Wednesday, August 6, 2014

How to fight someone wearing a powered exoskeleton

Powered human exoskeletons have been in the dreams of science fiction enthusiasts for decades, but in the last few years, they have started to become a reality.  The united states military is currently working on a prototype of the TALOS Suit,  dockworkers are already using them in South Korea, and a powered exoskeleton even helped a paraplegic kick off the 2014 world cup.

With all of these amazing steps forward in technology, pushing the limits of human capabilities, the question arises "what would you do if you ended up in a fistfight against someone wearing a powered exoskeleton?"

Of course, I've never fought an opponent in an exoskeleton before (I'm pretty sure nobody has), but drawing from what I know about robotics, physics, and martial arts, here are a few of my my best guesses at how to win that fight.

Evaluate your opponent:

  • Am I about to punch someone who can't walk?  This should be the first thing you ask yourself when facing an opponent in an exoskeleton.  A large number of exoskeletons are specifically built to help people walk who would otherwise be confined to wheelchairs, so if you are fighting someone with a medical exoskeleton, unless you want to be remembered as a horrible person for more than a hundred years, you should turn around and run away immediately.  Here are a few examples of exoskeletons built for mobility:

    • Note that most of these have slightly awkward walks (forearm crutches or a walker may still be necessary), the mechanical joints only go waist-high, and they are not reenforced, since they are not designed to be any stronger than regular human legs.
    • I should also point out that Cyberdyne's HAL has a lower body exoskeleton for medical use and another for non-medical use and they look almost identical, so be careful:

Non-Medical, strength enhancing exoskeleton
  • How does the exoskeleton work?  There are a lot of different types of exoskeletons out there, so it would be smart to try to figure out what you are up against.
    • What is the power source?  Exoskeletons require a lot of power for extended use.  Some are able to run on batteries, but others require a combustion engine worn as a backpack or a tether (a fancy power chord).  If your opponent has a tether, you need to find it and yank on it immediately.  It is probably not going to unplug easily, but if you can pull him to the floor with it, you just won your fight.  If not, try to wrap it around anything you can to limit his mobility.
    • How do the joints move?  Most exoskeleton joints are either hydraulically actuated or they are controlled by servomotors.  Servomotors will make a noise like an electric scooter or an RC car, and they almost certainly use load bearing gears, so there is a chance (no promises) that a sudden impact along the direction of regular motion could cause a joint to seize up.
    • Which joints are powered?  Some exoskeletons only enhance the legs, while others include the arms.  The hands are typically not powered, so you should probably expect more chops than punches.
    • Where is the center of mass?  A regular human's center of mass is located just above his bellybutton.  A lower center of mass will make a person harder to knock over.  If the exoskeleton tends to do a "shuffle step" when it walks, there is a good chance it has a low center of mass.  If your opponent leans forward, or walks with raised knees, there is a good chance the center of mass is higher.
Cyberdyne's HAL

  • Things an exoskeleton does very well:
    • Exert force: Absolutely do not try to struggle against the exoskeleton, or block an incoming strike with force against force.  Avoid the ground if possible.
    • Stomp: If your opponent steps on your feet you are in big trouble.
    • Hurt you:  The exoskeleton is made from some combination of metals, plastics, and other hard materials.  If you are going to strike the exoskeleton instead of the squishy person inside, try to use open palm strikes or kicks with the sole of your foot.
  • Things an exoskeleton does poorly:
    • Complicated motions:  The human body has hundreds of skeletal muscles, and complex motions (like throwing a punch) require subtle contributions from muscles throughout the body.  Powered exoskeletons sit on the outside of the limbs and the back of the body, and they only provide support for a few primary muscle groups.
    • Positional awareness:  There is no computer system to keep track of all the limbs and make sure they are not obstructed by immovable object or another limb.  If the joints are actuated by servomotors, attempting an impossible motion could burn out a servo or break a limb.
    • Loose resting joints:  In order to support the forces generated at the joints, and in order to handle the large load carrying capacity, it is necessary for the resting position of each joint to be completely rigid (this will be very important later on).


Your Winning Strategy:

Now that you have assessed the situation and you know what to keep in mind, let's discuss how you are going to win this fight:
  • Throw and run:   Chances are, your opponent does not have a lot of experience catching things in mid air in the exoskeleton. Throw everything and anything you can at his face (damaging or harmless)...  coins, crumpled up paper, pens, shoes, anything nearby.  This will buy you some time to run away or circle behind him, and if you are lucky, his flinches might even cause him to topple over, punch himself, or damage the joints on his exoskeleton.
    Your secret weapon is considerably less expensive than your opponent's
  • Make him flinch: Fake a punch or a kick whenever possible.  His reactions are stronger than he thinks they are and he may throw himself off balance.  In addition, if he flinches, there is a chance the "flinch-ey" signals his brain sends his muscles will be misinterpreted by the exoskeleton's joints, resulting in unexpected actions.
  • Keep yourself at 45 degrees:  All exoskeletons that exist today provide enhanced joints and limbs that sit on the left and right side of the person wearing it.  These limbs are incredibly effective at enhancing motion along that plane of movement, but not so great at movement off at an angle.  Stay off to the side to avoid the worst of your opponent's blows.
    A view of the fight from above.  Stay out of the red zone if possible.
  • Use his rigidity against him:  If your opponent has enhanced arms on his exoskeleton, wait for him to reach out to you, and in a single, quick motion, squat, push up (and back) on his wrist from below with both hands, and push off with your legs.  Because of the rigidity of the joints, as long as he does not anticipate your action, you will have used the entire leverage of his arm to toss him on his back.
    The leverage you have here is comparable to catching someone's leg when they try to kick you in the face.  Dump your opponent on the ground and walk away like a badass.