Making an exoskeleton for combat

Question

Exoskeletons are primarily used for lifting strength and durability in our world. Most exoskeletons are not adapted for purposes such as general combat and punching.

• The exoskeleton should give the user the ability to kill or inflict significant damage with a single attack.
• It should be durable enough to withstand the impact of its attacks.
• The exoskeleton should possess the ability for it to use multiple attacks in a day

So how could an exoskeleton use powerful and fast strikes for combat provided that the world is current with modern day technology?

Answer 1

Simple answer: This can't be done yet

I had a good time watching this YouTube video about powered exoskeletons for commercial or industrial use. As an engineer, I wondered why anybody would buy one of those things when a simple forklift could do the same thing for a fraction of the cost — and the complexity just begs for high maintenance.

But the greater problem is that each and every one of them is a prototype.

The technology is getting closer! Companies are advocating their use to reduce worker compensation costs, which is a fancy way of saying, "there should be fewer injuries."

Not surprisingly, the first attempted application of powered exoskeletons was for the military. They appeared to have great promise! Ultimately, the prototypes failed and the military stepped away from exoskeletons due to their enormous power requirements. Considering we're still working on perfecting batteries for cars and trucks (and haven't even begun to seriously consider batteries for planes, trains, and boats) it's little wonder that an object intended to magnify or multiply human strength (therefore requiring power!) isn't ready for prime time.

I assume you're talking about powered exoskeletons

Because exoskeletons for commercial purposes have existed for some time, but we're talking about things like leg braces or camera mounts. Stuff one straps to their body to enhance the body but aren't powered at all.

If we ignore the word "exoskeleton" and look at drones (probably a much more likely development path for the military) then we've had human-enhanced robotics both commercially in manufacturing and in the military for a while now.

I'm assuming you're looking for the human-inside-a-walking-tank type of robotics. Honestly, if you think about this it's not a very practical solution. Despite stories probably starting with Heinlein's Starship Troopers through games like Starcraft and today's latest entry, the TV series Fallout, the reality is that putting a human inside a defensible can that can be a wonder soldier on the field is most likely an impractical nightmare.

• There's a LOT that can go wrong with such a complicated piece of equipment.
• When the power is drained, you're screwed.
• Almost nothing such a suit can do can't be done better using a combination of other, cheaper solutions.
• And it doesn't help that the groin and armpits will always be incredibly vulnerable.

Man... give me a tank. Or better still, give me a Boeing MQ-28 Ghost Bat. There's a huge advantage to not having to worry about dying.

To get back to your question...

Given today's technology, what you're looking for can't be done. But let's look at what you'd need to do in the near future to make it plausible:

• Let's assume that we're a few more years advanced and that one or more of the current exoskeleton prototypes has moved into commercial manufacture.

• Let's also assume that battery technology has advanced such that you don't need a refrigerator-sized battery on your back to achieve 2-3 hours of sustained combat. Note that this has its own problems as compromising a battery with that much power is devastating, especially when its second-heaviest load is the weight of the human inside the suit (see why a drone is better?). And I'm assuming the munitions+suit are heavier than the human.

So...

1. It's easy to see that strength will be enhanced.
2. Dexterity must also be enhanced. That isn't a goal with current commercial exoskeleton designs, which are only focusing on keeping the wearer upright. Speed need only be adequate when it comes to stacking boxes in a warehouse.¹ The problem with dexterity is that there's a difference between instantaneous strength (e.g. how fast a hydraulic ram can extend itself) and durable strength (e.g. how much that same hydraulic ram can push an object). Those two attributes don't tend to go well together as one tends to rip the other apart. However, are you really expecting the exoskeletons to get into pugilism? Non-stealthy hand-to-hand combat has (I believe) diminished over time as range and precision have improved.
3. Range of motion is a necessity. Have you ever heard of anyone tripping a tank? An exoskeleton-using soldier must be capable of getting up from a prone position, and in combat that must be done quickly. No exoskeletons that I reviewed for this answer had a sufficient range of motion to achieve this goal. It looked like some could get up given enough time, though. Along with getting up from a prone position is the need to climb, which also requires a larger range of motion.

I'm going to stop there. Do I see this in the next ten years? No. Do I see it in the next 50 years?...

No...

There are other ways of achieving the same results with less investment and fewer risks to human life. I'm a fan of exoskeletons in fiction — they're cool! But in real life they'll never be more than an expensive passing fancy. At least that's my story and I'm sticking with it.

But could we get powerful, fast strikes?

Well...

I'm delighted with the imagination of Guillermo del Toro and his Pacific Rim production team.

