Infantry: MUTT Outperforms MULE


January 15, 2020: For the third time in the last decade the U.S. Army is trying out another small UGV (unmanned ground vehicle) to carry supplies or casualties or whatever for infantry in a combat zone. The latest effort is called MUTT (Multi-Utility Tactical Transport) and can carry up to 454 kg (1,000 pounds). MUTT is able to travel 100 kilometers (60 miles) in a 72 hour period without refueling. MUTT is actually an all-electric vehicle that carries on an onboard generator that is silenced sufficiently to satisfy user noise complaints. MUTT is led, like a live mule, by a soldier using a wireless controller that has the MULE following the soldier at a walking pace. Actually one MUTT can electronically follow another so that a soldier can lead a small convoy of them if needed. The MUTT has sensors and control software that enables it to move over most terrain that a human can handle.

The basic MUTT design has three variations; 6x6 and 8x8 wheeled versions and a tracked version. The army found the one ton 8x8 design worked best in the field. MUTT can also recharge battery-operated equipment at the rate of 3 KW while stationary and 1 KW while moving. What the MUTT carries is most of the load a nine-man infantry squad would normally carry on their backs. By putting about half of that on the MUTT, plus extra ammo (including missiles) and other equipment the troops carry on them, MUTT leaves the troops, still carrying their weapons, protective vests and some ammo, which alone adds up to about 20 kg (44 pounds) each, better able to fight. Troops are more effective in combat when not loaded down by the extra weight they would normally carry on them.

MUTT was part of a five year competitive effort in which three designs were evaluated and MUTT was selected as the winning design. Now MUTT is ready for testing with troops in the field and then in a combat zone. These tests will be quite extensive and 624 MUTTs are being purchased, for $260,000 each, in order to get a large, and wide range of troop responses. After all, the army based the spec for the MUTT on all the responses it had received about earlier infantry UGV designs.

If MUTT is successful the army plans to buy 5,000 or more. Initially, a dozen or so will be given to each infantry battalion and they can be assigned to subordinate units as needed. A battalion has three infantry companies, nine infantry platoons and 27 squads, as well as more than a dozen other small specialist units in the battalion that can use a MUTT on occasion. If battalions find they need more the army is ready to provide them. A larger order would considerably reduce the price per vehicle.

In 2012 the U.S. Army's previous design of, well, a mechanical mule for the infantry, spent three months being tested in Afghanistan. Four of these vehicles were sent there to operate with the troops. This SMSS (Squad Mission Support System) was a six wheeled, 1.7 ton vehicle that could carry 544 kg (1,200 pounds) of cargo and follow whoever is carrying its controller. SMSS could 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 or anywhere close to the enemy. Patrols are what infantry spends most of their time doing out in the bush. The noise issue had been noted earlier and the manufacturer reduced it somewhat and added the capability to run very quietly for a short while. This was not enough because troops in the field reported 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 could solve this problem, the grunts were 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. But that was not useful enough to order more SMSS vehicles.

SMSS was built as an independent research project by Lockheed Martin to step in after the previous official effort in this area was canceled in 2010. That was the U.S. Army MULE (Multifunction Utility/Logistics and Equipment). This was a UGV that was part of the (now canceled) 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 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, which can be 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 items) 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 could 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) 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 were unforeseen problems revealed. This indicated what modifications had to be made or if MULE was a failure. But before that happened field tests in the United States were held and the results were disappointing. So MULE was canceled. The idea was still popular 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.

All this began in 2006 when the army put UGV development into high gear in an attempt to get more UGVs (unmanned ground vehicles) into the hands of the troops. After 2003 thousands of smaller UGVs were used by American troops for checking out caves and buildings. Some of these lightweight (under 45 kg/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 50 kg (over a 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. Initially, this proved to be a major obstacle. But even as engineers develop technology that solves this problem, the tests of Mule and SMSS revealed a more intractable one: noise. It was thought that the only way around this was 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. Many believe that MULE, and its descendants, will be relegated to logistics work, as they are simply too noisy to sneak around with the infantry. Despite that attitude, each mule design has been quieter.

When SMSS was canceled the army concluded that they were close and drew up a new specification that took into account all of the infantry complaints and who those complaints had to be addressed. That led to MUTT, which is not only built to deal with past experience but is a vehicle designed to be quickly and easily reconfigured to deal with user suggestions and complaints. This one might work and the users will decide.




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