#robotics Logs

Jun 08 2015

00:14 rue_shop3 I have literally hundreds of scrounged gears, I need to use them up
00:15 rue_shop3 I have a new activity
00:15 rue_shop3 going thru the box of gears, pairing up geartrains
00:15 rue_shop3 if I have pre-paired trains, making up the gearboxes goes much faster
00:15 rue_shop3 when I have a few boxes done, I'll make some kinda generic servo controller
00:16 Casper you know what?
00:16 rue_shop3 probably based around a $2.50 arduino and a stepstick modded to drive a dc motor
00:17 rue_shop3 I know lots of whats, are you reffering to one in particular?
00:17 Casper you should make a robot which can analyse the gears and sort it for you based on the shaft size, if it have a notch or not, diameter, number of teeth, straight or angled, size of teeth, angle, gear thickness and all!
00:17 Jak_o_Shadows size would totally be feasibe
00:18 Jak_o_Shadows through, more like a coin sorter type thing
00:18 Casper that would already be a good start
00:26 rue_house that would make an interesting opencv project
00:26 rue_house outline the gear, find the average radius and count the teeth
00:27 rue_house anyone here ok with opencv?
00:27 Casper yeah, then analyse the teeth and mesure the angle :D
00:27 Casper I wish I knew opencv
00:28 Jak_o_Shadows Why not make something like https://www.mmfind.com/MMFIndFiles/ProductImages/786_550_223400000_W_SpeedSortShaking.jpg
00:28 Jak_o_Shadows Just to sort sizes
00:28 Jak_o_Shadows TBH, I want something like that for nuts and bolts
00:29 rue_house have you not seen my box of gears?
00:29 Jak_o_Shadows not recently
00:29 rue_house its about 4x the size it was last time I took a pic
00:30 Jak_o_Shadows I remember seeing a pile of gears, not a box.
00:30 rue_house http://ruemohr.org/~ircjunk/tutorials/mech/gearbox/dscn7580.jpg
00:30 rue_house its more now
00:31 rue_house hah, cool, I see one of the gears I picked out for a gearbox today
00:32 Jak_o_Shadows That is a much better lot than my collection
00:34 rue_house it used to just be a little cardboard box, now its an overflowing tote
00:57 rue_house http://ruemohr.org/~ircjunk/images/p1070272.jpg
00:59 rue_house http://ruemohr.org/~ircjunk/images/p1070276.jpg I do 2d outlines
01:00 rue_house http://ruemohr.org/~ircjunk/images/p1070275.jpg and just extrude them in openscad, its WAY faster than CSG
01:01 Jak_o_Shadows Openscad is ick sometimes. The way you're doing it is not so ick.
01:04 rue_house :)
01:05 rue_house <rue_house> http://ruemohr.org/~ircjunk/images/pcb_reuse2.jpg
01:05 rue_house <rue_house> http://ruemohr.org/~ircjunk/images/pcb_reuse1.jpg
03:04 wolfmanjm deshipu: what is the best way to test that each leg is moving correctly? I think the heel joint may be reversed on some but it is hard to tell
04:07 wolfmanjm I presume when any leg moves up in Z the hip stays the same, the ankle moves in and the knee moves such that the tibia moves up?
04:07 wolfmanjm or is negative Z up?
05:34 deshipu wolfmanjm: negitve z is down
05:56 mrdata isnt positive z usually away from observer?
