#robotics Logs

Mar 11 2017

02:30 AM rue_shop3: nobody got my joke
02:33 AM zhanx: nope
02:33 AM Jak_o_Shadows: I missed it.
02:33 AM Jak_o_Shadows: I might gt the irc bouncer working again tomorrow
02:33 AM zhanx: not hard to
02:33 AM rue_shop3: oh hum
02:33 AM Jak_o_Shadows: Oh for piss sake. THe irc bouncer doesn't auto-connect to the network after a reboot
02:34 AM Jak_o_Ombroj is now known as Jak_o_Shadows
06:19 AM Jak_o_Shadows: I think I have a leg configuration that's feasible for the robot! Now I just need to figure out if it's actually amplifying the torque I get
06:22 AM Jak_o_Shadows: Through I wonder sometimes if I should be trying to increase velocity instead
06:27 AM Jak_o_Shadows: Hmm. Ultimately the driving joint is torque limited.
06:27 AM Jak_o_Shadows: Ok! Got it I think. Cause this is the upper leg, I need to work out how my driving torque joint works out to my other stationary joint troque
12:12 PM branjb: my friend made this in inventor, do you think it is realizable in a 3D printed model? http://imgur.com/a/I6U9c
12:13 PM branjb: never 3D printed gears but I am suspicious that it will work
12:15 PM rue_bed: it wont let me see the image
12:16 PM branjb: weird
12:16 PM veverak: damn it
12:16 PM veverak: need to replace json
12:16 PM branjb: http://i.imgur.com/aNhJ4OD.gif
12:16 PM branjb: direct link
12:16 PM veverak: C++ graph -> pack to json -> send over network -> unpack -> ...
12:16 PM veverak: 100% cpu usage at 50Hz
12:17 PM rue_bed: heh
12:17 PM rue_bed: branjb, got it
12:17 PM rue_bed: how big?
12:17 PM branjb: i'm printing it now anyway, it maxes out my printer tray
12:17 PM rue_bed: 30cm dia
12:17 PM branjb: eyeballing it diameter of turret is ~5 inches at widest point
12:18 PM rue_bed: 3d printed gears will probably work
12:18 PM rue_bed: I'v been surprised so far
12:18 PM branjb: mostly i'm wondering how well 3D printed gears will work, i feel like it will sieze up but idk
12:18 PM rue_bed: I have a 3d printed gearbox on my new printer for the Y axis, so far, no slop
12:19 PM rue_bed: but use course teeth
12:19 PM rue_bed: that are properly shaped
12:20 PM branjb: hmm
12:20 PM branjb: ok
12:20 PM rue_bed: and notice you dont need to bother will the full 360 degrees for hte side gear
01:25 PM robotustra: good day
01:26 PM Snert: How's the roll around motorized platform going?
01:27 PM robotustra: waitng for its time
01:28 PM Snert: I know the situtation :)
01:28 PM robotustra: doing legs and bottom of the robot
01:28 PM robotustra: slowly slowly
01:28 PM robotustra: what to put all stuff together
01:28 PM Snert: I think we're in a race for last place in the category.
01:29 PM robotustra: going to print robot butt tomorrow
01:29 PM robotustra: I don't participate in any race
01:30 PM robotustra: new job, some home stuff slow down a little bit
01:30 PM robotustra: I'm doing robots at work now :)
01:32 PM robotustra: Snert: what is your status?
01:32 PM Snert: I got my display board done...gonna mount motors on a demo piece of plywood next.
01:33 PM Snert: and use absolute encoders and steppers and such.
01:33 PM Snert: and exert complete control of the motors using an arduino.
01:34 PM Snert: a closed loop motor control system.
01:36 PM robotustra: how do you control your motors?
01:36 PM robotustra: I mean feedback
01:37 PM Snert: in the end I might do a custom HBridge but at first it will be just little aliexpress stepper control boards.
01:37 PM Snert: o.
01:37 PM Snert: well.....
01:37 PM robotustra: I use A4988 drivers
01:37 PM Snert: I get used absolute position encoder off aliexpress for under 30bucks each.
01:38 PM Snert: I see no reason to make an arduino ride herd on the count.
01:38 PM Snert: when you can just read the absolute encoder and know position with no further work.
01:39 PM robotustra: what motors do you use?
01:39 PM robotustra: stepped or DC?
01:39 PM Snert: steppers is all I have collected...from nema17 down to nema8.
01:40 PM robotustra: do you know about mechaduino?
01:40 PM Snert: but I'll have a couple regular motors too.
01:40 PM Snert: no, haven't checked into that or heard of it.
