#robotics Logs

Mar 31 2013

04:25 ocei3ko e.g. http://www.watterott.com/en/Power-Supply-3-12V-1A
04:29 Triffid_Hunter ocei3ko: I use 3 types of power supplies: phone chargers (5V 1-2A), ATX (5v 30A, 12v 15A) or laptop (15v 6A)
04:29 Triffid_Hunter grabbed some LM2596 board from ebay for $1.50/ea for almost everything else I might need
04:29 ocei3ko What is that?
04:30 Triffid_Hunter ocei3ko: LM2596 = very simple buck switcher, gives less voltage than power supply at up to 2A.. the chip is rated to 3A but needs a bigger heatsink for that
04:31 ocei3ko hmm
04:31 Triffid_Hunter ocei3ko: good for servos and weird voltages and things like that
04:31 ocei3ko Define "less"
04:31 Triffid_Hunter ocei3ko: whatever you want, there's a multiturn pot on the board to adjust
04:31 ocei3ko ah ok
04:32 ocei3ko Is 1A enough for most things?
04:32 Triffid_Hunter it's plenty for logic
04:33 Triffid_Hunter gets a bit tight once you start adding motors though
04:33 ocei3ko Hmm
04:33 ocei3ko Thinking of getting a beagle bone
04:33 ocei3ko Arduino seems weak
04:34 ocei3ko The new due is 46�, whereas beaglebone is 85 but does moar
04:36 Rif ok i'm back, had little nap
04:37 Rif Triffid_Hunter, have read through your posted link on tuning pid, i might try out the library after i have messed with this one a bit more
04:38 Triffid_Hunter ocei3ko: haven't checked out beaglebone just yet, but from what I read it's very capable.. a linux SoC and a smaller micro for hard realtime tasks on one board is brilliant
04:38 Triffid_Hunter or are they on the same die? might be same die with shared memory or something, even better
04:52 ocei3ko Waiting for the new version to come out in april
05:12 Hukka ocei3ko: So, what kind of thing do you have in mind that avr is not enough?
05:16 ocei3ko Nothing, just thinking is all
05:16 ocei3ko Want to make a spider :>
05:17 ocei3ko Probably dont need a beagle board for that, but was thinking it would be ok to get eventually
05:18 Hukka You are dropping to the crevasse of overspeccing
05:19 Hukka That is, you don't have a clear need for a more powerful part, yet you are still thinking if you should get one anyway
05:21 ocei3ko Ah
05:21 Hukka It's an infinite road, really. If you don't have a clear need to fill, you can always think whether you should just upgrade just in case
05:23 Hukka Arduino -> Due -> Beagle (Cortex A8 @ 600MHz) -> Cubie (A8 @ 1GHz, more ram) -> Atom -> AMD APU -> Celeron -> i7 -> GPU -> and so on and so on
05:23 ocei3ko Hmm
05:23 ocei3ko So you think I should get an avr programmer and some avrs?
05:23 Hukka Well, I don't know really what you are doing
05:24 Hukka It's a huge difference whether you just need a motor controller for some premade poses, or realtime CV and IK
05:24 ocei3ko Hmm
05:28 Triffid_Hunter ocei3ko: see if the TI LM4F120 devboard promotion is still going
05:28 Triffid_Hunter ocei3ko: if you're just starting in microcontrollers, definitely get an arduino
05:32 Hukka Hm, Stellaris, right?
05:32 Hukka I heard that it has pretty much disappeared
05:33 Hukka Just yesterday someone from local hackerspace was complaining that it was out of stock on TI, Farnell and DK
05:33 Hukka We were wondering if TI is killing it
05:35 Hukka ocei3ko: Depending on your background, you might want to skip arduinos and go to plain avr tools. Though you also might want to skip atmegas, and use something like atxmegas instead
05:37 Hukka For robotics, definately make sure to get at least an arduino that has an available UART
05:37 Hukka That means something that has integrated usb, or just more than one UART (like mega)
05:42 ocei3ko Will check here before any purchases
05:42 ocei3ko Hard to pick the correct avr chip to begin with
05:43 Triffid_Hunter yeah the stellaris.. cortex-m4 are very intriguing cores, all the fun of a real microcontroller, with added benefit of limited pin remapping, multiple DMA, floating point coprocessor..
