The Technology Drivers of Unmanned Aerial Vehicles
defence.professionals | defpro.com
06:28 GMT, September 30, 2009 The following article is part of defpro.com’s newest feature which will be available as of today: the defpro.focus. As one of the first focus entries of this innovation we have chosen one of the currently most pioneering fields of technology: unmanned aerial vehicles and systems. A link to the new defpro.focus will be made available here in the course of the day. -- Luca Bonsignore, Publisher
[You may find part 1 of the below published article here:
]defence.professionals | defpro.com
Technological advances are bringing new capabilities and functionalities to UAVs, to the point where they can be feasible, cost-effective alternatives to their manned counterparts in an ever-increasing number of mission sets. UAVs are now at the crossroads where growing technological capabilities are beginning to meet operational requirements.
Advances in micro-manufacturing technology will allow us to place a billion transistors on a single silicon chip in the 2010 timeframe, 20 times more than what current technology allows. Smaller transistors also mean faster processing speeds, resulting in an exponentially increasing trend for processing power. In this timeframe, defence scientists hope to use the available processing power to replace the pilot with its silicon equivalent - no less than a “pilot-on-a-chip”.
While one school of thought aims to effectively interface and integrate the pilot's thought processes with his machine, UAV proponents seek to develop a silicon-based pilot which can take inputs from sensors, make decisions based on that input, and engage the enemy with the appropriate effects - without the inherent reaction time delays associated with the human pilot.
The outdated mental model of an unmanned platform being an expendable camera with wings must be refreshed. The preferred model would be that of a pilot-on-a-chip able to perform at least as well as, if not better than current manned systems in a variety of missions.
The prime technology drivers for UAVs can be broadly categorised into the following groups: autonomy, communications, sensors, weapons systems, survivability and reliability, propulsion and ground control station.
Autonomy
Exponentially increasing signal processing speeds will enable greater levels of autonomy resulting ultimately in hands-free UAVs that could accomplish entire missions without man-in-the-loop (MITL) intervention if necessary. By the next decade, the sheer amount of brute computing power available will render human operators obsolete in an increasing number of tasks and missions.
Key foci for the development of autonomous technologies will include fault-tolerant flight control systems (FCS), in-flight mission management, cooperative engagement, distributed data fusion and automatic target recognition/engagement.
Fault-tolerant FCS under development can utilise alternative combinations of remaining control surfaces to maintain flight stability when a primary control effector fails. In-flight mission management refers to the ability to reconfigure flight path and navigation controls combined with onboard capability to react to changing mission needs. UCAVs will be capable of swarm engagements leveraging artificial intelligence and robust, Terabytes per second-capable data links to develop a decentralised, multiple tactical picture compilation of threats and targets before modifying in-flight tasking to cope with the altered tactical situation. Amongst other things, swarmed UCAVs can re-task each other, minimise target search time by cooperative searching, and engage targets and threats detected by other UCAVs.
Decentralised Data Fusion (DDF), i.e. the ability to fuse data from a variety of on- and off-board sensors without a central processing facility, will give UAVs situational awareness without having to transmit bandwidth-consuming video imagery back to a ground station. Taken to the next level, this battle awareness will allow next-generation UCAVs to automatically recognise targets and engage them with the appropriate munitions. They will demonstrate consistent positive identification of legitimate targets and rejection of illegitimate targets, with the degree of accurate identification impacting the Man-In-The-Loop (MITL) requirement and consequently the ORBAT needed to man such a system.
Datalink and Communication
High data rate, wideband, Low Probability of Interception (LPI), secure, all-weather data-links are needed for responsive C3 battle management. UAVs must be networked with other manned aircraft, UCAVs, off-board sensors and ground stations for overall battle management, in order to develop a single integrated air picture.
Optical systems based on lasers can potentially offer data rates two to three orders of magnitude greater than those of the best future RF systems. Airborne laser communication systems with small apertures (7-13cm) using low-power semiconductor lasers have a significantly lower probability of detection, weigh 30-50% of comparable RF systems and consume less power, whilst offering Tbps rates of data transmission.
