#robotics Logs

Nov 28 2020

03:29 AM ragarain: wow, I'm still here
03:35 AM ragarain: rue_mohr: I was paying usd24 for these, which isn't far off... any in particular you'd recommend?
04:12 AM rue_mohr: what
04:12 AM rue_mohr: WHAT?
04:13 AM rue_mohr: you were paying $24ea for pwm servos that have that much deadband!?
04:13 AM rue_mohr: their $2 ea...
04:28 AM ragarain: where? lowest I see for an ldx-218 on e.g. aliexpress is usd 13
04:29 AM rue_mohr: https://www.aliexpress.com/item/4000536728030.html
04:29 AM rue_mohr: $4.50 ea....
04:30 AM rue_mohr: huh, maybe the prices went back up
04:32 AM rue_mohr: yea, they seem to not go much lower than 5 now...
04:33 AM rue_mohr: https://www.aliexpress.com/item/1005001501011838.html
04:33 AM rue_mohr: yea, huh
04:33 AM rue_mohr: but for $23ea you should be able to get serial addressable digital ones
04:34 AM ragarain: ah those guys... have 2 of the mg995 here as well... found them a bit weaker and not sure about the resolution/mechanics
04:34 AM rue_mohr: yup, their cheap!
04:34 AM ragarain: and the S3003... I don't think I want plastic anything rly
04:35 AM rue_mohr: I was amazed when those robots did 4 8 hour days of maker faire continious without anything breaking
04:36 AM rue_mohr: esp the one I had moving marbled
04:36 AM rue_mohr: esp the one I had moving marbleds
04:36 AM rue_mohr: esp the one I had moving marbles
04:36 AM ragarain: I don't rly mind paying 20-30 per piece, my goal isn't necessarily to go as cheap as possible...
04:36 AM ragarain: <rue_mohr> I was amazed when those robots did 4 8 hour days of maker faire continious without anything breaking
04:36 AM ragarain: <<< orly... well it depends on the loads as well, right?
04:37 AM rue_mohr: https://www.youtube.com/watch?v=j4uz_yha9uI&t=4s
04:38 AM ragarain: "serial addressable digital" ... hmmm ... do ppl refer to those also as "bus servos" ?
04:38 AM rue_mohr: maybe
04:38 AM rue_mohr: https://www.youtube.com/watch?v=5vLEtVLV71I&t=5s
04:39 AM rue_mohr: you can see the approx performance I was getting
04:39 AM ragarain: wow ok that's pretty damn good
04:39 AM ragarain: nice oldschool trance, too :P
04:40 AM rue_mohr: hah this player has no audio
04:40 AM rue_mohr: there are other vids in my collection of the bots
04:40 AM rue_mohr: I think there is one there where I have 4? of them doing synchronized motion
04:41 AM rue_mohr: my software can interpolate 65536 axies at once :)
04:42 AM rue_mohr: I really do need to get back to my robots
04:42 AM rue_mohr: thats what the LVDT are for
04:42 AM ragarain: nice
04:42 AM rue_mohr: specifically pressure sensors for pneumatic muscle servos
06:44 AM ragarain: this LX-16A serial bus servo was looking pretty good, but from what I'm reading its using a closed-source protocol and so you have to use their control board to communicate with it... wtfwtfwtf
06:45 AM ragarain: "Because the bus servo is using our private protocol, so you need to connect our debug
06:45 AM ragarain: board to control bus servo no matter what single chip you are using(we provide
06:45 AM ragarain: communication protocol)."
06:47 AM veverak: false
06:47 AM veverak: using LX-15D
06:47 AM veverak: no prop. protocol :)
07:08 AM ragarain: aha!
07:09 AM veverak: it uses uart over one line
07:09 AM veverak: which is not really common
07:09 AM veverak: but that's all
07:09 AM ragarain: how do you drive them? available libs or your own code?
07:09 AM veverak: own code
07:09 AM veverak: (own code)^2 to be exact
07:09 AM * veverak written custom library for protocols for this
07:10 AM ragarain: uart? hmm... I wonder if the 16A is different then... (why is it so hard to find specs, argh)
07:11 AM ragarain: ahh cool, maybe I can bug you one of these days for your github (if you put it out there)
07:11 AM veverak: hmm
07:11 AM veverak: there should be pdf with protocol description somewhere
07:12 AM ragarain: there's a "manual" but it doesn't really have a wealth of information
07:13 AM veverak: https://gitlab.fi.muni.cz/xkoniar/schpin-ros/-/blob/devel/schpin_blob/src/blob/lewan.h
07:14 AM ragarain: cool thx!
07:14 AM ragarain: yeah ok 16A is also using uart... I'm guessing there's not much difference between the two
07:16 AM ragarain: how does it fare with slow, small movement?
07:17 AM veverak: I have to say "meh"
07:17 AM veverak: I've ot some problems with servos finishing movement
07:17 AM veverak: (my code is state machine, that waits with next command until actual is finished)
07:18 AM veverak: I feel like the PID settings is meh
07:18 AM veverak: thing is that you can't change it
07:24 AM ragarain: mmmh... right
07:25 AM veverak: I have _some_ teolrance for the commands
05:02 PM -!- #robotics mode set to +o by kornbluth.freenode.net