05:43 Hukka Have you done any embedded stuff before?
05:43 ocei3ko No
05:43 Hukka If not, just pick some dev board and play around
05:43 ocei3ko Done some C programming, learning perl atm but no hardware related stuff
05:43 Hukka Without any experience you don't even know what the right questions are
05:43 ocei3ko Have components for electronics
05:43 ocei3ko Second
05:44 Triffid_Hunter ocei3ko: get an arduino from hong kong via ebay. when you finally hit the limits of what it can do, you'll know exactly what questions to ask
05:44 ocei3ko I bought a fairly cheap set of parts to play with
05:44 Hukka Arduino is ok since it's easily available. Just keep in mind that many available examples are made by people who don't really know much about what they are doing
05:44 ocei3ko http://www.ebay.co.uk/itm/Electronic-Components-Starter-Kit-huge-633-piece-kit-/190712040817?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item2c6752cd71
05:44 Hukka Reading criticism is recommended
05:44 ocei3ko Buying those individually would have cost a lot more than 30�
05:45 Triffid_Hunter ocei3ko: yeah looks like a decent basic kit
05:45 Hukka Triffid_Hunter: I've heard that to get a reliable arduino from HK, you need to know quite a lot... otherwise you end up spending time with faulty boards
05:45 Triffid_Hunter ocei3ko: you'll also want to grab some L293D at some point
05:45 ocei3ko What is that?
05:46 Hukka But that's just second hand, I haven't bought clones so I haven't had bad samples either
05:46 Triffid_Hunter Hukka: hm, I've heard that the hong kong boards are higher quality than genuine italian ones
05:46 Hukka Triffid_Hunter: Some, sure
05:46 Triffid_Hunter ocei3ko: L293D is a driver for small motors
05:46 ocei3ko Ah, ok
05:46 Rif all my clones work fine
05:46 Hukka And some are just cheap in every way
05:46 Hukka So that's the trick, you need to be lucky or know where to buy and what
05:46 Rif only issue so far is the mini usb connector falling off a few of the nanos
05:46 Triffid_Hunter ocei3ko: may want to browse sparkfun, adafruit, pololu as well ;)
05:46 Rif but is fine with resilder and superglue
05:47 Rif resolder*
05:47 Rif and for $10 or so each you can get a few so you don't have to keep ripping apart projects to test something else
05:48 Triffid_Hunter ocei3ko: you'll be soldering sooner than you think :) if you can afford it, get a temperature controlled station.. if not, a 20-30w pencil iron will do in the interim
05:48 ocei3ko Well, I have a few hundred to spend but not sure if I need to invest in a new laptop first
05:48 Hukka People have recommended aoyou stations
05:49 Triffid_Hunter yeah aoyue are hakko clones, apparently decent quality
05:49 Hukka Of course the best bang for the buck is to go communal
05:49 Hukka Join a hackerspace or some other group that has the heavy hardware
05:50 Triffid_Hunter and the experience to let you know right before your project loses its precious smoke
05:50 Triffid_Hunter rather than finding out right after
06:03 Rif Triffid_Hunter, mg996 pcb from yesterday http://imagebin.org/252316
06:04 Triffid_Hunter yikes, that smoke sure was in a hurry to leave
06:04 Rif yep
06:12 ocei3ko What is everyone working on here?
06:13 Rif balancing
06:13 Jak_o_Shadows Robot.
06:13 Jak_o_Shadows Wheeled robot, perhaps vision controlled, but a manual h-bridge capable of about 5-6A
06:13 Rif and about a million other projects in various states
10:18 Hukka ocei3ko: I'll be making a pair of RCJ robots
10:19 ocei3ko rcj?