01:41 PM robotustra: https://hackaday.io/project/11224-mechaduino
01:41 PM robotustra: may be you can use it
01:41 PM robotustra: stepper which does not loose steps
01:44 PM Snert: I'm not opposed to the mechaniduino stuff, looks neat. I can learn alot.
01:44 PM Snert: but steps are not ever lost with absolute encoding.
01:45 PM Snert: I'm just gonna cut to the chase and use absolutes.
01:45 PM robotustra: this mechaduino is good for 3d printers
01:46 PM robotustra: yeah, I also will need encoders to read position of the robot body
01:46 PM robotustra: and a lot
01:46 PM Snert: and I admit..I need to learn about quad encoders so I'll have at least one of those on my motor control board.
01:46 PM robotustra: which encoders do you have?
01:46 PM Snert: https://www.aliexpress.com/item/Original-Koyo-Encoder-TRD-3A1024-2610-absolute-encoder-1024-line/32565870870.html
01:46 PM robotustra: optical?
01:47 PM robotustra: it's big
01:47 PM robotustra: 1024 steps per 360 degree?
01:47 PM Snert: yes, but it'll be belt driven and out on the open maybe gear driven, for demo purposes.
01:47 PM Snert: I don't buy less than 1024.
01:48 PM Snert: I have a quad encoder that does 2000ppr.
01:48 PM Snert: it's tiny.
01:48 PM robotustra: I think I'll do my own encoders
01:49 PM robotustra: because I need to encode angles from 0 to 90 degree mainly
01:49 PM Snert: buying encoders let's me focus on the code parts first.
01:49 PM robotustra: may be
01:49 PM SpeedEvil: magnetic resolvers are $4 and a teeny magnet
01:50 PM robotustra: I decided to focus on the software after I finish all hardware :)
01:50 PM robotustra: that's what I want to use
01:51 PM robotustra: like hall sensors + small magnets
01:51 PM robotustra: I use 4 hall sensors and 1 msgnet in my robot eyes
01:51 PM Snert: I'll probibly drive one of those off the belt too and play with it.
02:00 PM robotustra: where are other ppl?
02:14 PM anniepoo_: hey rue, you on?
05:27 PM benny_ is now known as BMejia
05:28 PM BMejia: /msg NickServ VERIFY REGISTER BMejia lkggigggrpbl
05:32 PM deshipu: BMejia: better change your password now
05:34 PM BMejia: Was that public?
05:34 PM ace4016: yup
05:34 PM BMejia: im still new to this lol
05:34 PM BMejia: haha
05:34 PM BMejia: any clue what the command is?
05:35 PM ace4016: that's the command, you just put a space in front of the /
05:35 PM * ace4016 thinks that's client specific
05:35 PM ace4016: yup
05:35 PM BMejia: ahh. thanks
05:35 PM ace4016: some clients eat the space; yours did not
05:38 PM BMejia: thanks for the heads up everyone
05:39 PM BMejia: anyone here familiar whith mecanum wheels?
05:43 PM deshipu: they are horrible
05:44 PM deshipu: only really work on even flat surfaces
05:46 PM BMejia: well i intend to make a warehouse platform that will only run on an even flat surface
05:46 PM BMejia: I was hoping someone could point me in the right direction for figuring out motor sizing
06:07 PM deshipu: that's a tough one
07:29 PM Jak_o_Shadows: I MAY have the force calculations in thsi 4 bar linkage correct.
07:30 PM Jak_o_Shadows: I mean, I'm not actually gaining very much, because it's almost parallel
08:03 PM Rez is now known as LoRez
08:24 PM Jak_o_Shadows: https://github.com/Jak-o-Shadows/jak-o-shadows.github.io/blob/master/picturedump/fourBarLinkageCalcs.PNG
08:24 PM Jak_o_Shadows: Moments, angle limits, and stuff.
09:47 PM Jak_o_Shadows: Hmm. https://www.youtube.com/watch?v=tf7IEVTDjng Why has boston robotics got their back legs with the knee joint hte same way as the front legs?
09:47 PM Jak_o_Shadows: Or why aren't dogs/etc the same like that?
09:48 PM Jak_o_Shadows: Also, that video makes me happy
09:51 PM Jak_o_Shadows: I suppose with the back legs going inward, you get a better jump?
09:53 PM Jak_o_Shadows: deshipu, any thoughts?
10:05 PM rue_house: forward
10:06 PM Triffid_Hunter_ is now known as Triffid_Hunter
10:06 PM tumdedum_ is now known as tumdedum
10:46 PM Jak_o_Shadows: Sorry. Um, knees forward of hip?