Load cells on stage!

30/04/2018
With theatres striving to create breath-taking spectacles and leave the audience gasping for more, there is often world-class engineering behind the scenes. Sensor Technology is developing technology to ensure safety when excited performers and heavy machinery share the same space.

If live theatre is to compete with film and television, it has to produce visual spectacles to complement the performance of the actors, singers and musicians on stage. Hollywood’s increasing reliance on CGI (computer generated imagery) has upped the ante for stage set designers, who have to work before a live audience, in restricted space and with a constant eye on the safety of the many people working frantically round the set.

Many stage props and almost all of the backdrops are lowered onto the stage from the fly tower just behind it. Usually this is done quickly between scenes, but sometimes it is during – and as part of – the actual performance. Either way, safety and reliability are essential.

“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.” explains Tony Ingham of Sensor Technology who is helping to introduce safety systems and automation to the theatre industry.

“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.”

Sensor Technology is achieving this using real-time load signals from each winch. The data is monitored by a computer in the control room so that instant action can be taken if any loads move out of tolerance.

“We developed the load cells, which we have called LoadSense, a couple of years ago, originally for monitoring cargo nets carried under helicopters.” says Tony. “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 realise it would get to be a backstage pass to a world of greasepaint and legwarmers!”

That critical characteristic was robust, industrial-grade wireless communications, something in which Sensor Technology already has a 15 year track record from its TorqSense transducer range. In basic terms, each LoadSense has an on-board radio frequency transmitter which sends signals to the control room computer. The transmitter has to be physically robust to cope with the environment it finds itself in and capable of maintaining its signal integrity through the most corrupting of 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.”

LoadSense is proving so sensitive that it can provide a feedback signal to close the control loop on a vector drive controlling the winch. Normally theatre engineers use sensorless vector drives, which offer good dynamic performance without the complications of wiring in a feedback sensor.

Sensor Technology is closing the loop which improves system integrity and enhances safety by a significant margin.

“Not that many years ago, stage scenery was fairly static, being moved only during the interval when the curtains were closed,” Tony recalls. “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.”

In fact, theatre engineers probably work in more demanding conditions than manufacturing engineers. Everything has to be right on the night, harmonic corruption is at stratospheric levels, there can be major changes at a moments notice, people run through the ‘machinery’ without a thought for 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.”

@sensortech #PAuto #Stagecraft

Electric vehicle pioneer favours wireless test rigs.

12/02/2018

A company that has been at the forefront of electric vehicle design and development for over 20 years has supplied a test rig based on a wireless torque sensor to a world renowned British University automotive research facility.

Tirius has been built on pioneering work on an all-electric single seat racing car and a series of record breaking vehicles. It continues to bring the latest technology to clients in the form of product design and development and the provision of its range of electric drive systems.

Head of Tirius, Dr Tim Allen, explains: “We are helping the university’s research team develop electric drive train technology typically found in ‘A-Class’ cars, for example urban runarounds and small family hatchbacks. Specifically we are currently looking at permanent magnet traction motors in a number of sizes and configurations, with a view to optimising electronic control for each motor type.”

The research involves running each motor on a test rig through its full output range and mapping its torque output at many points to build up a performance profile. The design of the controller can then be matched to the motor characteristics. This should be able to ensure that the motor runs in its optimum operating zone as much as possible, maximises motor life and regenerative braking, minimising wear, and is as energy efficient as possible.

The design of the test rig is in fact quite simple, thanks to the torque sensor, a TorqSense, as made by Sensor Technology.

“We are pleased to promote TorqSense and the guys at Sensor Technology,” says Tim. “We have been using their kit for many years and in many different roles. The bottom line is that they are easy to use, accurate and great value – partly because they can be re-used once their original project has been completed.

TorqSense is a good choice for this work because its non-contact operation allows rapid set-up during the profile building test runs. It also means extra drag forces are not added to the system, so measurements represent true values and calculations are therefore straightforward.”

TorqSense uses two piezo-electric combs which are simply glued to the drive shaft at right angles to one another. As the shaft turns it naturally twists along its length very slightly and in proportion to the torque, which deforms the combs changing their piezo-signature. This change is measured wirelessly by a radio frequency pick up and is a measure of the instantaneous torque value.

Its data is output to a very user-friendly computer screen which uses graphics to aid easy interpretations. In fact the display on the computer is similar to a car’s dashboard, so most people understand it intuitively. Further, the data is automatically logged for further analysis.

Tim again: “With our type of research work there are some potential errors that we have to look out for, including time-based zero-drift, bending moments on the shaft, bearing losses, temperature fluctuations etc. These are easily accounted for with TorqSense-based test rigs. Normally you have to account for the drag caused by the slip rings, but the wireless TorqSense does not use them, so that is one less calculation – and one less fiddly fixing task.

