Brains and eyes: manning a drone from the ground is easy, but on paper only. What the people behind the controls really lack is not only the pants-and-seat feeling, but also the environmental assessment. We tend to forget the incredible benefits we get from stereoscopic vision and the incredibly fast and automatic ability of the eye and brain to adjust or focus on a point of interest.
Except for unbelievably irresponsible designs (and yet some made it to active service level) and mechanical failure, drones more often crash for two main reasons: bad handling and loss of environmental reference.
Bad handling is a common occurrence, this because the ground crews are rarely aviators themselves and often lack the aviation spirit generally acquired at light aviation club level by pushing an aircraft out of a hanger to start with. Some footage of army soldiers unloading drones from a lorry clearly show that they wouldn't handle wings in such a manner, for example, if they had to board the aircraft themselves. This has only recently been corrected with adequate training to seed the 'this is an aeroplane' notion.
Even the smallest aero clubs either have their own weather station or at least a direct link to one. Meteorology is part and parcel of flight safety. Several companies offer 'met' kits, like Climatronics, that provide wind, temperature and pressure data (see picture herewith).
Turning to drone attitude control, and particularly those that are flown beyond the pilot's range of view, one must not forget that their 'flyability' depends on a number of sensors that not only constantly correct the aircraft's attitude (straight and level) but also altitude. This is very important as thermals and downdrafts may not change their attitude or heading but dramatically alter their height above the ground without the pilot immediately noticing the change. Heading is now usually provided by satellite navigation receivers. This is the reason why ground control stations are usually manned by a pilot and sensor operator.
One of the major players in the field of navigation and control systems is Athena. The company offers a wide range of products. One that probably best provides a yardstick to the state of the art is the Gus. This unit packs accelerometers, rate gyros, magnetometer, air pressure data sensors and meets shock, vibration, temperature and humidity requirements--all in a case that is about the size of a portable telephone for a weight of 114 grams, which also happens to be the weight of the authors cell phone. When one is in the flight instrumentation and avionics business and in need of widening one's range of activities, a short cut method is to acquire a drone avionics manufacturer. This is exactly what Rockwell Collins did earlier this year (2008). Other drone autopilots manufacturers include Cloud Cap with its Piccolo series, UAV Navigation and Micropilot.
Drone capabilities are almost proportional with their size (for systems of a same generation of course). The farther they need to go, the more fuel they have to carry, the bigger the engine, the larger the airframe volume and the more accurate the navigation systems need to be. Thus, at the opposite end of Athena's spectrum of products is the 4.5-kilo Guidestar 611 with a 0.003[degrees]/hour inertial measuring unit. Microstrain is another producer with the 3DM-GX2 and the Inertia-Link.
Quite apart from a new tend to use drones as radio relays (an interesting development using hand-held radios is explained in "The Hand-held Uprising" article in the main issue of Armada with which this supplement has been despatched) drones also need to communicate. This too has opened up a new field of specialisation to cope with range, size and weight requirements of datalinks. Typical suppliers here are firms like Microhard Systems, Free-wave and Advanced Microwave Products.
Eyes and Ears
The primary electronic system of a drone is its optical sensor. Depending on the type; from mini drones all the way up to the male types, the range covers simple miniature black-and-white pen-sized cameras (available in video shops) to the large, multiplechannel, fully-stabilised turret.
The largest players in stabilised systems are Flir, Elbit, Denel, DRS (which was about to be bought up by Finmeccanica at the time of writing) and Sagem, but newcomers providing smaller and lighter sta bilised systems have emerged and include Cloud Cap and Optical Alchemy
Flir Systems is probably the largest producer of stabilised mounts due to the fact that it also manufactures stabilised turrets for fixed and vehicle-mounted land surveillance applications. During the last DSA exhibition in Kuala Lumpur, the company told the author that there were 65 Flir systems operated in Malaysia alone and approximately 200 in the region. In fact, Flir is now aiming at opening a maintenance centre in Malaysia and is currently looking for partners.