Besides increasing available transmission rates, ongoing research into connectivity concepts such as the Small Unit Operations Situational Awareness (SUO SAS) programme will drive efficient bandwidth management using a “LAN within LANs” concept. Dynamic datalink sizing and nodal management will allow users to maintain low-, medium- or high-data rate connections with a continuously moving and changing host of nodes depending on proximity and community of interest.
Weapons Systems for UCAVs
• Advanced Seekers
Internal carriage and aircraft survivability have driven the next generation of missile seekers towards a fire-and-forget capability, away from those requiring human guidance and intervention. These new weapons will likely rely on low-cost imaging infrared or millimetre-wave seekers that have become available. The degree of autonomy built into these weapons will impact the degree of human involvement required, directly relates to how many targets can be engaged in a given period of time, and translates to weaponised UAVs and UCAVs lethality and mission effectiveness.
• Smaller Munitions
For weaponised UAV and UCAVs to achieve their initial cost and stealth advantages by being smaller than their manned counterparts, they will need smaller munitions that are more powerful and more precise.
• Directed Energy Weapons (DEW)
In a not too distant future, weaponised UAV and UCAVs are expected to deploy DEWs such as high powered microwave (HPM) weapons systems. The HPM weapon system emits a transient, high-powered energy spike which shorts closely spaced transistor lines, destroying micro-fabricated sensors and processors. It is aimed at disabling platforms, transmitters in C3 centres, enemy radars and weapons with electronic sensors. Unmanned platforms are therefore most suited for deploying such weapons, where the possibility of self-inflicted damage from induced skin currents and electromagnetic interference (EMI) is far from trivial.
Sensors
Passive and low-signature sensors with LPI are essential to boost stealth and survivability of UAVs. Noteworthy advances include Hyper-spectral Imaging (HSI), Laser Radar (LADAR), and Synthetic Aperture Radar (SAR) with Moving Target Indicator (MTI).
Multi-dimensional sensors will provide increased target signature information by scanning across a large number of discrete spectral bands (multispectral, 10-100 and hyperspectral, more than 100) to gain more information about each image pixel, additively adding information gleaned from each band to form a more complete picture than single and dual band systems. Benefits of HSI include improved clutter rejection, decoy discrimination, higher reliability of detection and target ranging. An autonomous SAR/MTI radar detecting both ground and air targets is envisaged to be the primary sensor in future UAVs used mainly for air-to-ground warfare. With high resolutions of 30cm or better, the SAR/GMTI radar will locate precisely both fixed and moving ground targets while an AMTI radar surveillance mode may be required for air situation awareness.
Other techniques to achieve Low Probability of Detection (LPD) include frequency selective radome design, stepped Linear Frequency Modulation (LFM), pseudo-noise radar emissions, civilian waveform mimicry, and bistatic radar cooperative imaging.
Survivability and Reliability
The level of survivability for a UAV must be strictly defined at specific levels of attrition, beyond which performance and cost cannot be traded. This will determine its mission effectiveness vis-a-vis available platforms such as manned fighters and cruise missiles. Survivability of the platform will depend on its speed (see next section “Propulsion”) and low observability (“stealth”).
Stealth design considerations include engine intake/vent design, internal weapon bays, seamless composite skins, fewer windows and hatches, smaller platform sizes and radar-absorbent structures and material to reduce the IR/RF signature.
One way to minimise detection for the tactical UAV is to reduce acoustic signature by use of quieter electrical propulsion systems. However, despite extensive studies for airborne applications, electrical propulsion systems will meet the power requirements of only a limited number of UAV applications in the near future. Instead, in the near term, acoustic signature reduction will focus on areas traditionally associated with ship and submarine design such as acoustically absorbing materials; signature modelling, phenomenology and control; and structural characterisation.
With the increase in size, platform and sensor cost, future UAV systems are aiming for Mean Time Between Loss (MTBL) of at least 10,000 hours. Higher-value UAVs such as those in the strategic class are targeting 100,000 hours, equivalent to that of a business jet. The use of manned rated engines, triply redundant flight critical equipment, adoption of soft- and hardware architecture equivalent to that of manned aircraft with air-worthiness qualification are just some of the solutions to meet the expected demand for highly-reliable UAVs in the future.