• Some of the Jaegers used rockets to move the punching arm faster and harder.

• Some of the Jaegers used what appeared to be spring-loaded or pneumatic (compressed air) to pop a punch.

• One used three arms... now, those had blades on them, but multiple arms means multiple strikes in less time. Call it the "paddle-wheel approach."

All three of those ideas could be achieved with today's tech... so long as you don't mind the reset time or the consumption of limited fuel.

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_{¹ I'm putting this in as a footnote even though it's an important perspective. My brother-in-law is a forklift mechanic at a large warehouse where the forklift users are always moving SO FAST that the radiators are constantly overheated — which gives him good work security. None of the exoskeleton prototypes I reviewed could match what those forklift drivers are doing right now. The idea of people in exoskeletons running around at those speeds stacking boxes makes my oh-that's-a-liability alarm blare. Given what I know about warehouse operations, I don't see exoskeletons ever making a serious dent in forklift sales. I could see their value in manufacturing... but, then again, we're already using robotic automation for that.}

Answer 2

A fighter aircraft is a sort of powered exoskeleton. It allows the pilot to fly and can carry weapons.

Pilots have trouble pulling more than 10G. There are pilotless airframes that can go over 20G. AI has won a simulated dogfight with humans with matching airframes.

If we extrapolate this to conventional exoskeletons, the weakest point is bound to be the driver. An intelligent exoskeleton will be able to react faster than a human, but this may involve moving so suddenly that the human gets damaged. The better solution would be to take the human out of the exoskeleton and have them operate it remotely, with the suit intelligence having the option to autonomously react to threats.

Answer 3

Not without a handwave

The issue with super-strong exoskeletons is that they are either a) made of lightweight, fragile material or b) are made of such durable material that it becomes so heavy that it's just a statue. It's not a problem of withstanding its own impacts; if you can drop it from arm's length and it doesn't break, you can do the same thing but on someone's head and achieve an attack without breaking the exoskeleton. It's a problem of withstanding attacks from others. If your opponent dodges and then slashes the cables connecting the servo motors to the batteries, then your exoskeleton has just been turned into a giant metal weight which will inevitably make you much easier to kill.

The solution is to have thicker armor that can't be effectively cut or shot through to protect the fragile electronic components of the exoskeleton. The issue is then that the armor eventually becomes so heavy that the servo motors can't lift it, in which case you have again just dressed up in thick plates of metal so that your enemy can stab or shoot you to death while you're immobilized.

Fallout solved this issue for its T60 powered armor using a "fusion core", which is a device that can efficiently cause hot nuclear fusion in a small space when supplied with fuel. Fusion cores produce an enormous amount of energy that can then be used by the power armor to run much bigger servos that can lift the huge armor that protects the servos, making for an effective exoskeleton/exoskin.

All that is to say that the issue isn't that modern-day exoskeletons can't be used for combat, they'd just end up being big dead weights because you can't attach enough armor to them to protect their delicate circuitry without overweighting them. If you had a very large and compact power source - i.e., a device that generates nuclear fusion on very small scales, definitely not something that exists today - then you could just add arbitrarily powerful motors and carry as much armor as you like. Then you can just do a normal punch and let inertia do the rest to your opponent's delicate skeleton.

Answer 4

It could be useful

I think the main usefulness, depending on the strength of the exoskeletons, would be the ability to carry far heavier weapons that infantry can usually use, and normally have to be vehicle mounted. However, even then, the recoil will be hard to deal with, but possibly manageable. That's about it though, since an exoskeleton isn't armor, and melee combat is mostly a thing of the past, so punching someone with it is probably doable but is less effective than just shooting them from far away. The heavy weapons would be useful though.

Answer 5

The problem with an exoskeleton is that it can move only as fast as the person inside it. An exoskeleton uses negative feedback to maintain a constant pressure on the user's body, and hence moves with the user at the user's speed.

While an exoskeleton can be very strong, it is limited to the user's speed unless it is larger than the user. If the exoskeleton is larger than the user, then the user's movements are magnified to the same degree that the exoskeleton is larger than the user.

So, by placing the user at the centre of a particularly large exoskeleton in a motion-capture harness, and linking that to the large exoskeleton, if the exoskeleton is three times the size of the user, then a punch by the user at, say, 5 metres per second would translate to a punch by the exoskeleton at 15 metres per second.

However, it should be remembered that merely going through the motions of combat would be tiring to the pilot, much as if they were performing a martial arts kata. It would require that the pilot be as fit as any elite soldier, as well as being trained to use the exoskeleton to the best effect.

