6
Unmanned Ground Vehicles: Capabilities and Potential

INTRODUCTION

Unmanned ground vehicles (UGVs) have great potential for naval operations, playing an important role in support of Marine Corps combat; they can also assist in logistics operations ashore and afloat. The full development and deployment of UGVs capable of operating in a wide variety of situations require solving a number of difficult technical challenges.

Fortunately, the Navy and Marine Corps are not alone in developing UGVs, as the naval applications of UGVs overlap significantly with Army applications. In parallel with naval efforts, development programs sponsored by the Army, the Defense Advanced Research Projects Agency (DARPA), and the Office of the Secretary of Defense (OSD) have been ongoing for 20 years. At the system level, much progress has been made in road following; less progress has been made in off-road, cross-country navigation; and very little has been made in autonomous navigation through complex urban terrain. Some of the progress has been achieved through better understanding of the problems and through better algorithms; much of the headway may be attributable to faster computation.

Other government agencies are also developing UGVs or related technology: the National Aeronautics and Space Administration (NASA) uses UGVs for planetary exploration; the Department of Energy needs UGVs for nuclear site maintenance and coal mining; the Department of Homeland Security employs UGVs for search and rescue; and the Department of Transportation is developing UGVs as cars, trucks, and buses that can drive themselves or assist a human driver.

Commercial applications of UGVs are also beginning to be made—for example, in underground mining, strip mine haulage, crop harvesting, golf course



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Autonomous Vehicles in Support of Naval Operations 6 Unmanned Ground Vehicles: Capabilities and Potential INTRODUCTION Unmanned ground vehicles (UGVs) have great potential for naval operations, playing an important role in support of Marine Corps combat; they can also assist in logistics operations ashore and afloat. The full development and deployment of UGVs capable of operating in a wide variety of situations require solving a number of difficult technical challenges. Fortunately, the Navy and Marine Corps are not alone in developing UGVs, as the naval applications of UGVs overlap significantly with Army applications. In parallel with naval efforts, development programs sponsored by the Army, the Defense Advanced Research Projects Agency (DARPA), and the Office of the Secretary of Defense (OSD) have been ongoing for 20 years. At the system level, much progress has been made in road following; less progress has been made in off-road, cross-country navigation; and very little has been made in autonomous navigation through complex urban terrain. Some of the progress has been achieved through better understanding of the problems and through better algorithms; much of the headway may be attributable to faster computation. Other government agencies are also developing UGVs or related technology: the National Aeronautics and Space Administration (NASA) uses UGVs for planetary exploration; the Department of Energy needs UGVs for nuclear site maintenance and coal mining; the Department of Homeland Security employs UGVs for search and rescue; and the Department of Transportation is developing UGVs as cars, trucks, and buses that can drive themselves or assist a human driver. Commercial applications of UGVs are also beginning to be made—for example, in underground mining, strip mine haulage, crop harvesting, golf course

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Autonomous Vehicles in Support of Naval Operations mowing, ship cleaning, and for many other purposes. For logistics applications, a number of commercial automated guided vehicles (AGVs) are in daily use in factories around the world. It is important that the Marine Corps and Navy leverage the efforts of other Services and industry. Several formal mechanisms exist to help with coordination. In 1990, the OSD established the Joint Robotics Program,1 to coordinate all of the ground robot programs of the individual Services. The Department of Defense’s (DOD’s) UGV Master Plan2 provides a comprehensive overview of the current programs and their status. The Joint Robotics Program works with the Unmanned Ground Vehicle Joint Program Office (UGV JPO) in Huntsville, Alabama; with the PMS EOD (Program Management Office for Explosive Ordnance Disposal in the Naval Sea Systems Command); with the Program Manager-Physical Security Equipment (PM-PSE); with the Air Force Research Laboratory; with the Army’s Tank and Automotive Research, Development, and Engineering Center; and with technology base programs at DARPA, the Special Operations Command, and the Army Research Laboratory (ARL). The UGV JPO is a joint Army and Marine program. Significantly, the Future Combat System program, initiated by the Army and DARPA, is now a joint Army and Marine program also. The Marine Corps directly sponsors UGV development through the Marine Corps Warfighting Laboratory (MCWL). The Navy is active through the Naval Research Laboratory (NRL) and the Office of Naval Research (ONR). Navy laboratories have also played an important direct role in building robot vehicles: the Space and Naval Warfare Systems Command (SPAWAR), over the past two decades, has built a number of prototype UGVs both for naval applications and for other Services. A recent study by the National Research Council3 reviews UGV technology, applications, and programs in a U.S. Army context. The reader is referred to that report for a more complete treatment than appears here. This chapter discusses the potential of UGVs for naval operations. It includes a description of the UGVs currently available or under development and a discussion of naval operational needs and technology issues and of opportunities for improved operations. It then presents the conclusions and recommendations of the committee with respect to UGVs. 1   For additional information, see the Web site <http://www.jointrobotics.com/>. Last accessed on March 31, 2004. 2   For additional information, see the Web site <http://www.jointrobotics.com/activities_new/masterplan.shtml>. Last accessed on March 31, 2004. 3   National Research Council. 2002. Technology Development for Army Unmanned Ground Vehicles, The National Academies Press, Washington, D.C.

