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Collaborative safety - a critical marker

16 May, 2017

Barry Graham, automation product marketing manager, Omron, looks at why collaborative safety is a critical marker for the smart factory.

The picture of Industry 4.0 frequently painted for the future is of the “lights out factory” – a completely automated smart factory, and with no human intervention. But that’s not so much a journey forward as a complete step change, and for many it doesn’t represent a practical implementation of Industry 4.0 at all. Operators and maintenance staff are going to be key elements of any Industry 4.0 smart factory installation well into the future, and that in turn will mean that safety will continue to be a vital consideration.

For those businesses on the Industry 4.0 journey, the issue is not so much one of removing people from the plant floor as implementing systems where people work in harmony with the processes. In short, it is about harmonising the legal requirements for safety with the operational requirements for optimum productivity.

The path to Industry 4.0 defines an environment of ‘collaborative safety’, where instead of bolting-on safety systems, we are designing-out risk so that processes are inherently safe, and personnel and machines can work in harmony.

For machine builders, this means embracing safety from the outset of a project, rather than designing-in safety almost as an afterthought. It is with this latter approach that we end up with machines surrounded by guards and non-collaborative safety systems. Here, while the machine will be considered safe, machine performance is compromised because operators cannot interact with it effectively. When the default reaction of a machine is an emergency stop whenever an operator approaches, productivity can never be optimised.

Indeed, such safety arrangements will almost always be considered to be confrontational from an operator’s point of view. The daily quest to optimise productivity means that operators and maintenance personnel are almost forced to try to defeat the safety systems. The best safety system will be all but invisible to operators and maintenance personnel; they will have no reason to try to defeat the safety technologies because they are no longer slowing them down.

Fully integrated safety

To deliver the benefits of collaborative safety, machine builders must free themselves from the physical and conceptual limitations of a purely hardware-based response to safety, and focus instead on design principles where safety is fully integrated within the automation system design from the outset.

The term ‘integrated safety’ has become a somewhat overused and misapplied phrase in recent years, with many considering it to be simply the ability for the safety network to exchange data with the standard control network. But truly integrated safety fully embeds the safety aspect as part of the wider control system: safety controllers and safety I/O can be freely distributed around the standard I/O, with a single environment for configuration, programming and maintenance.

As such, fully integrated safety places a much greater emphasis on software than on hardware, and recognises two important trends within machine design. The first is that within a business, as manufacturing requirements evolve, so the safety requirements also need to evolve to support productivity. This is much harder to achieve with inflexible hardware than it is through software with integrated safety technologies. The second is that the approach to safety as defined by international standards continues to evolve in response to new technologies and new ideas. Fixed and inflexible hardware systems can end up working against the legislation, while properly integrated safety technologies allow designers to more easily react to changes.

We can see already that there have been partial moves towards a picture of truly integrated safety, with the emergence of technologies such as safety PLCs, safety camera systems and safe robots. But as we look to the goal of genuine collaborative safety as the emergence of the smart factory continues, then it becomes clear that these technologies represent a step in the right direction rather than the end of the journey. Even these seemingly cutting edge safety technologies do not truly provide safety functionality that fully satisfies performance and flexibility requirements.

So what, then, do we mean when we talk about fully integrated safety systems that deliver on the goals of collaborative safety to fully support productivity? The first point is to look at how we can design out risk. If a high speed section of a machine needs to stop so that an operator can approach to load it, instead of asking how quickly the machine needs to stop, could we instead ask if the operator could load the machine from a different location where there might be less or no danger? We fit guards because we have failed to remove the operator from danger; but if we change to the process so that the operator’s intervention is inherently safer, the machine might not need to stop at all.

As plant floor space becomes more valuable and as we try to squeeze more in, fixed guarding becomes more of a design restriction. But without it, the chances of operators encroaching into a danger zone increase. But again, does the machine necessarily need to stop? Could it not simply slowdown in response to the approach of an operator, only stopping when a set threshold is finally passed? If this approach is applied, for instance, to the interaction between an operator and a robot, productivity is immediately improved.

Zones of safety can be defined with scanners instead of physical guards, and software functions such as safe speed 1 (SS1) or safe torque off (STO) can be implemented in variable speed drives. Different modes of operation can be defined depending on whether it is operators or maintenance staff who are interacting with the machine, each with their own requirements, and limiting speed and/or functionality accordingly.

Change of mind-set

All of this requires a change of mind-set to machine design, and perhaps we could sum it by asking not how quickly can we stop the whole of the machine, but rather which sections of the machine can we allow to keep running? Of course there is the moral and legal obligation to ensure that the machine is safe, but increasingly there is the recognition that effectively implemented integrated safety can deliver on safety requirements and still boost productivity.

In particular, as machine builders take a fully integrated approach to safety, there is the growing realisation that the key safety standards are not a hindrance to innovation at all.

New era of machine design

We can see, then, that collaborative safety defines a new era of machine design where machines and operators work in harmony, and where safety design has a genuinely positive impact on productivity. And it is fully integrated safety within the automation platform that makes it possible.

Collaborative safety lays down an important marker on the path to Industry 4.0, but the future will see plenty of other developments before we reach the lights-out factory, if indeed that is the ultimate goal. Omron, for example, has research focused on finding ways to use vision technology to capture the essence of a scene and extract valuable information from it.

These technologies already surpass the human eye in their capacity to quickly and accurately detect and recognise various targets, as well as identify those targets’ location, shape, material, colour and other attributes. It surely won’t be long before those same technologies can also recognise and respond to danger, before an operator even realises that a hazard exists. That really will open up vast new possibilities for collaborative machines.

Recognising the importance of safety within the truly collaborative machine, Omron has fully integrated safety within its Sysmac automation platform, making it easier for machine builders to consider safety functionality from the outset rather than as a costly and inflexible bolt-on at the end of the design process. A full suite of tested, proven and certified safety function blocks within the Sysmac Studio development environment eliminate the cost and risk of a software free-for-all, and make it easy for designers to implement safety functions as required. Thus safety is no longer a ‘road block’ within the design process.

The approach to fully integrated safety also means that systems can be much more flexible in terms of the flow of data. Just as greater access to, and availability of standard control automation data has massively increased the performance and productivity of machinery, so the integrated flow of safety data can be used to optimise processes for improved productivity and reduced unscheduled downtime.

Of course a vital aspect of this approach to integrated safety is the integrity of the safety controller itself. If an unauthorised user could get into the safety control program, what might the implications be? Omron has addressed this with full password protection on the safety program, and signature tracking within Sysmac Studio, creating a log of any changes to the program and who has made them.

For further information please visit: www.industrial.omron.co.uk

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