05:57 mrdata but, i guess it doesnt matter
05:57 deshipu well, there is no observer
05:57 deshipu it was convenient for me to have x y on the horizontal plane
05:58 deshipu that left z as the vertical axis
05:58 deshipu axe
05:59 deshipu wolfmanjm: there is a table in servos.ino for reversing the servo directions
05:59 deshipu wolfmanjm: but the leg also seems to be reversed if you move out of its range
07:07 veverak fuuu
07:07 veverak that darpa fails video
07:07 veverak lolz :)
07:08 veverak but that korea's team that won
07:08 veverak I like that one
07:10 deshipu DERP Robotics Challenge
07:10 veverak :)
07:11 veverak well
07:11 veverak kind of curious why they want to make humanoid so much for this task
07:11 veverak pure humanoid seems not practical for me
07:11 deshipu well, 6 of them just bought a ready robot from Boston Dynamics
07:12 veverak lol
07:12 veverak well, spider-like seems much better for me
07:12 deshipu hard to fit in a car
07:12 veverak small car
07:12 deshipu or to go through the door
07:13 veverak RoboSimian seems like exactly the think I was thinking of :)
07:13 deshipu you know, I think that a quadruped with wheels on the ends of the legs is really the best approach
07:13 deshipu tachikoma-like
07:13 veverak yeah
07:13 veverak exactly, for legs, abillity to somehow stand on two legs and wheels
07:13 deshipu you have the speed and stability of wheels, but then you can also take steps when you need
07:14 veverak *four legs
07:14 deshipu well, standing on the hind 2 legs and using the front 2 for manipulation is fine too
07:14 deshipu as long as you don't have to carry anything
07:15 deshipu robosimian is nice design-wise
07:16 deshipu but they need more hardwired movements
07:24 veverak deshipu: btw: that tutorial of yours looks nice
07:24 deshipu thanks
07:25 deshipu suggestions for improvement/extending welcome
07:25 veverak for PCB layout maybe
07:25 veverak deshipu: any important reason for smd resistors to be so close together?
07:26 verak got low smd skills, so little space between tham would be helpfull :
07:28 veverak but awesome tutorial, lots of pictures! :)
07:42 deshipu veverak: no reason, no
07:42 deshipu veverak: I just thought it looks nice
07:42 deshipu veverak: and I never had any trouble soldering them
08:04 deshipu if anybody's in .ch, http://www.meetup.com/pyzurich/events/223096685/
08:06 veverak nah
08:06 verak got robot that is powered by ARM computer and controlled via pololu mae
08:07 veverak not sure about how reliable it is
08:07 deshipu what does it do?
08:07 veverak (I don't mention the python program)
08:07 veverak well, unfinished airship project
08:07 veverak it's slow vehicle by definiton
08:07 deshipu well, I have one like that and it's quite reliable
08:07 deshipu pyboard + maestro = hexap[od
08:08 verak is using normal py
08:08 veverak C event library
08:08 deshipu ah, so linux?
08:08 veverak yeah
08:08 deshipu I don't like having an operating system on my robots
08:09 deshipu too much overhead administering it
08:09 veverak C event library, pyserial, pyudev, pygame, threading
08:09 veverak (all libraries that are itneresting)
08:09 veverak nah :/
08:09 deshipu no opencv? :P
08:09 veverak not yet
08:09 veverak :D
08:09 deshipu have you considered using ROS?
08:09 veverak ROS?
08:09 deshipu it will really let you skip a lot of work
08:09 veverak not yet
08:10 deshipu as it has a lot of ready things
08:10 deshipu Robot OS
08:11 veverak well
08:11 verak got finished the r
08:11 veverak :D
08:11 veverak now I am just working on wireless settings
08:11 deshipu congratulations
08:11 veverak well, not finished, missing PID + sensor reading
08:12 veverak but I did that once and it's practically no big deal now
08:12 veverak just another "Serial" device and another "calculations"
08:13 veverak it's just
08:13 veverak I can put a lot of work for that app to be bulletproof, and it's not my point of concern now
08:14 veverak it's about the rest, like the OS and arm pc and ...
08:14 veverak on the other hand, I can't imagine how to replace it, with something that wouldn't cost much money and wouldn't end up with much more complicated app
08:15 deshipu I hate those "I know how to do it, now I just have to do it" moments
08:15 deshipu they suck out all the motivation
08:16 veverak :D
08:16 veverak not really, I like my program now
08:16 veverak oh, yeah, I used some things that people consider as dark magic, but nah
08:17 deshipu goto? ;)
08:17 veverak python descriptors
08:17 veverak deshipu: not so dark yet :)
08:17 deshipu what's wrong with that?
08:17 veverak ask on #python
08:18 veverak :D
08:18 veverak https://github.com/SquirrelCZE/ROBOTZ/blob/master/BRAINZ/main.py
08:18 veverak on line 60 starts class where I use it
08:19 deshipu well, it's bad if you use them when you don't really need them -- but that's true for anything
08:19 veverak well
08:19 veverak I don't really needed them
08:19 deshipu veverak: consider using functools.wraps() in your decorators
08:20 veverak it's just that it was most convecience tool this time
08:20 veverak deshipu: true to that!
