Unmanned ground vehicles (UGVs) actually date back several centuries, to Leonardo da Vinci’s self-propelled carts (apparently intended to move cargo, not people), but did not see their first significant use in combat until World War II, when Nazi Germany built some 7,000 Goliaths – wire-guided small rolling bombs used to attack Allied troops and armor.

The first Gulf War brought unmanned aerial vehicles (UAVs) to public attention with the Pioneer, a simple reconnaissance aircraft that proved invaluable in locating Iraqi forces, and enabling ships and artillery batteries miles away to zero in on them with deadly accuracy.

By the time post-September 11 military operations got under way in Afghanistan and then Iraq, UAVs had advanced in both number and capability, including the ability to deliver weapons directly on target. But the second Gulf War also saw the arrival of a new breed of modern UGVs.

These initial robots were small platforms with cameras, operated remotely by soldiers or Marines up to a few hundred feet away. Their primary use was checking vehicles at checkpoints, allowing warfighters to identify potential car bombs without exposing themselves to danger. Ultimately, they were applied to the singular enemy weapon of Southwest Asia – the improvised explosive device (IED).

“Combat engineers are using small robots and light flails in road clearance efforts where they basically roll along a specific area of interest and ensure it is clear of IEDs or similar obstacles,” said Col. Jim Braden (USMC), Robotic Systems Joint Project Office (RSJPO) program manager. “The newer mission has moved over to ground maneuver forces, so if you are out in a Stryker or Marine LAV [light armored vehicle], you can use a small robot to look around the next corner, inside a building, check something that does not appear to be a natural part of the landscape.

“The next step we’re working involves significant logistics issues with both the Marine Corps and Army for offloading soldiers’ and Marines’ [backpacks], focused right now at the squad level, plus or minus, to enhance their mobility. In the longer range, we’re looking at some armed robots, currently in prototype. There are several initiatives, none robust enough to put into the hands of operational forces yet, but you might put an armed robot between a wounded soldier and the threat.”

Dr. Jim Overholt, director of RSJPO’s Joint Center for Robotics, is cautious to separate military reality from Hollywood fiction.

“We have to be very careful with the phrase ‘fully autonomous.’ In the most general sense, I don’t think we’re ever looking at that in terms of military robots. You won’t see robots being given orders and then going out and doing them,” he said.

“We can run autonomously for a period of time in getting from point A to point B, but the more autonomy we put into the system, the more we will have to address safety certification around humans. And if anything is preventing autonomy, it is making sure these systems will be safe around human beings.”

Indeed, despite the specter of Hollywood’s fictional Terminator raised by some critics, the robots currently fielded are at about the stage of Operation Desert Storm UAVs and commercial robotic carpet sweepers.

“Will it grow at the same level as UAVs? There are a lot of differences. UAVs are in an environment unlike ground, which is incredibly complex and, frankly, we don’t yet have the science and math to truly model it,” Overholt said. “Once we have that, we will see great advances.

“Right now we are being conservative in adding capabilities to help the warfighter, but I definitely see robots expanding. There were maybe 160 systems in 2004, growing to 6,000-plus in 2009. They save lives, carry out dull, dirty, and dangerous [3D] missions, and are a valuable tool to the warfighter. That is not going to stop.”

Dr. Robert Mandelbaum, a program manager at the Defense Advanced Research Projects Agency (DARPA), said there are four major areas where progress needs to be made for robots to really take their place in and among humans. DARPA has efforts under way in all four:

• mobility – to cross over terrain with the speed and agility to keep up with human warfighters;

• manipulation – to interact with the environment and do real work;

• cognition – which includes perception, the ability for the robot to understand its environment, where obstacles are, where objects are it is trying to manipulate, where other robots and humans are, and the ability to navigate and manipulate in the world around it; and

• power – with an emphasis on light weight, compact size, at least 24-hour full charge for batteries, easily recharged/replaced, quiet, no “footprint” indicating it was there.

