#robotics Logs
Oct 13 2014
#robotics Calendar
00:00 rue_house thats so hard,
00:00 rue_house well this one I'm gonna use cables, and it just occured to me that I can skip the whole mess by using cable tubes like on bike brakes
00:08 rue_house http://mirror.zaleski.org/public/BatteryCharger-12vSLA/BatteryCharger-12vSLA.html
00:30 T3rr0rByte13 Anyone ever play with neural networks?
00:46 rue_shop2 doing good, I'm at the wrist now
00:47 rue_shop2 the cables drives will simplify this incredibly
00:47 rue_shop2 T3rr0rByte13, not I
00:47 rue_shop2 well, yea, but they were organic :)
00:47 T3rr0rByte13 hmmmm
00:49 T3rr0rByte13 Organic neural networks are to hard to program... they require to much dedication
00:49 orlock i survived my daughters 3rd birthday party!
00:53 rue_house T3rr0rByte13, YOU HAVE SOFTWARE YOUR PLAYING with , or you wanting to make soemthing
00:55 T3rr0rByte13 yea, a bunch of youtube videos by this guy https://www.youtube.com/channel/UCRAmB5K-2GLvtaXcH9GCy-A
00:55 T3rr0rByte13 watched them all and tried to implement his Libraries, however making it recognize pictures is proving difficult
00:58 T3rr0rByte13 fascinating stuff though, if I could make it recognize a beer bottle, and then have a robot find and bring me said beer bottle... well life would be good.
00:58 rue_house this looks like its on the wrong track, I should code soemting up for what I know about all this
00:58 rue_house T3rr0rByte13, hello australlia?
00:59 orlock heh
00:59 orlock nah
00:59 orlock not with that ISP
00:59 orlock rue_house: So, i got some of those wifi modules/CPU's
01:00 rue_house hmm, so more than just australlians are crazy enough to build a robot just to get them beer?
01:00 T3rr0rByte13 ruehouse, me in Canada
01:00 rue_house orlock, tell me what you do with it, not that you have it
01:00 rue_house T3rr0rByte13, east coast?
01:00 orlock rue_house: havent managed to do anything with them yet - need to dig up some appropriate jumper wires, as the pinouts are not breadboard friendly
01:00 rue_house orlock, so they aren't really even usefull paperweights just yet
01:00 rue_house }:|
01:01 orlock but a 2x8 IDC cable should make a nice breakout board
01:01 orlock yeah, they dont weigh enough
01:01 T3rr0rByte13 rue_house: Calgary, western central
01:01 rue_house ah
01:01 rue_house east sucks, go west!
01:01 orlock T3rr0rByte13: ahh my brother in law is over there
01:01 orlock somewhere near Banff i think
01:02 orlock with all the other aussies i hear
01:02 T3rr0rByte13 orlock, yea its not bad... yes aussies a plenty in Banff, specially around winter time
01:02 rue_house now I cant get the idea of a robot that gets excited when it sees a beer bottle out of my head
01:03 orlock rue_house: whats a good way to provide up to 500mz @ 3.3v?
01:03 orlock uhh
01:03 rue_house his math is all really grand and all, but he dosn't move along much and his stuff is not really well implemented on a computer
01:03 orlock 500Ma
01:03 rue_house crazy
01:03 T3rr0rByte13 then you could figure out a way to make the robot drunk.
01:03 rue_house orlock, $2 ebay module
01:04 orlock apparently those chips can draw a reasonable amount of current
01:04 orlock ok
01:04 rue_house http://www.ebay.ca/itm/400440730939
01:04 rue_house current limited switching votlage limited regulator
01:04 orlock also, serial, and 2x GPIO (not usable with stock firmware)
01:04 rue_house or, if you dont need the current regulation
01:04 rue_house http://www.ebay.ca/itm/371054648639
01:05 rue_house and if you want a now solution , use an LM317
01:05 orlock i wonder how long until wifi smoke detectors are available
01:06 orlock so your house can SMS to tell you its burning down
01:06 rue_house oh damn, somehow all the thinking I was doing about my robot arm got derailed for the idea of writing a proper nural simultor
01:06 orlock "Better grab a beer on the way home, your fridge melted"
01:06 T3rr0rByte13 This is the robot that the Neural network is supposed to be for: http://www.hobbyware.org/Projects/Project%2013/developmentProgress.aspx
01:06 rue_house hmm, I have a temp sensor network thru the house, but the data is stored in the house
01:06 rue_house maybe I should adjust that
01:07 orlock thats why i bought one of those $25 linux computers
01:07 orlock to handle backing up data to a location thats not in the house
01:07 orlock LM317 in old PC PSU's?
