Eye in the sky
From the Engineer
Unmanned aerial vehicles are moving into the mainstream and being used in many civilian applications. Berenice Baker and Stuart Nathan report.
Unmanned Aerial Vehicles (UAVs) are the quintessential military system. Familiar as reconnaissance drones and even weapons systems, they have seen action in the Middle East and in other areas, and are an increasingly important component in modern battlefield strategy. However, their small size, nimble manoeuvring and versatile payload capacity makes them useful for far more than just military applications. A growing number of UAVs are now being developed for civilian applications, ranging from military-style surveillance to search-and-rescue operations and even climate and atmospheric research.
In the world of UAVs, BAE Systems is a veteran, having been involved in developing military systems for decades. Andrew Mellor, head of civil autonomous systems at BAE’s military air solutions division, said: ‘The work we have been doing with UAVs in the last decade has been focused around the latest generation of UAVs, and our projects using these see us developing new aircraft in six to nine months, right from a new concept design through to flying.’
BAE currently develops winged and lighter-than-air craft, and is now looking into rotary and other platforms. ‘We are trying to focus on the architecture not the platform, from the collector to the ground collector to exploitation of the imagery,’ added Mellor. ‘To us, the platform just gets the sensor to the right place.’
BAE’s fixed-wing UAV is used for patrolling over a significant distance, and the company is looking at maritime patrol applications. One customer is the South Coast Partnership. ‘The partnership sprung from Kent police deciding whether to buy a helicopter or share one with Essex, so they came to us to discuss the possibility of using UAVs instead,’ said Mellor.
Using the detailed design and systems specifications, BAE will build a model of the system in a computer simulation that will allow the customers to try the hardware before it is built. To keep the weight down, the UAV will combine its on-board systems with ground assets, so instead of fitting a radar, it would employ higher-spec coastal radar to cross-cue the aircraft to investigate something.
The supporting system will also use image recognition and artificial intelligence applications similar to those the company uses in its ground-based security systems.
‘The controllers won’t have to look at miles and miles of coastline, as the system will only return interesting images, such as ships,’ said Mellor. ‘We see this reduction in human intervention as one of the main differentiators of BAE’s UAVs. They largely fly themselves, deliver essential surveillance capability, and only return relevant information to the operators.’
The business of modifying military-grade UAVs for civilian surveillance applications is becoming more crowded. For example, Staffordshire-based MW Power started life importing mobile power systems, before its latest incarnation as a bespoke remote-control surveillance equipment company. It was this that led it to the UAV market.
Alistair Fox, the company’s UAV business development manager, said: ‘At a police-authority conference, somebody made a throwaway comment that they were destroying vehicles driving round fields and what they would actually like is an “eye in the sky”. We looked into it and came across Microdrone, a German military piece of kit, and struck up a reseller agreement.’ MW Power’s first customer was Merseyside police, which began an initial three-month trial in May 2007, using Microdrone’s small MD4-200 model. Initially the force wanted an overt tool to combat antisocial behaviour, so MW Power broadcast the downlink to police television trailers with huge plasma screens. They would drive it into parks so young troublemakers would know they could not get up to no good without being spotted.
The trial was so successful it was extended for 15 months and was used for applications including road-traffic incidents, collision monitoring, crowd control, events policing and cannabis-farm detection using a thermal imaging camera.
British Transport Police has also used MW Power UAVs in a series of operations, including a major push to identify perpetrators of cable theft in the north west.
Away from security applications, fire services are also deploying UAVs.West Midlands fire service adopted the MD4-200, dubbing it ISIS — Incident Support Imaging System — for officer protection, ensuring fire-fighters go to the right part of a fire, and for rescues from collapsed buildings. It is now looking at taking on the MD4-1000, a UAV with a 1kg payload, which is more resistant to high winds. Pat Mika, watch commander at West Midlands Fire and Rescue Service, said: ‘We used ISIS at a fatal incident involving a collapsed building on West Bromwich high street. We assisted our technical incident team, which operates to shore-up the building before doing the rescues, by providing images from directly above the incident. We couldn’t use a helicopter as the roof was in a very frail state, and any downdrafts would have forced it down onto the building where we knew there were missing people.’ The West Midlands fire-fighters also used it at a large college fire in the early hours of the morning, using the thermal imaging camera to show hotspots on the roof, which helped them identify areas to break in and put out the flames.
