#robotics Logs

May 08 2013

00:00 vatula Triffid_Hunter: theta angle is not rigid, it's still generic enough :) It's just your suggestion is better (more precise)
00:01 Triffid_Hunter and requires less math, and less knowledge about the physical platform involved :)
00:01 Triffid_Hunter if you want to detect junctions or forks you'll need something a bit more intelligent though
00:02 vatula Triffid_Hunter: arguable :) Your approach requires knowledge of the distance between sensors. Since they are in arc (not in line), then to get precise numbers, you have to know geometry of your robot ;)
00:03 Triffid_Hunter nope no distance, go and read again. I suggest using the sensor index directly
00:03 Triffid_Hunter ie they're numbered -2, -1, 0, 1, 2 and that's your "distance"
00:03 Triffid_Hunter doesn't matter where they're placed, that'll shake out when you tune the PID
00:03 Triffid_Hunter although you do want consistent spacing between them
00:05 vatula Triffid_Hunter: Ah! But that means discrete behaviour, isn't it? Since sensors can have ib-between values like 2500, or 3900
00:06 Triffid_Hunter vatula: sure. so start with a simple threshold, then upgrade that one component to an algorithm that finds the center of the bell curve
00:06 Triffid_Hunter will give you much finer control when the line crosses from one sensor to the next :)
00:07 Triffid_Hunter a modular approach allows you to replace individual modules with more advanced or simply different ones
00:09 vatula Triffid_Hunter: Yeah, looks like it :) Thanks! I still need to understand how PID works though. I'll try your suggested model this evening (I see it is better, I just need to change my formulas :). Thanks for a great advice!
00:11 Triffid_Hunter vatula: P = coarse drive to get closer to target when far away. I = long-term fine tuning to bring fairly close towards dead on. D = resists changes in sensed value- prevents overshoot and gives quick response to external influences
00:12 vatula Ah, proportional-integral-derivative and great example with cars - I saw this and understand. I just haven't had a practice to apply it and REALLY understand :)
00:13 vatula Triffid_Hunter: There is a huge difference between understanding in theory and understanding in practive. I don't have the latter
00:14 Triffid_Hunter vatula: understanding comes from experience. experience comes from doing and experimenting. so stop mucking about with theory and begin!
00:14 vatula That's why I'm here :)
00:16 Triffid_Hunter vatula: http://brettbeauregard.com/blog/2011/04/improving-the-beginners-pid-introduction/ and http://brettbeauregard.com/blog/2012/01/arduino-pid-autotune-library/ may be good reading
00:23 lolina8088 \
00:24 lolina8088 \
00:24 lolina8088 \
00:24 lolina8088 \]
00:34 MrCurious i just had to describe the networking as rock solid
01:11 rue_bed so, a serial comm protocol for operating 6 stepper motors
01:11 rue_bed and managing 6 digital inputs
01:12 rue_bed brensham speed control?
01:12 rue_bed hmm
01:13 rue_bed needs to by synchronous
01:13 Curious ponders 0mq patt
01:13 rue_bed 3 elements, outputs, inputs, and a timer
01:14 rue_bed ok for step control
01:14 rue_bed 1+
01:15 rue_bed where 1 is the stepper motor number and + is the direction
01:15 rue_bed or
01:15 rue_bed A where a is the motor and uppercase means forward
01:15 MrCurious you driving the wheels with the steppers?
01:15 rue_bed no, a small robot arm
01:15 MrCurious use gear motors, not steppers
01:15 rue_bed ok so there is aA bB cC dD eE fF
01:15 rue_bed its already made
01:15 MrCurious steppers wont have the torque....
01:16 rue_bed they are gearsteppers
01:16 MrCurious i TRUST they have gears to torq them up
01:16 MrCurious ok
01:16 rue_bed !assist robots/arm5/
01:16 tobbor Possibly http://eds.dyndns.org/~ircjunk/robots/arm5/
01:16 rue_bed wrong arm
01:16 e_bed th
01:16 rue_bed !assist robots/arm4/
01:16 tobbor Possibly http://eds.dyndns.org/~ircjunk/robots/arm4/
01:16 MrCurious satellite linear possitioners?