01:08 rue_house I'm starting to get tired of youtube videos I can skip 1/3 of at a time and not miss anything
01:08 rue_house orlock, no
01:08 rue_house hmm
01:08 rue_house maybe a vcr
01:08 orlock Not in a hurry to get one - just curious
01:08 rue_house probably not
01:08 orlock oh, PC's would be switching everything?
01:08 rue_house maybe a battery charger
01:09 rue_house oh oh, a selectable voltage car power adapter
01:09 rue_house or for that matter, almost any power supply with a selecable output voltage
01:10 rue_house or, a 7805 with a -1.7V ground reference
01:10 orlock apparently those chips can draw a "large" amount of current
01:10 rue_house 400ma?
01:10 rue_house oOOOOOooo
01:11 rue_house use large guage wire!
01:11 rue_house :)
01:11 orlock i've never used 3.3v arduino stuff before either
01:11 orlock i think i have one, but it doesnt have serial UART usb thingy
01:12 orlock so i'd need to program it using ICSP or whatever its called?
01:22 rue_shop2 I like pvc
01:22 rue_shop2 I like m3 screws
01:23 rue_shop2 I can just drill a 2.5mm hole in the pvc a CRAM a m3 into it
01:23 rue_shop2 self thread
01:23 rue_shop2 s
01:28 rue_shop2 grrr, I'v not yet made a stock of dowel nuts
01:39 rue_shop2 these robot arms are almost getting menotinious to make
01:39 rue_shop2 "build peice A"
01:39 rue_shop2 "build peice B"
01:39 rue_shop2 "build peice C..."
01:39 rue_shop2 glue B to C
02:16 rue_shop2 OOOOooo cables free things up enough that I might even be able to do the wrist spin direct drive
02:16 rue_shop2 and use the cables to still do the pitch
02:18 rue_shop2 ok, if your building an arm, go cable drive!
02:24 rue_shop2 gee, I'm losing steam
02:34 rue_shop2 hmm I need to make up drive pullies for all these servos
02:50 deshipu rue_shop2: have you considered those delta arms?
03:34 rue_shop2 cable pullies are significantly different than belt pullies
03:35 rue_shop2 I'm not into the delta ones, except to play with the math
03:35 rue_shop2 but its 1am and i need sleep
03:42 Tom_itx no you just think you do
03:45 rue_house http://www.parktool.com/uploads/files/library/ta-noddle-route1.jpg
03:45 rue_house hmmm
03:46 Tom_itx what about it? it's a pulley
03:46 m_itx looks at rue_house's l
03:47 rue_house unlikea belt pulley, cables need a system to keep the tension on them, and they also have to have the cable locked to it to keep it from slipping
03:47 Tom_itx ever build a model airplane?
03:47 rue_house rememebr how the old radios used to do the tuning linkage?
03:47 Tom_itx they use a pull pull cable system alot of times
03:48 rue_house no, I didn't do rc planes :(
03:48 Tom_itx yes i know how radios used to be
03:48 Tom_itx also how ships pull rope
03:48 Tom_itx wind a couple loops to create enough friction on the drum to pull it in
03:50 Tom_itx so, is the arm done yet?
03:50 rue_house no I'm calling it a night, I'm outa steam
03:51 rue_house maybe there want' enough caffeenne in the tea or soemting
03:51 Tom_itx put more water in the tea to create steam
03:51 Tom_itx At 211 degrees water is very hot.
03:52 Tom_itx At 212 degrees water boils.
03:52 rue_house the closest existing thing to the linkages used in the radios is throttle linkages, and they aren't even close
03:52 Tom_itx When water boils it produces steam
03:52 Tom_itx With steam you can power a locomotive.
03:52 Tom_itx 1 Degree makes all the difference.
03:53 Tom_itx bulk bicycle cable
03:53 Tom_itx old printers used cables too
03:55 rue_house http://i.ebayimg.com/00/s/MTIwMFgxNjAw/z/le0AAMXQC-tTE9gY/$_35.JPG
03:55 rue_house that seems to be the height of the tech, sad, isn't it?