08:20 deshipu except Exception as e:
08:20 deshipu self.log.warning("Shit just got real: %s", e)
08:20 deshipu that is evil
08:21 veverak well, yeah
08:21 deshipu veverak: use https://docs.python.org/2/library/logging.html#logging.Logger.exception
08:22 veverak AWESOME
08:22 veverak :D
08:22 veverak P.S: to be hoenst this is first time I use logging
08:33 veverak well, to think of it, I am too library dependent to leave linux
08:34 veverak well, i was told that debian can run 1000 days without a problem
08:34 veverak let's hope so
08:36 veverak deshipu: btw: if you see any other glicthes, you are more than welcome to present your opinion :D
08:38 deshipu veverak: sure
09:39 rue_house it can do more than that
09:46 deshipu it?
09:48 rue_house <veverak> well, i was told that debian can run 1000 days without a problem
09:48 veverak yeah
09:49 veverak so as long as my app will autostart properly and restart on fail, it should be OK
10:20 deshipu plus security updates
10:32 veverak yeah
10:32 veverak need a test suit
10:32 deshipu e
10:32 veverak yeah
10:32 veverak dozens of test
10:33 veverak s
13:34 veverak for that feeling, whan most part of your code is the part after 'except'
14:56 wolfmanjm deshipu: ok go tit, so if I do move_leg_by(0,0,-10) it should move the leg down from the knee and I suppose the heel will move outwrds a bit to keep the foot in the same place?
14:56 wolfmanjm that should allow me to get all the servos correctly reversed or not
15:41 theBear heh, go tit indeed do move_3rd_leg_normalized(0,0,-12) ... good call
16:17 deshipu wolfmanjm: I suppose so
17:46 wolfmanjm well I need a simpe move I can issue that will be easy to identify as being correct, as right now somethign is terribly wrong ;) I suppose the IK could be incorrect for my leg geometry.
17:47 wolfmanjm also I'll need to convert my quad into a hex as it is too heavy for 4 legs :(
18:40 deshipu wolfmanjm: both quad and hex need to be able to lift the robot on 3 legs
18:41 deshipu adding legs will only make it heavier
18:41 wolfmanjm hmm that is a bummer then ;(
18:41 deshipu maybe make the legs shorter?
18:41 wolfmanjm shorter tibia?
18:41 deshipu coxa
18:42 wolfmanjm coxa is already about as short as I can make it I think
18:42 deshipu no, wait
18:42 wolfmanjm from joint to joint 45mm
18:42 deshipu longer coxa, shorter femur and tobia
18:42 deshipu tibia
18:43 deshipu coxa has no impact on weight
18:43 deshipu so it can be long
18:43 wolfmanjm ahh I can make tibia much shorter cna;t make femur shorter, may be able to make coxa a little shorter
18:44 deshipu femur is the worst in a reprile stance
18:44 deshipu reptile
18:44 wolfmanjm I may be hosed then :( stuck with 18 useless servos
18:44 deshipu of course in mammal stance it's much better
18:45 deshipu do you have a photo?
18:45 wolfmanjm I was think of switchng to a dog like legs
18:45 wolfmanjm yea https://flic.kr/p/tnecAv
18:46 wolfmanjm https://flic.kr/p/pkcwTy
18:46 deshipu ah, lots of plastic
18:46 wolfmanjm yea
18:46 wolfmanjm but that is ok it is the electronics and batteries that put it over the edge
18:47 deshipu but I'm surprised
18:47 wolfmanjm it can stand ok with just the frame but the batteries are too much for it
18:47 deshipu what kind of batteries?
18:47 wolfmanjm I'm using MG90S metal gear servos
18:47 wolfmanjm I have one Lipo and 4 AA nicd
18:48 wolfmanjm 4 AA are for servos lipo is fro the edison
18:48 deshipu nicd are heavy, but lipo should be fine, how big is it?
18:48 deshipu ah, consider powering it all from a lipo
18:48 wolfmanjm it is a 1C 2700ma standard round cell a bit bigger than a AA
18:49 deshipu like in usb power banks
18:49 wolfmanjm yea exactly
18:49 deshipu I have one such battery, it works fine with Tote
18:49 wolfmanjm not sure how well the edison wil like sharing the lipo with the servos
18:49 wolfmanjm I can try it
18:50 deshipu https://youtu.be/2oY1tgPdmVQ
18:50 deshipu add a capacitor and it should be fine
18:51 wolfmanjm yea that is the same Lipo I have
18:52 ace4016 3d printed legs?