01:17 rue_bed no, hospital beds
01:17 rue_bed ah, yea, its arm4
01:17 MrCurious rue? you live with parrents, married, single, other?
01:17 rue_bed http://eds.dyndns.org/~ircjunk/robots/arm4/p1010990.jpg
01:17 MrCurious looks like you may have a hoarding issue
01:18 rue_bed heh
01:18 rue_bed its modled after an ABB arm
01:18 rue_bed I cant just *get* parts here, so I keep a collection
01:18 MrCurious looks like the 2nd joint
01:18 MrCurious to raise lower arm
01:18 MrCurious that has 2 springs, it likely underpowered?
01:19 rue_bed its a 100% balanced robot
01:19 MrCurious nm, forgot geared steppers
01:19 rue_bed when you take the belts off, it prettymuch stays in position
01:19 rue_bed ok, step sync, can be /r
01:20 rue_bed timer, hmmm
01:20 rue_bed t65535 where the number is us?
01:21 rue_bed 65ms, ~60Hz,
01:21 rue_bed slower than mollases
01:21 rue_bed ok
01:21 rue_bed and it would reply with . when time is up
01:22 rue_bed T could be used to set the time and t to manually trigger an interval, with a sync also triggering an interval
01:23 rue_bed i could trigger an input status reply
01:23 rue_bed maybe just ascii hex
01:23 rue_bed so to controller is aAbBcCdDeEfFtTi
01:24 rue_bed replies are . and %02x
01:24 rue_bed hmmm
01:25 rue_bed so to controller is aAbBcCdDeEfFtTi\n
01:25 rue_bed or \r
01:25 rue_bed whatever
01:28 rue_bed The pc sets up the timer and steps, triggers the first one, and is responcable for setting up the next step set before the trigger timer fires, then acking the step sync which triggers the next time
01:28 rue_bed ok
01:29 rue_bed so thats 7 characters max per movement
01:29 rue_bed at 115200...
01:30 rue_bed 0.06ms
01:31 rue_bed not bad
01:31 rue_bed and the latency wouldn't be terrible on the hardware side
01:31 rue_bed pc os side might be fun
01:32 rue_bed I should do a ping test program set, see how fast an avr and pc can play badmantan with a byte
01:33 theBear badminton, or shuttle-cock <grin>
01:47 GargantuaSauce https://www.youtube.com/watch?v=g9EOOdAicQU
03:21 RifRaf Triffid_Hunter, am liking this version lots better http://imagebin.org/256898
03:21 Triffid_Hunter looks v. nice
03:21 RifRaf got it assembled on 30 minutes which was mostly hacksawing the screws to the right length
03:22 RifRaf in 6mm ally will be so strong, but will use this to biuld and debug
03:22 RifRaf the parts on ground are 3mm ally, including bed holder
03:23 RifRaf bit closer http://imagebin.org/256899 , http://imagebin.org/256900
03:26 Triffid_Hunter you have to edge-light it :)
03:26 RifRaf used new router bit to make it clean, was a very nice fitting cad file
03:26 RifRaf yeah a few rgb leds
03:27 Triffid_Hunter yeah would expect prusa et al to turn out some decent files
03:27 RifRaf was a bit of hassle to open the file though, others seem to have same issue
03:27 RifRaf corel was able to open it and resaving in there allowed me to use in cad software
03:28 Triffid_Hunter RifRaf: hm, I'd put washers in where the nuts are if they'll fit
03:28 RifRaf most definatly
03:29 RifRaf just had none, but i have glue thats stronger than the acrylic, so might just glues once tested, or screw and glue even
03:30 RifRaf but glueing would be enough, is like a super super glue, better than the chem weld stuff for acrylic
03:32 RifRaf and will change to nylocks, tonight i just wanted to get it assembled to look it it, has about 20 screws or more and is pretty stable already
03:32 Triffid_Hunter don't glue anything untill you've worked out all the bugs
03:32 Curious writhes in back
03:33 RifRaf yes for sure
03:34 RifRaf the parts did fit ok over the other files delusr linked me too, and i added mounting holes for the control board
03:35 RifRaf you think the part i am getting will fit ok? i know that alot of these parts replace the printer parts, dunno where all the aluminium bits even go yet
03:36 RifRaf er printed* parts
03:36 Triffid_Hunter yeah should all fit nicely
03:36 RifRaf maybe i don't need all the printed parts
03:36 RifRaf but will use as many as i can
03:39 RifRaf the bed holder has a bunch of extra holes than i acrlic one i cut yesterday
03:39 RifRaf and a bit chunkier in places, looks nicer
03:51 RifRaf also installed scad today, is gonna take me a bit to work that one out
03:51 Tom_itx i didn't like it
03:52 Tom_itx nice job rif
03:52 RifRaf thanks, i am so happy with the fit
03:52 Tom_itx is that poly?
