Comment by bahmboo
13 hours ago
I was surprised to see this here and was wondering if he updated anything from a year ago when I first watched it. Doesn't seem like it but I haven't dug into it. Really nice stuff and I'm hoping he got a job from it or got really busy doing stuff around it that pays the bills.
edit: direct link to the video: https://www.youtube.com/watch?v=MgQbPdiuUTw
Curious how temperature and so forth are managed --- that was a notable effect back in the days when folks were doing things such as engraving The Lord's Prayer on a piece of metal type.
I'm not an expert but the video is very comprehensive. There is closed loop control that is extremely precise in a relative way. In this domain it's all relative anyway because there's no GPS so to speak. It's all reference frames and 3-2-1 locality. [edit: ahhh at 21:47 in the video he says (paraphrasing) "there is offset due to thermal drift of the plastic parts as they get warmed by the motors". ]
In general, platforms are placed in a temperature-controlled/heated draft-guard chamber, on a vibration isolation table, and use uniform materials that do not deform much in the narrow operating temperature range (+-0.5'C).
The stage is not the primary design constraint, but rather it is the position sensors that still cost. At a certain point, some realize the pi-usa stages lofty price was actually fairly reasonable in retrospect.
Best regards, =3
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