10:19 dunz0r Wheeled minisumo robot and a larger robot with a web-camera for vision control.
10:19 dunz0r Planning a microsumo robot too
10:20 Hukka ocei3ko: Robocup Junior
10:20 ocei3ko ah ok
10:20 Hukka I'll also need to do a remote platform with a webcam at some point
10:20 Hukka But no time yet. If you know of good wireless solutions, I'm interested
10:20 dunz0r Just waiting for the webcamera now. Ordered a cheap one from DX.
10:20 Hukka Wifi is perhaps too short range and too big bandwith for the use
10:21 Hukka I've had the webcam for some time now
10:21 dunz0r Hukka: Maybe 3G?
10:21 Hukka For "unlimited" range, yeah, but I'm looking for a p2p link
10:22 NightRavenXS guys, what platforms do you use?
10:22 NightRavenXS i mean, rPi, Arduino?
10:22 NightRavenXS or microcontrollers?
10:24 Hukka That's... a bit odd question
10:24 Hukka Arduino has an mcu
10:24 Hukka Also I've found raspi to suck for robotics
10:25 Hukka Of course the few io pins was a known fact beforehand, but the almost unusable usb wasn't
10:25 dunz0r The Arduino is just a microcontroller with a name on it.
10:25 NightRavenXS well
10:25 Hukka I delegated one into mediapc use, and another is just idling
10:25 NightRavenXS and an easier interface
10:25 ghtRavenXS doesn't lik
10:25 NightRavenXS i want MCU from scratch
10:25 NightRavenXS which is pretty difficult, but really interesting
10:25 dunz0r NightRavenXS: You can just as well use regular AVR C on it.
10:26 NightRavenXS dunz0r, well than why buy it?
10:26 NightRavenXS if i can buy the prototyping kits
10:26 Hukka Sooner or later I'll buy a cubie to do some heavier robotics
10:26 NightRavenXS and learn prototyping
10:26 NightRavenXS anyone worked with PIC32s?
10:26 Hukka I haven't but based on what I've heard I don't want to
10:26 home I use an arduino and rpi
10:26 dunz0r NightRavenXS: I build my smaller robots with Atmega328s with the arduino bootloader on them. Who says you need to use the arduino-boards? I do my own pcbs :)
10:26 home I really need a battery
10:26 Hukka Then again, I guess I don't want to use atmegas either
10:27 home dunz0r: yeah :D I want to do that
10:27 dunz0r Got a Beaglebone for the web-cam-robot.
10:27 home how cheap is it?
10:27 dunz0r home: Really cheap :)
10:27 home ooh share some link? I want to make my own
10:27 home and share it with some friends, if possible.
10:27 dunz0r home: Your own PCB or your own arduino? Or both?:)
10:28 Hukka dunz0r: Yeah, beagle is an option too
10:28 Hukka But cubie is kinda more interesting
10:28 home my own pcb for the arduino?
10:29 dunz0r home: Here's schematics and PCB of my current build: http://hax0r.se/files/img/robot/Perfected_Titan/
10:32 Hukka Any hope somebody here would have made a literature review of legged robotics balancing and posturing :?
10:33 Hukka I haven't found any books or comprehensive intros on the subject, so I've just started to gather a bunch of articles. But it's a lot of work to go through them and weed the uninteresting ones
10:35 home wow :/
10:37 Hukka Wow?
10:37 dunz0r Hukka: I would say that some sort of PID-control is what you would like to start looking at.
10:38 Hukka PID is... somewhat orthogonal
10:38 Hukka Alone it's useful only for unperturbated static balance
10:39 dunz0r Start looking I said, not a complete solution :)
10:39 dunz0r You'll most likely need some filters on the input / output as well for it work nicely.
10:39 Hukka There are no leads from PID to onward
10:39 Hukka You could have at least said Kalman filters or ZMP...
10:45 ocei3ko So either Arduino Uno, or an avr on its own, if so which one?
