#robotics Logs

Mar 29 2019

12:03 AM rue_mohr: I wonder if 19.5rpm is close enoguh to 0
12:08 AM rue_mohr: 0.3 rev/sec, hmm
07:38 AM veverak: so
07:38 AM veverak: you have a array of points representing line
07:38 AM veverak: and you want to estabilish rule "points are no more than 'x' distance from each other"
07:39 AM veverak: so you go through the array, and insert new points (which are lineary interpollated) between points that are too far away from each other
07:39 AM veverak: how to call this process?
07:43 AM veverak: hmm
07:43 AM veverak: "line split"
07:46 AM veverak: yeah, that's used in the context
07:47 AM veverak: "std::vector< Pose > splitPath( const std::vector< Pose >& ipath, Distance d_step, Angle a_step )"
07:47 AM veverak: cool enough
07:52 AM SleepyTurtle: veverak: interpolation
07:53 AM veverak: oh...
07:53 AM deshipu: tween
07:54 AM deshipu: no, that's not it, sorry
07:55 AM veverak: interpolation it is
07:56 AM RoboCop: oversampling? upsampling?
07:59 AM veverak: https://en.wikipedia.org/wiki/Interpolation
07:59 AM veverak: fits the bill just right
11:02 AM gaze___: @rue_mohr No, no. I want to measure the displacement of a dancer arm for a coil winder tensioner
11:02 AM gaze___: I need to apply 40-60 g of tension consistently to some magnet wire
11:03 AM gaze___: but you know, I want it to be compatible with thicker wire so I'll derate to 100-200 g of transferse force
11:03 AM gaze___: and if I use the potentiometer as a bearing, it'll need to bear that force diametrically
11:03 AM gaze___: but that seems like a really tiny force
11:04 AM gaze___: I set up a scale, spring, and wire to pull on the pot shaft while I turn it with approximately that force applied
11:05 AM gaze___: and the pot didn't bind up
11:05 AM gaze___: but it didn't feel.... happy
11:06 AM gaze___: I also have piles of skate bearings and a 3d printer so I could make a little coupler and support pillow block
11:07 AM gaze___: but how that should look idk
11:07 AM gaze___: but you know, I think what I'll actually do is use one skateboard bearing, a magnet, and a hall displacement sensor I have from another project.
11:50 AM mrdata_: "it didn't feel.... happy" -- because too much tension? not enough? or inconsistent?
12:20 PM gaze___: well it was binding slightly.
12:20 PM gaze___: more friction than I'd expect.
12:20 PM gaze___: maybe fine.
07:24 PM rue_mohr: so, why not just make the pot slave its motion of a heavier arm?
07:50 PM Tom_L: rue_mohr you should watch that video with sound. pretty interesting what he's testing
08:05 PM rue_mohr: whcih video?
08:11 PM Tom_L: the one in your little channel on adaptive feed
08:38 PM rue_mohr: I got the idea he's interoperating the axies so that if one drags, the others slow down to keep sync
08:39 PM Tom_L: measuring power
08:40 PM Tom_L: on the spindle
08:40 PM Tom_L: lcnc has M52 adaptive feed control
09:14 PM rue_mohr: ok
09:36 PM Jak_o_Ombroj: Hmm. I need to axially and radially support a large (10cm) rectangular shaft with a bearing
09:36 PM Jak_o_Ombroj: Or potentially a bushing - I am probably more interested in lower static friction.
09:36 PM Jak_o_Ombroj: Radial bearings this large aren't really a (cheap) thing are they?
09:38 PM Tom_L: probably not so much
09:38 PM Tom_L: what's it going on?
09:39 PM Jak_o_Ombroj: Let me make a quick illustration I think
09:40 PM Tom_L: https://www.vxb.com/Bearings-with-Large-inner-diameter-s/186.htm?searching=Y&sort=13&cat=186&show=15&page=1&f-100mm=526
09:42 PM zhanx: Jak_o_Ombroj, an illustration will help
09:43 PM zhanx: but this should help http://www.microbluebearings.com/bearing-size-charts/
09:44 PM Jak_o_Ombroj: http://pasteall.org/pic/show.php?id=a8cbd095c799c503ef37bcaac09cfcd8
09:45 PM Tom_L: you don't want to round the corners?
09:45 PM Tom_L: better bearing contact for loading
09:45 PM Tom_L: etc
09:45 PM Jak_o_Ombroj: Nah, the rectangle thing is a removable piece
09:45 PM zhanx: or an adapter at least
09:46 PM Jak_o_Ombroj: Yeah, some sort of an adapter would be made - i have to attach to the cube somehow
09:46 PM zhanx: looks like you need a 6020 or 6021 bearing
09:47 PM Jak_o_Ombroj: I'm a little concerned about excessive static friction
09:47 PM zhanx: deep grove or double row bearing then
09:53 PM Jak_o_Ombroj: Hmm, thanks.
09:53 PM Jak_o_Ombroj: Now to convince work that we should do it this way
09:54 PM Jak_o_Ombroj: The current design has it grabbing on from either end - which just means it sags a lot in the middle, and the whole structure is a bit overcomplicated
09:54 PM zhanx: that is on you
09:56 PM Jak_o_Ombroj: Yep.
09:56 PM rue_mohr: ah whats up
09:57 PM Jak_o_Ombroj: https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSAof-NuPsw_LL6V8oZxwnJwMKQHOuG1p7EoSYzvdZOP7-NTTC3nw is similar to current
09:57 PM zhanx: Jak_o_Ombroj, was looking for a bearing
11:47 PM rue_mohr: oof