers removes the entire nature of the machine. Put simply, it is no longer collaborative.

In these instances, it is worth considering whether a cobot is what you really need or if a traditional robot might be more suitable. Six-axis robots, for example, have long been used to increase productivity in packaging applications. For many of these packaging and palletising tasks, there is no real need for human interaction with the robot. As a result, enabling this collaboration through investment in a cobot does not assist productivity or output.

There is no doubt that cobots have their place in the factory and reports suggest that the global cobot market is growing rapidly. This represents the view that cobots can be an ideal first step towards automated processes. However, as the Global Robotics Report 2019 suggests, understanding of these machines and their safety requirements is lacking and this is an issue that must be addressed. 

Nigel Smith is managing director at TM Robotics, a Toshiba Machine partner.

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