[Engineering Feature]
Unmanned Military Vehicles: Robots On The Rise
These mighty machines are taking to the land, sea, and sky to keep soldiers out of harm’s way.
UNDERWATER CHALLENGES 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.
UNMANNED CHALLENGES 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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