As with most leading-edge technologies, DARPA is the U.S. Defense Department’s primary focal point for adding ground robots to the warfighters’ tool set.

“It’s actually a very broad range [of potential capabilities], basically involving the 3 Ds,” Mandelbaum said. “For example, carrying equipment. Ground soldiers and Marines are now burdened with in excess of 100 pounds on their backs in very, very difficult terrain. That impacts both combat capability and long-term health; there are a tremendous number of back injuries among people carrying these backpacks for extended periods of time, resulting in them being removed from duty.

“DARPA is looking at addressing that issue by creating robots that can carry the load for ground troops. But a side effect is the ability to take equipment into the field you otherwise wouldn’t take, such as artillery, giving our squads an unfair advantage against the enemy. That is one of many traditional applications of robotics DARPA is looking to provide by filling technology holes that currently prevent them from being deployed.”

Feedback from the field is a major driver for ground robot development, often in response to an immediate need.

“We get operational assessments and feedback all the time to modify for the threat or look at for the next system design. That’s how we have been driven to lighter robots,” Braden said. “I just fielded a large number of medium robots [the 50-plus pound xBot] in both Iraq and Afghanistan and, having finished that, we’re moving down to one about 35 pounds.

“The robots over there before were 65-plus pounds. We sent the xBot over specifically for the grunts, who very much like the lighter robot, then the EOD [Explosive Ordnance Disposal] guys saw it and wanted it because it was lighter to backpack in and out; the engineers, working on route clearance, did the same.”

However, ground robots are still new to the military and far earlier in their development than UAVs.

“When we started going into the caves in Afghanistan and IEDs started showing up on the battlefield, we got serious about ground robots,” Braden said. “Because we are at war, you have a higher level of interest and funding and I think we have made tremendous progress since 2004.

“Unfortunately, this war isn’t likely to go away anytime soon, so we will be pressed for more progress, to continue to press forward at an accelerated pace. Robots are enabling tools and what we’re doing now is making them more agile and intuitive, but using a robot is a very deliberate thing and I don’t really see any danger of us going to a robotic battlefield.”

One of the top requests is for mobile robots that can do more heavy lifting. There are a number of potential ways to achieve that – and an even greater number of obstacles.

Wheels offer speed and versatility when operating on roads, but quickly bog down in off-road terrain. Tank-like tracks improve off-road capability, but cannot move with the speed, agility, and reliability of a military patrol in forests, jungles, or mountains. Simple obstacles, such as fallen trees or large rocks, are quite literally insurmountable for both in any practical combat application.

This led researchers to legged locomotion – more C3PO than R2D2. Various experiments looked at the advantages and disadvantages of multiple legs (akin to a centipede), six legs, four legs, and two. The fewer legs, the more closely a robot can mimic the movements and agility of a human; in addition, equipment and much of the environment is designed for bipeds in a fairly limited range of sizes. However, fewer legs also increase the problems of balance, speed, and the amount of weight the platform could carry – including its own power system.

Mandelbaum was program manager on Big Dog, completed in 2008, and has just begun a second – the Legged Squad Support System (LS3). Each demonstrates both the promise and the extent of difficulty involved, but LS3 is not considered a direct follow-on to Big Dog.

“Before Big Dog, it wasn’t clear we as a community knew how to control a very-high-degree-of-freedom legged platform. Legs can go over any terrain a human can go over, but it is much more difficult to control. When you go off road, it is a much higher degree of variability, which you have to match with a much higher degree of locomotion, then match that with a higher degree of control,” he said.

“Big Dog proved that, but LS3 is looking to carry a real payload – we have suggested 400 pounds – be able to operate at least 24 hours, and cover 20 miles with the same tempo of a regular squad, meaning it must have burst modes. The idea is to accompany a squad and carry a significant portion of their equipment, but not impact where they go.”

