Feature: Sensors
Electronic setups in the film and theatre industry
T
By Tony Ingham, Sales and Marketing, Sensor Technology cargo nets carried under helicopters; now these cells have found their way into film sets and theatres. Te load cell for theatre applications is
elevision and film’s increasing reliance on computer-generated imagery (CGI) has upped the ante for stage-set designers, whose work
can involve live studio audiences, restricted spaces and constant considerations for the safety of the many people working on the set. Many stage props and almost all
backdrops are lowered onto the stage from the fly tower above it. Tis is usually done quickly between or during scenes, requiring utmost safety and reliability. Until recently, sets were manually
controlled, with a technical stage manager supervising from the wings, and giving instructions by intercom to the winch operators, making sure nothing fails, as it could damage the set or injure a person. To guarantee safety and reliability, Sensor Technology uses real-time load signals from each winch, with the data monitored by a computer, so that instant action can be taken if a load moves out of tolerance.
LoadSense Sensor Technology originally developed the technology called LoadSense for monitoring
customised with robust, industrial-grade wireless communication. Each LoadSense has an on-board RF transmitter that sends signals to a control-room computer. Te transmitter must be robust to cope with its environment and maintain signal integrity through the most corrupting of harmonic conditions. Working in real time, problems are
instantly flagged and addressed. For instance, if a load starts running too fast, it can be immediately slowed. If a prop is heavier than expected, this could suggest someone was standing on it, so it won’t be whizzed 50 feet into the air at high speed. In this case, the computer ‘jiggles’ the load for a second or two to warn the person to step away. If the load then returns to normal, it will be allowed to rise; if not, an alarm alerts the floor manager to check the situation. LoadSense is so sensitive that it can
provide a feedback signal to stop a winch when its load reaches the floor, for instance. Normally, theatre engineers
34 July/August 2022
www.electronicsworld.co.uk
use sensorless vector drives, which offer good dynamic performance without the complications of a feedback sensor. Sensor Technology is closing that loop, improving system performance and safety by a significant margin.
Good for big sets Not that long ago, stage scenery was fairly static, being moved between scenes or acts. But, West End and Broadway theatres have started to emulate some of the effects used in film, which requires customisation. Today theatre engineers would be lost
without wireless communications; too many wires everywhere can inevitably bring problems, such as being unplugged or broken at the most inopportune moments. In some ways, theatre engineers work
in more demanding conditions than manufacturing engineers. Everything in a theatre has to be right every night; RF interference (from wireless mics and intercoms) is at stratospheric levels; there can be major changes at a moment’s notice; and people sometimes run through the ‘machinery’ without a thought for personal safety, among the many challenges experienced in this environment.
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