Army Researchers Advance ‘Third Arm’ Project to Next Testing Phase

ABERDEEN PROVING GROUND, Md. — Soldiers may be asked to carry heavier, more lethal weapons in the near future, but they soon might have a “third arm” to improve their accuracy and reduce fatigue.

Using a mechanical apparatus that resembles something out of a sci-fi movie, the lightweight device will help redistribute some of the burden Soldiers carry in their arms and shoulders to their abdomen. Engineers at the Army Research Lab here have been developing a mechanical “third arm” that attaches to a user’s back hip.

Army Research Lab engineer Dan Baechle demonstrates how to strap on the “Third Arm,” a mechanical device designed to improve Soldiers’ accuracy and reduce fatigue. (Photo Credit: U.S. Army photo by Joe Lacdan)

The project, unveiled last year at a conference, is scheduled to be tested again sometime this spring with a minimum of 15 Soldiers.

“Right now we have a prototype that’s essentially a research platform that we’re using to investigate different types of materials — how materials and structures can stabilize a weapon or a shield, reduce fatigue on the Soldiers’ arms, but also improve accuracy,” said mechanical engineer Dan Baechle.

The project is currently on its second prototype model with improvements based on Soldier feedback. Some of the improvements include an extendable hinge plate so that a single plate can fit Soldiers of different sizes and body types. Baechle said further research must be completed before the device can be fielded. The current prototype at 3.5 pounds can now support weapons such as the M249 light machine gun that weighs about 27 pounds.

The project not only helps stabilize weapons, but can aid Soldiers for defensive purposes while carrying 20-pound shields. The project team developed a custom mount that connects from the arm to the shield so Soldiers can use the Third Arm to help alleviate muscle fatigue.

The “Third Arm” project is being developed not only for weapons but for defensive purposes. Army researchers at Aberdeen Proving Ground created a special mount to attach the apparatus to a shield and also provide stability and balance. (Photo Credit: U.S. Army photo by Joe Lacdan)

Concept development began in late 2015 when ARL engineers brainstormed ideas on how to make a dismounted Soldier more lethal. Engineers began building the first prototypes in 2016. The focus of the project centered on providing stability for dismounted Soldier. ARL engineers are examining different types of spring materials to further balance the weapon against gravity. Baechle said they used a carbon fiber material in the current prototype because of its light weight and density.

“We started out with just trying to think of a way to help improve the lethality for the dismounted Soldier,” Baechle said. “Generally that means stabilizing the weapon or giving the Soldier a more powerful weapon. Can we stabilize that weapon to improve accuracy? But also if we’re stabilizing the weapon and taking the load off of the Soldiers’ arms, does that improve the Soldier’s readiness? Does it also improve the Soldier’s accuracy with the weapon?”

Last summer, six Soldiers volunteered to take part in a pilot study, where researchers placed electromyography sensors to measure muscle activity. In particular, when holding a weapon or shield for extended periods of time, the arm begins to shake, impacting shooter accuracy. The six-person research team tested Soldiers firing weapons with and without the apparatus.

“We found that it reduced the fatigue and reduced the muscle activation for some Soldiers,” Baechle said, explaining that data is being used to motivate a larger trial this year with more Soldiers. This year he also plans to get more feedback on what Soldiers think about the device and what should be changed.

Last year researchers collected data on how much muscles were firing with the use of the third arm compared to without it.

“There are studies showing that, if you hold a weight out at arm’s length, eventually your arm starts shaking,” Baechle said. “And that shaking is going to reduce your accuracy with the weapon … and if you’re holding a shield, it’s going to reduce the amount of time that you can hold that shield. So we’re taking that weight of the weapon or the shield off of the arms and transferring it back to the torso.”

While the test yielded positive results, Baechle said some of the Soldiers had problems with the device. Improvements made this year include changing the mounting location from the front of the Soldier’s vest to the back.

Researchers hope to further improve the device to make it more comfortable and reduce fatigue even more. They are continually attempting to make adjustments to the device to boost a shooter’s accuracy.

Baechle demonstrated how ARL researchers use a motion capture system, using monitors and infra-red targeting to track a Soldier’s weapon and target.

“We use this system to evaluate both how subjects or Soldiers move the weapon and with and without the third arm,” Baechle said. “But also how the arm improves the accuracy or changes the aim point while they’re using the weapon.”

Finally researchers hope the project can reduce some of the recoil force after firing a weapon.

“You have a lighter weight weapon but potentially a higher caliber weapon which normally would increase the recoil on your shoulder,” Baechle said. “Could you use Third Arm and some clever materials on the arm to redirect that recoil back toward the body and thus allow the Soldier to wield a higher energy weapon without necessarily burdening the Soldier more?”

By Joe Lacdan, Army News Service

38 Responses to “Army Researchers Advance ‘Third Arm’ Project to Next Testing Phase”

  1. Ben says:

    How many months and how many dollars to develop tech the movie industry has had since the early 70’s? Awesome.

  2. SShink says:

    The pictured prototype looks rudimentary and not ergonomic…why not some molded carbon fiber or something along those lines?

    • Adun says:

      It is probably a lot easier to make rapid changes to the prototype with a simpler design with less expensive materials and then they will scale up to their full production model which would be a more polished design.

