#robotics Logs

Jan 08 2012

00:42 Kimlaroux makes sens
00:42 SolarNRG How long will it be before we can afford robot housewives?
00:44 theBear depends how rich "we" are i suppose <grin>
00:44 theBear heck, if you got enough cash you can have a non-robot housewife right now !
00:44 SolarNRG Yeah I got one of those already
00:45 SolarNRG I want one that moans less, at least moans in a different way
00:45 SolarNRG ;)
00:46 theBear you need more money then <grin>
00:54 SolarNRG http://www.youtube.com/watch?v=tEkqYta-i3s&feature=related
00:54 SolarNRG Have a look
00:57 SolarNRG Or this one http://www.youtube.com/watch?v=SqmlUUYEOKA
00:57 SolarNRG This is funny
00:57 SolarNRG They move back and forth
00:57 SolarNRG They cost like $2000
01:21 rue_house *sigh*
01:45 SolarNRG What makes the best robot legs?
01:45 SolarNRG Gears?
01:45 SolarNRG Pulleys?
01:45 SolarNRG Hydraulics?
01:51 rue_house pneuamtics?
08:25 SolarNRG I've had another idea
08:26 SolarNRG You know how you have fast twitch muscles and you have strong muscles, well I thought about using the same principle for building humanoid robots
08:26 SolarNRG Use a planetary gearbox
08:26 SolarNRG Have the inner "sun" gear a hi torque motor for strength
08:26 SolarNRG And have the outer "pluto" gear have a hi speed motor for punching or moving a leg real quick
08:26 SolarNRG Then use the the sun gear to hold it in place
08:27 SolarNRG Do you think it would work?
08:54 elektrinis no.
08:55 elektrinis one motor will always be in generator mode
08:55 SolarNRG Generator?
08:56 elektrinis take a sheet of paper and a pencil. draww some forcec
08:56 SolarNRG OK
08:56 elektrinis you'll see that one motor has a negative torque
08:56 elektrinis = renerating power
08:56 elektrinis generating
08:57 elektrinis planetary gearbox = differential with different ratio
08:57 SolarNRG OK my design is a differnt type of planetary gearbox
08:57 elektrinis :)
08:58 elektrinis I gad ideas like this
08:58 elektrinis had
08:58 SolarNRG The inner sun gear rotates 5 planets
08:58 SolarNRG each planet has a bearing
08:58 SolarNRG Inside the bearing is a solid shaft
08:58 SolarNRG As they go around the sun, the 5 shafts come out and merge on top of the sun but not connected to the sun
08:58 SolarNRG So that one shaft can rotate round
08:58 SolarNRG The outer ring connects to the planets
08:59 SolarNRG The outer ring and the sun ring do not touch
08:59 elektrinis typical planetary gear.
08:59 SolarNRG If the sun goes the ring gear does not move
08:59 SolarNRG The outer ring gear has teeth on the inside AND on the outside
08:59 SolarNRG On the outside is a motor with a step-up gearbox
09:00 SolarNRG The sun gear is turned by a motor with a hi torque step down gearbox
09:00 SolarNRG The two motors won't interfere with each other at all
09:00 elektrinis it is always a case with perpetum mobile projects - overcomplicating things.
09:00 SolarNRG The shaft taht the 5 planets connect to is say an elbow
09:00 elektrinis ok, time to go home.
09:01 ektrinis
09:01 SolarNRG :o
14:05 rue_house what happens when it gets to the point EVERYONE is looking for work?
14:05 rue_house and nobody can afford anybody
14:57 Tom_itx we start over
14:57 rue_house but, but , but, I lost me garden hoe...
18:40 theBear and here i am like a sucker, don't even have an indoor hoe
21:09 Kimlaroux I opened my drill to oil it up because it was starting to make painful noises... but now it's worse. When I make it turn slowly, it "jumps" back and forth. It sounds like something in the transmission is not fitted properly, but I reopened it and reclosed it making sure everything was fine... didn't help. Anyone ever experienced that?
21:10 Triffid_Hunter Kimlaroux: bearing has worn out?
