While medical facilities continue to improve worldwide, access to expensive treatments still eludes a vast amount of people. Especially when it comes to prosthetics, a lot of people won’t be able to afford something so personalized even though the need for assistive devices is extremely high. With that in mind, [Guillermo Herrera-Arcos] started working on ALICE, a robotic exoskeleton that is low-cost, easy to build, and as an added bonus, 100% Open Source.
ALICE’s creators envision that the exoskeleton will have applications in rehabilitation, human augmentation, and even gaming. Also, since it’s Open Source, it could also be used as a platform for STEM students to learn from. Currently, the team is testing electronics in the legs of the exoskeleton, but they have already come a long way with their control system and getting a workable prototype in place. Moving into the future, the creators, as well as anyone else who develops something on this platform, will always be improving it and building upon it thanks to the nature of Open Source hardware.
Is the problem one doesn’t know how to build, or that one can’t afford, even if it’s open source?
I always am afraid someone will have their knee in an exoskeleton and drive the motor too far, folding it over the wrong way or crunching it. Is this a legitimate concern? Do they all just have hardstops, or is there a more complex solution?
Along with hardstops for added safety they probably would implement controlled movement such as in car and truck steering: the movement is driven by a difference in pressure so that when the part moves to the desired position and the wearer stops applying pressure the actuator also stops moving. To get an idea, imagine a potentiometer body fixed to a motor shaft, then the circuit driving it connected to the pot leads: in center position there is no voltage applied to the motor (forget about PWM, I’m simplifying it) but as soon as you rotate the pot shaft, the motor receives some power and counteracts the displacement making the pot body follow its own shaft until it reaches the center position again. A knee could not damage itself because the actuator would not move beyond the position the knee tried to reach, although I expect safety measures like redundant position checking and hardstops to be implemented anyway.
I would also think it would be attached to the leg in a manner that could be disengaged; perhaps analogous to toe clips on a bicycle, such that the leg can be pulled free if bent in the wrong direction.