Military MULE

At first glance, the unmanned ground vehicles under development for the Army’s Future Combat Systems program couldn’t be more different from the robotized SUVs that participated in DARPA’s recent Urban Challenge. Think of it as the difference between a baby Hummer in the suburbs and a Humvee in Iraq.

Yet, when it comes to autonomous navigation, the FCS’ Multifunctional Utility/Logistics and Equipment (MULE) Vehicles and DARPA vehicles have plenty in common. “We use many of the same sorts of technology for autonomous navigation as the DARPA vehicles,” says Dr. Alan Walls, Future Combat Systems lead for unmanned ground vehicles and vice president of Science Applications International Corp. (SAIC), one of the lead systems integrators for the FCS program.

The MULE platform, which will include variants for transport, armed reconnaissance and countermine missions, will all navigate under the control of sensors and sophisticated software algorithms. Like the DARPA vehicles, the MULEs will sport a variety of complementary sensing technologies — including LIDAR, millimeter-wave radar, optical systems on all sides and a vehicle positioning system that combines GPS and inertial data. Walls says the MULEs will likely roll with some advanced sensors, particularly higher-resolution LIDAR, unavailable to the DARPA teams. But the general approach to sensing remains similar.

And like the DARPA vehicles, much of the development effort in the MULEs autonomous navigation systems relate to motion planning and behavioral algorithms that can give the vehicles enough smarts to navigate tough terrain, avoid obstacles and make some tactical decisions on their own.

Perhaps the biggest difference with the DARPA demonstration vehicles and the real-world MULEs relates to what you might call the joystick factor. In contrast to the full-autonomy demonstrated in the DARPA race, the MULEs will operate with semi-autonomy — a mixture of autonomous navigation with tele-operation of some vehicle functions. “They’ll blend autonomy with some human control,” Walls says.

The tasks expected to require some human control highlight some of the current limitations in autonomy — both from a technology standpoint and our willingness to rely on robots to perform tasks that call for human judgement. For example, Walls says humans might take the joystick when the MULE has to cross difficult terrain, particularly when the terrain has changed relative to the MULE's waypoint programming. “There will be unknowns that may require human control,” he says.

Another important area where the Army wants to retain human control is firing weapons. Walls says FCS rules insist human operators visually confirm targets before firing weapons. “The MULEs will not automatically fire weapons,” he says. And that’s not likely to change any time soon.

Aside from the approach to autonomy, the MULEs do have some important design features to make them battlefield-ready. Among them are a diesel hybrid-electric powertrain and an articulated suspension system for its six wheels. Walls says the suspension will allow the vehicle to drive over steps and other obstacles more than 1.5m high.

The MULE platform will have its preliminary design review next week, while first prototypes won’t be ready until early in 2011, Walls reports. Once it does go into the field 12 to 18 months later, it will be the military’s first full-sized robotic vehicle.