21:10 Kimlaroux Oh crap, I never thought about this option
21:10 orlok Kimlaroux: no, generally from what i remember you dont want to bother trying to open the gearbox, you will generally never put it back the correct way
21:11 Kimlaroux haha, thanks orlok, I guess I learned that the hard way =P
21:12 Kimlaroux Triffid_Hunter, when the gear box was empty, I turned the socket and it was smooth
21:12 Kimlaroux any test I could do to see if it's the bearing?
21:13 Tom_itx take it out and check it
21:14 Kimlaroux mkay, I'll try to get to it
21:21 Tom_itx or if you had a stethoscope
21:21 Tom_itx you could listen for it
21:22 Triffid_Hunter Kimlaroux: worn out bearings usually only crunch under load, eg when the off-axis torque from another gear is pushing on the shaft
21:23 Kimlaroux hhmm, doesn't seem to be the bearing
21:23 Kimlaroux I think orlok's right... I just can't manage to put the gears correctly in
21:23 Kimlaroux it's a weird type of gearbox I never seen before
21:24 Kimlaroux there's 3 gears inside a tube with a reversed gear on the inside...
21:25 orlok planetary gearset iirc
21:25 Kimlaroux http://www.robotpower.com/images/cm-80_gears-sm.jpg
21:26 Kimlaroux I'll try to assemble it the other way around
21:27 Triffid_Hunter Kimlaroux: oh a planetary? they can be tricky, the planets need to be inserted in the correct order and orientation or they bind
21:28 Kimlaroux I believe this is what's happening
21:28 Triffid_Hunter unless the sun and ring have a number of teeth that's an integer multiple of the number of planets (usually 3)
21:29 Kimlaroux I think I need a course on planetary gears so I can understand you
21:30 Triffid_Hunter Kimlaroux: the sun is the gear in the center. the planets orbit around the sun. the ring is the outer part that. the planets are all connected together by a Y arm
21:31 Kimlaroux alright
21:31 Triffid_Hunter turning any of the sun, ring or planets will produce rotational torques on the other two. usually one is fixed
21:31 Tom_itx Triffid_Hunter, do you know if anybody has started firmware for this arm board project?
21:32 Kimlaroux yeah the ring is "fixed", it's hooked on a ratchet
21:32 Triffid_Hunter if the planets are inserted incorrectly, then the ring and sun are no longer on the same axis- the planets push one or both into an eccentric orbit vs the other
21:32 Kimlaroux ah I see... there probably lies my problem
21:32 Triffid_Hunter Tom_itx: smoothie is currently the general arm reprap firmware, still in early beta
21:33 Kimlaroux is there a trick to get them in correctly?
21:33 Tom_itx i just need to find some pinouts
21:33 Triffid_Hunter Kimlaroux: yes probably, don't know what it is though
21:34 Triffid_Hunter Kimlaroux: from first principles I'd assume that if you're really careful about the alignment and understand that they have an order and try various orders until one gives all contact points fairly equal spacing you should be good
21:34 Kimlaroux well thanks a lot for the information =) I'll go for trial-and-error
21:34 Triffid_Hunter Kimlaroux: you know how to read a vernier scale? the sun and ring have a relationship like that, bridged by the planets
21:36 Kimlaroux what's a vernier scale? you mean a caliper?
21:36 orlok type of readout on calipers and other gear
21:36 Triffid_Hunter Kimlaroux: yes, the scale used on non-digital calipers where you have to see which lines align
21:37 Kimlaroux oh you're saying there should be some sort of line or dot on the ring I see use to align things?
21:37 orlok http://en.wikipedia.org/wiki/Vernier_scale
21:39 Kimlaroux hhmm, I always used digital ones actually
21:51 Triffid_Hunter Kimlaroux: there should be, but if there's not you'll have to look at the alignment of the teeth
21:52 Kimlaroux yeah I counted the teeth and used a sharpie to identify every 1/3 of turn
22:13 rue_house whats my name again?
22:13 rue_house Triffid_Hunter, you want help reading a vernier?