10:46 dunz0r ocei3ko: It depends. The Arduino is easier to start with, but the AVR on it's own is cheaper and better.
10:46 Hukka ocei3ko: I highly recommend you to get something else than uno, if you are going to do robotics
10:46 ocei3ko Not sure which avr to get
10:46 dunz0r ocei3ko: One that has as many outputs as you need basically :)
10:46 Hukka ocei3ko: Overall it wouldn't matter much, but the lack of separate uart can be a serious pain if you want to use for example robotics servos
10:47 home I tried PID
10:47 home and all I got was jitter
10:47 home ....
10:47 Hukka Also in robotics the shields are not very useful, so you do not need the formfactor
10:47 Hukka So I recommend teensys
10:47 dunz0r I tried PID and I got a really good linefollower :)
10:47 Hukka Cheaper than uno too
10:47 dunz0r Upgrading it soon. Waiting for new motors and a new sensor array.
10:48 dunz0r 8 sensors instead of just 5. And 10:1 geared motors instead of 35:1.
10:48 dunz0r It'll be blazing fast :D
10:48 Hukka dunz0r: Micromouse fast?
10:49 Hukka ocei3ko: How well do you solder? What about could you choose components for a 8MHz resonator circuit?
10:49 ocei3ko Hukka, I'm a real noob with this, I don't own a soldering iron
10:49 ocei3ko Really just getting interested
10:49 Hukka If both are not routine for you, I'd say that a premade dev board is better than a plain mcu for now
10:51 Hukka ocei3ko: http://www.pjrc.com/store/teensy.html
10:51 Hukka Good and cheap way to start
10:51 Hukka Will be useful later too for all sorts of small things
10:52 ocei3ko Hmm
10:52 Hukka If money isn't a problem, you can spend $5 more and get the ++ for more pins
10:52 Hukka Sorry $9
10:54 ocei3ko 15$ shipping
10:54 Hukka Ah, not american
10:54 Hukka Well, then you might want to see what you have locally
10:54 ocei3ko Finland
10:54 Hukka Ah, I forgot
10:54 Hukka Hm
10:55 ocei3ko Know any good shops here? Online
10:55 Hukka Not for teensys
10:55 ocei3ko But electronics related
10:55 Hukka When I bought mine, the shipping was much less
10:55 dunz0r Hukka: I hope so :)
10:56 Hukka ocei3ko: partco for "I need it now" stuff
10:57 Hukka mansteri.com is the best arduino shop. They also resell sparkfun, pololu and adafruit with reasonable comission
10:57 ocei3ko partco.com?
10:57 Hukka .biz
10:57 ocei3ko Also this http://paeae.com/
10:57 Hukka They were going to stop their business
10:58 Hukka But yeah, good shop too
10:58 Hukka Avoid robomaa
10:58 ocei3ko partco looks nice
10:58 ocei3ko Partco seems quite expensive though
10:58 Hukka It is
10:58 Hukka But they have stock, and it's local
10:59 Hukka Like I said, for stuff you need immediately
10:59 Hukka They also resell everything farnell has for 25% comission
10:59 Hukka Not that reasonable, but sometimes still the best option
10:59 ocei3ko farnell?
10:59 Hukka Big international wholesale of electronics
11:00 Hukka The other two usual being Digikey and rs-online
11:00 Hukka ocei3ko: You were in the area, IIRC, so I recommend you just don't buy anything and join Helsinki Hacklab
11:00 Hukka There you can learn how to use arduino and avrs
11:01 Hukka After you know the basics with those, you are closer to figuring out what you want and need
11:01 ocei3ko If farnell is wholesale, you think its worth buying individual things from there?
11:01 Hukka Sometimes
11:02 Hukka The shipping is expensive, but partco orders from there anyway
11:02 Hukka I usually get stuff with a group buy and a shell company
11:02 ocei3ko ah ok
11:09 Hukka You can become my apprentice too ;)
11:11 ocei3ko You live in Helsinki?