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Autonomous Vehicles in Support of Naval Operations THE POTENTIAL OF UNMANNED GROUND VEHICLES FOR NAVAL OPERATIONS The Marine Corps can use unmanned ground vehicles (UGVs) in support of all phases of its operations ashore. They can be used to reconnoiter beach areas and landing zones prior to and during offensive operations, they can be used to explore “around the corner” or investigate interior spaces during urban operations, they can be used to investigate caves or other concealment areas in nonurban operations, and they can be used to provide physical security patrols for established or expedient command posts or bases in any hostile environment. UGVs can also carry weapons for use in any of the applications listed. Other naval applications include uses in base security, surf zone and beach mine clearing, explosive ordnance disposal at ranges, logistics (warehouse operations, ship lading, ammunition handling, supplies transport), and use as forward fire-control observation platforms for shore bombardment. It is common to talk about autonomous vehicles, or robots in general, as being applicable in environments characterized by the three D’s—dull, dangerous, and dirty. While that is certainly true, there are other words beginning with “D” that also make compelling cases for unmanned ground vehicles: Diameter. Unmanned vehicles can be built smaller or more strangely shaped than can a vehicle that must include a crew compartment. This latitude allows them to go places that a manned vehicle cannot go, to hide in smaller sites, and to be harder to see and to hit. Difficult. A small, manned vehicle bouncing over rough terrain gives images from its onboard camera that are very hard to follow. Teleoperation of such a vehicle is difficult, even for an experienced operator. Autonomous technology, doing computer-based visual surveying with onboard sensors and processors, can do a much better job of vehicle guidance. Duration. Autonomous vehicles can be capable of operating for much longer periods than a crewed system can. For a ground vehicle performing a mission such as overwatch (or artificial guards), the endurance can be measured in days or weeks instead of hours. Digital. Computer-controlled systems are inherently easier to integrate into the digital battlefield than human-controlled systems are: they accept commands in digital forms, they can have exact replicas of maps, and their reports come back as digital messages or digitized images. The Navy (including ONR and SPAWAR) continues to be a leader in the research and development of robotic ground vehicles for naval as well as other Service and law enforcement applications. There is still a gap, however, between the research projects and the effective use of UGVs in real naval operational applications.

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Autonomous Vehicles in Support of Naval Operations Unmanned Ground Vehicles and Unmanned Aerial Vehicles The relative roles of unmanned ground vehicles and their airborne counterparts roughly correspond to the relative roles of Marines on the ground and Marines in the air. Unmanned aerial vehicles (UAVs) can travel long distances, have an excellent vantage for seeing large areas, and have easier lines of sight for communications. In many ways, aerial vehicles are easier to build, deploy, and control. Some jobs, however, must be done from the ground. UGVs have the potential to carry heavyweight payloads, to look inside buildings and under tree canopies, to persist for days, and to operate in all weather conditions. They also occupy ground: in some cases, the physical and visible presence of an armed unit on the ground is itself important. Thus, while the balance between air and ground forces is constantly being adjusted, the best approach for unmanned vehicles is to look at UGVs and UAVs as complementary parts of a team rather than as rivals for missions (and for funding). In recent experiments sponsored by DARPA and by ARL, an unmanned helicopter and an unmanned ground vehicle demonstrated autonomous cooperation. In the experiments, the helicopter previews the ground vehicle’s intended corridor of advance, building a three-dimensional model of the terrain. The ground vehicle then plans a detailed path, avoiding obstacles that the helicopter sees in the path of the ground vehicle. As the ground vehicle moves along the path, it compares its three-dimensional perceptions with the helicopter’s three-dimensional map, registering the aerial and ground world models. The result is efficient travel, as well as a detailed map containing registered information from the vantage of both ground and air. Overview of Current Military Unmanned Ground Vehicles Unmanned ground vehicles can be described in terms of their size and functional utility. Included in this discussion are U.S. systems developed by or on behalf of all of the Services. The heaviest class of UGVs is 15 tons and above. (See Table 6.1 for basic characteristics of these vehicles.) The fighting members of this class include automated or remotely controlled tank vehicles such as the Abrams Panther (over 40 tons); the D7G (a combat engineering vehicle) (28 tons); and the deployable universal combat earthmover (DEUCE) (18 tons). Each of these has the Standardized Robotics System (SRS) for teleoperation; the SRS provides a kit-based approach to converting standard vehicles to teleoperated mode. Also in this class is the automated ordnance excavator (AOE), a large (34 tons) armored excavator to be used for explosive ordnance disposal. All of these large vehicles are tracked. Of the four vehicles referred to here, only the Abrams Panther is deployed, with six Abrams Panthers operationally deployed in the Balkans and in the U.S. Cen-

