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First video of CM6 in action!

A project log for CM6 - Compliant 3D printed robotic arm

Cheap, safe, and compliant 6 - Axis 3d printed robotic arm based on Quasi direct drive BLDC drives.

Petar CrnjakPetar Crnjak 03/07/2021 at 12:065 Comments

First video of CM6 in action! Here you can see joint 1 being used as master and joint 2 as a slave (joint 1 is disabled, so it is really easy to move it). Atm, I only wired up the first 3 joints, and the software I wrote is configured for 3 DOF arm so there is a lot of work there. I tested multiple control techniques and one in this video works best and smoothest. In the future, I will show you other techniques I used but they did not perform as well as this one.

Discussions

Petar Crnjak wrote 03/07/2021 at 16:33 point

Drivers are running FOC algorithm. Then I am taking position feedback from J1 as commanded position and J2 needs to follow it. MCU is then running a formula like this:

T = K * ( Commanded position - Current position) + ......( here can be some other parameters to smooth stuff out and make it more precise). T in this formula is commanded voltage Amplitude of motor phase on BLDC driver. 
It is basically what you see in this video: https://www.youtube.com/watch?v=FnQGPGG-vuQ&ab_channel=BenKatz

I will post more stuff about this as the project progresses so stay tuned :D

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QuestForMotion wrote 03/07/2021 at 17:05 point

Cool, thanks. I (and I guess a lot of others too) really enjoy this kind of technical insight, so don't hesitate to also post about the "...some other parameters to smooth stuff out and make it more precise..." even if it is just experimental and not fully backed by control theory. Anyway, great work, I am looking forward to your next update!

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Petar Crnjak wrote 03/07/2021 at 18:24 point

Thanks for the advice! 

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QuestForMotion wrote 03/07/2021 at 16:24 point

Amazing! Can you give us some details about the control techniques you implemented?

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Petar Crnjak wrote 03/07/2021 at 17:01 point

I posted a comment not a reply sorry. The answer is on top.

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