Designing Porton Man: Under the skin of the UK's new chemical warfare defence technology

With this year seeing the 100th anniversary of the outbreak of the First World War, it is sobering to remember that it was this war that saw the first ever use of chemical weapons. A century on, weaponised chemical agents still represent a threat to military and civilian personnel alike. Devoted to the protection of the UK's population and armed forces from chemical, biological and nuclear threats, Porton Down in Wiltshire was founded in 1916 to respond to the threat of chemical warfare – a job it still does today under the aegis of Dstl (the Defence Science and Technology Laboratory), an executive agency of the MoD. It would, therefore, seem counter-intuitive to find a BAFTA-winning company that cut its teeth in creating effects for film and TV in such an environment, but that is what i-Bodi (AKA Crawley Creatures) is. The reason is the latest version of Porton Man, an animatronic mannequin designed to test and evaluate the CBRN suits and other protective equipment used by infantry soldiers. Using state-of-the-art technology, Porton Man can walk, sit, march, run, sit, kneel and even lift its arms as if to sight a weapon. This latest mannequin replaces an original first introduced in the late 1990s. Colin Willis, group principal chemical biological radiological defence at Dstl Porton Down explains the reasons behind this: "Terms like nerve gas and mustard gas are all misnomers as these are not gases at all," he says. "These are in fact colourless, oily liquids with boiling points higher than that of water. Skin contact with either the liquid or the vapour from that liquid can cause serious injury or death." Clearly it's important to be able to develop protective equipment to block these agents. There is a pretty simple quantitative penetrative test on clothing that involves putting the fabric into a simple cell whereby the agent is put in one side and the degree to which it penetrates can be measured over a period of time. However, says Willis: "That doesn't tell us how that material will perform when turned into a suit. For instance, it tells us nothing about the effect of movement, incident wind, seams and seals. In the 1990s, we embarked on a programme to test the whole suit as an ensemble. Out of that came our early Porton Man." When it was introduced it was the first system of its kind in the world for demonstrating and testing CB fabrics and data Dstl was able to collect from Porton Man was invaluable and was used to develop the existing Mark 4A CRBN suit that is currently in use. However, having seen a range of upgrades and adaptations over the years (even at one point being dressed as a female), it started to become clear that the original Porton Man was, as Dr Jaime Cummins of Dstl's Chemical and Biological Physical Protection group puts it "an ageing capability". With this in mind, Dstl put the proposal to develop a new mannequin out to tender. The winner was i-Bodi, whose historical and award-winning expertise in animatronics for TV and films has proved ideally suited to this type of application in the industrial and military sectors. Even so, however, the challenge was not insignificant, which meant that the i-Bodi team had to approach it systematically. Says the company's director Jez Gibson-Harris: The thing we did first was to get an idea of how the old system worked. So we were taken to the chamber where all the testing was done. It had a small, airlocked doorway and we had to jiggle it through. There was a cable that had to feed into the chamber. Two people had to handle this figure, it weighed 80 kilos and it had to be winched into position to dock it. Spanners then had to be used to get it together. Jaime and Colin were in full protective gear, including gloves and respirators. So to say the least, it was quite challenging to set the test up. And simplifying that was really our first challenge. Weight reduction has been achieved by the use of light, but highly-durable carbon composite to create the mannequin's body. This, Gibson-Harris concedes, was an idea taken directly from Formula One technology. "We're based in Buckingham – right in the Formula One corridor, so we were able to find out about thus material and to find a company to machine the carbon composite body parts for us pretty easily," he says. This process got the body weight of the mannequin down to just 14 kilos. In terms of the other problems, the mannequin is now mounted on a wirelessly-controlled turntable, which makes it much easier to operate. In addition, it operates on a simple, no-tools locking and unlocking process and is easy to move in and out without any need for additional equipment other than its specially-designed trolley. I-Bodi also developed a system of drop-down feet for the turntable that allow it to be used on uneven surfaces. i-Bodi's chief design engineer Mike Franklin says of the project: "The main issue was that it had to be useable – what [Dstl] wanted more than anything was a tool. The last thing you want is to have a tool that's harder to use than the old version. So getting rid of hand tools was vital. They used to have to wheel