Meet AJAX. And also, meet Sammy Kroner, Joseph DeRose, Gabriel Perko-Engle, Ed Burke, Thelonious Breskin, Ian Simons, Connor Dietz, and Cole Yarbrough. They are students at the Bay School of San Francisco, and the makers of AJAX, a hydraulic exoskeleton that looks like something from a movie. In fact, the team cites Edge of Tomorrow, RoboCop, Iron Man, Elysium, and Aliens as inspiration. To name a few.
“We (our family) had been throwing the idea of building an exoskeleton around for a while, but we passed it off as too dangerous and too ambitious, fearing that something could go wrong and hurt the user,” says DeRose. That was more than a year ago; since then, the concept bloomed, DeRose and his dad brought on other families to work together, and they finally have a working prototype, which they are bringing to the Bay Area Maker Faire.
“There are lots of interesting solutions to complicated problems that we’ve come up with, but one of the hardest (to me) was figuring out a way to easily and accurately sense the user’s motion without conflicting with the operation of the suit,” says DeRose. The machine needs to recognize and match the wearer’s movement, and it has to do so without moving too rapidly, or in the wrong direction, for obvious safety reasons. Hall effect sensors paired with magnetic straps proved too difficult. Linear potentiometers couldn’t be easily mounted and were too sensitive. Finally, by strapping force sensors to the wearer’s legs and changing the design of the suit’s foot, they made the suit move independently of the user, whose feet stay on the ground.
Meanwhile, the arms are controlled by a set of joysticks located near the hands. This way, the suit can actually support the wearer’s arms. “The beauty of potentiometers (in the joysticks) is that a micro controller, such as Arduino, can be programmed to increase or decrease the acceleration, and not just the speed,” says Dietz, who designed the arm control. “This means that moving forward a little bit will yield slow movement, while large movements will yield faster movements.”
The build has been a learning experience all around. “My piece of the suit involved designing the control methods for the suit and learning how best to use them to control the suit,” says Yarbrough. “I think one of the coolest parts was seeing all of the different systems we designed working together to control something much larger.”
Working together is an important point, agrees DeRose.
“I think the coolest part of the process has been seeing how the design and look of the suit slowly takes shape,” he says. “It’s far from what I initially had in my mind, but that’s the fun part of working with a bunch of people who all have different solutions to problems: The end product results from an organic evolution of ideas.”
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