Tom Shelley reports on a small company with some interesting and useful technologies for making advanced robotics using leading edge materials
 A company that made its name making animated dinosaurs has not only developed a plethora of skills in low cost mechanisation, but has since moved onto machines that simulate humans performing tasks, to perfect personal protective clothing. In doing so, the company has made important developments in composites that could revolutionise unmanned aerial vehicles.
Crawley Creatures is best known for making the animatronic models that played a crucial part in the BBC programmes 'Walking with Dinosaurs' and 'Walking with Beasts'. After initially using compressed air operation, the firm standardised on servo motors controlled by pulse position modulation.
As a direct result of appearing in the credits for the TV series, the Defence Science and Technology Laboratory asked if the company could devise an animatronic head that could reproduce human movements, including speech, as well as breathe, become hot and perspire like a human.
The first version – the Porton Head – was built in 2002 and is used for testing respirators. It has speaking and mouth functions, including an articulated jaw, a breathing capability and soft polymer skin. This was followed two years later by FARSS – the Fogging and Respiratory Simulation System – a static head used to test for fogging in aircrew head gear. To do this, it has cameras for eyes which look at test patterns, 22 sweat ports in its soft polymer skin, each with an individual valve to control what comes from a central syringe pump, plus a body heat and breathing capability.
These are produced by spinoff business i-bodi and, in addition to military applications, the company envisages civilian chemical and biohazard applications, citing the need for people to be able to work efficiently and see what they are doing. In order to make comparisons between different designs in the global environment, it is necessary for all concerned to use the same 'head' for their developments.
All movements in the talking heads are produced by Parker servo motors and actuators. US and UK laboratories use heads that correspond to somebody speaking the same standard 'Rainbow passage' text, but a French speaking version reproduces Gallic head movements. All functions of the static heads have been built using National Instruments' LabVIEW.
This work has led to the development of complete animated human mannequins. These devices are made of carbon fibre and can bend, walk and even run within a framework. Their purpose is to help in the development of nuclear, biological and chemical survival suits for military and civilian tasks.
The mechanics are designed with the help of Autodesk Inventor 9, which chief design engineer Mike Franklin said provided useful animation facilities, along with the ability to test out mechanisms.
The running mannequins are made of carbon fibre epoxy forms made by local F1 manufacturer Delta Composites. Unlike carbon fibre forms designed for racing cars, these include a number of sophistications. Because they have to reproduce the effects of hot bodies, the company has developed an ingenious way of heating their outer surfaces and there are separate temperature controllers for each zone.
The final design is proving to be of interest to designers of unmanned aerial vehicles. De-icing is problematic, even on full sized aircraft, despite their having the ability to release chemicals over wing surfaces from rubber boots. If ice forms behind the boots, the aircraft is liable to lose its ability to fly because of the change in wing shape. UAVs, being smaller, pose even more difficult problems.
In addition, the ability to 'sweat' opens up the possibility of delivering controlled amounts of de-icing fluid, but also keeping skin friction reducing riblet and dimpled surfaces clean, so they continue to function despite impacting dust in the air.
Alongside sweating pores, the mannequins have passive absorption sensors. These devices can soak up chemicals and simulate contamination that has been able to get past seals. This is a particular problem with biological applications, where trace contamination could be disastrous.
Simulant chemicals are typically methyl salicylate and the bleach used to wash it off, both of which are extremely corrosive. This has led to the development of other transferable technologies that help mechanical devices to continue working in corrosive environments. Even so, some working parts cannot be made from sufficiently corrosion resistant materials, which means they have to be enclosed and protected.
Apart from the carbon fibre epoxy, seals, plastic parts and bearings have to be selected to resist corrosion and use is made of both PVDF and fluorelastomers. Notably, the company has standardised on igus 'X' plain bearings, which Franklin described as 'the most chemically resistant bearings we could find'.
Customers for the mannequins include Defence Research and Development Canada, its Australian and US equivalents and 3M. And there are still customers for the animated dinosaurs, typically German museums, who want models that are increasingly sophisticated, as well as work from the Film and Television industries, although animatronics are being increasingly replaced by computer graphic animation.
Pointers
* Animatronics based on servo motors have been used to reproduce movement, heat, sweating and breathing in human head and whole body mannequins.
* A technology has been developed to heat the surface of carbon fibre in a precise manner, which could prove useful to deicing the wings of UAVs. The company has also developed a means of delivering controlled amounts of fluid
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