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Autonomous Vehicles in Support of Naval Operations TABLE 6.1 Heavy and Medium-Weight Unmanned Ground Vehicles Developed by or on Behalf of All of the Services Name Weight (tons) Use Traction Status Heavy Abrams Panther/SRS More than 40 Mine clearance Tracked 6 deployed AOE 34 Explosive ordnance disposal Tracked Prototype D7G/SRS 28 Mine clearance; excavation Tracked Prototype DEUCE/SRS 18 Mine clearance; excavation Tracked Prototype Medium T3 Dozer/SRS 9 Bulldozer Tracked Prototype Smoke HMMWV 6 Obscuration Wheeled Prototype ARTS-FP 4 Explosive disposal Tracked 20 in use DEMO III XUV 1.50 Experimentation Wheeled Prototype Mini-Flail/Robotic Combat Support System 1.25 Mine clearance Tracked 15 in use NOTE: A list of acronyms is provided in Appendix D. tral Command. The other over-15-ton UGVs are in development programs that have reached the prototype stage. UGVs weighing between 1 ton and 15 tons are in the medium class. These vehicles include the All Purpose Remote Transport System (ARTS) (4 tons), which allows for multiple attachments or payloads for various combat-support activities; the mine-clearing Mini Flail (1.25 tons); and the eXperimental Unmanned Vehicle (XUV) (1.5 tons). (See Table 6.1 for basic characteristics of these UGVs.) All of the 1-ton-and-above UGVs in both the medium and heavy classes are automated or remotely controlled versions of manned vehicles except for the DEMO III XUV. The next two classes (described in Table 6.2) are small (400 to 2,000 lb) and lightweight (less than 400 lb). These include vehicles designed from the start to be autonomous. Figure 6.1 shows these various UGVs by weight class. Table 6.2 describes the small and lightweight UGVs that exist as prototypes or fielded systems. (Note that the weight is in pounds rather than tons.) The total number of fielded small and lightweight systems is 67 units of five types. The Dragon Runner and Gladiator are on track for future deployment. The Mobile Detection Assessment Response System (MDARS, both interior and exterior versions) is being developed to conduct security patrols and alarm response. Many of the other developmental efforts are dormant.

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Autonomous Vehicles in Support of Naval Operations TABLE 6.2 Small and Lightweight Unmanned Ground Vehicles Developed by or on Behalf of All of the Services Name Weight (lb) Use Traction Status Small Gladiator 1,600 RSTA direct fire obstacle breaching Tracked Prototype MDARS-E 1,500 Guard duty–exterior Wheeled SDD MDARS-I 600 Guard duty–interior Wheeled SDD RONS 600 Ordnance disposal Wheeled Fielded Lightweight TALON 34 to 80 Multipurpose Tracked COTS URBOT 65 Surveillance of small spaces Tracked 2 deployed—SEALS BUGS 45 to 60 UXO clearance Tracked Demonstration Packbot 50 Multipurpose Tracked Fielded ODIS 45 Undercarriage vehicle inspection Wheeled Demonstration Matilda 40 Special operations, cave clearance Tracked 24 in operational use Dragon Runner 16 Situational awareness sentry or can be thrown Wheeled ACTD NOTE: A list of acronyms is provided in Appendix D. Status of Naval Unmanned Ground Vehicle Efforts Some of the research and development programs on unmanned ground vehicles under way within the Navy and in the other Services and DARPA are described below. Gladiator The Gladiator tactical unmanned ground vehicle (shown in Figure 6.1) will be teleoperated or semiautonomous. This 1,600 lb UGV will operate in harsh, off-road environments. A prototype exists; the current program is expected to produce a fielded capability in 2006. The Gladiator will provide the Marine Air Ground Task Force (MAGTF) with a teleoperated/semiautonomous ground vehicle for carrying out combat tasks remotely in order to reduce risk and neutralize threats. The Gladiator is designed principally to support dismounted infantry during the performance of their mission, across the spectrum of conflict and the range of military operations. The primary functions of the Gladiator will be to provide the ground combat element with armed unmanned scouting and surveillance capabilities.

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Autonomous Vehicles in Support of Naval Operations FIGURE 6.1 Examples of mission-specific unmanned systems, by weight class. NOTE: A list of acronyms is provided in Appendix D. SOURCE: Michael Toscano, Joint Robotics Program Coordinator, Office of the Under Secretary of Defense for Acquisition, Technology, and Logistics (OUSD(AT&L)), Strategic and Tactical Systems (S&TS)/Land Warfare, “Autonomous Vehicles,” presentation to the committee, December 10, 2002. With the development of future mission payload modules (MPMs), projected operational capabilities may include reconnaissance, surveillance, and target acquisition (RSTA); engineer reconnaissance; obscurant delivery; direct fire (lethal and nonlethal); communications relay; tactical deception (electronic and acoustic); combat resupply; or countersniper employment. These modules will be field-installable, allowing commanders to increase their operational capability by tailoring the capabilities of the Gladiator to best meet their mission requirements. Dragon Runner The Dragon Runner (see Figure 6.2), at 16 lb (about 16 in. × 11 in. × 5 in.), can be tossed around a corner or through a window, for example. The wheeled vehicle can then be driven by remote control from an operator control unit (OCU) that displays imagery to the operator. The OCU is adapted from a Sony PlayStation, a system familiar to many of today’s young Marines. In motion, the