The big challenge has always been a self-sustained system that can carry its own fuel source and power system. The bigger the vehicle, the more power required and the larger the engine. Adding a requirement for long endurance adds the additional weight and bulk of carrying its own fuel. DARPA has a variety of programs under way, not all specific to robotics, to develop advanced fuel cells, batteries, and new kinds of engines that might be applicable to a range of robot requirements.

“We still need to deal with the overall power problem, not just the engine, so we’re looking at hybrid systems – internal combustion and batteries, using the batteries when we need quiet operations – sort of a Prius-type engine,” Mandelbaum said, referring to the fourth-generation Toyota Prius, one of the most popular of the new breed of hybrid automobiles.

“Further into the future would be fuel cells; right now, the state of the art is not quite there in terms of the energy and power density required to power something like Big Dog or LS3. However, we have proof in nature that it is possible; all animals are essentially fuel cells. Even if you had to provide specific types of fuel for it, the concept of generating enough power to operate the vehicle from a fuel cell is a great concept.”

DARPA also has looked to nature for concepts of controlled movement to increase efficiency and reduce power requirements.

“When a kangaroo jumps, it extends its tendons and when it lands, those huge leg tendons stretch, which convert their energy into spring energy. By proper timing, it can recover up to 93 percent of the energy from one jump to reuse in the next jump,” Mandelbaum explained. “Our current systems do not recover very much energy, certainly not on the magnitude of a kangaroo, because the state of the art in control and coordination of motion is not there.

“There are very good walking systems out there that are extremely energy-efficient. However, those aren’t designed to carry payloads or move over rugged terrain. Then you have systems like Big Dog that can walk over rugged terrain, but not very efficiently. What we need to do is combine the two. Once we do, our power requirements are much lower and we might get into the capabilities of fuel cells. So by using control to help us address power requirements, at some point, we will have advanced the state of the art in fuel cells to the point that we can produce much more animal-like vehicles in terms of endurance and the ability to move through rugged terrain.”

Other DARPA program examples include LANdroids (Local Area Network Droids), which is entering into its second phase. The concept is to ensure radio communications when a squad storms a building. Each foot soldier carries several LANdroids, tossing them out of his bag as he moves through the building. They are basically mobile radio nodes, tasked to configure themselves into an ad hoc radio network, then reconfiguring to compensate for the loss of any node destroyed by an enemy, providing every soldier with assured high bandwidth to communicate voice, data, and video back to a base station.

In terms of manipulation, the most advanced of currently fielded robots are those used to defuse or destroy IEDs. Hundreds of those have been deployed to Southwest Asia, where the number of IEDs they had dealt with through the end of 2008 exceeded 11,000. While there is no way to determine how many lives those robots saved, it easily could average two or more per IED. As successful as that effort has been, however, those robots still require a human controller.

Practical autonomous manipulation is as much a matter of perception as degrees of physical movement and fine control. But perception, from depth to recognition, requires far more than a good imaging system. Major breakthroughs are needed in cognition to understand images, for the robot to be able to interpret its sensors and fully understand what is going on around it, for navigation as well as manipulation.

“There is a difference between seeing and understanding – cameras see, they grab an image, but human eyes understand what they see within a split second of opening,” Mandelbaum said. “But a human’s full understanding of separating and identifying objects and their location is still a ways off in terms of computation and robotics. We’re getting there and there has been a tremendous amount of advancement in the last 20 years, but we still have a very long way to go.”

In 2000, DARPA set out to advance robotic technology in terms of mobility and perception, initially through two parallel programs that decoupled those issues. The Unmanned Ground Combat Vehicle (UGCV) looked at a high-capability platform with no perception, while Perceptor used standard all-terrain vehicles (ATVs) to develop sensor packages and algorithms to do sensor processing and planning for off-road navigation. When completed in 2004, DARPA took the best performers of both and put them together into one system – UPI (UGCV Perceptor Integration).

“UPI was a very capable system, working in complex terrain, but it was not designed to work in and among people or maneuver among things moving about it,” Mandelbaum said. “On the other side, you have Urban Challenge, which demonstrated the ability to work in and among other moving vehicles and people in a structured terrain of roadworks.”