03:52 Tom_itx not acrylic
03:53 RifRaf and will do it all in aluminium when i know the parts need no changes
03:53 RifRaf its 6mm acrylic for the main parts and 3mm ally for the rest
03:54 RifRaf just a scrap from work, will be broittle but will just glue and strengthen if it breaks
03:54 RifRaf is to get things happening when i get some parts\
03:54 Tom_itx did you get a ramps board?
03:55 Tom_itx or something else
03:55 RifRaf got a nice sheet of 6mm structural grade ally coming whatever that is, they tell me its alot stronger but dunno what grade
03:55 RifRaf yeah a ramps 1.4 i believe
05:34 theBear oooh, it's trenchcoat weather... nice
05:34 theBear doesn't happen often here, and i do miss wearing my trenchcoats
05:36 RifRaf only upto sloppy joe here
05:36 Jak_o_Shadows Was shorts and shirt weather today, was good
05:37 theBear heh, sometimes it's nice not caring.... my beard and moustache are all in my mouth at the moment, but, pfft, who do i wanna impress ?
05:37 theBear and this fluffy inch high hue over my cheeks is kinda entertaining me
05:37 theBear probly makes lots of other people smile when they see it too <grin>
05:37 RifRaf you can get trimmers nice and cheap at woolies theBear, its all i use these days, 1 aa battery
05:38 theBear i got clippers, traditionally i use scissors for around my mouth, but, why ? no job, don't meet anyone, don't see anyone, can barely get out of the house on a good day.... since i got no alternatives, may as well enjoy living like a bum for a little bit
05:39 RifRaf yep, just chew off the hairs that get into yer mouth so they don't get stuck in sangas
05:40 theBear hey, now yer talkin !
05:41 RifRaf theBear, i joined the reprap world, are you one as well?
05:41 theBear i noticed... not quite, but i been head-planning, i'm poised if i ever find some cash or get my hands on some rails and motors maybe
05:42 RifRaf seems they just use threaded rod
05:42 theBear well kinda, more bearrap (yeah, i saw yer pic :) ... i feel they do a lot of things wrong, maybe it helps no-brainers build them, but i don't think it's good
05:42 RifRaf the motors are about 120 or so for a set
05:42 RifRaf i will add washers if thats what worried you, and make it from strong ally
05:42 theBear yeah, that's about half what i owe on power, and i had a bowl of rice since sunday, and no milk or sugar for over a week :)
05:43 RifRaf and weld what can be welded, we have tigs that would not warp
05:43 RifRaf and even 2pac it after to make it pretty
05:43 theBear heh nah, just the way they put the whole thing together, mk2 seems better, but there are at least a bunch of little things that someone like you or me or rue would do without even considering it a 'design change' that will make a world of difference
05:43 Jak_o_Shadows I was mentioning welding aluminium today, and somebody mentioned glue.
05:44 RifRaf am thinking a study frame would be a good starting point
05:44 theBear gluing ally ? that sounds a bit silly
05:44 Jak_o_Shadows That was my reaction.