03:56 Tom_itx that's fastenend inside the pulley
03:56 rue_house yea, its got springs to keep the tension on it too
03:57 Tom_itx they also make kevlar fishing line that is very lightweight and very strong
03:57 rue_house ma had some beading wire called 'tiger tail' its steel with with a plastic coating
03:57 rue_house stranded
03:57 Tom_itx i know about that stuff too
03:58 rue_house http://vintagepc.site50.net/site/images/photos/large/IMG_1062.JPG
03:59 rue_house he redid it witht eh wrong string, heh
03:59 Tom_itx that looks like cotton cord
03:59 rue_house yea
04:00 Tom_itx they used cotton cord in window weights
04:00 Tom_itx it worked for many years
04:00 Tom_itx position didn't matter though
04:01 Tom_itx there also was a pull pull cnc design
04:01 Tom_itx one stepper controlled 2 axis iirc
04:01 Tom_itx err maybe 2 steppers and one cable. i forget now
04:01 rue_house http://speakeasyradios.com/yahoo_site_admin/assets/images/Pulley.296200542_std.jpg
04:02 rue_house never seen a tensioning spring like that before
04:03 Tom_itx http://forums.reprap.org/read.php?1,110637
04:03 Tom_itx pic near the bottom
04:04 Tom_itx dual purpose spring to hold the pulley on and still be a spring
04:04 Tom_itx ole farts are genius
04:04 rue_house indeed
04:05 rue_house I hope to be an old fart one day
04:05 Tom_itx http://3d4u.org/MyFDM/?p=152
04:06 rue_house nice captures
04:08 Tom_itx as i recall that's all one cable
04:08 Tom_itx there was another set of pics on anohter one somewhere with a diagram
04:09 rue_house almost 2am, gnight
04:09 Tom_itx mkay
12:32 rue_shop2 I'm sure that the 'pul' in the 'pulse' audio system on linux stands for 'Purely Unneccisary Layer' I'm working on the rest
12:33 deshipu 'Spelling Edition"
13:00 rue_house where the hell is zhanx,
13:15 Tom_itx why are you playing hookey today?
13:36 rue_house thanks giving day (canada)
13:36 Tom_itx are you thankful?
13:36 rue_house I needed a day off
13:37 LoRez rue_house: don't you have vacation days?
13:38 Tom_itx he gives them away since he likes his job so well
13:39 LoRez smart
13:39 Tom_itx gettin much rain down there?
13:53 rue_house yup
14:14 rue_house "AWE not CHICKEN flavored noodles AGAIN!" "Look, we have two flavors available, chicken, and human." "chicken! yum! thanks, bye!"
18:16 rue_shop2 "I asked you to charge and date all these batteries, these stickers just say 'today'" "yea, I printed them as a batch, saves time"
18:16 Tom_itx better than 'yesterday'
18:21 deshipu you just have to print and stick a new batch every day
18:22 deshipu I think I figured out what was wrong with IK in my 2dof quadruped
18:23 deshipu the last segment of the legs wasn't centered on the axis of the leg
18:23 deshipu gave me much bigger errors than I expected
18:24 deshipu I'm re-gluing the legs now to align it properly
18:26 wolfmanjm deshipu: do you have a good link for gaits :)
18:27 deshipu wolfmanjm: there is one paper that cleared up a lot for me
18:28 wolfmanjm any code for a very basic starter gait for a quad?
18:29 wolfmanjm before I invest too much time I need to see if this bot can at least move itself. The legs all work, but not tried coordinating them yet
18:29 deshipu wolfmanjm: http://www.diva-portal.org/smash/get/diva2:9172/FULLTEXT01.pdf
18:29 deshipu wolfmanjm: you can look at the code for my robots
18:30 deshipu wolfmanjm: https://bitbucket.org/thesheep/ukubik/src/tip/creep.py
18:30 rue_shop2 "what did you just say to them" "I dont know, but its in the right language" "your NOT a 5 star translator.."
18:30 wolfmanjm great thanks that'll get me started :)
18:30 deshipu wolfmanjm: https://bitbucket.org/thesheep/katka/src/tip/katka/creep.ino
18:30 rue_shop2 deshipu, why didn't you just offset it in the maths
18:31 deshipu rue_shop2: the ranges would be all wrong
18:31 deshipu also, basic trygonometry is hard enough ;)
18:31 rue_shop2 its thinking outside the box, I should commend you
18:32 rue_shop2 instead of making the math work to the real world, your modifying the real world to work like the math
18:32 deshipu wolfmanjm: I also wrote down some notes myself: http://sheep.art.pl/Quadruped%20Gait
18:32 rue_shop2 your ik should not be so evil you cant offset a leg by a bit
18:32 deshipu wolfmanjm: but that's mostly what is in that paper
18:33 deshipu rue_shop2: the whole idea with a 2dof quadruped with IK is already quite evil
18:33 deshipu rue_shop2: you see, the angles of servos depend on the positions of all 4 legs...
