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Assistive Exoskeleton Arm (ExoArm)

A cheap Exoskeleton Arm (ExoArm), that will help elderly, disabled people and workers complete everyday tasks with less exhaustion.

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We are developing a relatively cheap, simple and yet powerful exo-arm design that will allow for a easy usage, which is especially important for elderly and other people who need this kind of help in everyday life.
Since the muscle sensor outputs data that is not suitable for "intuitive control" we are looking in the other way. Right now the cheapest and the most simple option is to place two switches on the upper and bottom part of the fore arm. When arm is pressed down, the exo-arm will follow. You can see this in the first video.
Processing will be done with an Arduino, so the code will be fairly easy to understand and modify when wanted.
Current prototype will feature an motor on the elbow, but in further designs we will also implement a shoulder actuator. The exo-arm will have back support, so that all the weight will be evenly distributed to your body.
Lifting capacity will be around max 10kg or 22 pounds.

First prototype is complete!

How to make it:

Measurements are not defined because until the arm is "universal size" the lengths vary from person to person. So the best act will be that you measure your own arm and use those measurements.

ExoArm_test1.ino

Arduino sketch IMPORTANT: PID regulator is not in use yet

ino - 2.42 kB - 05/04/2017 at 12:21

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  • 1 × Force pressure sensor (resistor)
  • 1 × Aluminum 4 x 30 x at least 2000mm
  • 1 × Arduino Uno/Nano
  • 1 × VNH2SP30 motor driver
  • 1 × Car Windshield Wiper Motor

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  • june 20, 2017

    Kristjan Berce06/20/2017 at 17:47 0 comments

    I'm still waiting to receive the strain gauge that will be placed in the middle of fore arm. It will be used to determine if there is any object suspended on the ExoArm.

    So far my idea is as following (it's just the idea and may have big flaws, but until I receive the part I can't be sure)

    - There is no weight on the ExoArm:

    This one is simple. Strain gauge will deflect when my arm is moved up or down, so controlling this movement shouldn't be so hard.

    - An object is suspended on the ExoArm:

    The strain gauge sensor will detect a mass of the object, therefore we know the force and also torque. Torque changes with the angle (theta) of the object but if we say that the upper arm is parallel to the body, then the Phi angle is the same as -Theta angle.

    So now we have a good estimate of the torque. Here is the part where I lose my "insight" into the mechanics. If an object is suspended on the ExoArm when I try to move my arm up, the torque on the ExoArm changes. And if torque changes, the output of strain gauge also changes, therefore the ExoArm will follow your arm depending whether the strain gauge output it bigger or smaller. So this could maybe be an effective way to control the ExoArm. I'm still thinking and trying to come up with a 100% effective way, but at the moment this is as furthest as I am.

    Would love to hear your ideas and suggestions!

  • may 4, 2017

    Kristjan Berce05/04/2017 at 12:38 2 comments

    may 4, 2017

    Arm works as it should. The biggest problem now is figuring out the way to control it in such a way that it follows your movement. After few days of playing with Myoware Muscle Sensor, I figured out that it is not as useful as I thought. The main problem is that it can only "usefully" detects two values (flex and not flex) therefore it's useless for our goal.

    I'm thinking of developing similar control as is shown in the video. There would be two sensors each placed on opposing sides of the fore arm, and they would detect when user pushes arm down or up.

    This type of control works, until I try to lift heavy objects and force of the Exo-Arm triggers bottom sensor and I trigger upper sensor. So we are still a long way to go, but I'm staying positive!


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Samtw2005 wrote 05/04/2017 at 19:54 point

thanks 

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Samtw2005 wrote 05/04/2017 at 01:01 point

job

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Samtw2005 wrote 05/04/2017 at 01:01 point

and  great jo

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Samtw2005 wrote 05/04/2017 at 01:01 point

the code 

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Samtw2005 wrote 05/04/2017 at 01:00 point

where is the cod

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Kristjan Berce wrote 05/04/2017 at 12:32 point

I just added it to "FILES" tab.

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Ember Leona wrote 03/31/2017 at 22:48 point

Can you add a cherry picker... I learned 3 pulleys two on ceiling and 1 on floor divides the tensions so that makes lifting easier. Maybe keep that idea in mind I wish we made pulleys like this tiny.cc/faradayrim

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