05:44 theBear i spose if you key the hell out of it it could work, but, meh
05:44 RifRaf Jak_o_Shadows, we weld ally all day long, have 2 dudes doing it with mig and tig
05:45 RifRaf but i do have glue that'll glue ally together it glues anything almost
05:45 theBear a sturdy frame is indeed a big step in front of what they do, doesn't have to be cnc sturdy, but not something built like a kids swingset :)
05:45 RifRaf but a weld is far better
05:45 RifRaf 6mm high grade allu should do it
05:46 theBear if i was gonna glue ally i'd probly try generic brown building adhesive and if that didn't cut it move up to black+white double-glue-gun epoxy, that stuff is WAAAAAAY stronger than ally, or steel, or really most things
05:46 RifRaf this plexi is almost ok, cept it needs some extra support which i'll just glue on
05:46 theBear 6mm is huge, that'd be rock solid
05:46 RifRaf yep :)
05:47 theBear have to be way stronger than say, 2mm 90deg angle in most situations, and that's without any bracing
05:47 theBear heck, i've got some roughly 4mm ally checkerplate and it's rock solid over about 10"
05:47 RifRaf i don't do much past 4mm ally at work, but i reckon a new 3mm bit would go through it fine and do a clean job
05:47 RifRaf used a crappy old 3mm bit to do the 3mm ally parts today
05:47 RifRaf but a new one for the plexi
05:48 theBear what kinda bits you use on plexi ?
05:48 RifRaf theBear, it changes when you cho out 90% of the center though
05:48 RifRaf chop*
05:48 theBear hmm, what part you using it for ?
05:48 RifRaf just single flute
05:49 theBear like regular hss ?
05:49 RifRaf i do upto 25mm thick, which a 32mm cutting bit
05:49 theBear or are they double ?
05:49 theBear they must be double thinking back to manual sharpening
05:49 RifRaf i think they are carbide, at least the stainless bits are solid carbide
05:49 theBear i just mean the flutes
05:49 RifRaf can't sharpen em, i use em till they snap
05:50 theBear more thinking about thin plexi, tends to split when you drill it, i heard there are some special bits you use
05:50 theBear or one uses
05:50 RifRaf but have to use newer bits to get clean edges on acrylic, cause i cut compisite stuff all day
05:51 theBear surely 'normal' bits are double flute ? don't make me go look
05:51 RifRaf i reckon a 6mm acm would make a great frame too, with 1mm ally on each side
05:51 RifRaf nope
05:51 RifRaf for stainless i use triple
05:51 theBear hmmmm
05:51 theBear so basically you use 'normal' hw store bits for plexi ?
05:51 theBear at least shape wise
05:51 RifRaf but for general day use all single, this thing just chops stuff up
05:52 RifRaf i go like 100mm/sec for alot of stuff
05:52 theBear seriously ? jeeez
05:52 RifRaf yep, for ally its about 25mm with a 6mm bit
05:52 RifRaf for 3mm thick plate
05:52 RifRaf but you can fly through the composite stuff
05:53 RifRaf even the 3mm parts had to be done at 15mm/sec with a 3mm bit, or the ally melts on itself
05:53 RifRaf has fluid blowing on it
05:53 RifRaf well a mist
05:54 theBear mist eh ? fancy :)
05:54 RifRaf yeah, sucks to breathe it in for hours
05:54 theBear meh, i've breathed worse stuff for a living :)
05:54 RifRaf cause you canot use the vacuum extractor with the mist
05:55 RifRaf is just a metal thing
05:55 RifRaf can cut 25mm plexi with no coolant
05:55 RifRaf but it does make things smoother
05:56 theBear hmmm, is it wrong to go to church for moral guidance if you don't agree with the churchs beliefs ?