Propulsion
No longer limited by human physiology, the UAV propulsion and airframe can now be designed beyond the 10g regime, to the theoretical limit of 20g where current turbines go out of round due to centrifugal forces. Greater speeds and higher manoeuvrability translates into greater survivability. Hypersonic UAVs may be contemplated - besides having a higher thrust-weight ratio and reduced aerodynamic drag, they do not need the pressurisation and temperature shielding required to accommodate human beings.
Ground Control Station
Future-oriented UAV operation concepts call for a Ground Control Station (GCS) to possess the capability to control multiple and different UAVs, in order to serve various users of the network. Such a GCS could easily be re-configurable in the field to control a different UAV or another payload. In addition, scalability facilitates the increase of GCS consoles to control many UAVs and perform additional applications or off-line processing.
Future GCS design will enable portability to different hardware, allowing easy customisation for Naval, Land and Air applications. It comprises commercial off-the-shelf (COTS) items for greater supportability and to harness the latest technology, incorporating intelligent design to reduce the task load imposed on the operators associated with UAV control and monitoring.
Being a crucial element in the UAV system, the next-generation GCS needs to be highly reliable. Hot backups for the critical control functions in different levels of system operation must be designed with fail-safe and fail-soft features.
Impact Of UAV Proliferation
The paradigm shift embodied by UAV employment spawns a multiplicity of implications.
First and foremost, population size will no longer be the system resource bottleneck. The balance of power is then no longer dominated by brute size and strength, but by the economic prowess of combatant nations. The considerations for “exchange ratio” will shift from lives and platforms lost, to the dollar value of the UAVs and unmanned platforms.
On the other hand, peacetime training requirements will significantly shape future UAV developments. To address safety concerns of operating in civilian airspace, UAV systems will have to become more reliable - with no small impact on system cost. Airworthiness certification issues have to be comprehensively tackled, to adequately address the concerns of airspace administrators in the operation of unmanned vehicles in civilian airspace.
With the proliferation of UAVs and other unmanned systems in the longer term, the barriers to entry will increasingly be lowered both in terms of cost and availability. What then constitutes an adequate defence against swarms of "fearless" UAVs? More so than manned assets, UAVs are more susceptible to electronic countermeasures such as jamming, spoofing and deception due to their reliance on a datalink to the ground crew as the primary control mechanism. However, increasingly autonomous and intelligent UAVs with “adaptive autonomy” may be able to overcome ECM by adaptively nulling interfering signals, or may even be sufficiently autonomous to complete the entire mission without input from the ground. Also, the increased employment of UAVs will result in greater amounts of information being produced by the sensor grid. From the defender’s point of view, emphasis will thus shift from destroying large numbers of enemy sensors, to exploiting the information they produce, either to sow confusion with false data or to gain information about enemy intent. The operational utility of manipulating enemy unmanned assets, as well as the threat of them doing the same to us, will spur continued advances in IW.
Unmanned systems may potentially be most vulnerable to HPM effects. Due to its asymmetric effect against semiconductors, the pilot-on-a-chip would be completely devastated. This in turn will drive the adoption of circuits which are not affected by this class of weapons, including micro-fabricated fluidic and optical chips, to offer the next level of sophisticated signal processing.
More fundamentally, the advent of UCAVs will likely spur a mini-arms race to develop and acquire increasingly capable attack-oriented systems. It appears that the only counter to UCAVs which can manoeuvre beyond the 10g regime would have to be even faster UCAVs or missiles.
Conclusion
UAVs are evolving rapidly to emerge as indispensable weapons of war. In order to stay ahead in the future unmanned battlefield, strategic technological areas must be identified early and built up as the technology matures. Otherwise, developments in UAV and unmanned technologies may outpace both our capacity to assimilate them and the ability to formulate coherent and effective warfighting strategies.
) the US might sell us come predator/reaper post inducting them in sufficient numbers in their own forces..........a UCAV along with a govt permission to strike would certainly strike fear for all insurgent/terrorists
