Animatronic mannequin helps test protective equipment for the military

6 mins read

It's 100 years since the outbreak of the First World War and sobering to remember it was this war that saw the first use of chemical weapons. Today, weaponised chemical agents still represent a threat to military and civilian personnel alike.

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 creating effects for film and TV in such an environment. But i-Bodi (also known as Crawley Creatures) has used its expertise to create the latest version of Porton Man – an animatronic mannequin designed to test and evaluate the chemical, biological, radiological defence (CBRD) 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 the original introduced in the late 1990s. Colin Willis, group principal CBRD at DSTL Porton Down, explains the thinking. "Terms like nerve gas and mustard gas are misnomers; these are not gases at all. They 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 develop protective equipment against these agents. There is a pretty simple quantitative penetrative test that involves putting the fabric into a cell and measuring the degree to which the agent penetrates over 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 introduced, it was the first system of its kind in the world for demonstrating and testing such fabrics. The data collected from Porton Man was used to develop the Mark 4A CRBN suit that is currently in use. However, after a range of upgrades and adaptations (at one point being dressed as a female), it became clear the original Porton Man was, as Dr Jaime Cummins of DSTL's Chemical and Biological Physical Protection group notes, 'an ageing capability'. Having won the tender for a new Porton Man, i-Bodi found the challenge to be not insignificant, despite its animatronics expertise. The i-Bodi team had to approach the project systematically. Company director Jez Gibson-Harris recalls: "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 through which we had to jiggle the mannequin and a cable that had to feed into the chamber. Two people had to handle this figure; it weighed 80kg and 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. To say the least, it was quite challenging to set the test up. Simplifying that was our first challenge." Weight was reduced using carbon composites for the mannequin's body. This, Gibson-Harris concedes, was an idea taken directly from Formula One technology. "We're based right in the Formula One corridor, so we could find out about this material pretty easily and find a company to machine the carbon composite body parts for us." This reduced the mannequins' body weight to 14kg. The mannequin is now mounted on a wirelessly controlled turntable, which makes it easier to operate. In addition, it features a 'no tools' locking and unlocking process and is easier to move, with no need for additional equipment, other than its specially designed trolley. i-Bodi's chief design engineer Mike Franklin says: "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 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, winch the mannequin into place and then link it up using socket sets and spanners. All of 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 comprehensive and the organisation had spent a great deal of time ensuring it took everything important into account. "It was 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." The mannequin – designed using anthropometric data gathered from the 50th percentile of 2500 people from all branches of the services – is moved using twinned pairs of drives and servomotors, which support a complex range of motions. Franklin says: "The drive design was linked to the limb lengths. 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. "At the end of the day, it's a two axis robot arm; the only difference is that it's been designed to be sealed and chemical proof. If we could have bought the right kind of robot arm in the right materials off the shelf, we'd have done so." Matt Goodliffe, software developer and robotics engineer with i-Bodi, explains more about the electronics. "The main challenge was the unit had to be in a sealed chamber, so that placed limits on how we could communicate with it." A number of cables run from outside the chamber to Porton Man in order to provide power to the motors. "But we wanted to keep the number of cables to the minimum," Goodliffe notes. "And, because some of the mannequin's elements can be removed – it can operate without the breathing machine, for example, or without the animatronic head – we needed to support a modular design, so it had to be wireless." All control is handled wirelessly using Digi's XBee modules and adaptors, connected to RS485 and RS232 links, where appropriate. "Servos moving the various drive systems communicate with the wireless system using a custom designed PCB," Goodliffe continues. Control is enabled using Arduino microcontroller boards, he adds. "These are easy to use. We have used them before and they are very much 'plug and play' and easy to replace." He accepts the system could have been controlled using a wired network, but says this would have been a noisier environment and would have impacted the ease with which things could be taken in and out of the chamber. One ZigBee transmitter is located outside of the chamber, but this doesn't affect performance. "We need a maximum range of about 5m through stainless steel walls," Goodliffe says. In addition to greater ranges of movement and usability, Porton Man can also provide real time data – something its predecessor couldn't. Dr Cummins points out: "Using the original Porton Man, we could only get the performance data at the end of the trial. We didn't actually know what was happening while the suit was 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. "The real time sensing technology, positioned in six locations across the mannequin, will use ion mobility spectroscopy to sample the atmosphere underneath the suit approximately every 5s. The information will be transmitted wirelessly to a location outside of the chamber. "This, coupled with the increased range of movements, 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 wind speeds. Goodliffe says converting the sensors to wireless operation was challenging. "Using documentation from the sensor manufacturer, we developed wireless converter boards which plug directly into the sensor and which are powered by the mannequin's internal supply. However, because the supplier's software required individual COM ports for each sensor, there is one module per sensor, although there is only one receiver for all the data." Controlling the mannequin's movements also posed something of a challenge. "The system uses equipment from Parker, but we don't use it in quite the way the company would expect." The reason, he explains, is that the equipment is aimed at repetitive automation tasks. "Our system doesn't do the same things over and over again. We needed the ability to do one movement, then a different one, then another one; Porton Man needed a dynamic control element." This is provided by downloading an array of values to the ACR9000 motion controller. This array comprises three sets of information: a transition into a particular movement; the movement itself; and a transition out of that movement. "The program tells the motion controller to run the first section, then repeat the second section until told to stop, then execute the third section. It was a little bit tricky getting things to happen at the right time," he says. Looking ahead, i-Bodi factored in the ability to update and adapt the new Porton Man. 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. Franklin says: "If they want to update it to a heated, sweating model, we can do that. Equally, the actuators can accommodate slightly different sized mannequins, which means a female mannequin could be developed." The final word, however, belongs to those who will have to wear the equipment developed using the data collected from Porton Man. Major Ralph Livingstone, military advisor to the project, says: "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."