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Unattended Ground Sensors
Written by Peter Buxbaum
Navy aircraft would then fly over the areas seeded with the sensors to pick up their output. All of the processing, analysis and interpretation of the sensors’ work was done on the back end, by highly trained personnel working with the computer systems of that day.
Sensor technology has progressed markedly since then. The sensors themselves are loaded with sophisticated software that allows them to identify, and in many cases, classify, an approaching threat and transmit that information directly to those who need it. Wireless and satellite communications make the transmission of that intelligence easier and more efficient.
Besides acoustic and seismic capabilities, sensors these days are also capable of electro-optical, infrared, and magnetic detection. Ground sensors come in a variety of flavors and are sold as integrated packages, each with its own mix of capabilities. The choice of a sensor package depends on specific unit missions.
The earlier generations of ground sensors were designed primarily to pick up the signatures of Soviet-style military vehicles. After 9/11, and the beginning of the U.S. operation in Afghanistan, the military was confronted with the challenge of detecting weapons such as mobile launchers that were mounted on vehicles like pickup trucks and SUVs.
“By the time we got involved in Afghanistan and Iraq, the threat of Soviet-style military vehicles had greatly diminished. They were easy to eliminate at the first stages of a conflict by conventional means,” said Gervasio Prado, president, Sentech Inc., a developer of acoustic and seismic sensors based in Stoneham, Mass. “Once we were confronting the Taliban and Iraqi insurgents, we were no longer going after tanks or armored personnel carriers. The old type of targets was easy to pick up because they had very loud distinctive signatures, but the new targets were indistinguishable from everyday civilian traffic.”
One of the implications of the type of warfare being pursued in Afghanistan and Iraq is that imaging of the potential target became more important. “You now needed an image of the target before you can reach any conclusions,” said Prado. “The new generation of sensors has now become a collection of different types of sensors all linked together to a device called a gateway. One of the important functions of the gateway is the ability to control imaging devices. A signal from a sensor may notify the gateway turn on the imager and take a picture of the target.” The same function is performed by a human operator in some systems.
Operations in Afghanistan and Iraq, in which U.S. forces are operating in close proximity to local populations, present other challenges as well. “The indigenous people know the areas they are operating in very well,” said Mike Barthlow, director of sales for Special Operations Command at Harris Corp. “It is difficult to position most equipment or a road or a trail in a target area without being discovered. That makes the use of long-range imaging capabilities important.”
The various modalities on board a modern ground sensor are controlled by sophisticated software that allows it to define what it is hearing and feeling. “These sensors can make determination whether it is a tank, a heavy wheeled vehicle or a person walking,” said Jay Johnson, senior director, business development, for ground systems at Textron Defense Systems in Wilmington, Mass. “Each of the sensors is looking for some characteristic of the target. The algorithms that have been loaded into a fairly capable computer processor on board the sensor are well-defined and have been built over the last 25 years.”
Many, but not all, of the most modern sensors being marketed today include onboard signal processing capabilities. “Processing onboard and not on the back end means that the sensor itself makes the decision about what the sensitivity is that it just felt,” said Patricia Driscoll, CEO of Frontline Defense Systems, a developer and manufacturer of sensors headquartered in Washington, D.C. “Instead of getting data, bringing it back to a computer, and the computer telling you what was detected, you get a faster response with the processing on-board the sensor.”
A somewhat different approach is being taken by developers at the QinetiQ North America’s Technology Solutions Group in Pittsburgh. QinetiQ’s SUSS sensor provides target detection but not target classification, meaning that it is not loaded with software that can distinguish between different kinds of potential targets.
“This is for very rapid, visual feedback for immediate use,” said Hagen Schempf, the group director. “It is not meant to be dozens of miles away but within wireless range.”
Schempf’s point is that a sophisticated sensor may successfully detect a specific type of truck, for example, but cannot discern who is in that truck. “Warfighters want eyes on target,” he said. “There is no replacement for visual confirmation and feedback. That is how our brains work. That is how we make decisions.”
QinetiQ’s SUSS sensor is currently in beta testing and has been put through its paces in theater. Three Marine Corps units in Southwest Asia have provided feedback, according to Schempf. Among other things, SUSS has been put to use in counter-IED operations.
SUSS combines sound and motion detectors with two cameras, one electro-optical and one heat-sensing infrared. The cameras can pan, tilt, zoom and are connected to a controller through a wireless connection with a range of 30 yards. SUSS is also compatible with QinetiQ’s Dragon Runner unmanned ground vehicle platform.
Unattended ground sensors have been one of the major components in the ill-fated Future Combat System (FCS), an Army program. Although FCS’ vehicle program is being terminated, other FCS technologies presumably will persist, either through a reorganized FCS or by being reassigned to other programs.
Textron is supplying two kinds of ground sensors as a Tier One supplier to Boeing, the FCS lead systems integrator. The first is for urban operations—to help troops verify that areas under their control are still clear of enemy combatants.
“Imagine that a soldier goes into a building somewhere in theater and clears a particular room or hallway or building,” said Johnson. “He wants to make sure no one comes in behind him to reoccupy the area, so he carries a sensor system, which he puts up on his way out.”
This particular sensor combines a motion detector and a small camera with a night illuminator. Once the sensor detects motion, the electro-optical sensor comes into play to take a picture of the intruder.