05:56 Jak_o_Shadows no
05:56 theBear hmm, i been considering it more and more regularly recently
05:56 RifRaf nope, they are the most helpful people some of the time
05:56 RifRaf just whatch out for thoise weird priests
05:57 theBear hehe, i'm a big boy, and somewhat cracked in the head and missing my violent youthful days... i'll be fine
06:10 theBear hmmm, how does your average cheap timer-light work these days ? if the power was off for about 2 hours, does that mean it's just 2 hours late now, or it aint gonna come on at all ?
06:25 RifRaf no idea really, but i'd say not at all if not by now, surely they don't have a timer as well as light sensor
06:27 RifRaf buts its incredible what you can get on a chip for a dollar these days, but why, if its dark its dark, and you want a light
06:35 RifRaf only problem with making things in clear acrylic is i lose the parts, just cannot find this switch holder i made the other day for foxy
06:35 Jak_o_Shadows lol
07:16 theBear hehe, you crazy foo'
07:16 theBear looks like it came on a couple hours late... nah, i mean a timer light, not a sensor light
07:17 theBear as in, the one outside my flat frontdoor
07:17 theBear not very welcoming when the whole place is pitch black
07:25 theBear oh wow ! a hotdog and a beer make you feel REALLY good after not eating anything real for 72 hours
07:34 Tom_itx that's real?
07:37 theBear what ? hotdogs or timerlights ?
07:57 theBear err, i mean, that's what she said :-)
19:52 GuShH eadthem: are you familiar with hand plane nomenclature?
19:52 eadthem hand plane as in wood tool?
19:52 GuShH yep
19:52 eadthem a bit
19:53 GuShH "Lap frog face on edge of stone to protect yoke" http://virginiatoolworks.files.wordpress.com/2012/06/frog-lapping.jpg
19:53 GuShH Is the yoke the lever used to "steer" the iron?
19:53 eadthem i think
19:54 GuShH I have a number 5 stanley, which is what they show on the photos I think although mines not old
19:54 GuShH they are pretty much useless out of the box
19:54 GuShH but you know a design is good when they haven't changed it since the 50s
19:55 eadthem http://blog-imgs-54-origin.fc2.com/w/o/o/wood378/Woodworking-Plane-3.jpg
19:56 GuShH neat thanks!
19:56 GuShH but then, where's the yoke?
19:56 eadthem http://www.japanwoodworker.com/newswire.asp?month=8/2006
19:57 ShH frowns at a casting defect on his
19:57 GuShH Heh funny to find a western plane on a japanese wood working site
19:57 GuShH wish I had some japanese tools
19:57 GuShH they're amazing
19:57 GuShH specially the saws and the planes
19:57 Tom_itx dude in #linuxcnc collects planes
19:58 GuShH Is he one of those micron-thin shaving weirdos?
19:58 Tom_itx no
19:58 Tom_itx i've seen those videos though
19:59 GuShH Were you impressed? I was
19:59 Tom_itx yeah
20:00 GuShH But it's not just honing and tuning, the quality of the steel is what makes it all possible, plus the type of wood -- they seem to use very straight grain stuff.
20:01 GuShH I'm happy if I can get a relatively plane surface.
20:04 GuShH it seems stanley cut down on costs by using steel instead of brass on their latest models
20:04 GuShH what a shame, not even the blade is made in the US
20:05 GuShH (I know it used to be)
20:16 eadthem GuShH, go to local auctions
20:16 eadthem get your hand tools from that
20:16 eadthem such as planes
20:36 MrCurious no! just buy a cnc off the get go
20:36 MrCurious and forget needing tools
22:03 GuShH CNC... instead of tools? Only if I were born talentless.
22:16 Rif pfft
22:22 MrCurious and web cam from 27" imac has been extracted, and a usb connector wired to it, and working :D
22:24 MrCurious chrome book c7 is upgrading to ubuntu 13.04
22:25 MrCurious and my upper spine is currently not exploding. the day is now a WIN!
22:26 MrCurious so i now have 3 ultra tiny usb laptop web cams
22:55 Rif good to hear you're feeling better MrCurious
22:56 MrCurious thanks!
22:57 MrCurious as long as pain doesnt come with a spasm overlay i will be fine