April 1, 2012: The U.S. Army's latest design of, well, a mechanical mule for the infantry spent the last three months being tested in Afghanistan. Four of these vehicles were sent there to operate with the troops. The SMSS (Squad Mission Support System) is a six wheeled, 1.7 ton vehicle that can carry 544 kg (1,200 pounds) of cargo and will follow whoever is carrying its controller and can operate by itself for short distances.
The SMSS had passed most of its tests in the United States and was then used by some troops with combat experience. There it was discovered that the vehicle was too noisy for patrol work (which is what infantry spent most of their time doing out in the bush). The noise issue was noted earlier, the manufacturer reduced it somewhat and added the capability to run very quietly for a short while. But this was not enough because troops in the field noted that even with no engine noise, the sound of the vehicle moving and breaking branches as it moved was enough to alert any nearby enemy. The manufacturer insists they can solve this problem, the grunts are not so sure. Silence is very important in a place like Afghanistan. The SMSS vehicles sent to Afghanistan were quieter but troops found them still too noisy for many patrol situations. But the idea of having a vehicle to haul a lot of the stuff usually carried on the backs of soldiers had a huge appeal in Afghanistan. So the troops improvised and the SMSS was found to be useful under some conditions. It's still unclear if SMSS will be bought and used in large quantities.
SMSS was built as an independent research project by Lockheed Martin. The official effort in this area was cancelled two years ago. That was the U.S. Army MULE (Multifunction Utility/Logistics and Equipment). This was a UGV (unmanned ground vehicle) that was part of the (now cancelled) FCS (Future Combat Systems) program. While maligned by the media, many politicians, and even people in the army, as an expensive boondoggle, FCS provided the money to create some revolutionary and effective combat technology. MULE was one of these futuristic vehicles, a robotic vehicle for carrying stuff on the battlefield. In practice, it did not work out. Close but not close enough.
MULE was a one ton, six wheeled vehicle that was 4.8 meters (15 feet) long, two meters (six feet) wide, and carried half a ton of equipment or weapons. Yes, it is very similar to SMSS, which built on what MULE had accomplished. Note that a pack animal, like a mule, can carry 200 kg (440 pounds) is silent and runs on biofuel (grass). The U.S. Army Special Forces will still use mules and horses but that's because the Special Forces have traditionally been left alone to get the job done any way they can.
The MULE operator (any infantryman with an hour or so of training) used a handheld controller to tell the MULE to go from Point A to Point B. The MULE had enough computing power to get over obstacles it could handle and go around those it couldn't. The MULE was to be used to do a lot of dangerous jobs normally handled by the troops. Like bringing supplies (ammo, water, weapons, or medical supplies) that last few hundred meters to where the fighting was going on. Currently, that means troops hauling this stuff themselves and exposing themselves to enemy fire. Troops in Afghanistan mentioned this as a useful task for SMSS, as well as hauling supplies from drop zones, landing zones, or from trucks to harder to reach (intentionally) FOBs (Forward Operating Bases).
The MULE or SMSS can also take casualties far enough away so a medevac helicopter can take over. MULE could also be equipped with mine clearing equipment to perform another dangerous job. MULE was also to be equipped with heavy weapons (12.7mm/.50 caliber machine-gun, small caliber cannon, or missiles) that was to be fired under human control. The troops were really eager to have something like the MULE around, if only because it made their life in the combat zone so much easier and safer. The MULE was designed to take a lot of damage and keep going. However, only after actually using it in combat would unforeseen problems be revealed. This would indicate what modifications had to be made. But before that happened field tests in the United States were held and the results were disappointing. So MULE was cancelled. The idea is still alive and Son of MULE, in the form of SMSS, showed up for testing a year after MULE was put down. Another contender, which did less well in stateside testing, was Camel (from Northrop Grumman). This one was smaller than MULE and proved less stable on rough terrain.
Six years ago the army put UGV development into high gear in an attempt to get more UGVs (unmanned ground vehicles) into the hands of the troops. Over the last few years thousands of small UGVs have been used by American troops for checking out caves and buildings. Some of these lightweight (under a hundred pounds) robots were even equipped with weapons but not used much when armed.
Based on the positive experience with the little robots the army hoped that the next class of UGVs would be heavier, weighing 1-3 tons. That's where the much anticipated MULE came in. There was a need for something like the MULE to deal with a growing problem. As more gadgets are invented for the troops the weight they have to carry keeps increasing. One solution was believed to be a UGV that can accompany troops, carrying a lot of this load (otherwise, each soldier is going to be carrying about 55 kg/hundred pounds of gear, which is hardly “fighting weight”). There was one known problem, a major one, and that was the building of a sensor/software system that would allow the mule UGV to move along the ground without a human driver. So far, this has proved to be a major obstacle. But even as engineers develop technology that solves this problem, the recent tests of SMSS revealed a more intractable one: noise. The only way around this is a six legged vehicle. These have been in development for years and the technology is there. But these vehicles require a lot more power and there's always an acute shortage of that in the combat zone. So it looks like MULE, and its descendants, will be relegated to logistics work, as they are simply too noisy to sneak around with the infantry.