18:33 wolfmanjm deshipu: thanks again, to be honrst I find reading thesis papers very hard on my brain ;)
18:34 deshipu wolfmanjm: the basic idea is to keep shifting the body in the direction you want to go, and then make a step forward with the legs that move out of range...
18:34 lfmanjm being " an old fa
18:35 deshipu the average age of robot makers tends to be quite high
18:36 rue_shop2 I'm nolonger holding any merrit to papers like that, that do not show implementation code
18:37 deshipu rue_shop2: the main advantage of that paper is that it has a very long introduction that explains basic concepts
18:37 rue_shop2 deshipu, no ik is evil,
18:37 rue_shop2 just the math people try to implement it with
18:37 deshipu rue_shop2: the "meat" of that paper can be safely ignored
18:37 deshipu as well as the "results"
18:39 deshipu rue_shop2: I can't wait to try to get the derivatives of those formulas, for proper handling of inertia ;)
18:40 deshipu right now it just bangs its legs into the ground with full force
18:42 wolfmanjm comun gfdorm the 3fd printer world of steppers, I am tryin gto apply the acceleration techniques to servos :) I wnat much smoother motion, rather than full speed ahead
18:42 deshipu yeah, I didn't even start with that
18:43 deshipu one problem is that 50Hz is not really a lot
18:43 deshipu and they have quite a dead band
18:43 wolfmanjm I'm thinking along the lines of an S curve, wher yu start of ncrementing the angle slowly and increasing the angle to a stable point then towards the end of th emove reduce the delta angle, this shoul siumulate an acceleration curve
18:43 deshipu so small changes are simply ignored
18:44 deshipu wolfmanjm: except you want to start with full force anywas, because inertia will slow it down
18:44 deshipu wolfmanjm: so it's more like J than S
18:45 wolfmanjm well mor elike a trapezoid in my case I don't want it to jerk on start
18:45 deshipu there is so much one can improve
18:46 deshipu and the tweening affects the perceived personality of the robot a lot
18:46 wolfmanjm I'm thinking this can be applied to the angkes so you do the IK for the entire move, then you apply the angles in 0.1° increments initially
18:46 deshipu the problem is, servos have a dead band
18:46 deshipu they won't even start moving at 0.1° difference
18:47 wolfmanjm yea but it will accumulte and have the effect of slowin gthe entire move down Iwould hope
18:47 deshipu 0.1° at 50Hz is 5°/s
18:47 wolfmanjm yea I am so used to stepper motors where that is not an issue
18:47 deshipu not very fast
18:48 wolfmanjm mine are running at 60Hz not sure if that makes any difference
18:48 wolfmanjm but that was the default for the chip I am using
18:49 deshipu they are analog or digital?
18:49 deshipu I think the digital ones can go much much faster
18:49 wolfmanjm the servos?
18:49 deshipu yeah
18:49 wolfmanjm are analogue
18:50 wolfmanjm I'm using a 16 chanel servo driver board from adafruit
18:50 deshipu then you might have the angles shifted a little, due to the capacitor not discharging completely, but it should be fine
18:50 wolfmanjm takes the load off the arduino
18:50 deshipu wolfmanjm: the i2c one?
18:50 wolfmanjm yea
18:50 deshipu nice
18:50 deshipu I was thinking about it
18:51 deshipu it's a little overpriced
18:51 wolfmanjm it is quite nice and seems to work well, I can make it use 50Hz but then I need to redo the min/max frequencies
18:51 deshipu yeah, that's what I meant by the angles being shifted :)
18:51 wolfmanjm yea the chip is nice but buying the board saves having to design and manufacture a PCB
18:52 deshipu I want to design a pcb for this at some point anyways
18:52 deshipu have holes for screws for the servos directly in the pcb, etc.