Despite these successes, the service did encounter a few problems. Because the MD4-200 cannot operate in wind speeds over about 12mph, around 60 days a year where it could have been used were lost, although this should be overcome when the larger model comes into service. The UAV was originally designed to only deploy in daylight, but fitting LEDs — one to each corner under the rotors — means it could be deployed after dark if the risk assessment showed it to be worthwhile. ‘We found success using UAVs is very dependent on the skills of the operators,’ said Mika. ‘We don’t use it as much as we thought we would, but when we do use it, it has proven indispensable.’
Another recent adopter of UAVs is the Health and Safety Laboratory — a division of the Health and Safety Executive (HSE) — which began looking at the technology following the 2005 Buncefield fuel depot fire. According to MW Power’s Fox, the laboratory wanted to look at how it could get around the problem of reconnaissance helicopters blowing toxic clouds further. ‘The HSE now has a UAV in operation to look at aerial mapping of incidents, such as cranes falling over, so they can take high-level shots of the mountings and other details,’ said Fox.
Clearly, adapting a military-grade UAV for civilian use requires some technical modifications. For instance, to adapt its Microdrone UAVs, MW Power changes the control frequency to operate within Civil Aviation Authority (CAA) regulations, which restricts the range to about 500m, down from 3km. The zoom on the cameras is also brought down in spec. The standard craft includes a 12 megapixel still or HD video camera, or thermal imaging camera that beams images live to the operator. The company is trialling a camera for the West Midlands fire service that provides radiometry, the next stage on from thermal imaging, giving a real-world temperature of targets.
The company also carries out customisation on the payload to reduce the weight. ‘The Flir thermal imaging equipment we use normally weighs 450g, and we can get that down to 210g,’ said Fox. ‘We also selected a special lens to give us the maximum field of view but be as lightweight as possible.’ But UAVs are not limited to fires in buildings and industrial facilities.
On a wider scale, NASA is developing their use to help fight the enormous wildfires that occasionally strike the dry, forested areas of the US. The Dryden Research Centre at Edwards Air Force Base in California operates a modified military Predator B aircraft, called Ikhana, which is the platform for fire-fighting efforts. Ikhana carries a thermal imaging system called the Autonomous Modular Scanner (AMS), which incorporates a telescope, infrared detectors and a spectrometer. It can see straight through heavy smoke and operate in darkness, locating hotspots, flames and temperature differences, and can send its information to fire-fighters in near-real time, allowing them to direct their resources and predict how and where the fire might spread. The system has been used several times in recent years, notably in 2007 and 2008 to fight wildfires in southern California.
Back in the UK, aerial observation specialist Flying Scots Cam uses UAVs alongside ground-based systems for commercial and academic photography and data-collection services. Company owner Michael Smith said that he has worked with Archaeology Scotlandusing UAVs to capture information on archaeological sites and historic buildings, and is Heriot-Watt University’s main contact for any researchers needing a birds-eye view for their work. The company’s main UAV is a quadricopter; an aluminium X-shaped craft with a motor and propeller on each leg and a flight controller in the middle that controls the rotational speed of each of the propellers. It comes from UAVP, a European open-source project where operators can buy the gyroscopes, circuit boards and other components and build their own aircraft. ‘Getting a camera into the air in a stable and controlled manner and getting pictures from it gives people a real sense of satisfaction — think how people react when they see their house from the air,’ said Smith. ‘To use open-source projects to do that, to genuinely elevate the prospectus in an affordable manner means academics are not paying exorbitant amounts for the technology out of their research grant.’