18:52 wolfmanjm it is all 3d printed :)
18:52 ace4016 try using a lattice of some sort to cut weight
18:52 wolfmanjm it uses honeycomb 10% infill for the base that is about as light as I can make it
18:53 ace4016 hrm...
18:53 wolfmanjm but it is really the batteries that is puttin git over the top
18:53 ace4016 can some of those components use more holes in them? :P
18:53 wolfmanjm the edison is no weight at all, and the servo controller is small
18:53 ace4016 some of those pieces don't look like they need to be as big as they are
18:54 ace4016 though you might also have a power issue
18:54 deshipu on the other hand, mg90 is stronger
18:54 deshipu also heavier, slightly
18:54 wolfmanjm stringet then MG90S?
18:54 wolfmanjm sronger?
18:55 deshipu than sg90 that I use
18:55 wolfmanjm eh typing is bad today
18:55 wolfmanjm ah yea sg90 vs mg90s
18:55 wolfmanjm sg90 is plastic gear though
18:55 deshipu nylon
18:55 deshipu that's why it's lighter
18:56 deshipu 9g
18:56 deshipu how much is mg90s?
18:56 wolfmanjm about $4 each on ebay
18:56 wolfmanjm from china
18:56 deshipu how much weight
18:57 wolfmanjm ahh http://www.electronicoscaldas.com/datasheet/MG90S_Tower-Pro.pdf
18:57 wolfmanjm 13.4g
18:57 deshipu not on a computer now :(
18:57 deshipu 50% more
18:58 wolfmanjm hmm seems i can get more torque if I run it at 6v
18:58 deshipu you know what may also work? higher voltage
18:58 wolfmanjm but then heavier batteries
18:58 deshipu yeah
18:58 deshipu not nrcessarily
18:58 deshipu get a boost converter for that lipo
18:58 wolfmanjm yea I have one, not sure it can source that much current though
18:59 deshipu 1A at 6V?
18:59 wolfmanjm yea I'd need to get a bigger boost min eis about 500mA
18:59 wolfmanjm I can get a bigger one
19:00 deshipu well, I would try it
19:00 deshipu maybe it will hold ;)
19:00 wolfmanjm yea or add another nicd/nimh
19:00 wolfmanjm I'll try it :)
19:00 deshipu aa batteries are a bad idea imho
19:00 wolfmanjm I already ordered more servos though
19:01 deshipu btw, I've seen some designs where they tried to limit the weight of the body by putting the aa batteries on tibias
19:02 wolfmanjm that is an iteresting idea
19:02 deshipu this makes the legs heavier, though and you start to have to deal with inertia when moving them
19:03 deshipu still may be worth a try
19:04 deshipu well, you can always build another robot with the spare servos
19:04 deshipu like the Bob
19:04 deshipu a nice 4-servo biped
19:07 wolfmanjm yea may try that :)
19:15 wolfmanjm for now I still want to get your quadruped code running, there is something I got wrong I think...
19:19 wolfmanjm actually got the MG90S for $3 each so not a bad deal
19:47 wolfmanjm Hmm just noticed that the servo controller I am using is sending out PWM less than 3.3v which maybe the servo does not like. that may also explain why it is weak.
19:50 Casper I don't think it would make it weak
19:50 Casper and how did you mesured the 3.3V? with an oscope? or a multimeter?
19:51 wolfmanjm yea not sure, the servo is runnign at 4.8v but the PWM is 3v, the spec says the pwm should be 4.5-6v
19:53 wolfmanjm seems there is some debate what the PWM pulse voltage needs to be, it is not documented anywhere
19:56 wolfmanjm this would suggest 3v is ok for the PWM pulse... http://pdf.datasheetcatalog.com/datasheet/MitsubishiElectricCorporation/mXyyzzzr.pdf
19:56 wolfmanjm presumin gthat is the chip my servo uses.
20:58 rue_shop3 I printed a second one of the gearbox I made last night
20:58 rue_shop3 :)
20:58 rue_shop3 one design, two prints, sweet
21:01 rue_shop3 I'm gonna sit down and match up more gears
21:29 _moon hay rue
21:32 _moon or anyone who wants to land me some more assembler perspective
22:39 rue_shop3 hey
22:40 rue_shop3 gone again
23:17 rue_shop3 gearboxes
23:18 rue_shop3 gearboxes
23:18 rue_shop3 must make more gearboxes
23:18 rue_shop3 hmm I should make some that are pulley input