The other FCS sensor that Textron supplies detects vehicles. This tactical sensor can identify everything from tanks to pickup trucks as well as boats approaching a shoreline or a helicopter hovering close to the ground. The tactical sensor combines acoustic, seismic and electro-optical capabilities.
“Once a threat is picked up, the sensor starts sharing information with other like sensors in the field,” said Johnson. “They triangulate the sounds and vibrations to be able to track the threat vehicle. This is conveyed to a soldier operating a laptop at a command and control station. The soldier can then activate the electro-optical sensor to take a picture of it.”
The camera can also be activated through an infrared sensor, which acts as a tripwire should a suspect vehicle pass its way. Milestone 3 decisions are approaching for these sensors, and a decision to produce them is expected before the end of the year. Already fielded by the Army is a Battlefield Anti-intrusion Sensor produced by L-3 Communication Systems. “These products are meant to serve small dismounted units with extremely lightweight and low-power usage devices,” said Robert Lisowski, director of RF Systems for L-3 Communication Systems–East.
This UGS is also used to augment the systems protecting forward operating bases with aerostats, tower-mounted cameras and ground-based radars, according to Lisowski. “Those are still not able to see into gullies, into areas with dense forestation, or through hills and mountains,” he said. “This sensor provides an additional level of security.”
The sensor, which is equipped with seismic, acoustic and magnetic components, can classify personnel, wheeled and tracked vehicles, and helicopters, and is being enhanced to identify wheeled vehicles by weight. “The magnetic sensor detects metallic objects and vehicles,” said Lisowski, “and is also capable of supporting reporting on the direction of travel. Through a software enhancement, we are also able to provide some estimation of the speed of the target.”
The L-3 sensor provides 450 linear meters of detection against personnel targets. Its wireless communications range is 15 kilometers. An entire system of three sensors, a handheld monitor, batteries, and manuals weigh less than 11 1/2 pounds.
“The guys are already carrying over 100 pounds into battle,” said Lisowski. “Especially in rigorous environments like Afghanistan, they can become exhausted before they have to fight if they are carrying too much.” L-3 provides a similar sensor to the Marine Corps.
Frontline Defense Systems’ Dragon Sense mini sensor combines an acoustic sensor sourced from a Norwegian company with U.S.-made seismic, infrared and electro-optical capabilities. The company currently supplies the sensor to the U.S. Border Patrol and the U.S. Army.
The sensor communicates wirelessly with a controller logged on to a Windows-based system to choose, through a check-off menu, the capabilities to be deployed on the sensor. The system easily integrates with mapping applications such as FalconView, ArcView and Google Earth. The sensors organize themselves into a mesh network that finds the shortest path back to the base station.
“If there is a failure point, the sensor sends a signal to next unit,” said Driscoll. “It is a self-healing network so you can just set it down, turn it on and walk away, and it will report back to you.”
The networking of ground sensors is important for missions such as force protection, perimeter control, and intelligence, surveillance and reconnaissance, according to Mike Casey, director of business development at Trident Systems Inc., a San Diego-based company. Trident manufacturers a small, lightweight sensor node called the Sentry, which is essentially an integration platform for a variety of different sensors such as motion, magnetic, infrared and electro-optical. The nodes communicate with each other over a 2.4 GHz ultrawideband network.
Trident has configured its nodes so that “the network itself is a sensor,” said Casey. “If someone walks between two nodes and the signal is disrupted, that activity can trigger an alert for sensors such as the infrared or electro-optical to activate.”
Much as unattended ground sensors have progressed in their capabilities in recent years, so are they expected to provide enhanced capabilities in the future. L-3’s Lisowski predicts that the Army will want to take sensor messages to smaller warfighter units. “The concept of the soldier as sensor is important to the Army,” he said. “Anything to enhance situational awareness is a high priority for the services.”
Driscoll sees more and different cameras, including ones that can zoom directly on a target, being incorporated into ground sensors in the future. Frontline Defense Systems is now finishing up work on a small disposable sensor that can be airdropped to its target and that will use robotics to secure itself to the ground.
Harris Corp. is working on developing advanced video capabilities. One is to provide video surveillance over fairly long distances given sufficient bandwidth. Another is the ability to transmit low data rate video over very narrow channels.
“It will provide enough information so an operator or analyst can see what is going on in an area,” said Barthlow. “It can’t identify an SUV by make and model, but it can tell the difference between a pickup truck and a military vehicle. It will be able to discriminate between a human being and an animal. You won’t be able to see facial features, but you will be able to discern the outline of a weapon.”
Future unattended ground sensors will be further miniaturized and embedded with electronics, according to Casey. “Especially in special operations, they want sensors that are small and easy to use. They want to be able to place the sensor and just switch on the device.”
Prado and Johnson both foresee sensors becoming weaponized in the not too distant future. One such sensor currently under development would detonate a mine after a particular kind of vehicular target is identified, according to Prado. Johnson said that Textron is working on a weaponized anti-personnel sensor called Spider and an anti-vehicular sensor called Scorpion. “With this mix of sensors and munitions, the sensor would send a signal to soldier on a laptop that a particular threat has been identified,” he said, “and the controller would then decide whether the target is friend or foe and whether to engage.”
The array of available unattended ground sensors and their combination of capabilities may appear like a Chinese menu to the uninitiated. But it need not be confusing to the decisionmaker, according to QinetiQ’s Schempf.
“Some sensors can do things others can’t,” he said. “There is room to use a lot of different devices. You should think of them as different tools in your tool box.” ♦