While these applications tend to focus on airborne vision systems, the British Antarctic Survey (BAS) has been flying UAV missions for climate research. ‘We took four UAVs down to Halley Research Station last winter,’ explained project leader Phil Anderson. These all used the same platform — an off-the-shelf UAV called Carolo T200, made by Mavionics, a spin-off company from the Technical University of Braunschweig (TUB), BAS’s partner in the research. Anderson’s team was looking at how heat flows into the sea-ice during the nine-month Antarctic winter, when it is impossible for ships and aircraft to reach the base. TUB, meanwhile, was studying air turbulence over the ice shelf. The miniaturised turbulence probe measured wind speed and temperature, while a downward-looking infrared sensor measured the heat radiated into space; combining these gives the rate of cooling of the ice and the sea. But it was the turbulence studies that determined how the UAVs would fly. ‘To measure turbulence effectively you have to fly in a dead straight line,’ Anderson said. ‘The Carolo T200 has a flat wing, which makes it aerodynamically neutral — that’s great for studying turbulence. But it’s hell on the avionics, because it’s not very stable and you have to stop it falling out of the sky.’ As well as gathering some useful data, the mission also raised a number of technical challenges. The major problem the team encountered was icing. ‘We had one failure because a tiny piece of ice got into the wind-speed indicator, so the plane thought it was going too slowly when in fact it was going too fast and it landed far too hard,’ Anderson said. Other difficulties were caused by the extreme cold. ‘We had to insulate the batteries, but they could fly at -30°C quite happily,’ he added. The cold also caused problems for the ground staff operating the UAVs during take-off and landing. Of the four craft taken to Halley, only one returned in full working order. ‘That was not unexpected,’ Anderson added. ‘If none of them had failed, it would have indicated that we were being too conservative with them.’ Despite the difficulties, however, Anderson is convinced that UAVs are the best way to carry out this sort of research. ‘Ships are incredibly expensive, and it is far too risky to fly aircraft over sea-ice at low altitude in the winter. You can place a mast on the ice with instruments on it, but it takes about an hour to make the measurements; a UAV can take all the readings in a four- to five-minute snapshot.’ For next winter’s mission, Anderson is hoping to use UAVs with automated take-off and landing, equipped with laser altimeters to measure the distance from plane to ice. They will also be specially equipped to fly at night. ‘These sort of modifications are fairly routine,’ he added. This year’s plans also include air chemistry studies, which will require a larger UAV to carry a payload of several kilograms, rather than the 500g package carried by the Carolo T200. However, chemistry flights will not require the flight-path precision of the turbulence studies, so Anderson can use simpler avionics. ‘From there, we can look at flying physics sensors alongside the air chemistry, and then we will be able to do some wonderful experiments with teams of aircraft flying as a flock or a swarm. That’s our wish-list for three or four years’ time.’
The future for civilian UAVs might be glimpsed via some research carried out by Ordnance Survey (OS), directed by Richard French, who has since left the organisation to join defence firm General Dynamics. ‘The work came out of texture analysis and feature extraction from aerial imagery, which OS uses to collect data for its maps,’ he said. ‘I thought it would be fun to use that to influence the behaviour of a UAV, so it could notice something, move away from its waypoint navigation and do an autonomous investigation.’Generally, UAVs fly between pre-programmed locations that cover the area of interest. French said: ‘You would initiate the system with these waypoints, but also gift it with imagery of things that you find interesting; you would programme these into the neural network of the UAV’s avionics. So it would start off on its programmed course, but then notice something on the ground that matches some of the features you have said you are interested in, and it will swing away from its course to investigate for a pre-programmed period of time.’
This is obviously also of interest for military applications, but French pointed out that the system is not limited. ‘The neural network just accepts data, and that could be anything: hyperspectral imaging for archaeological investigations; infrared measurements; or chemical traces in the air. As long as you tell the system what to investigate and what to ignore, it will do data fusion and respond to things that are similar to what you have taught it to notice; it can generalise and interpolate to find items of interest.’ Such a system could be of great use in search-and-rescue operations, French said. Four or more UAVs could search individual zones of a large mountain-rescue site simultaneously, each primed to look for a missing climber by noticing the colour of his jacket, for example. They could then relay information back to a rescue team in a helicopter or off-road vehicle.
This, French said, could speed up rescue operations. It could also be of use in mapping, he added. ‘You could imagine a number of UAVs stationed around the country that would do periodic flights undertaking texture analysis and feature extraction to build up a map of the area. The next time they fly, they could compare that map to what they are seeing at the moment, and then update the map database automatically. That would give you change detection, which is the holy grail of mapmaking; it’s currently a manual process, with people in a basement at OS’s headquarters poring over large monitors.’ Equally, such a system could be used for routine checking of power transmission lines and pipelines. The UAV would be equipped with edge-detection software and the knowledge of the route of the infrastructure, and primed to investigate any changes that have occurred between flights.
The only stumbling block to these applications is the difficulties of flying UAVs in civilian airspace, which French puts down to a lack of confidence in unmanned aircraft. ‘But nearly all modern airliners can take-off, fly and land completely automatically; these systems are robust and trusted,’ he said. ‘As greater technology and research is put into autonomous flight, along with more backup systems to allow the UAVs to complete their mission, they will become more reliable in the air and, I am sure, will just become accepted.’
