Becoming Unbeatable at Arm Wrestling with an Exoskeleton

Exoskeletons are a hallmark of sci-fi, because the idea is undeniably alluring. Who doesn't want to gain superhuman speed or strength by strapping on a suit? But it turns out that exoskeletons are very difficult to implement in any kind of practical way and we tend to only see prototypes built for specialized applications in which the expense becomes worthwhile. That's why it is so fun to watch Allen Pan build an exoskeleton for the sole purpose of becoming unbeatable at arm wrestling.

Exoskeletons tend not to be practical because the human body is already far more efficient at converting energy into motion than batteries and motors are. To get an exoskeleton that both increases a person's strength and can run for a long time, you need a massive battery back. But that increases the weight, which increases power consumption and required motor power. So you end up in an endless cycle where you're increasing weight to increase capacity, ad nauseam. However, an exoskeleton can be practical if you only need it for a short time — maybe only long enough to win a few arm wrestling matches.

That's how Pan was able to approach this project. He started by building an arm brace with two thick steel bars. Those provide support for the exoskeleton and keep it (or an opponent) from breaking his arm. A Harbor Freight winch, like the kind you'd use for an ATV or a small off-road vehicle, pulls a cable that forces the brace to collapse. That winch has its own gear system to increase torque, so Pan just ran the cable directly between the two bars of the brace. It has its own controller and power comes from a LiPo battery pack meant for RC cars. Finally, Pan secured the brace to his body using an aluminum frame that straps onto his back.

To test this exoskeleton, Pan headed over to Muscle Beach and challenged passersby. He said he would give $100 to anyone that could beat him at arm wrestling. Numerous people took him up on that offer, but nobody was able to overcome the mechanical strength of the exoskeleton arm. That was until the cable got snagged and that over-exerted the electrical motor, causing it to blow a fuse. When that happened, an arm wrestling champion that just happened to be strolling by was able to best Pan.