By armouring the exoskeleton, it could be made resistant to small arms fire. However, an exoskeleton would be mechanically very complicated, and with a humanoid form, it would be less compact and less well armoured than an equivalent sized armoured vehicle, and being a larger, taller target for modern weapon systems would make a poor combat tool compared with armoured fighting vehicles or tanks. The science-fiction tropes of mecha destroying tanks are just that: fiction. The converse would be far more likely.

If exoskeletons were easy to make or would be more effective than modern fighting vehicles, they would have been invented and would be in use today.

Answer 6

Short answer: Springs!

From an engineering standpoint, it is very hard to produce something which is strong, can be powered for a long time and isn't incredibly bulky. Most motors also need gears to have significant torque without being incredibly large. It isn't technologically feasible to just add more electronic based muscles to a person just yet.

This begs the question: How can you produce strong power from motors small enough to carry around without being slow from a horrid gear ratio?

The answer is to offset the small power of portable motors by taking advantage of the fact that kinetic energy can be stored while every motor isn't always being used. This can be done with springs being wound back through high gear ratio motor and released partially when the user moves the internal suit in a certain direction. This would effectively make everything 'weightless' while giving large corresponding power. It could even be set to snap if intentionally allowed to do so. The only drawback is that once a spring is fully contracted, the spring would need to be wound up again by the motors. It could be built in a way where the springs don't stop movement when they are contracted, but just don't add a power bonus. This could be done by connecting the springs to strong wires which are similar to human tendons.

Answer 7

Powered exoskeletons

First off, punch force is not a design consideration for any exoskeleton. If you're using your fists on a battlefield, it means things went seriously FUBAR, but that does not mean that an exoskeleton that grants improved strength isn't useful on a battlefield. The original goal of exoskeleton research was the ability to carry more armor. Back in the 90's, powered exoskeleton development was mostly abandoned because it was determined that you would need to carry 500lb (220kg) of armor to cover the whole body in Class IV protection which was too much of a power burden, but today with better battery technology and lighter armors, this prediction has been reduced to about 180lb (80kg) which is the current goal of the Russian Sotnik powered armor program which is expected to offer protection against up to .50cal rounds over 90% of the body by 2025.

That said, powered armor does have a notorious reaction delay time, and tends to move a bit slower than the pilot could otherwise move to prevent injuries. So if you try to throw a punch as the OP asks, you will have a bit more weight behind your swing from the extra armor, but it will be a lot harder to land, and a little bit slower. So, actual impact force and efficacy in a fist fight should not see a meaningful increase.

Even though we've closed the gap a lot between science fiction and reality, powered exoskeletons have never seen practical battlefield applications because of how hard it is to power an exoskeleton in a wartime situation. That said, current prototypes are very close to seeing action in more controlled combat environments like SWAT operations. Unlike a wartime operation; SWAT powered armor can be safely transported by truck to a hostage situation or criminal compound, and be able to clear the area in just a few minutes eliminating most of the concerns about battery life that come up for military use, and most of the concerns about endangering civilians that come up when talking about comparable kill drones.

Unpowered exoskeletons (AKA: exosuits)

If you're thinking a military setting, you should be considering unpowered exoskeleton instead. An exosuit does not make you faster or stronger; so, you won't be using it to punch people out better. What it is is a harness that helps your body distribute weight and shock better which reduces fatigue, and can provide selectively engaged mechanical advantages to help you do what is normally too hard or dangerous to do. It also comes with the advantage that there is no sensor delay between when your body moves and when the actuators detect it and start moving the exoskeleton; so, a person in an exosuit has no delayed reflexes.

For example, the American SABER exosuit is designed to offset up to 100lb of stress on the body when doing common soliderly duties like lifting, carrying, etc. which reduces injuries and increases a soldier's ability to perform repetitive heavy lifting which is a very common part of daily life for a soldier. Soldiers need to be able to spend hours on end digging trenches, filling sandbags, breaking down and setting up equipment, carrying and loading munitions, etc.

Just by reducing fatigue and injuries, unpowered exosuits increase how much work an average soldier can do in a day by 60%. It also makes it much more practical for soldiers to wear the heavy body armor that already exists while going on long patrols or marches because it can take the weight of the armor and suspend it on the frame instead of on your back making your muscles just responsible for overcome its inertia, not its weight too.

So, current real world exosuits are not what you are picturing as something that actually makes you stronger, but they will help you in fight anyway because it increases your ability to be battlefield ready faster and longer than if you are not using one. A soldier wearing an exosuit may have a slight advantage in hand-to-hand combat simply because they are less likely to be going into the fight fatigued or injured, though it is just as likely to make your actions feel unnatural and put you at a disadvantage unless you've specifically trained to fight in it.