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Autonomous Vehicles in Support of Naval Operations FIGURE 6.2 Dragon Runner system, including vehicle, operator control station (OCS), and backpack. SOURCE: Marine Corps Combat Development Command. Dragon Runner will provide 6 hours of operation, and in a stationary “sentry” mode, 24 hours. The primary sensor is a low-light-level video camera. Dragon Runner is part of an ACTD program, with delivery scheduled in 2004. Very Shallow Water/Surf Zone Mine Countermeasures The Naval Sea Systems Command (NAVSEA) is conducting a Very Shallow Water/Surf Zone (VSW/SZ) Mine Countermeasures program for surf zone robotics. The goal is to develop a vehicle type that can be used to form teams for surf zone land-mine mapping and clearance. The concept is to use multiple vehicles to perform a coordinated search of a beach or surf zone area, send back imagery of suspected mines, document the location of each suspect object well enough to support reacquisition, and demonstrate the reacquisition, all in a timely fashion and robust against countermeasures. The required supporting technologies in the challenging surf zone environment are navigation, autonomous control of multiple vehicles, sensing—including detection, initial classification, and image capture—and communications. The “Very Shallow Water” part of the program introduces mine neutralization.

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Autonomous Vehicles in Support of Naval Operations Status of Unmanned Ground Vehicles Developed by the Navy for Other Services Mobile Detection Assessment Response System The Mobile Detection Assessment Response System-Exterior (MDARS-E) is a joint Army–Navy development effort to provide an automated intrusion-detection and inventory-assessment capability for use at DOD storage sites. The program4 is managed by the Office of Program Manager—Physical Security Equipment at Ft. Belvoir, Virginia. Overall technical direction for the program is provided by the Space and Naval Warfare Systems Center, San Diego. MDARS-E will patrol outdoor munitions and materiel storage sites. The onboard sensors support navigation (including obstacle avoidance), intruder detection, and inventory monitoring. The UGV patrols along a preprogrammed route defined by GPS coordinates. A system development and demonstration contract was awarded to General Dynamics Robotic Systems in January 2002, and an Initial Operational Test and Evaluation is scheduled to be conducted at Anniston Army Depot, Alabama, in FY06. Man Portable Robotics System The Army’s Unmanned Ground Vehicles/Systems Joint Project Office (UGV/S JPO) is sponsoring the Man Portable Robotics System as an initiative5 for the Joint Contingency Force Advanced Warfighter experiment. This tracked vehicle is intended to provide Special Forces with a means of reconnaissance in tunnels and sewers as well as other remote surveillance capability in urban warfare situations. Early experimental versions of this system were demonstrated in experiments conducted in 1999 and 2000. The system incorporates a digital telemetry link, which allows access by any Internet Protocol-based network. Future Combat System The Future Combat System (FCS) program is often described as a “system of systems.” It includes innovations in ground force organization, communications, command and control, manned vehicles, munitions, and other areas. Most importantly for the purposes of this study, it also includes three unmanned ground vehicles: the armed robotic vehicle (ARV), the multifunction utility logistics 4   For additional information, see the Web site <http://www.nosc.mil/robots/land/mdars/mdars.html>. Last accessed on March 31, 2004. 5   For additional information, see the Web site <http://www.jointrobotics.com/history/program_his/2000.html>. Last accessed on April 1, 2004.

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Autonomous Vehicles in Support of Naval Operations FIGURE 6.3 The Retarius vehicle from Lockheed Martin, featuring active articulated suspension. SOURCE: Defense Advanced Research Projects Agency. equipment (MULE) vehicle, and the small human-packable ground vehicle. The ARV is to be a 6-ton scout vehicle, capable of long-distance, unrefueled travel over a wide variety of terrain. The MULE is smaller, approximately 2.5 tons, and is sized to carry rucksacks and to follow soldiers or marines cross-country. The small, human-packable UGV is designed to be carried in a rucksack by a single soldier for rapid deployment over short ranges. Each of these vehicles will have communications and command-and-control functions built in to connect with the larger FCS network system. The FCS program began as a jointly managed DARPA/Army program. DARPA has sponsored the initial vehicle prototypes under its Unmanned Ground Combat Vehicle (UGCV) program, which includes the Retarius (Figure 6.3) from Lockheed Martin and the Spinner (Figure 6.4) from Carnegie Mellon. Besides sponsoring the development of the vehicle hardware for the Perceptor (Perception for Offroad Robotics), DARPA also sponsored intelligent mobility software under its Perceptor program.6 The Perceptor teams took standard Honda 6   For additional information, see the Web site <http://www.darpa.mil/tto/programs/fcs_Per.html>. Last accessed on March 31, 2004.

