Closed control loop on standard stepper motors


Hey @dan how about these as drop in replacements on a Glowforge…


Laser is kinda the poster child for not needing closed loop, no? But this is still really cool. And there are a lot of things I want closed loop controllers for. (Hmm, if their encoders are really good, maybe they get around the problem that microstepping isn’t so accurate.)


I agree, I don’t think it is necessary. Dan had mentioned in a post that he originally wanted to do closed loop servos, so this was kind of a “have your cake and eat it too” sort of thing. :slight_smile:


Neat idea! Very cool how it uses a hall effect rotation sensor instead of a mechanical encoder - I always love fewer moving parts. The obvious problem comes in when something else in the drivetrain slips - no longer closed loop :frowning2:


Y’all need to talk American 'round here, so us common folk can know what’cha talkin 'bout…


I have looked up Hall effect sensors so many times to remind myself how they work. Repairing old Kitchen-aid mixers from before the solid state models came in was where I first encountered them. I think electrical engineers are the true magicians of this age! Speaking of tribal languages: if you have never watched one of AvE’s YouTubes, it’s an eye/ear opener. He’s Canadian with a vocab all his own! Won’t do a live link because almost any video demonstrates the “colorful language” that @likeablejerk illustrates. I would love to see his tear down of a Chinese laser, even though he tends to the machinist part of making.


In my never ending quest to understand the tech talked about in this forum, here is a great tutorial on controlling servos and eventually explaining the PID part. It does begin with an Arduino controlling LEDs but that is to establish the basics of control, feedback and regulation. This guy is good with real world examples. I know the CNC world is mainly stepper motors and I understand why now a lot better.


That is a great video!
Years ago I spent a bunch of time trying to figure out how to reuse the parts from old ink jet printers.
I wrote a bunch of Arduino PID code and made some videos.
The code is useless, having been replaced by the excellent libraries available now, but I think the discussion is still worthwhile.


I really came late to the Arduino revolution. You were there from the get go. I keep thinking about all this electronic hacking and repurposing and just imagine what I would have done as a kid. I took apart all my toys and played for hours with the motors but I had no resources to figure out what to do with them. So now is my second chance to be a child tinkerer. Thanks for sharing your old stuff. More than ear I want to expose young folks to all this to inspire them with becoming makers instead of mere consumers.

And I love the colophon for your blog. Yes. I just cleaned out my garage of all the junk accumulated in two years in my house that never even made it in!

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