the frame in and then winch the mannequin into place and then link it up using socket sets and spanners. And all this had to be done in 30 minutes or so in NBC suits in a potentially toxic environment." According to Franklin, the original brief from Dstl was very comprehensive and the organisation had spent a great deal of time ensuring it took everything important into account. "They split it into 'must-haves' and 'nice-to-haves'," he says. "The idea was that we could comply with virtually all their requirements. I think the only thing was they wanted a slightly faster run, but that's a lot of weight to be throwing around when you put the suit and boots on it, so there were some compromises there. " The design was based around anthropometric data gathered from the 50th percentile of 2,500 servicemen from all branches of the service. From this, i-Bodi was able to create a CAD figure and the CAD work was sent off to be five-axis machined. Says Franklin: "From the frame and drive point of view, the important thing is the limb lengths. At the same time, the body can be sculpted from a mechanical design point of view. From there, we can start putting the joints in." The movement of the mannequin is based on twinned pairs of drives and servomotors are used to create a very complex range of motions. Franklin says: "The drive design was linked to the limb lengths. As soon as we got the anthropometric data, we were able to get things like the distance from his elbow to the centre of his hand and from his elbow to his shoulder, shoulder width, hip width – all the main points, basically. From there, you can develop the drive mechanism to make sure you've got all the extremes of movement to make sure nothing crashes or breaks." "It's a pretty adaptable design," he continues. "Because you've got control of two axes on each limb,you can pretty much put that end point wherever you like. At the end of the day, it's a two-axis robot arm. The only difference is that it's been designed to be all sealed and chemical proof. If we could have gone out and bought the right kind of robot arm in the right materials off the shelf, we'd have done so." One of the biggest problems for Franklin was finding equipment off the shelf they could use, as the alternative was to design its own. Given that the alternative was to develop expensive bespoke solutions, however, it was on occasion necessary to find 'workarounds'. Says Franklin: "One of the gearboxes is a right-angled drive hollow-shaft gearbox, which I used to pass through the second axis from the first axis. The alternative was to design a whole unit from scratch, but it was too much for a one-off unit – maybe if we'd been making ten or 20, but not for a one-off." The need to cope with a variety of agents also restricted i-Bodi in terms of which materials it was able to use. "There were a lot of restrictions on what materials we could use," says Franklin, "because there were a lot of common materials either absorb agents or are destroyed by the agents. So, for instance, there were a lot of O-Ring materials that weren't useable. However, these guys [Dstl] have a huge amount of data on materials that they were able to share with us, so we always knew what we had to work with." In addition to its greater ranges of movement and usability, Porton Man is also able to provide realtime data when undergoing test – something its predecessor was unable to do. Says Dr Cummins: "Using the original Porton Man, we could only get the performance data at the end of the trial. We don't actually know what's happening while the suit is under test. With the new mannequin, we can insert an active sensor into any of the 270 cavities and pick up data in real time during the test. Coupled with the increased range of movements, this means we can really start to understand the effects of different movement profiles on the efficacy of the equipment – as well as factors such as different windspeeds." Looking ahead, the capacity to update and adapt the new Porton Man is something i-Bodi was careful to factor into its design. For instance, there is already talk of creating a female mannequin ("Women have different air gaps," as Dr Willis delicately puts it), while the ability to sell the concept to friendly nations with different anthropometric requirements is obviously a factor. Mike Franklin is in no doubt of the possibilities, saying: "If they want to update it to a heated, sweating model, we can do that. Equally, the actuators can accommodate slightly different sizes of mannequin, which means a female mannequin could be developed quite easily." The final word, however, belongs to those who will have to wear the equipment developed in response to the data collected from Porton Man. Major Ralph Livingstone, who was military advisor to the project, says: "From the military perspective, it's the end result that counts and this gives us that. A few small, but significant changes resulted in a suit that gave much more protection to the end user. It allows these scientists to get the job done as well as it can be. We're looking at the next generation of suit and that's why we need this now – to give us the knowledge to build that suit."