      You don’t want to have to make things out of carbon fiber every time you need to make a small change. This could also be a much earlier version of the design that they are showing us that at least gets the basic design across.

      • Adun says:

        We used to do the same thing with delrin before we spent the time and money cutting something out of steel or aluminum, it is just easier and faster material to work with for certain prototyping applications.

  3. Justin says:

    This whole concept looks like a waste of time at first glance, but I’m interested in what happens when a decent power system and AI is added.

    • Adun says:

      To me, it looks like a furthering of the MAWASHI unpowered exosuit concept and that looks pretty promising. If you combined the two concepts this could make rucking a machine gun a lot easier. Unpowered systems are a lot more attractive to military logistics too, so as long as this arm doesn’t make it impossible to go prone, sit comfortably in a vehicle, or pose an additional injury risk, I can see the idea having some promise.

      • Joglee says:

        Until you take fire and have to dive to the ground. Have to go crossing a canal. Have to traverse a jungle type climate. Have to climb a wall. Have to get out of a HMMWV quickly or just even move within one.

        Overall it’s a terrible idea.

    • joe says:

      Adding a servo controlled, AI assisted aiming system can be done right now with today’s tech. After all, that’s tech that been on tanks for decades.

      Heck, you can use a smartphone as the brains as it has the computer power, gyroscope, and camera.

    • Don Dan says:

      Reminds me of Rouge Trooper, Bagman…

  4. AbnMedOps says:

    “like something out of science fiction…” Now, THAT’s an original phrase…

  5. joe says:

    “There are studies showing that, if you hold a weight out at arm’s length, eventually your arm starts shaking,”

    This is why I thing bullpups are better, all the weight is in the back, meaning there’s less weight wobbling out in space causing fatigue, makes for better standing accuracy.

    For the shield, I can see that mounted on some sort of Segway as a better option, which would be full body, heavier duty and not something you need to lug..

    Has anyone tried that, mounting a ballistic shield on a motorized platform? Mount on your EOD robot maybe?

    • Sean says:

      I could have sworn I’ve seen a pic of something like this from some asian military or police force.

      • Matthew says:

        Chinese anti-terrorism police, Beijing Olympics, 2008.

        • joe says:

          The Chinese thing is just cops on Segaways.

          I’m looking at mounting a large, 200LBS Level IV Ballistic shield on a Segway with a handle on the back to push/move it around with.

          Think of it as taking the large shields at the gate of JBLM and making it tactically mobile instead of a static defense.

  6. Ed says:

    Smartgun from aliens

  7. SSD says:

    If it actually came with a Crye JPC, everyone would want one and the third arm would sit in wall lockers.

  8. James says:

    Probably thinking of the Chinese antiterrorism police Segway.

    Once upon a time, guys would collapse their stocks and use the magwell or a VFG placed in close. The proliferation of NVG and the now required laser along with increased suppressor use added a need for more rail space and pushed the weight toward the front of the gun. Which is why we see lighter barrels, rails and recievers. Guys are still running stocks fully extended and the off hand as far forward as possible , so the can have leverage on the gun. Some of that may be addressed with optics integrated lasers and better rounds for short barrels, like the Navy is looking at with their 300Blk PDW, but I wouldn’t expect it to change much. Still going to be a lot more time spent standing around on security, and if this helps guys actually keep the gun up and not slung……

  9. Vic Toree says:

    Somewhere, someday, there will be a Joe in a portajohn using this in ways that violate general order #1.

  10. SGT Rock says:

    Hmm… What about a ‘Third Leg’ project instead?

    • Maskirovka says:

      I was really hoping to get to the bottom of the comments and see “third leg” jokes unused and mine for the picking. Thanks for dashing my hopes.

  11. Kirk says:

    It would be interesting to see what the actual inherent performance characteristics are, here, and what the potentials are for doing things like automate the equipment to respond to fire control commands from the leadership.

    You can’t make a bipod-mounted MG perform similarly to that MG mounted on a tripod; if this system can be made sufficiently stable for something like that, then we may have a replacement for the tripod. Looking at the complexity of the task, though… I think it’s going to be a long damn time before this sort of thing is going to be capable of supporting accurate MG fires out to 1800m or so.

    But, as the nice man said, you have to start somewhere.

    I’m thinking that we probably need to start working on the supporting framework of “how the hell do we use this stuff”, and how to best take advantage of these things. Back in the old days, it was fire control commands, today we’re using personal radios. In the future, are we going to be relaying fire control commands to our gun teams and riflemen via virtual reality HUD interfaces? What are the conventions we’re going to use?

    I think that it’s best to think about these things in advance, so that you can cope with the innovation as it happens, instead of in retrospect.

    There’s no doubt in my mind that we’re going to have to put ELINT and electronic command and control features down to the squad level, and that our future squad/platoon leaders are going to have to deal with things we currently think of as strictly company-level issues, like RPV and ELINT warfare. How we integrate all this together is going to be a major issue, and we’d better start thinking about it right now.

  12. Neal says:

    That thing looks awesome.

  13. Jay says:

    Is the idea for this to may the infantry’s job easier?

  14. Resurgens6 says:

    Nice to see some miney been spent on grunt research and not just another billion dollar plane. That said, im still waiting for a shoulder mounted predator cannon…