#robotics Logs

Jun 09 2015

04:57 deshipu fortunately it's a small thing
04:59 veverak nah
04:59 veverak fucking 3d printers
04:59 veverak hammer on them
05:00 verak is at the mood that he wants to throw it in thrashbin and build new one from the
05:03 veverak alu profiles, corexy
05:03 veverak nah
05:06 deshipu have a cup of tea
05:06 Jak_o_Shadows I have huge trouble with bed adhesin
05:10 veverak look at that sucker
05:10 veverak for a few minits I googled printers and it started to print
05:14 deshipu you have to keep them short
08:36 deshipu https://www.youtube.com/watch?v=K51vA5vYtLg
08:36 deshipu yay chinese clones ;)
15:50 deshipu wolfmanjm: https://www.youtube.com/watch?v=3NeJisPvHcU
15:51 deshipu wolfmanjm: 18 dunamixel servos \o/
15:51 deshipu dynamixel
15:51 deshipu $50 each
15:53 Anniepoo they're Intel
15:55 deshipu nah, pretty sure Dynamixel is not Intel
15:56 Anniepoo no, I mean 'they're intel, $900 worth of servos is not a big deal'
16:00 wolfmanjm "at some point hey will be open source"
16:00 wolfmanjm mine already is open source :) and edison based ;)
16:01 wolfmanjm BTW seems 6v is better, can almost stand now.
16:01 deshipu I had some guy lash out at me recently for using hobby servos
16:01 wolfmanjm Still not get it walking properly though
16:01 deshipu wolfmanjm: ditch those AA batteries, use just the lipo
16:02 wolfmanjm it simply is not economical to use expensive servos, even at $3 each it gets expensive for a hobby
16:03 deshipu wolfmanjm: I'm thinking about using just the motor and pot from the servos, and doing the control on my own
16:03 deshipu wolfmanjm: but then I would need two mosfets for each servo
16:04 deshipu I wonder if there is an IC with a lot of H-bridges
16:04 deshipu L293D has 2
16:06 wolfmanjm the chip most servos use is http://pdf.datasheetcatalog.com/datasheet/MitsubishiElectricCorporation/mXyyzzzr.pdf
16:06 deshipu well, I don't want the full servo logic, that's the point
16:06 deshipu I want to do PID myself, then I can have the position and force feedback
16:07 deshipu on just 3 pins
16:07 wolfmanjm there is probably a chip that has a bunch of msofets on it :)
16:07 deshipu (1 analog for the pot, 2 for the h-bridge)
16:07 deshipu then a single pro mini could drive 6 servos
16:08 deshipu so a quadruped could get intelligent servos for just $4 extra
16:09 wolfmanjm well to get to 6v I am using 5 subC NIMH
16:10 wolfmanjm but it is on a long wire so not on the bot
16:10 wolfmanjm I'll need to get a beefy buck to get to 6v from sa single lithium
16:11 wolfmanjm or I could use 2C lipo and a down converter
16:11 wolfmanjm I'll figur ethat out if I can get the ting to walk
16:11 deshipu or you could risk one servo and see if they work on 7.6V
16:11 deshipu 7.2
16:11 deshipu sorry
16:12 wolfmanjm I'malso not sure the PWM at 3v is an issue
16:12 deshipu shouldn't be
16:12 wolfmanjm seems to work but there is no rating for the PWM signal
16:12 deshipu ttl logic levels at 3V3 and 5V are compatible
16:12 wolfmanjm good
16:13 wolfmanjm also I was running it at 60hz and it seems better at 50hz but I need to re center everything as at 50hz they are no longer centered
16:13 wolfmanjm and that means taking every leg apart and redoing the horn
16:13 deshipu yeah, for analog servos, the higher the frequency, the more current they will eat and the more torque they will have
16:14 deshipu nah
16:14 wolfmanjm (or do an offset in S/W and lose some degrees of movement)
16:14 deshipu you just adjust the trim
16:14 deshipu because they are at their physical center
16:14 deshipu just the frequencies are shifted
16:14 wolfmanjm more torque at higher PWM frequency?
16:14 deshipu so you don't want to adjust physically
16:14 deshipu yes
16:14 deshipu because the analog servos only drive the motor when they get the signal
16:14 wolfmanjm so I should leave it at 60hz then
16:15 deshipu so if you send the signal more often, they will drive the motor more often
16:15 deshipu at some point they may start to heat though
16:16 deshipu wolfmanjm: ah, by the way
16:17 deshipu wolfmanjm: don't power them up all at once
16:17 deshipu wolfmanjm: if you look at my servo init code, I start them with a delay between them
16:17 wolfmanjm I can;t help but do that with the PWM controller I use
16:17 deshipu it has no commands for powering the servos down?
16:18 wolfmanjm I think it is always sending PWM to all of them.
16:18 deshipu that sucks
16:18 deshipu what controller is it?
16:18 wolfmanjm not in the default library anyway
16:18 wolfmanjm https://www.adafruit.com/products/815
16:18 deshipu ah, that LED controller
16:19 deshipu I use that one in Kubik
16:20 deshipu by the way, you can try lowering the voltage back and upping the pwm frequency
16:20 deshipu at lower volatage they won't heat as much
16:20 wolfmanjm it was alrady runnign at 60Hz
16:20 wolfmanjm how much higher can it go?
16:20 deshipu I think you could go as far as 300Hz
16:21 deshipu at least with digital servos you can
16:21 wolfmanjm Oh ok I can try that
16:21 deshipu but slowly
16:21 wolfmanjm these are not digital
16:21 deshipu or you can burn them
16:21 deshipu try in 10Hz increments maybe and see what happens and if they are getting hot
16:22 deshipu hmm, maybe try with a single one first
16:23 wolfmanjm I'll wait to get the new batch, i don;t have any spares at the moment
16:25 deshipu I'm waiting for a bunch too, this thing get addictive
16:26 deshipu I should probably start dismantling the old robots
16:26 deshipu but I don't have the heart to do that
16:29 deshipu I have that hexapod to program too :(
16:31 veverak hmm
16:31 veverak I finally found usage for my servo I don't use
16:31 veverak (it turns 360 for each pwm signal)
16:31 veverak http://www.thingiverse.com/thing:849938
16:32 LiohAu so I think someone said that it knows solidworks here?
16:45 wolfmanjm deshipu: this does not look right does it? https://flic.kr/p/upPjWJ
16:51 veverak guys
16:52 veverak stil filesize 1Gb and still rising
17:43 JT-Shop LiohAu, yea I did
18:26 veverak http://i.imgur.com/9UHTX8k.png
18:26 veverak archimeds screw, version one
19:38 SpeedEvil veverak: you do know it can't be vertical?
21:53 rue_house I love unprintable things on thingverse
21:53 rue_house prolly 25% of things are unprintable
22:06 wolfmanjm a lot are just upside down or sideways, most of them will print if you rotate them correctly
23:58 rue_house I printed a gearbox with the gear spacing out by 4mm
23:58 rue_house can we fix it by turning soemthing sideways?