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Full metal jacket: the fashion of Iron Man

A superhero flying through a library

Industrialist Tony Stark always dresses for the occasion, even when that particular occasion happens to be a fight with the powers of evil. In the Iron Man comic and movie franchise Anthony Edward Stark, Tony to his friends, becomes his crime-fighting alter ego by donning his high tech suit. The character was created by Marvel comic legend Stan Lee and his team and first hit the pages in 1963. The back story tells how industrial armaments engineer and international playboy Stark is kidnapped and forced to work to develop new forms of weapons, but instead manages to escape through building a flying armoured suit.

Though the escape is successful Stark suffers a major heart injury during the kidnap ordeal, becoming dependant on technology to keep him alive. The experience forces him to reconsider his life, and the crime avenging Iron Man is born. Lee’s ‘businessman superhero’ has proved extremely popular and in recent years the Iron Man movies, starring Robert Downey Jr have proved box office hits. But as Tony himself would be the first to admit, there is more than a little computer science supporting Iron Man’s superhero standing.

Suits you

The Iron Man suit is an example of a powered exoskeleton. The technology surrounding the wearer amplifies the movement of the body, a little like a wearable robot. This area of research is often called ‘human performance augmentation’ and there are a number of organisations interested in it, including universities and, unsurprisingly, defence companies: the real equivalent of Stark Industries. Their researchers are building real exoskeletons which have powers uncannily like those of the Iron Man suit.

To make the exoskeleton work the technology needs to be able to accurately read the exact movements of the wearer, then have the robot components duplicate them almost instantly. Creating this fluid mechanical shadow means the exoskeleton needs to contain massive computing power, able to read the forces being applied and convert them into signals to control the robot servo motors without any delay. Slow computing would cause mechanical drag for the wearer, who would feel like they were wading through treacle. Not a good idea when you’re trying to save the world.

Pump it up

Humans move by using their muscles in what are called antagonistic pairs. There are always two muscles on either side of the joint that pull the limb in different directions. For example, in your upper arm there are the muscles called the biceps and the triceps. Contracting the biceps muscle bends your elbow up, and contracting your triceps straightens your elbow back. It’s a clever way to control biological movement using just a single type of shortening muscle tissue rather than one kind that shortens and another that lengthens.

In an exoskeleton the robot actuators (the things that do the moving) take the place of the muscles, and we can build these to move however we want, but as the robot’s movements need to shadow the person’s movements inside, the computer needs to understand how humans move. As the human bends their elbow to lift up an object, sensors in the exoskeleton measure the forces applied, and the onboard computer calculates how to move the exoskeleton to minimise the resulting strain on the person’s hand. In current strength amplifying exoskeletons the actuators are high pressure hydraulic pistons, meaning that the human operators can lift considerable weight. The hydraulics support the load, the humans movements provide the control.

I knew you were going to do that

It is important that the human user doesn’t need to expend any effort in moving the exoskeleton; people get tired very easily if they have to counteract even a small but continual force. To allow this to happen the computer system must ensure that all the sensors read zero force whenever possible. That way the robot does the work and the human is just moving inside the frame. The sensors can take thousands of readings per second from all over the exoskeleton, arms, legs, back and so on.

This information is used to predict what the user is trying to do. For example, when you are lifting a weight the computer begins by calculating where all the various exoskeleton ‘muscles’ need to be to mirror your movements. Then the robot arm is instructed to grab the weight before the user exerts any significant force, so you get no strain but a lot of gain.

Flight suit?

Exoskeleton systems exist already. Soldiers can march further with heavy packs by having an exoskeleton provide some strap-on mechanical support that mimics their movements. There are also medical applications in development to help improve hospital patients move around. But current exoskeletons still don’t have the ability to let you run faster or do other complex activities like fly.

Flying is another area where the real trick is in the computer programming. Iron Man’s suit is covered in smart ‘control surfaces’ that move under computer control to allow him to manoeuvre at speed. Tony Stark controls his suit through a heads-up display and voice control in his helmet, technology that at least we do have today. Could we have fully functional Iron Man suits in the future? It’s probably just a matter of time, technology and computer science (and visionary multi-millionaire industrialists too).