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Autonomous Vehicles in Support of Naval Operations FIGURE 6.4 The Spinner, from Carnegie Mellon University, with turbine power, electric final drives, and long-travel suspension. SOURCE: Available online at <http://www.darpa.mil/body/team_spinner.htm>. Last accessed on March 31, 2004. all-terrain-vehicle platforms and added computer-controlled actuators, sensors, communication links, and power supplies to turn them into robot vehicles (Figure 6.5). The intent was to develop the vehicles under the UGCV program and the software under Perceptor, and then to use the knowledge gained from those two projects in the ongoing FCS program. The other thread of robotic vehicle development is the ARL’s Demo III/Collaborative Technology Alliances program. This program uses the XUV, a vehicle built by General Dynamics and specially designed to be a robotics testbed (Figure 6.6). The main emphasis of this program is tactically relevant mobility—which means driving over a variety of terrain and being supervised by soldiers over a moderate-bandwidth radio link. The Demo III vehicles have recently completed a series of tests covering more than 500 km, running in a combination of desert terrain, forest trails, and urban environments. This program continues in active development as part of the ARL Collaborative Technology Alliances program.7 An important distinction between the Perceptor and Demo III is the 7   For additional information, see the Web site <http://www.arl.mil/alliances/>. Last accessed on March 31, 2004.

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Autonomous Vehicles in Support of Naval Operations FIGURE 6.6 The General Dynamics experimental unmanned vehicle (XUV). SOURCE: National Institute of Standards and Technology; see the Web site <http://www.isd.cme.nist.gov/documents/hong/SPIERoad_Detect.pdf>. Last accessed on March 31, 2004. mines inland endanger and impede the advance of the landing force. Current approaches to detecting and clearing these mines are either inadequate or slow and expensive. For example, Bangalore Torpedoes or snake charges work to clear the antipersonnel mines, but they are heavy and impose a large logistics burden. Remote-sensing techniques are not up to the job, especially when there is vegetative cover. Surf zone mines, intended to destroy landing craft, can be dealt with by SEAL (sea, air, and land) teams (sometimes aided by aquatic mammals), but this is a dangerous, time-consuming, and expensive process. The VSW/SZ Mine Countermeasures program as described earlier is working to address these issues using UGVs, but the results of that program are not mature enough for deployment. Many other applications of UGVs in support of Navy and Marine Corps operations are possible; they overlap with Army or civilian applications. These applications are briefly outlined in the section above entitled “The Potential of

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Autonomous Vehicles in Support of Naval Operations Unmanned Ground Vehicles for Naval Operations,” and they are detailed in the 2002 report of the National Research Council on Army UGVs.8 Unmanned Ground Vehicle Technology Issues While unmanned ground vehicles share many technical challenges with unmanned aerial vehicles and unmanned undersea vehicles, several unique aspects of UGVs have influenced and limited their development. The most obvious is the complexity of the operating environment. Ground vehicles operate in a cluttered and unpredictable environment containing obstacles that are not known at any detailed level before the mission. Thus, as discussed below, the basic problem of planning and executing a route from point A to point B is one of the fundamental tasks still being researched. Basic Mobility Issues Sensors. Very little sensor development has been specifically driven by the needs of ground robots. Military sensors are typically developed for long-range target detection. The resulting sensors typically are large (e.g., 8 in. optics) and heavy and have a very narrow field of view. Sensors for local navigation, in contrast, must be small enough and light enough to be mounted on a small robot bouncing over rough terrain, and they must have a wide or adjustable field of view in order to see objects in the path of the vehicle. Typical mobile robot sensors include video and infrared (IR) imagers, stereo video systems, scanning laser rangefinders, millimeter radars, and ultrasound. Trade-offs between these sensors include active versus passive sensing, limited capability versus all-weather day-or-night operation, required range and resolution, and required recognition capabilities. Sensor Interpretation. Raw sensor data (such as images and range measurements) need to be interpreted by computer algorithms in order for useful information to be generated. It is fairly straightforward to measure distances and sizes: stereo or LIDAR (light detection and ranging) or radar processing can yield the range of an obstacle, the roughness of the terrain, or the size of a rock. It is much more difficult to automatically label the data: is an object a soft bush or a hard rock, a hard surface or quicksand, a fixed obstacle or a mine or an unpredictable pedestrian? Some of those decisions can be made reliably with current technology, but others are beyond the state of the art. More difficult yet is generating inferences—a person acting in 8   National Research Council. 2002. Technology Development for Army Unmanned Ground Vehicles, The National Academies Press, Washington, D.C.