11:11 Hukka Still in Espoo
11:11 ocei3ko Ah right, forgot
11:23 home I need a mentor :/
11:23 ocei3ko For what?
11:36 home meh
11:37 home to help me learn stuff
11:37 home liek tools
15:51 chris_99 hi, does anyone know what you'd call a gas bottle with inlet and outlet
16:34 RifRaf odd
16:56 Tom_itx a filter
20:46 RifRaf http://www.youtube.com/watch?v=sIkj6OUEQSM
20:52 Tom_itx it balances sideways
20:52 RifRaf yes sorry
20:53 Tom_itx i think the battery weight is a bit much for the servos to recover from
20:55 RifRaf it recovers ok if i make it faster, but that was just a non shaky balance, need to use those PID setings when it near center, and stronger ones for when it moves away
20:56 RifRaf but finding the balance between good recovery and stable when balanced is hard
20:56 Tom_itx yep
20:58 RifRaf nice 75 car pileup in virginia, good to see you guys drive to the conditions
20:59 rue_house most peoples condition is about 4 inches behind the last person
21:00 Tom_itx they drive nuts out east
21:02 RifRaf ok will move one battery down the bottom
21:02 RifRaf as long you you don't say i am cheating
21:02 RifRaf rue_house, see the balance?
21:03 RifRaf it falls over in 1/2 second when turned off, longest balance is a few minutes now
21:03 Tom_itx well you can do that or get motors with more torque
21:03 RifRaf have them ready, will make new frame tomorrow
21:03 Tom_itx now make it move forward
21:03 Tom_itx tell it to fall over and it will move
21:03 RifRaf 12V 3A with 2 pwn drivers
21:04 Tom_itx are you feeding the PID to the motors differentially?
21:04 RifRaf well with the new motors i'll then use a gyro and use the ultrasonic to avoid objects
21:04 RifRaf yeah, one adds the values and one subtracts it
21:59 Rif how cool is it when you get it dialed in right, has been going for ages now
22:01 Tom_itx what's it do when you push it?
22:02 rue_house and kick it
22:02 rue_house all inverted pendulum bots get kicked
22:02 Rif it kicks back
22:03 Rif just crashed and knocked sensor off
22:03 f warms hotglue gu
22:03 Jak_o_Shadows1 lol
22:05 rue_house [poor robot
22:07 Rif you made me kick it
22:08 rue_house :/
22:08 rue_house i was really only joking
22:08 Tom_itx when has he ever done what you told him?
22:08 Tom_itx until now?
22:14 Rif rue now that i have settings, or will have when i enable the lcd can start making the pid adaptive
22:15 Rif these are for when almost upright or upright, need some others to handle the kicks better
22:28 Lolina8088
23:03 MrCurious trying to get a jpeg image from a camera in python. i can get an image, but i have to save it to a file to make it a jpeg/png. i want to send it over a socket, so i want to avoid the file step. anyone have a hint
23:07 Triffid_Hunter why do you have to save it to a file?
23:07 MrCurious cant work out how to get it in jpeg or png without dumping it to a file
23:33 rue_house imagemagick
23:33 rue_house oh I see
23:33 rue_house hmm
23:33 MrCurious its driving me nuts
23:33 rue_house I think you can catch the buffer before its written to a file
23:34 rue_house iirc it converts it, and you have to write it to file seperatly
23:34 MrCurious think i need some fake memory file
23:35 Triffid_Hunter named pipe or mmap :P
23:35 MrCurious perhaps StringIO
23:38 MrCurious success!
23:38 MrCurious StringIO
23:49 Triffid_Hunter MrCurious: excellent! for extra points, find a way to do it without storing the entire resulting file in memory before moving on :)
23:50 Triffid_Hunter pipes are good for that.. if the kernel wants more ram, it stops the writing end and lets the reader run.. when it has plenty of ram it lets them both run
23:50 MrCurious i can live with this solution for now. prototype in python, harden in c++
23:50 MrCurious can optimize in teh c++ phase