Unmanned vehicles represent the new cornerstone of the military. The U.S. Army’s Future Combat Systems (FCS) augmented its latest manned ground vehicles (MGVs) with an array of unmanned air and ground vehicles. The U.S. Air Force and Navy also have a number of unmanned vehicles in the works and deployed around the world.
Because of their lower cost, these vehicles are quickly finding their way into every military organization on the planet. The U.S. Army expects 15 brigades to be equipped with complete FCS vehicles by 2030.
The U.S. Air Force uses Northrop Grumman’s Global Hawk surveillance aircraft to provide high-resolution synthetic aperture radar (SAR) images with 1.0/0.3-m resolution (WAS/ Spot) (Fig. 1). It can survey as much as 40,000 square miles in a day, with a maximum endurance of 35 hours. Powered by an Allison Rolls-Royce AE3007H turbofan engine, it also has a ceiling of 65,000 ft. The 32,250-lb unmanned aircraft features a 130.9-ft wingspan and a payload of 3000 lb as well.
Some of the rugged subsystems within the Global Hawk come from Curtiss-Wright Controls Embedded Computing, including the Integrated Mission Management Computer (IMMC) and Sensor Management Unit (SMU). An IPv6 Gigabit Ethernet network provides the communication between various modules.
As with most remote-control vehicles, the Global Hawk utilizes wireless communication. Consequently, pilots can be located on the other side of the planet. Removing the pilot from the aircraft’s equation requires additional hardware, but it eliminates an even greater amount of hardware needed to support a human occupant.
The MQ-1 Predator (Fig. 2) and the MQ-9 Reaper (Predator-B) are medium- to high-altitude, long-endurance unmanned aerial vehicles (UAVs) that pack a punch. In addition to surveillance chores, they can be armed with a range of payloads including the GBU-12 Paveway II laser-guided bomb and the AGM-114 Hellfire II air-to-ground missiles.
The 432d Air Wing from Creech Air Force Base (AFB), located near Indian Springs, Nev., is the first wing that’s totally dedicated to operating the MQ-1 Predator and MQ-9 Reaper. The U.S. Air Force UAV Battlelab flight test and development facility at Creech AFB is dedicated to developing UAVs. It’s one of six original Air Force battlelabs operated under the Air Warfare Center.
The Predator, smaller than the Global Hawk with its 66-ft wingspan, can carry smart bombs in addition to heavy sensor packages up to 1.5 tons on external hard points. Though not as fleet as an F-16, the Predator’s endurance of 14+ hours puts it in high demand on the battlefield.
As with the Global Hawk, Predator crew size isn’t limited since it operates at a remote site. Shifts of pilots and operators can handle a single vehicle, and work on unmanned vehicles in general is moving toward a single pilot controlling multiple, semi-autonomous vehicles at once.
This can also allow specialists to quickly move between input sources by simply clicking on the appropriate window of their command console. Having a team available means pilots and operators can be fresh even when the vehicle has been in the air for half a day.
YOU’RE IN THE ARMY NOW
The air may be great for junior birdmen, but plenty of unmanned vehicles roam down on the ground, too. There’s even a range of small unmanned ground vehicles (SUGVs) like the Dragon Runner from Foster-Miller (Fig. 3) or iRobot’s PackBot (see “Real- World Robotics: An Appetite For Construction” at www.electronicdesign.com, ED Online 8076).
Standing only 5 in. tall, the Dragon Runner will give the Energizer Bunny a run for its batteries. It’s designed to operate even after being tossed through a window two or three flights up, over a wall, or down a flight of stairs. This lets operators place the robot close to its target before it proceeds under its own power. For great video of the Dragon Runner in action, go to www.automatika.com/downloads/DR_Tough_Cookie.avi.
Foster-Miller’s 350-lb Modular Advanced Armed Robotic System (MAARS) is the follow-up to the popular Talon and Talonbased Special Weapons Observation Reconnaissance Detection System (SWORDS). These platforms address a range of applications, from explosive ordinance disposal (EOD) to offensive capabilities like the Predator, albeit with bullets instead of missiles.
Land-based vehicles tend to have more challenges than airor water-based vehicles because terrain and obstacles are major issues. Aircraft often die when they hit obstacles. Underwater vehicles operate in a similar open environment, but at slower speeds. Likewise, surface water vehicles function in a relatively open 2D environment.
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The U.S. Navy is following a similar trend of large and small remote-controlled underwater vehicles. For example, Boston Engineering and the Franklin Olin College of Engineering are teaming together under a U.S. Navy grant to create GhostSwimmer, which will use Boston Engineering’s FlexStack. The Flex- Stack computer is about the size of a coffee cup.
Unmanned underwater vehicles (UUVs) tend to be more challenging because of power issues. Nonetheless, a variety of commercial and military solutions is out there. Autonomous underwater vehicles (AUVs) such as the Bluefin Robotics deep-water Bluefin-21 BPAUV (Fig. 4) and Hydroid’s Remus 100 often follow the design of torpedoes or submarines and utilize conventional propellers for propulsion (see “Robobusiness 2007,” ED Online 15723).
The Bluefin-21 BPAUV can operate for 18 hours at 3 knots. Its 455-KHz sidescan sonar can cover widths up to 150 m with a 7.5- by 10-cm resolution. The BPAUV also can operate at depths up to 200 m. Its self-contained navigational systems don’t require acoustic beacons for positioning. The Bluefin-21’s battery modules can be changed in under 2 hours, providing a fast turnaround time. Possible uses include mine detection.