18:52 wolfmanjm thre are two baords one is a breakout board the other is a shield, I got the breakout board
18:53 deshipu except I will probably use the pro mini as a module on that pcb
18:53 deshipu because buing the parts separately and adding it to the pcb would actually be more expensive
18:53 deshipu than a ready chinese board
18:54 wolfmanjm yea I get pro minis for $3 canl really beat that price
18:54 deshipu but a voltage regulator for the servos, an accelerometer and maybe a servo controller chip would go on the board
18:54 wolfmanjm but I may end up using a teensy3 anyway or another arm based board
18:54 deshipu and a charger for the lipo
19:00 rue_house whats the update rate of your servos, 50 or 60hz?
19:00 deshipu mine 50, wolfmanjm's 60
19:02 rue_house d you know the timeframe you want your moves to be done in?
19:02 deshipu as fast as possible :P
19:03 rue_house but you want a S curve velocity profile?
19:03 deshipu for raising the leg and making a step with it, yes, for moving the legs that are on the ground I want slow continous motion
19:04 rue_house so its not always as fast as possable
19:04 deshipu so that the legs are not moved outside their range before it's time to make a step with them
19:04 deshipu there basically three animations, superimposed
19:05 deshipu 1. moving all the legs on the ground continously backwards
19:05 rue_house https://www.youtube.com/watch?v=qZF9WJ1Ueew
19:05 deshipu 2. swinging the body around to keep the center of gravity over the support area
19:05 deshipu 3. making a step with individual legs
19:05 rue_house that is't really right, but it uses 10 midpoints for every move over the timerame of that move
19:06 rue_house there are only about 10 points in its cycle
19:06 rue_house or 5
19:10 deshipu yeah, I have something like that right now -- a hardcoded stopping point a few milimeters over the ground
19:11 deshipu so it gets there as fast as possible, and then to the ground
19:11 rue_house no, I take the linear path between point A and B, break it into 10 midpoints and clock them out over a period of time
19:11 rue_house I should put them in 1/60sec points, I didn't
19:11 deshipu what I would love to be able to do, though, is to tell the robot how heavy its leg is, and have it calculate the best trajectory by itself
19:12 rue_house you can
19:12 deshipu I know I can, it's just math :)
19:12 deshipu and Newton's mechanics are simple
19:12 rue_house use the mpa function
19:13 rue_house map()
19:13 rue_house on the arduino
19:13 deshipu nah, that just rescales linearly
19:13 rue_house I just assume your using an arduino
19:13 rue_house yea
19:13 rue_house 0-100%
19:13 rue_house from start to end of your points
19:13 deshipu that;s just simple proportion
19:14 rue_house its not an S curve, but it could be
19:14 deshipu that's not the problem
19:15 deshipu the real problem is that I need time to implement and test it all
19:15 deshipu I will get there
19:15 deshipu sooner or later
19:15 rue_house https://www.youtube.com/watch?v=B2fl8-L6xcA
19:15 deshipu it's just that there are so many other improvements I can add
19:15 rue_house that has to be the first counterbalanced bot I'v seen
19:15 deshipu like the kalman filter for the accelerometer
19:16 deshipu the yellow crimps look nice with the black cable wrap :P
19:18 rue_house see if i can finish mine today
19:19 deshipu anyways, 2am, good night
19:41 rue_shop2 288 degrees in, 180 degrees out
19:41 rue_shop2 1.6:1
19:42 rue_shop2 26mm pulley in
19:42 rue_shop2 41.6mm pulley out
21:30 rue_house https://www.youtube.com/watch?v=M8f3tqY5ZC8
21:30 rue_house neat design
21:36 rue_house https://www.youtube.com/watch?v=t7cGbLSnN78
21:36 rue_house oo nice
21:43 rue_house https://www.youtube.com/watch?v=nEKQ6BEe2qI <-- how many times have I told you to NOT do this stuff in the hosue!!!
23:35 rue_shop2 "this obviosly isn't gona work!, I need two springs, and the only spring I have is twice as long as I need!"
23:41 rue_shop2 stringing these cable drives is hairy, one wrong move and its an instant ratsnest
23:41 rue_shop2 ratsnest even
23:45 wolfmanjm yea I've done two 3d printers that used cable drive (well technically spectra drive) and they are tricky to wire up.
23:45 wolfmanjm I found that a clip that goes over the capstan to keep the wraps on there is enormously helpful
23:47 wolfmanjm I eventually switched both bots over to gt2 belt, which was a lot easier to setup, but I think overall cable drive was better in many respects