3D zone monitoring
Light curtains can also be the source of problems if the machine is modified. Consider the example of a machine that is upgraded to run faster in order to increase throughput. If it runs faster, the time it takes to stop will most likely also be longer. This might mean that the safety light curtain has to be moved further away, but this will also require the physical guarding to be modified. And what if the light curtain has to be moved so far back that it encroaches on the walkway between the machines? Pilz recently had a customer who found himself in a similar situation and he was considering replacing the light curtain and some of the physical guarding with a Pilz Safety EYE 3D vision-based safety system, as this would be cheaper and easier overall, and could be done with less disruption to production.
Safety EYE is the latest safety technology to have come to the market and is unlike any other safety product currently available. The nearest thing you could compare it to is a safety light curtain or a laser area scanner, but both of these just monitor a flat plane and, after someone has broken the beam, there is no way of telling which side of the beam they are unless you use another safety sensor. Safety EYE, on the other hand, monitors a three-dimensional volume - which is configured in software - and the system therefore knows when the hazardous zone (or the outer warning zone) is being breached. But what you have to bear in mind with both light curtains and scanners is the hidden costs associated with the physical guarding that you still need, plus the substantial cost of setting-up and maintaining the system. Engineers at Pilz in Germany have estimated that a Safety EYE system can be 70 per cent cheaper to install and maintain.
Something else that Safety EYE can do is perform standard logic functions. For example, if SafetyEYE is being used to safeguard a robot that is placing product in a collection bin, the system can also be used to monitor the level in the bin and signal when it needs emptying. In this type of application you effectively get the bin monitoring hardware 'for free', and you just need to configure the program using the software.
Integrated safety
Indeed, there is a definite market demand for integrated safety and standard control functions. Pilz launched its 'Safety & Control' initiative three years ago, taking the view that safety controllers are becoming so sophisticated that in many cases they could absorb the standard control functions currently performed today by separate PLCs. By adopting this approach, machine builders, system integrators and end users can benefit from lower costs, reduced development time, closer integration of safety and standard control, and improved machine availability due to the standard control being handled by higher-integrity hardware and software.