One of Flir's latest systems is the Star Safhire HD, where the HD suffix stands for high definition. The sensor is not interleaved and thus offers a true 720-line picture while most other so-called high-definition devices do not offer 1080 lines but in fact 420.
Another recent Flir development is the Mep (Mission Equipment Package) of which a first batch of three has been delivered to the US Army's Night Vision and Electronic Sensors Directorate. The system has been integrated into the Directorate's UH-1 test helicopter, but is in a first stage aimed at the US Army's Tier II drone programme. The Mep incorporates no less than five sensors: two infrared cameras, a colour television camera, a laser rangefinder and a laser designator. A key feature of the system is its secondary steering system that provides a co-operative wide field-of-view (WFOV) and narrow field-of-view (NFOV). The WFOV IR is mounted on an internal gimbal. This scheme significantly enhances the operator's situational awareness by allowing the WFOV IR to be pointed separately from the other four sensors. The WFOV IR is used to detect potential targets of interest and the NFOV IR with its improved range performance is used to identify, track and designate the targets. The Mep thus supports simultaneous acquisition and tracking in both the wide and narrow fields of view.
Elbit's Compass IV is now becoming the company's optical payload flagship, being installed on the Hermes 450. This carries a third-generation 3-5pm 320 x 256 infrared camera, a colour or black and-white television camera, an eye-safe 1.54[micro]m laser rangefinder with minimum and maximum operational ranges of 100 and 2000 metres respectively, a diode-pumped 1.064[micro]m, 80 m J/pulse laser target designator and a night vision-compatible ten-kilometre range laser target illuminator which, with all the gimbals and turret put together, tips the scales at 38 kilos.
The Emos from the same company weighs less than 6.5 kilos but carries an 8-12[micro]m infrared sensor and day colour television camera and can optionally carry a night camera a laser target illuminator or an eye-safe laser rangefinder.
Sagem has recently released news that is so fresh that little is known of the Euroflir that the company is developing. Basically the new infrared sensor, destined for the longer-range Mk II version of the Sperwer, is to offer a higher resolution.
In total contrast in terms of size and weight, Optical Alchemy's K J600 is being developed to offer maximum capability for drones with limited payload capacity. An Optical Alchemy official explained, <<Unfortunately, most gimballed systems address providing the warfighter imagery of the target of interest, but do a poor job of getting co-ordinates (i.e. locations of the target). OAI [Optical Alchemy] payloads have been designed from the ground up to be provide both imagery of the targets (ISR) as well as high accuracy targeting information (Fires support)/ (location of targets). This is accomplished by having the sensor fully geo-referenced with the ability to slew to co-ordinates instantly. This is the big difference between existing payloads and OAI payloads as well as the fact that we do this in 1/10 weight of existing systems>>. The 2.3-kilo K J600 carries an 8-12~m infrared sensor, daylight camera and a laser marker. The larger 5.9-kilo KJ800 is still at lab oratory development stage and adds a laser rangefinder.
Turning to radars, particulary those able to provide synthetic aperture, inverted synthetic aperture and moving target indicator modes, recent articles in Armada International have extensively described state-of-the-art systems, particularly from Elbit and General Atomics. Joining the band is now Thales UK with the 30 km Coastmaster, officially announced in September 2007. The coastmaster is targeting a potential requirement for counter-piracy capabilities as it is, according to Thales UK, suited for the detection of small and fast-moving targets on land or offshore.
|Printer friendly Cite/link Email Feedback|
|Title Annotation:||Complete guide|
|Author:||Bias, Eric H.|
|Date:||Jun 1, 2008|
|Previous Article:||Combat drones: the ideal of usefully sized drones that can be operated without runways or catapults, and can be recovered safely without nets or...|
|Next Article:||Big deals in short.|
|On the road. (Driving And MS).|
|Legally stepping into civilian airspace: what may at first sight seem to be a contradiction, putting a pilot into an unmanned aircraft can make sense...|