The Rafael Advanced Defense Systems Protector operates atop the waves (Fig. 5). It can run autonomously or be remotely controlled. It has been used for a range of missions, including anti-terror force protection (AT/FP), intelligence, surveillance, and reconnaissance (ISR), anti-surface warfare (ASuW), anti-submarine warfare (ASW), and anti-mine warfare (AMW). It can be used for long-range standoff surveillance or to patrol naval vessels.
The highly maneuverable, 30-ft Protector is based on a rigidhulled inflatable boat. It has a low profile for a stealthy visual and radar footprint. A diesel engine drives water jets, giving the Protector a top speed of 40 knots. It can sport a range of devices, including a Mini-Typhoon stabilized machine gun. On-mount cameras allow day and night operation. Navigation can take advantage of GPS and inertial navigation system (INS) support. The Protector can also utilize radar, forward-looking infrared (FLIR), and laser range finders.
Lighter, cheaper, more compact designs are definite advantages to unmanned vehicles, as is removing the human component from harm’s way. Most unmanned vehicles carry heavy pricetags, but these robotic vehicles are more disposable than their manned counterparts, allowing for their use in more dangerous situations.
Not all is rosy when it comes to unmanned systems, though. Issues of response time, field reliability, bandwidth, and even congestion of frequencies used to control vehicles arise in the real world. Response time is something any multiplayer gamer will recognize. Lag, the delay between tapping a control and a visual response, is often part of a game, but it can mean running a robot off a cliff or stopping in time. Anticipation helps, but real-world conditions can work against a reasonable response.
Bandwidth will be an issue with any wireless solution and even some wired solutions. The Packbot from iRobot has an option to deploy a fiber-optic cable behind itself, which provides plenty of bandwidth, though wireless solutions have to contend with other devices or robots. Various schemes can be employed to improve bandwidth utilization, yet sorties may still need to be scheduled if full utilization would exceed the communication limits.
And there are plenty of reasons to want more bandwidth. One is vision fidelity. More cameras and sensors can improve situational awareness for pilots and operators. They also allow more information to be sent back instead of being stored in the vehicle. In many instances, data must be stored in the vehicle because the bandwidth required to transmit it is simply too great.
Bandwidth and reliability are two reasons why the U.S. Navy is looking at multi-antenna multiple-input multiple-output (MIMO) wireless technology from Silvus (Fig. 6). The technology is now being tested at Space and Naval Warfare (SPAWAR) Systems Command, as reliable communication is critical to remote operation.
Other challenges include power and cooling. Most unmanned vehicles operate in rugged environments, requiring electronics to be sealed. This tends to wreak havoc on electronics that like to generate lots of heat, so low-power operation and low-power devices are always desirable.
Cooling often remains an issue, even with low-power approaches. Mercury Computer’s PowerBlock highlights the trend towards compact, rugged platforms (Fig. 7). It’s literally a black box that can house anything from a multicore PowerPC to a Cell processor (see “CELL Processor Gets Ready To Entertain The Masses,” ED Online 9748).
Used in the SAFE OPS test vehicle, Act/Technico’s RAIDstor employs conduction cooling (Fig. 8). It provides network booting for multiple single-board computers as well as data-recording storage. Often, though, conduction cooling isn’t enough. This is where alternatives such as liquid cooling come into play.
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SprayCool uses a two-phase liquid-cooling solution. The trick is that SprayCool’s technology can work with air- or conductioncooled boards with minimal modification. SprayCool’s enclosures are sealed while providing high levels of cooling.
FPGAs can keep things cool by doing more in parallel while running at slower speeds than today’s quad-core power consumers, but they need to run in a rugged environment. Actel’s ProASIC3/ EL FPGAs meet this challenge, running at more than 250 MHz at 125°C. The company’s Flash*Freeze mode lets them switch from low-power mode to full operation in less than 1 µs. The A3PE600L’s static power consumption is only 0.55 mW at 25°C.
Remote-control vehicles dominate military applications because of their reliability. Keeping a human in the loop can be important, because making critical decisions with limited or contradictory information is still best done by people.
This works well with remote-control vehicles as long as communication can be maintained reliably. Unfortunately, reliable communications isn’t always possible. It may not even be desirable in some instances, since it could potentially give away the position of the robot or its controller.
The current state of autonomous affairs is highlighted by competitions like DARPA’s Grand Challenge and its recent Urban Challenge, where teams built autos that faced demanding courses without any drivers at all (see “Autonomous Vehicles Tackle The Urban Jungle,” ED Online 13115).
Fully autonomous military vehicles with limited intelligence like cruise missiles are used already. But applications such as ground vehicles require greater intelligence due to the more complex environment and conditions. A flying cruise missile always ends in destruction, which isn’t a desirable characteristic for ground vehicles designed to deliver supplies.
Still, a semi-autonomous mode is often attainable. In semiautonomous mode, a robot vehicle will be given a simple command such as fly a particular route and notify the pilot or operator if the sensors detect something interesting. Likewise, having a vehicle follow a person or another vehicle is a comparatively easy task.
Be they large or small, airborne or aquatic, unmanned vehicles will continue to improve and be deployed more heavily in the future. Significant improvements are in the works, but major design challenges remain, especially as these robots move toward autonomous operation.