Grab-Assist Exoskeleton

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  Grab-Assist Exoskeleton

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  Exoskeleton in construction

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  Conductive tape circuit-making

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  Adding the flex sensor

Inspiration

Every time I go shopping at Kendall or Central Square, I find myself struggling to carry everything I buy. My backpack is packed to the brim, and my arms chafe under the weight of my many grocery bags - it's quite the struggle! There have been multiple occasions where I wish there were someone to give me a hand. I thought to myself, "why not build an extra hand?" And so the concept of this Grab-Assist exoskeleton took flight!

What it does

What it's supposed to do - Lock into a user-specified location in free space and hold onto objects while the user uses their two other arms; also designed to support user movement when connected to the user's arm. The movement of this exoskeleton, when locked into position, is akin to that of a gimbal.

What it currently does - Support movement with button-controlled servo action.

How I built it

I used 80/20 frames to create the mechanical components of the design and a Teensy microcontroller to program the motors. Moreover, I used epoxy to fix the motors to the 80/20 frames. I also used conductive adhesive, wiring, and electrical tape to build circuits. Finally, my electronic components were a flex sensor, a force sensor, and high-torque servos.

Challenges we ran into

Unfortunately, a couple of tools that I needed to create the biomechanical components of the design were missing, forcing me to develop analogs with 80/20 joints. Secondly, the motors that I selected were not powerful enough to move the 80/20 frames individually - by the time I realized this, it was too late: all the stepper motors were gone. On top of this, my computer repeatedly struggled to recognize the microcontroller, significantly slowing down the debugging process - in the end, I needed to go back to my dorm to get another microcontroller.

Accomplishments that I'm proud of

I'm pleased with having minimized my usage of wires by creating circuits with conductive tape! Doing so decluttered the design substantially and allowed me to seamlessly integrate the control sensors into the arm of the skeleton.

What I learned

Funnily enough, I had never programmed motors with an Arduino or microcontroller, and I had substantially more experience in mechanical design than circuit design. By the end of this project, I learned how signals and power lose their potency over long strands of wire, how to create circuits with conductive tape, how not to burn out a microcontroller, and how to integrate various motors and sensors to create a moving system, albeit through many struggles.

What's next for Grab-Assist Exoskeleton

I want to add better motors! Or at least, some method of increasing the motors' mechanical advantage to lock the limbs into place! Also, I would like to work on creating the claw-like contraption that grabs on to objects the user is interested in - otherwise, the only thing one can do is hang things onto the limbs of the design (not much grabbing there).

Built With

• arduino
• teensy