DARPA began its Challenge competitions in 2004, offering a $2 million prize to the first competitor (typically academic or corporate teams) able to complete a 132-mile course across the California desert in less than 10 hours with no human intervention. Some teams used highly modified commercial vehicles; others essentially built their own. In 2005, a team from Stanford University became the first to meet all requirements of the Grand Challenge.

That led DARPA to up the ante with Urban Challenge – not only did the vehicles have to duplicate the original challenge capabilities, they also then had to maneuver through urban traffic, both other vehicles and pedestrians (mannequins) set up on an abandoned California military base, without incident and without violating standard traffic laws. A team from Carnegie Mellon University completed the course and met all requirements to win first prize, but five other entrants also crossed the finish line.

Urban Challenge laid the foundation for robotic convoys and other wheeled or tracked logistics solutions in the future. That includes scenarios in which robots would move through a busy marketplace with a squad on patrol, carrying equipment and helping with surveillance. That would require an advanced perception and planning system capable of dealing with sudden and unexpected movement all around it.

For most combat operations, the ability to walk remains the preeminent goal of robotics. Ongoing combat operations in Southwest Asia add to the urgency.

“The LS3 program will run three to four years, after which we look to transition it to the Marines or Army. Realistically, 2015 is probably about the right time frame for it to begin fielding,” Mandelbaum predicted. “Legs for the future of robotics sounds a bit far-fetched to some – until you see videos of Big Dog [viewable on www.youtube.com] – but they also are the major solution developed by nature over millions of years of evolution.”

As more and more robots enter into military service, another factor will be pushing them toward greater autonomy: Limited battlefield bandwidth.

“Communications is a major issue. You’re talking about a series of platforms now being operated 99 percent of the time by the warfighter using the robot, all teleoperated or remote control, with very little if any autonomy,” Overholt said. “The problem on the modern battlefield is bandwidth, with several systems all connected and trying to use limited bandwidth to pass information back and forth. That bandwidth has to be robust or your ops tempo suffers. We are starting very slowly to integrate autonomous capability into these robots to reduce bandwidth requirements.”

Another issue, growing in importance as U.S. military operations in Iraq draw down while significantly increasing in Afghanistan, is meeting the often radically different needs of different combat environments.

“Robotic convoying was in response to moving goods and services around Iraq, where the convoys were targets and we wanted to help the soldiers by enabling them to take their eyes off the road,” Overholt said. “Convoying will still be important in Afghanistan, but there are other issues we must address. There are no roads and we have to hump these robots up some fairly steep hills and mountains, so making them lightweight is critical.

“As we continue the fight there, new information will be coming in and we will have to respond in kind. And if we go back into a jungle environment, we’ll have a whole new set of requirements. We have to respond to the environment and terrain in which the warfighter must work.”

There also are potential applications some might consider to be straight out of science fiction, such as sending robots ahead of warfighters to build base camps.

“That’s on the list. I have an idea for a standardized box of robots we configure on the plane and drop into a battle area and they set up the base for the warfighters. That is exactly what NASA is doing for deep space. When we go to Mars, robots will go out first, set up the habitat and a refinery for fuel when the astronauts show up a couple of years later,” Braden said.

“So that is not out of the question. But we also try to stay grounded in what the soldier and Marine needs now. That is a major tenet of what the Joint Center does now – what do they need right now. But we also spend some time looking into the future, trying to envision what we could be doing with robots.”

To Mandelbaum, the real goal of combat robotics is to change the very nature of war itself.

“The first applications of robotics will be things to help ground soldiers and the rest of the battle will remain the same,” he concluded. “But my view of the future of robotics – and I hope to get the right programs into DARPA – is to change the way we fundamentally think about battle. I can’t be more specific about particular programs, but you can think in terms of communications, remote surveillance, the ability to do things at a distance.”

Photo Credit:

• Multifunctional Utility/Logistics and Equipment (MULE) photo courtesy of U.S. Army

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