Answer 8

I believe that movies in the RoboCop, Pacific Rim, and Iron Man series demonstrate well some of the problems of building and controlling a powered exoskeleton. I recall in both instances demonstrations of failed experiments showing kinds of powered exoskeletons vibrating like mad, falling over and becoming largely immobilized, injuring the pilot by exceeding their natural range of motion, and perhaps other darkly comical outcomes.

One problem that is difficult to overcome is that of fine control. There can be sensors inside to detect motion of the pilot to indicate a desire to move. The suit moves, and that then changes the position of the sensors in relation to the pilot. If not controlled very very carefully this can result in the pilot getting shaken as the suit keeps moving back and forth in rapid succession to find the point in 3D space where the wearer wants to move. This can mean the suit falls over and just convulses on the ground as the pilot is beaten to a pulp bouncing about inside the exoskeleton armor.

Another problem of control is by dialing back the sensor sensitivity to avoid vibrating like mad from the pilot bouncing about inside is the exoskeleton is moving so slowly as to be maddening. Maintaining balance while walking would be exceedingly difficult if not impossible. The suit could perhaps be made to work, be incredibly durable, but so encumbered in motion that it's not likely advantageous over something like a forklift or skid-steer tractor in lifting items and traversing over the ground.

If the exoskeleton is not properly limited in range of motion then the pilot could be severely injured, such as having limbs ripped from the torso. Because each person has their own limits on comfortable range of motion the exoskeleton would have to be greatly limited in range of motion, have limits on who is allowed to pilot it, or have some means to adjust itself carefully to the pilot.

If the exoskeleton doesn't have all kinds of built in safety mechanisms to manage battle damage then a sufficiently damaged exoskeleton could become a coffin for a pilot that had otherwise sustained minor injuries. If the exoskeleton can't provide a means for rapid escape then the pilot could face suffocation, bleeding out, or something because medical care was impeded by having others trying frantically to cut through the armor to get the pilot out.

RoboCop doesn't have these problems because the pilot is a quadruple amputee, the suit being a prosthesis that's controlled by implants into the spinal column or something. Pacific Rim gets around the problems by the exoskeleton being so large that the pilots are not wearing the exoskeleton like a suit of armor, there's two pilots to presumably control different aspects of the exoskeleton and aided by some alien technology to synchronize motion, they can readily escape by unbuckling themselves or whatever from the sensor array, and there's just many layers of armor to penetrate before the pilots would sustain injury or some outside force influences their motion.

Iron Man is a bit of an interesting case, at least in my mind. They just kind of hand wave over the common problems of suit control and safety by making the pilot and builder so smart that he made an absolutely finely tuned control system that allows for voice commands, predictive controls, sensors embedded in the body of the pilot, and so on to the point that the armor is near sentient/autonomous and appears to read the mind of the pilot.

Then is the issue of powering the suit. Pacific Rim shows nuclear reactors powering the exoskeletons, reactors that are apparently leaking large amounts of radiation when in operation but is mitigated by the area of operation being devoid of any humans but the pilots that have a small heavy shield between them and the reactor. The Pacific Rim exoskeletons are likely irradiating their opponents but there's not likely to be much concern about that, it is likely considered advantageous. Iron Man has some fanciful power source that defies physics as we know it. Robocop apparently uses some kind of batteries or fuel cells that need to be recharged everyday or the pilot that is bolted inside will die.

With current technology we could possibly see someone able to build an exoskeleton that could be useful in combat. Powering the exoskeleton would likely be a problem so most of the load bearing would likely be with springs and other devices that maximize the efficiency of motion of the pilot than powering motions directly, provides weight redistribution around the pilot's body than through it, and so on to where the pilot is kind of "weightless" inside the armor. The pilot would not be fighting against gravity/weight but only inertia/mass. There could be some power source and motors that provides some bursts of power, aids in repetitive motions like walking, and reacts to some extent to short sudden motions like falls, impacts of weapons, or recoil from rifles. To keep the exoskeleton from becoming the pilot's coffin there would have to be some kinds of "circuit breakers" where the armor more likely comes off rather than crushing, spalling, or some such and injuring the pilot.

Making a practical combat-ready exoskeleton is really hard. I believe it is possible but it would likely quite the compromise compared to something like an armored truck that would cost about the same to build and maintain while providing greater capabilities on mobility, protection, and bringing mayhem to an opponent.