22:14 rue_house | | | | | | | |
22:14 rue_house | | | | | | | | | |
22:14 rue_house are you there?
22:14 Tom_itx that's invalid
22:14 Tom_itx too many lines align
22:14 rue_house :)
22:14 Tom_itx only one can align
22:15 rue_house its 3 and 2 it ligns up alot
22:15 rue_house not hte point
22:15 rue_house if he/she isn't here I cant educate the concept to it
22:15 Triffid_Hunter rue_house: I know how to read them well, I was explaining to Kimlaroux that inserting the planets into a planetary gearbox vaguely resembles reading a vernier
22:15 rue_house there you are
22:15 rue_house oh
22:16 rue_house ok
22:16 Triffid_Hunter rue_house: on an unrelated note, see http://youtu.be/C8OcIe47-4s and http://youtu.be/k6049YDO2KQ -- http://youtu.be/0l3Z7WVfa9c is up next!
22:16 e_house heard, for the record: the planets are a lot like a vernier s
22:16 Triffid_Hunter 3d printers win at hobby robotics :)
22:17 rue_house hah it can get up on its own
22:17 rue_house your kneee is trying to walk away
22:17 rue_house your hip has collision issues
22:18 rue_house try this:
22:18 rue_house http://www.youtube.com/watch?v=lTCACvgRZCY&NR=1
22:18 rue_house see how those were proposed?
22:18 rue_house its interesting idea
22:19 rue_house I think its mostly physically sound
22:25 rue_house I'm gonna life for about another 1.25 hours, everything I want to do needs to be finished by then
22:25 Triffid_Hunter ankle, yeah noticed the collission after I posted it, that's easy to change
22:25 rue_house k
22:25 rue_house that neo robot uses an interseting mod of a CV
22:27 Triffid_Hunter also I doubt it would work nearly as well in R/L
22:27 Triffid_Hunter needs a tail or arms or something to fine tune its momentum impulses with
22:28 Triffid_Hunter the one I'm building is mostly inspired by darwin-op but of course written from scratch in openscad
22:28 Triffid_Hunter gonna need some mega strong servos for the knees
22:30 rue_shop then your doing it wrong
22:30 Kimlaroux I got one of the planetary gear set correctly aligned, used a magnet to keep the gears aligned while I put it together
22:31 Kimlaroux but the other set is plastic gears... troublesome
22:34 Triffid_Hunter rue_shop: yeah probably.. but to fit standard size hobby servos, the shin and thigh is gonna have to be at least 80mm long, so even if the hip, torso, head, arms are only 2kg that's 16kg.cm of torque at the knees
22:34 Triffid_Hunter I know there are servos available that are that strong that don't cost hundreds which is good
22:35 orlok GWS, iirc, do some cheapish servos
22:35 Kimlaroux Success!!! Thanks for the information guys =)
22:36 Jora are some of you robotics researchers here or just hobbyists?
22:37 Triffid_Hunter Jora: what's the difference?
22:38 Triffid_Hunter Kimlaroux: hooray!
22:38 Jora Triffid_Hunter none, just was curious
22:38 Kimlaroux =D I learned something new today, that's always a good day
22:38 Triffid_Hunter Jora: I've been paid at various times to make robots but I mostly do it for personal enjoyment
22:38 Jora Cool
22:39 Triffid_Hunter Jora: see http://youtu.be/C8OcIe47-4s and http://youtu.be/k6049YDO2KQ and http://youtu.be/0l3Z7WVfa9c for what I'm working on at the moment
22:39 Tom_itx Triffid_Hunter, do you have one of the STM32F discovery boards?
22:39 Triffid_Hunter Tom_itx: no, I have futurlec's stm32f103 carriers and an R2C2 with LPC1758
22:40 Tom_itx ok
22:40 Jora ty Triffid_Hunter
23:33 rue_shop about 20 mins left
23:33 rue_shop then I cease to exist for 5 days
23:38 Tom_itx aww
23:49 Kimlaroux why?!?!
23:57 rue_house I become rue_work
23:58 rue_house odd, I'm 5 mins late