Kristjan Bercemay 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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Interfacing the Human Body with an electronical device is prolly the biggest challenge. For my upcoming Project (Controller for People with MultipleSklerosis) i ended up ordering a Myoware muscle sensor. however I had some more ideas. 1st i wanted to use a brain wave sensor and tinker around with that. however i am pretty sure it would only recognize very few Patterns and therefore would be just as restricted. 2nd measuring the Surface Tension of the Skin however i dont know how to go about that and revoked that thought. 3rd using other muscle Groups as InputTrigger(per. ex sternoclaidomastoideus) as well as combining multiple sensors that reference each other. (opposing muscle groups) because flexion of the biceps usually means Extension on the triceps. Biceps active + Triceps inactive = Flexion; Biceps inactive + triceps active = Extension; Biceps + triceps active = additional Action. For the latter you Need Knowledge of physiology anatomy and Motion.
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Hey thanks for ideas! I already thought about using torque sensor but the prices go up to $500 which makes it useless. At least for now.
To be honest I'm using two buttons at the moment. I need to do a research and find the optimal pressure sensor that I could use.
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You can also use a torque sensor placed on the elbow joint. With the motor stopped, torque would be generated on the rotation axis when the user starts to flex or extend the elbow. When the user wants to stop the flexion/extension movement, he or she will exert a resistance to the motion of the exoskeleton, which in turn will also result in a torque on the rotation axis. You could use these measurements as motion intention detection. The only problem is that torque sensors are not usually cheap.
Probably your idea of using two sensors (pressure?) located on opposing sides of the forearm is easier and cheaper to implement. With two well calibrated pressure sensors, you could even do some kind of force control to have a force augmentation device that feels transparent to the user.
Cool project by the way!!
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