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Autonomous Vehicles in Support of Naval Operations such and such a way is likely to be hostile, or a ball bouncing across a road may indicate that a child will chase it into the roadway. Planning. Geometric planning is fairly well understood. It is straightforward to plan a route that optimizes a combination of good traversibility, stealthy motion, and minimal travel time. It is also straightforward to update that route on the fly, as new information is perceived and added to the map. It is far more difficult to automatically plan and execute maneuvers that include multiple cooperating vehicles in combination with unknown terrain and unknown threat conditions and to assess those threat conditions. Behaviors. At the lowest level of robot driving, the fastest loops of the control system are referred to as “behaviors” instead of “deliberative plans.” Typical robot behaviors include reflexive obstacle avoidance, road following, formation keeping, or steering to avoid tipping over on steep-sided slopes. Building individual behaviors is often possible; combining multiple behaviors into a coherent system is still not completely understood but needs to be accomplished. System Architecture. To combine sensing, sensor interpretation, planning, plan execution, behaviors, and user interactions requires a systems architecture. Mobile robots have several different approaches to systems architectures, depending on the complexity of the various components. The “best” systems architecture for mobile robots has not yet been identified. User Interface. Even in the best of cases, teleoperation (remote control) of a ground vehicle is not easy. The optimal conditions for a remote operator include good video sensors on the robot that are properly positioned to see the edge of the vehicle as well as the surrounding terrain, high-bandwidth links (fiber optic or radio) with appropriate latencies to the remote control station, wide-screen displays, an “artificial horizon” indicator similar to those on aircraft, anomaly detection, and a comfortable layout of controls. Despite all these user conveniences, teleoperators can become disoriented, lose track of obstacles behind the vehicle, and fail to notice gradually increasing side slopes leading to vehicle rollover, and they often become nauseous when the bouncing video from a rough-terrain vehicle does not match the cues from their own inner ears. These difficulties are exacerbated by poorer-quality sensors on the vehicle, lower-bandwidth communications links, smaller or dimmer displays, and by operators being under pressure from fatigue or enemy fire. Research continues to improve the situation, through telesupervision (higher-level control, such as designating waypoints); better interfaces (wearable displays); and multimodal interfaces (robots that can follow voice commands or hand signals). The most sophisticated interfaces use a combination of levels of

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Autonomous Vehicles in Support of Naval Operations command, so the user can either work at a low level for tight vehicle maneuvers or can give the robot higher-level tasks and then focus user attention on other activities until the robot reports success or asks for additional directions. Communications, Power, and Mechanism Design. Besides all of the robot-specific issues mentioned above, unmanned ground vehicles need all the other components of any vehicle system. Communications can be by tether cable, line-of-sight radio, multihop links, or low-bandwidth, non-line-of-sight radio. For some environments (e.g., caves) or some missions (reconnaissance), complete radio silence may be enforced by physics or by doctrine. Power supplies for a large robot vehicle are not difficult—diesel engines or turbines provide good power sources, with battery backup. But for smaller robots, power supplies become a major limiter of speed and range. Similarly, mechanism design for a UGV can take advantage of military vehicle designs, including those for tracks, wheels, and hovercraft. Specialty vehicles have been built with legs (eight or six for stable walking; four, two, or even one for running and hopping) and hybrid designs (e.g., wheels on the ends of legs). Mission Payload Issues Beyond the problems of basic mobility, a UGV must perform a useful mission. Mission payloads involve another set of issues: target detection and tracking for a reconnaissance vehicle, cargo lifting and hauling for a logistics vehicle, path tracking and safe intervehicle separation for automated convoys, and so on. Each of these areas is partially understood and continues to be the topic of ongoing research and development. Surf Zone Unmanned Ground Vehicles The UGV technology need specific to unmet naval needs is surf zone mobility. This is a challenging environment for an autonomous vehicle that is attempting to conduct a complete survey of its assigned beach area. The many difficult technical problems in mine hunting in very shallow water include these: Mobility. Wave action, soft soil, and rough terrain all impede motion. Perception. In shallow water or the surf zone, the water is often turbid, making video sensing difficult. Acoustic sensing is also limited by reflections from the surface and bottom and by acoustic noise from breaking waves. Communications. Acoustic communications are typically limited to low bandwidths or short ranges, due to the same factors that limit acoustic sensing. Radio communications are only possible if the provisional antenna remains clear of the water surface.

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Autonomous Vehicles in Support of Naval Operations Power. Air-breathing power systems using a snorkel are difficult to implement in the surf zone. Battery power is the most practical approach, but that limits the range and endurance of the vehicles. Since the beginning of the 1980s, a series of research and development programs has addressed the issues listed above, first through the DARPA Lemmings program (by Arnie Mangolds at Foster-Miller) and then through the ONR VSW/SZ Mine Countermeasures program. The current state of the art uses the SeaTALON (a multimission detection and tracking system for littoral battlespace) platform, based on the Foster-Miller Talon land-based vehicle, which is in active military Service. The TALON is a straightforward vehicle with two nonarticulated tracks; the vehicle is 34 in. × 22.5 in. × 11 in. in its stowed condition. Work on the crawler platforms and the VSW/SZ countermine mission is in current progress on two main fronts—the SeaTALON platform and the associated sonar system are being implemented (Figure 6.7) and thoroughly tested in a progression of field tests and exercises, and the needed countermine sensors and imagers are being developed and put into configurations suitable for installation on the SeaTALON and use by the fleet. Current instrumentation on the SeaTALON includes a suite of sensors—low-light, gray-scale video cameras; specialized illumination sources for underwater viewing; a scanning laser; and a rotating sonar head (Figure 6.8). Nonimaging sensors under development include tactile sensors to feel mines, chemical sensors to sniff mine residue in the water column, and magnetic mine sensors. Typical communications systems either send compressed images directly over acoustic links or use a radio utility float that can transmit real-time video. There are alternative systems approaches to the problem of antipersonnel mines impeding dismounted advance ashore. Note that the use of Bangalore Torpedo line charges is very effective in clearing a path; however, the weight of the devices and the slowness of employing them make them logistically undesirable, because they have to be carried and manually handled in the landing operation. But a UGV could be designed to walk ahead of the advancing column: it could lay out the line charge ahead of itself and detonate the charge so as to semiautonomously (it could be steered by a member of the column advancing behind it) clear a safe path to the objective cover behind the beach landing zone. Alternatively, a UGV similar to the Mini-Flail could lead advancing troops. Note that the Mini-Flail has experienced difficulties with barbed wire entanglement; the line charge approach does not have that problem. The technology programs in support of UGV systems are “bottom-up” programs. That is, they are driven more by technological capability than by top-down consideration of unmet mission needs. The alternative approaches to surf zone mine clearing described above result from a top-down consideration of the mission need. The Navy (and Marine Corps) need a small group whose function