“A great benefit of TorqSense is the ease with which it can be mounted and dismounted, which simplifies research work where frequent reconfiguring is required.”

The University project will take two or three years to complete and the TorqSense test rig will be worked hard during this time. “At the end of the work, I have no doubt that the TorqSense will be reused in a new research program. It’s what we do in-house at Tirius.”

 

@sensortech #PAuto

#SPS17 Gearing specialist exhibits.

17/10/2017

Aerospace, medical and automotive engineers will be able to speak with Harmonic Drive AG to improve the accuracy and efficiency of their applications at this year’s SPS IPC Drives show in Nuremberg (D). Harmonic Drive AG will be launching its FHA-C Mini Servo Actuators with Absolute MZE encoder at stand 119 in hall four, from November 28-30, 2017.

The exhibition brings together suppliers of electric automation technologies from all over the world to discuss the future of automation and new innovative products. Visitors will have the chance to eat sushi while talking to Harmonic Drive AG engineers about its range of servo actuators and learn how its multi-turn absolute motor feedback system can increase productivity.

Designed to offer high transmission reliability, even in environments with high electromagnetic interference (EMI), the FHA-C Mini Servo Actuator has a specially developed output bearing, which uses preloaded precision and high tilting capacity.

With a multi-turn absolute encoder mounted directly on to the motor shaft, the actuator can provide accurate signals for positioning directly at the load. This is ideal for design engineers working in the medical and automation sector, where creating accurate and reliable devices is imperative.

“Automation provides a number of opportunities for businesses to improve the efficiency of their processes,” explained Graham Mackrell, managing director of Harmonic Drive UK. “Harmonic Drive FHA Mini Servo Actuators have been created so that they can be combined with the YukonDrive® Servo Controller. When connected, the actuator can be tailored for use in demanding dynamic applications.

“In addition to being customisable, the actuators feature a multi-turn absolute motor feedback system that acquires the absolute position directly at the load, with maximum accuracy over more than 600 revolutions. The productivity of the servo actuator is increased because unproductive referencing is no longer required, allowing it to deliver smooth and quiet running characteristics.”

• The SPS IPC Drives show brought together 63,291 people at last year’s event, with over 500 exhibitors coming from countries outside of Germany.

It IS rocket science!

13/03/2017

Graham Mackrell, managing director Harmonic Drive, explains why its strain wave gears have been the top choice in space for over forty years.

Anything that goes into space is seen as the pinnacle of human creation. Astronauts are highly trained and are at the peak of physical fitness, space shuttles are crafted by large teams of expert engineers and all the technology used is so high-tech it’s as if it belongs to science fiction.

Driving on Mars!

Many decades ago, the first Harmonic Drive gears were sent into space during the Apollo 15 mission. Even from the beginnings of the space race, the expectations for the technology used were high. The equipment used in space had to be reliable, compact and lightweight and given the increasing demands on equipment in today’s space missions, it must also now be highly accurate with zero backlash and have high torque capacity.

When aerospace engineers were recently designing a new space rover, they looked to Harmonic Drive gears for reliability. Due to the obvious difficulties of performing repairs in space, a high mean time between equipment failures is a high priority. Harmonic Drive products achieve this by prioritising quality throughout the entire design and manufacturing process.

It is vital that aerospace gears are thoroughly tested before they are sent to customers, ensuring that they always receive a quality product. At Harmonic Drive, we test products using finite element method (FEM) testing. This process simulates real world physics to ensure that the product is capable of surviving in space. For example, structural testing is carried out to ensure the product is robust and the space rover travelling over rough terrain will not damage the actuators used in the wheels. Thermodynamic properties are also important as aerospace gears are often exposed to both extremes of the temperature range, which are tested in the initial design process.

Also considered in the design process is the part count of the aerospace gears. Harmonic uses a low part count which means that they are maintenance free. In addition, there is a lower chance of components failing giving the gears a high Mean Time Between Failure (MTBF). This also contributes to the compactness and light weight of the gears, a feature essential in space.

Another key feature for aerospace gears is high torque capacity and zero backlash. This is essential for systems which communicate the location of the rover to the control room. If traditional, high backlash gears were to be used, the system would misreport the rover’s location. This would cause problems when the rover is used to survey uncharted areas of planets and could lead to inaccurate mapping. Due to the emphasis on high precision with Harmonic Drive gears, this problem can be avoided.

The numerous quality processes that Harmonic Drive undertakes have led to recognition from a number of accrediting bodies. Harmonic Drive products are AS9100 certified, a specific aerospace standard for the design, manufacture and sale of precision gear reducers, servo-actuators and electro-mechanical positioning systems.

To be the pinnacle of global technology, there are no shortcuts. Components used in aerospace technology must be subject to vigorous testing in order to be reliable, safe and have a long product life.

• The MARS adventure: The NASA site.
@HarmonicDriveUK #PAuto #Robotics @StoneJunctionPR