3D Printed Affordable Exoskeleton Arm V2

3D printed fully customizable exoskeleton arm that will help elderly and disabled people with everyday tasks.

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This project is version 2.0 from my 2017 Hackaday Prize. ( )

I remember watching my grandmother struggling when moving heavy things around when I was younger. So when I was 15, I had big plans on making an exoskeleton arm that would help her. I had a notebook filled with sketches and designs (I turned whole house upside down to find it but I think it's lost) of the ExoArm using buttons and no microcontroller. Good times. Now that I'm older, I have a new goal. The goal is that people who can't afford to buy those expensive exo-arms, have a chance of making one by themselves.

Again, pictures and everything else is imported from previous project, but I will update them as soon as I recieve all the parts and finish 3d models.

What's new and what's up:

As it turns out I only have less than a month to "finish" it, so here we go!

The first version was based on proper hardware, so you'd need drills, workbench, saws, etc. This time, I decided to make everything 3D printed. It's a lot more customizable and there will be almost no chance for somebody to lose a finger.

All documentation and pictures are from old project. I will start modelling everything as soon as I get the components I need, so sit tight!


Please ignore all the trash in the code. It works, but not really. I mean, I know what it does, but don't expect that you will, because it's really all over the place. If you have any questions, feel free to ask and I'll try to help as much as I can!

ino - 3.17 kB - 07/30/2019 at 17:59


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  • New 3D printable design prototype

    Kristjan Berce08/11/2019 at 13:44 0 comments

    Few comments:

    - This design is far from finished, however we are using this to get some sense of curvatures and best way to mount it.

    - Red gears are used because I had to move potentiometer (elbow angle sensor) away from the center of rotation due to practical constraints. So now it's excentric and thankfuly still in the range of movement (gear ratio) .

    - There is still no power window motor 3D model, so the only way for you to see how it's mounted is to look at the last picture and try to see the motor sketch. 

  • PID control

    Kristjan Berce08/01/2019 at 12:19 0 comments

    Here is a little test with PID control. As you can see it can hold a position pretty well. The PID is not tuned. That's why you can hear that beeping sound coming from the motor. 

    Now all I have to do is to join PID control with intuitive movement, so that I can actually lift something. 

    This video is without any regulator/power:

    Here you can see PID regulator in action. It is designed so that it holds a setpoint (angle), and tries to do that no matter whether there is a force on it or not)

  • Hardware

    Kristjan Berce08/01/2019 at 12:15 0 comments

    This are all the wooden and aluminum parts you'll need, minus the mounts that hold wood plates (check out the videos). Please keep in mind that there are no holes. But why Kristjan? Because I'm 99.9999% sure that every motor you'll find has different geometry, every arm is different and it goes on. So in order to make this arm, you'll need to be creative. You can follow my instructions as far as you can, but I can promise you that you'll have to figure things on your own too. But hey! That's all part of experience and that is the most valuable thing in life next to health and knowledge.

  • Muscle sensor and why not

    Kristjan Berce08/01/2019 at 12:15 0 comments

    I tried using it and it did not work as I thought it will. Not even a bit. See the problem is that when you put the electrode on your biceps, you can trigger it just by stretching your skin. it causes so much electricity that it false triggers and device thinks that you send a muscle signal. So when the Exo-Arm is fastened to your arm, the belt will stretch your skin, especially at the biceps. What happens? Exo-Arm flexes, but does not let go, because it thinks you're still sending signals to the biceps when the only signal is your stretched skin, if that makes any sense.

    Will stick to load cells (the same part that is used in weights to read weight). Will require some adaptations however. 

  • Software

    Kristjan Berce08/01/2019 at 12:12 0 comments

    As of now the code is really badly organized. I will clean it up and make it user friendly though. Just sit tight!

    Code? Well if I knew how to make a good program that runs it.. I spoke to a friend of mine that is extremely good in electronics and programming, and he said that the most optimal solution to intuitive control would be to insert strain gauge in your bones. But in this world that is not possible and probably never will be. So there's that. 

    See, the problem is that the ExoArm must read the weight of object you lift before it even tries to assist you in lifting. And that is so hard. So hard. Weight changes depending on the angle of fore arm, how your arm is angled in respect to earth, etc. I'm not saying it's impossible, but it would really take some time to make this happen. 

    SO if you are looking to make one yourself, and are not that good in programming you should just use 2 buttons (one for moving up, one for moving down). It's astronomically easier. 

  • Hardware schematics

    Kristjan Berce08/01/2019 at 12:09 0 comments

    The red part on the left is the HX711 board (load cell amplifier)

    Potentiometer is used to read angle of the arm at elbow.

    A schematics. I never got to make a PCB, but that doesn't mean you shouldn't. It's actually very easy, as you can see that there are no resistors, diodes etc.

    For components and links go to PARTS LIST.

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notrobot23 wrote 07/31/2019 at 17:44 point

Please could you respond, I am under a bit of a time crunch. 

  Are you sure? yes | no

notrobot23 wrote 07/30/2019 at 22:01 point

Where did the component diagram go, could you say which external library are necessary for the code, and add soldering equipment to the list of needed items.

Other than that awesome project Kristjan.

Please message me or update asap, as i'm building off your design right now, and my coding experience is very limited (a bit of c++).

  Are you sure? yes | no

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