Power take-off torque monitoring.

07/08/2018
AIM – Precisely & Quickly Monitor Power Take-Off Torque on A Wave Energy Converter

Challenge
As part of a project funded by Wave Energy Scotland, 4c Engineering needed to test various configurations of the SeaPower Platform, a Wave Energy Converter (WEC), to determine the effects on power capture.   To do this they needed a reliable and accurate way of measuring power take-off (PTO) torque, forces, positions and pressures of the waves on the SeaPower Platform.

Why? Establishing the most efficient design with the highest wave power generation, will make it a more cost-efficient form of wave energy.

The SeaPower Platform extracts energy from deep water ocean waves by reacting to long prevailing wavelengths in high resource sites.

Solution – Accurate DTD-P Parallel Shaft Reaction Torque Transducer
“We chose the DTD-P torque transducer for its high accuracy and compact size which we needed for tank testing the SeaPower Platform,” explains Andy Hall, Director at 4c Engineering.

  • Designed for In-Line Static or Semi-Rotary Torque Measurement
  • Capacities: 0-10Nm to 0-10kNm
  • High Accuracy – Ideal for Calibration, Development and Testing Applications
  • Accuracy: <±0.15% / Full Scale Output
  • Customised Capacities, Shaft and Configuration Options Available
  • IP67 Waterproof and IP68 Fully Submersible Versions Available

Complete Torque Monitoring System
Applied Measurements Ltd provided 4c Engineering with a DTD-P 100Nm parallel shaft torque sensor fitted with an ICA4H miniature load cell amplifier, calibrated to UKAS traceable standards and sealed to IP68 to allow complete submersion. This complete torque measuring system enabled their engineers to reliably and accurately monitor the torque applied by the WEC as it responded to waves in the test tank.

Save on Installation Time
The DTD-P torque transducer has keyed parallel shaft connections for in-line static or semi-rotary torque measurement in capacities from 0-10Nm up to 0-10kNm (custom capacities readily available). This version was fitted with a flying lead, however versions with an integral bayonet lock military connector are also available which promise simple and easy connection.

Guaranteed High Accuracy
The DTD-P torque transducer is highly accurate to better than ±0.15% (typically ±0.05%) of the full scale output, making it ideal for this high precision development and testing application. Additional applications include the testing of electrical motors, hydraulic pumps, automotive transmissions, steering systems and aircraft actuators.

Need a Specific Design?
The DTD-P torque transducer can be customised with bespoke shaft, configuration options and capacities (to 50kNm+) specific to your application. For 4c Engineering we customised the design of the DTD-P torque transducer to IP68 submersible for continuous use underwater to 1m, which was essential for use in the wave test tank.

High Stability, Fast Response, ICA4H Miniature Load Cell Amplifier
“The high speed, reliability and clean output of the ICA4H miniature amplifier enabled the data to be analysed immediately after each test.” says Andy Hall.

  • Very Compact 19mm Diameter
  • Low Current Consumption
  • High Speed 1kHz Bandwidth (max.)
  • 4-20mA (3-wire) Output (10 to 30Vdc supply)

Very Compact
To deliver a conditioned load cell output signal we supplied the DTD-P torque transducer with an ICA4H high performance miniature load cell amplifier. The ICA miniature load cell amplifiers are very compact at only 19mm in diameter allowing them to fit inside the body of most load cells. In this application the ICA4H was supplied in a gel filled IP68 immersion protected compact enclosure (see image above) along with 10 metres of cable making it suitable for this underwater application.

With High Speed Response
The engineers at 4c Engineering needed to have a quick and reliable way to process the power take-off torque data from the tests, to determine the power capture and effects of the control settings before running the next test. The ICA4H miniature load cell amplifier was chosen not only for its high stability and compact size but also for its 1000Hz fast response.


A sea platform off the Galway (Ireland) Coast – not far from the Read-out offices.

@AppMeas @4c_Eng #power #PAuto


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