Evolution of Emergency Stop in Large Scale Venues

We’re all aware of machine safety. We’ve all read the standards, but how do we apply them here at Stage One when, for example, in a large venue, we need to create a safe emergency stop for all automation control systems? Technology has evolved, and we’ve engineered software in-house to speed up the process and enhance the safety of Qmotion.

Let’s start with safety relays. These entered the industrial world in 1987 (thank you, Pilz) and immediately provided an easy way to create safe designs for machine stops. It was a tremendous step forward for machine safety as these units were compact, employed redundant self-monitoring hardware, and were accepted by all and sundry in machine designs.

But how does this apply to show automation when delivering large-scale events? Typically, a venue could have a perimeter of 400 meters with automation distributed at various points in groups called “farms”. Connecting these farms would use hundreds of meters of copper cable. There were different techniques for this, but the problems always amounted to the same thing. The longer the cable, volts drop, which causes tripping. One solution is to use expensive cable, which comes with its own problems of being heavy and hard to maul. Then there’s the inability to easily group selective automation without running in yet another pile of cables; the difficulty of diagnosing why the system would not reset because of poor monitoring capability; need I go on? Worse yet, if the original installation required a “creative change” then a technical team would descend on the farms brandishing soldering irons to create some wizardry to allow the show to go on.

Fast forward to modern times and we have Safety over Ethernet or another network. There exists a wealth of these; ProfiSafe, and Safety over EtherCAT. The list continues, but basically, they all have the same function. Safer for the user, performers and for audience.

Now we can run a single loop of fibre optic cable around the venue perimeter, place Safety Network Nodes at each farm, and add safe inputs/outputs with diagnostic monitoring within the individual drive so you don’t have one error message, and the entire show stops quickly and safely, and local information displays to suit. Site the Master Safety CPU in the control room or front of house, then sit back and relax.

These systems are simple, safe and reliable. But better still, they’re programmed using visual software. Drag and drop functionally safe blocks are drawn in and “soft connected” to create the required topology. Safe features for individual acts can be easily added as the show matures, and diagnostic information can quickly identify who hasn’t got their foot on the dead man pedal or who failed to release their emergency stop this evening.

Now we have the benefits of safety, simplicity, and flexibility with the absolute confidence that when someone shouts “stop” and we press the big red button, that is exactly without question what will happen.

Thought piece by Karl Bromage , Qmotion Director at Stage One Creative Services Ltd

#automation #safety #liveevents #shows #security