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Autonomous Vehicles in Support of Naval Operations FIGURE 6.7 Two SeaTALONs in a surf exercise. SOURCE: Department of the Navy. FIGURE 6.8 (A) Rotating-head sonar mounted on a tactical autonomous robot (TAR) crawler during reacquisition exercises. (B) An example of a half-field scan; range lines are 10 m per division; five targets are visible in the scan. SOURCE: Department of the Navy.

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Autonomous Vehicles in Support of Naval Operations is to investigate the possible fulfillment of unmet needs by UGVs (or indeed by any autonomous platform). The group needs to work toward the synthesis of systems that fulfill unmet mission needs in ways other than automating the operational procedures currently used by manned systems. OPPORTUNITIES FOR IMPROVED NAVAL OPERATIONS The main integration issue for improved naval UGV operations arises with the conduct and the products of reconnaissance, surveillance, and target acquisition (RSTA) activities. The use of UGVs in motion or “perching” ashore offers promise of an effective and inexpensive monitoring capability in support of shore bombardment and pre-invasion preparation of the battlefield. In order to reap the full benefit, the imagery needs to be formatted and indexed compatibly with RSTA products available from other Navy and other Service systems. Thus, UGVs with RSTA capability could use Internet Protocol packets for communication (to participate in the Global Information Grid (GIG)) and could use GPS coordinates for positioning information when possible. (In certain situations GPS is not available to a UGV—for example, in tunnels, caves, some urban environments, or in a jamming environment.) One of the goals of increasing the autonomy of UGVs is to decrease the operational demand on Marines in the field. The current mode of controlling UGVs locally creates a burden and a distraction for the operator. For long-range scouting missions, the control of UGV systems could be accomplished from onboard ship or from a secure facility. If significant advances in autonomy can be accomplished, the control could be integrated into the command-and-control system used for UAVs. On the other hand, in the case of UGVs used in close cooperation with ground forces such as for mine clearance to support advance from a beachhead, it will be essential that the control of the UGVs be possible from the forward-deployed units at a low echelon of command. This arrangement will facilitate flexible response as the tactical situation unfolds in the field. The advancement of UGVs is dependent on a wide variety of technologies that have matured to very different levels. Manipulators, arms, sensors, and basic mobility have been critical to commercial robotics for several decades and are well developed for controlled environments. Perception, planning, and navigation in cluttered and unpredictable environments are much less developed. In order to make useful progress, it is essential to focus on the system as a whole, beginning with a clear mission need and taking into account during the development of vehicles the entire range of considerations in the use of the vehicle. Such considerations include the following: How will the system be tested and validated? How will the vehicle be transported to the battlefield?

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Autonomous Vehicles in Support of Naval Operations Where will it be stored until it is used? How will it be fueled and maintained? How will it be deployed from its storage? Where will it be controlled/monitored from? How will it communicate? How will it handle unexpected situations? How will it be retrieved after it is employed? How will the users be trained? How will the vehicle be integrated into command-and-control structures? These are just some of the questions to be considered, but it is important that a major component of the research and development efforts be aimed at these types of practical considerations, framed by a clearly defined mission task description. One way to focus research on these types of issues is to develop real-world challenges and competitions that encourage researchers to focus on accomplishing a mission in a real-world environment with a view of the systems requirements. Allowing developers to compare the capabilities of their machines would provide regular benchmarks of the state of the art. Such competitions might be sponsored by professional societies or DOD entities, but they could be encouraged by Navy participation, as appropriate, and by encouraging Navy-supported researchers and developers to compete. CONCLUSIONS AND RECOMMENDATIONS Conclusions and recommendations based on the preceding discussions are presented in the following subsections. Conclusions Concerning Unmanned Ground Vehicles Leveraging Efforts of Other Services The Navy has a well-established position in the research and development of unmanned ground vehicles. Although certain specific needs are unique to the Navy mission, it is important that the Navy and Marine Corps leverage the efforts of other Services as well. Several formal mechanisms exist to help with this coordination, including the Office of the Secretary of Defense Joint Robotics Program.9 Programs of particular significance for collaboration are the Unmanned Ground Vehicle Joint Program Office; work at the Air Force Research Laboratory; the Army’s Tank and Automotive Research, Development, and Engineering Center; and tech- 9   For additional information, see the Web site <http://www.jointrobotics.com/>. Last accessed on April 1, 2004.

