Theaters are always trying to create incredible spectacles, leaving the audience asking for more, but behind the scenes, a world-class engineering feat is usually involved. In this context, a British company is developing technology to make sure that safety is not compromised when the same space is shared by heavy machinery and excited performers.
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If live theater is striving to compete with the television and film industries, then it needs to create visual, breathtaking spectacles to complement the performance of singers, actors, and musicians on stage. Hollywood is increasingly dependent on computer-generated imagery (CGI) that has raised the bar for stage set designers, who need to work before a live audience in space-constrained areas and, at the same time, have to always ensure the safety of several people working quickly around the set.
Ensuring Safety on Stage
The fly tower, placed just behind the stage, is used to lower several stage props and nearly all of the backdrops onto the stage platform. This task is generally carried out rapidly between scenes, but at times, it is done during and as part of the live performance. In either case, reliability and safety are very important.
Until recently, the sets were manually controlled with a technical stage manager watching everything from the wings and giving instructions by radio to the winch operators above.
Tony Ingham, Sensor Technology Ltd
Ingham is helping to introduce automation and safety systems to the theater sector.
“Speed is of the essence during scene changes, but you have to be confident the winches won’t fail—which could easily damage the set or injure a person,” he added.
Applying Sensor Technology’s LoadSense to Monitor Loads on Stage
To achieve this, Sensor Technology is utilizing real-time load signals from each winch. A computer in the control room monitors the resultant data so that immediate action can be taken whenever the loads move beyond tolerance.
We developed the load cells, which we have called LoadSense, a couple of years ago, originally for monitoring cargo nets carried under helicopters. We were asked to develop one specific capability within the cell and were delighted to do so because we could see that the technology would transfer to many other fields—although I didn’t realize it would get to be a backstage pass to a world of greasepaint and legwarmers!
Tony Ingham, Sensor Technology Ltd
That major characteristic happens to be the sturdy, industrial-grade wireless communications—a technology in which Sensor Technology already has a track record of 15 years from its TorqSense transducer series.
In other words, each LoadSense includes an onboard radio frequency transmitter, which transmits signals to the computer located in the control room. It is important that the transmitter is physically sturdy enough to withstand the environment to which it is exposed to and should be able to maintain its signal integrity even through the most aggressive harmonic conditions.
By working in real time, we can act instantly to any problems. For instance, if a load starts running too fast we would slow it down immediately. If a prop is heavier than expected this could suggest someone was standing on it so shouldn’t be whizzed 50 feet into the air at high speed. In fact, in this case, the computer ‘jiggles’ the load for a second or two as a warning to encourage the person to step away: If the load then returns to normal we are happy to let it rise; if it doesn’t, the floor manager is alerted by an alarm to check the situation.
Tony Ingham, Sensor Technology Ltd
Summary
LoadSense has been shown to be so sensitive that it is capable of sending a feedback signal to seal the control loop on a vector drive that manages the winch. Sensorless vector drives are generally used by theater engineers because these devices provide excellent dynamic performance without the need for wiring in a feedback sensor, which can be an arduous task.
By closing the loop, Sensor Technology not only enhances system integrity but also improves safety to a greater extent.
Tony Ingham added, "Not that many years ago, stage scenery was fairly static, being moved only during the interval when the curtains were closed. Then the big theatres in the West End and on Broadway started to emulate some of the things you see in the movies. Looking back, those early efforts were pretty crude, but you would say the same about long-running film franchises such as James Bond or Indiana Jones. Nowadays, film directors can produce their spectacular images using CGI, and this has upped the ante no end for their cousins in live theatre. The computer power they turn to is not virtual reality but industrial automation."
As a matter of fact, theater engineers may work in more challenging conditions when compared to manufacturing engineers. Yet, everything has to be perfect on the performance night, for example, considerable changes will be made suddenly, harmonic corruption will remain at stratospheric levels, and people will run through the “machinery” without sparing a thought for their personal safety.
"But with automation some order is brought to this creative chaos. In fact, the health and safety inspectors now insist on it, with lots of failsafes and feedbacks. I honestly don’t think theatre engineers would be able to achieve half of what they do without wireless communications. There would be just too many wires running all over the place and inevitably some would get broken at the most inopportune of moments," Tony Ingham added.
This information has been sourced, reviewed and adapted from materials provided by Sensor Technology.
For more information on this source, please visit Sensor Technology.