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Autonomous Vehicles in Support of Naval Operations nology base programs at the Defense Advanced Research Projects Agency, Special Operations Command, and Army Research Laboratory. Mine Detection and Clearance in the Surf Zone Mine detection and clearance in the surf zone and beach area constitute the most significant naval need that can be addressed by UGVs. Bangalore Torpedoes or line charges work to clear antipersonnel mines, but they are heavy and impose a large logistics burden. Remote-sensing techniques provide a partial solution but are inadequate in the surf zone and on land areas with vegetative cover. SEAL teams (sometimes aided by aquatic mammals) are very effective, but mine detection and clearance in surf zones and beach areas are dangerous, time-consuming processes. The Very Shallow Water/Surf Zone Mine Countermeasures program is working to address these issues. Surf Zone Technology Needs The surf zone is an extremely challenging environment for autonomous vehicles. Particular issues in this environment are mobility, perception, communications, and energy storage. Since the surf zone is rather unique to the Navy mission, the technology needs for UGVs operating in the surf zone are not likely to be addressed by the other Services or the commercial sector. Sensors and Sensor Data Interpretation There is a strong need for advanced sensing systems for UGVs. Very little sensor development has been specifically driven by the needs of ground robots. Thus, many sensors that would be useful on UGVs are large and heavy and have a very narrow field of view. Sensors for local UGV navigation, in contrast, must be small enough and light enough to be mounted on a small robot bouncing over rough terrain, and they must have a wide or adjustable field of view for seeing objects in the path of the vehicle. The perception subsystem of a UGV takes the data from sensors and develops a representation of the world around the UGV, called a world map, sufficient for taking those actions necessary for the UGV to achieve its goals. Without the perception capability, there can be no fully autonomous operation, and without a high level of autonomy the transformational potential of UGVs will not be realized. Raw sensor data (e.g., images and range measurements) need to be interpreted by computer algorithms in order to generate useful information. In particular, the ability to automatically distinguish, for example, between a soft bush and a hard rock, a hard surface and quicksand, a fixed obstacle and an unpredictable pedestrian, is important for path planning of USVs.

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Autonomous Vehicles in Support of Naval Operations Planning and Behaviors The onboard automated planning of vehicle actions is a fairly mature technology at present, but there are significant needs in this area as well. It is straightforward to plan an appropriate route using a stored map and to update that route as new information is received and added to the map. It is more difficult to automatically plan and execute maneuvers that include multiple cooperating vehicles in the presence of unknown terrain and unknown threat conditions. At the lowest level of robot driving, the fastest loops of the control system are referred to as “behaviors” instead of “deliberative plans.” Typical robot behaviors include reflexive obstacle avoidance, road following, formation keeping, or steering to avoid tipping over on steep-sided slopes. Building individual behaviors is often possible with current technology, but how to combine multiple behaviors into a coherent system is still not well understood. User Interfaces The remote operation of UGVs is a continuing area of difficulty. Teleoperation of a ground vehicle is usually difficult in many operational environments, as operators become disoriented, lose track of obstacles that may be behind the vehicle, fail to notice gradually increasing side slopes leading to vehicle rollover, and often become nauseous when the bouncing video from a rough-terrain vehicle does not match the cues from their own inner ears. There is an important need for effective human interfaces to facilitate the teleoperation of UGVs or to extend true autonomous capability. Recommendations Concerning Unmanned Ground Vehicles Recommendation: The Navy and Marine Corps should aggressively exploit the considerable warfighting benefits offered by autonomous vehicles (AVs) by acquiring operational experience with current systems and using lessons learned from that experience to develop future AV technologies, operational requirements, and systems concepts. Specifically: Accelerate the Introduction of Unmanned Ground Vehicles. The Office of Naval Research should support continued research into the use of unmanned ground vehicles (UGVs) as a potential solution to the mapping and clearance of surf zone and beach mines, and into UGV alternatives to unmanned aerial vehicles for surveillance missions in support of shore bombardment. Testing and development of the Gladiator and Dragon Runner should be increased in order to refine the capabilities of both systems. Partnering by the Navy and Marine Corps with the U.S. Army’s Future Combat System program in research and develop-

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Autonomous Vehicles in Support of Naval Operations ment efforts to develop UGV components should be encouraged by the Navy and Marine Corps. Recommendation: The Assistant Secretary of the Navy for Research, Development, and Acquisition and the Chief of Naval Research should direct the Navy and Marine Corps Systems Commands, the Office of Naval Research (ONR), and the Marine Corps Warfighting Laboratory (MCWL) to partner with the operational community and monitor the concepts and development of critical autonomous vehicle-related technologies considered essential to the accomplishment of future naval missions. The progress of these developments should be tracked year to year. Specifically: Pursue New Concepts and Technology Developments for Unmanned Ground Vehicles. The ONR should pursue a broad spectrum of research and development (R&D) on unmanned ground vehicles themselves and on their components. The R&D should range from basic research in sensors and sensor processing to field tests of complete systems. The Navy should continue to partner with the Office of the Secretary of Defense, the Defense Advanced Research Projects Agency, and the Army, as appropriate, utilizing the capabilities of the Space and Naval Warfare Systems Command for these activities.