#robotics Logs

Sep 06 2012

00:16 rue_house dosn't everyone have a box of gears?
00:58 MrTrick has anyone built a robot arm with a belt driving the secondary?
00:59 MrTrick So there are two points of articulation (lets say shoulder and elbow) that bend in the same plane, like an excavator
01:01 MrTrick The shoulder and elbow joint motors are both at the base of the shoulder. The shoulder motor drives the shoulder with a belt, the gear is fixed to the upper arm.
01:01 MrTrick The elbow motor drives the elbow with a belt to a freewheel gear on the shoulder axis, to another belt and a fixed gear on the elbow axis.
01:02 tsmeow-afk would give Rif's Foxy arm url to MrT if she ha
01:02 MrTrick eg like http://www.youtube.com/watch?v=tkDbmWAyHYw&feature=player_detailpage#t=140s
01:03 MrTrick any keywords that might be googlable?
01:05 MrTrick I just wonder if there are any downsides to doing it that way. The reduced weight/moment of the arm by having all the motors at the base is a good thing, but not sure about how it affects the backlash or accuracy of the arm.
01:05 katsmeow-afk or the stretch of every component tween the actuator and the moving part
01:07 MrTrick I suppose the belts might have some stretch in them, though I got the impression that belts didn't have the sort of effect on backlash that gears do.
01:08 MrTrick I originally wanted to use stepper motors with double-ended shafts, and have rotor/stator attached to either side of the joint.
01:09 MrTrick Direct drive. Very fast, but problems with resolution and have to be careful of torque limits.
01:10 katsmeow-afk everything stretches, i have ahuge problem with a slab of 1" thick steel a foot wide and 6ft long stretching, and that's ON EDGE
01:10 MrTrick heh
01:11 katsmeow-afk i had a pic of my F250, the frame was so stretchy the bed was offset from the cab by 4 inches in that pic
01:11 MrTrick Well, this is a scara robot. arm A and arm B are probably about 200mm each, and it just has to hold a pen.
01:12 Trick doesn't need 10um precision. 0.5mm is probably ple
01:13 katsmeow-afk if you can, use gears,, you can make the shaft supports to place the worm drive in a position to eliminate slop
01:13 MrTrick hmm... I was thinking of using a 4:1 belt reduction. You really think a gear mechanism will be better?
01:19 MrTrick what about universal joints? :-)
01:23 MrTrick (well not really. Wondering if I can use something like http://www.flickr.com/photos/matthias17/2845700481/ so as to be able to place the elbow joint on a different plane to the shoulder - so it's still SCARA, but looks more like a human arm.)
01:26 katsmeow-afk i aren't looking at the youtube videos, my brain is off anyhow, it's after midnite
01:27 katsmeow-afk you can prolly use belts from printers, and get the steppers too, and the pulleys
01:27 MrTrick no worries.
01:27 katsmeow-afk i dunno why you'd use universals
01:27 MrTrick I'm happy to buy proper timing-type belts, that's fine.
01:27 MrTrick Yeah, don't worry about the universal joints.
01:27 katsmeow-afk all the movement axis are int he same plane in your robot arm
01:28 MrTrick well, consider how you'd make a SCARA arm that looked human-ish.
01:28 katsmeow-afk well, junked printer belts are small, and already "broken in"
01:28 MrTrick true. As long as not 'broken'.
01:29 katsmeow-afk i bought a belt from an auto parts store a while back, i kept trying to buy the belt off their alternater tester
01:29 MrTrick I may give up on driving the elbow from the base.
01:30 MrTrick ooh, better example: http://www.heliumfrog.net63.net/hf06robot/hf06blog.html
01:30 katsmeow-afk he said he had to sell me only a new belt, and i handled it, and asked about a more flexable one, he said it gets more flexable with use,, and silly me, i explaimed "you meani haveto build soemthign to *use* this before i *use* it??
01:30 MrTrick heh
01:30 katsmeow-afk you cannot drive the elbow fromt he base thru a shoulder that moves much
01:31 MrTrick imagine like the robot in the link, but with no Z-axis, and preferably an elbow that's much lower than the shoulder. (although the rotation is still about vertical axes)
08:59 rue_house its funny how a lot of things are suddenly being built like a reprap
09:20 AR__ low cost sensors for detecting vehicles
09:20 AR__ go
09:20 rue_house birds, monitor their lifesignes
09:20 rue_house or squirrels, they are more reliable
09:21 AR__ :')
09:21 rue_house frogs! everyone knows frogs and cars dont mix
09:21 rue_house modulated ir light beams
09:21 AR__ yeah?
09:22 rue_house big coil of wire, cars generate pulses as they drive over them
09:22 AR__ no
09:22 AR__ needs to be small
09:22 rue_house air pipe, generates a pressure pulse as car drives over it
09:22 rue_house (gas station, ding ding)
09:22 AR__ nothing to be buried
09:22 AR__ must be modular
09:23 rue_house you can put enough wire into a blanket
09:23 AR__ i'd like to steer clear of things on the road surface
09:23 AR__ no pun intended
09:24 rue_house find a cat thats scared of cars and put it in a hamster wheel, watch the rpm of the wheel
09:24 AR__ and dont want to use something as expensive as radar
09:24 AR__ looool
09:24 rue_house a toll gate, every time you recieve a coin, there was a car
09:25 AR__ lol
09:26 rue_house a camera with opencv to detect circles of tires, put a stop sign up to give it enough time to detect
09:27 rue_house put a GPS on every car, track the positions that go by your detection area
09:28 rue_house a drive-by station with a pushbutton and a large sign that says "please stop and push this button"
09:29 rue_house a high resolution gravimetric sensor that detects the gravity change of large objects pasing near by
09:30 rue_house a ground-audio sensor that has a filter for engine noise of passing cars
09:31 rue_house a horn detector, and a large sign saying "HONK FOR FREE COFFEE"
09:31 rue_house OH GOD I'M LATE FOR WORK
09:31 rue_house and my caps is on
10:04 GuShH Tom_itx: I have not seen the drive wheels you made!
12:57 Tom_itx GuShH
12:58 Tom_itx http://tom-itx.dyndns.org:81/~webpage/reprap/drive4.jpg
12:58 Tom_itx http://tom-itx.dyndns.org:81/~webpage/reprap/drive5.jpg
13:22 GuShH Tom_itx: stainless?
13:23 Tom_itx the one is yes
19:10 MrTrick Tom_itx: nifty. What wraps around them?
19:38 rue_house nothing
19:38 rue_house it drives the filament
19:43 katsmeow-afk the chouffeur
19:43 katsmeow-afk the chauffeur
19:44 katsmeow-afk it picks up electrons from the buss, and takes them to the filament
19:48 rue_house todays ebay item is a little bluetooth adapter
19:49 rue_house now I have two, I can try to make a bluetooth data link for robots
19:49 rue_house hows the power supply?
19:49 katsmeow-afk not finished
19:49 katsmeow-afk how's the 12ft mecha?
19:58 rue_house ... not finished
19:58 rue_house on the weekend I got another dishwasher valve for it
20:00 haryv how active is this channel?
20:00 katsmeow-afk i been badly lacking in e-nergy today
20:00 haryv during the day
20:00 haryv okay
20:00 katsmeow-afk of the 80 nicks, 70 of them NEVER say anything, everyone else is in and out variously
20:01 rue_house I could pry myself awake if I tried, but I dont think I WANT to try
20:01 rue_house I get here about an hour ago
20:01 haryv I am new here in my mid 40s. Been a aiviation and automotive tech. Avionics and IT graduate but...I have always had a interest in designing systems such as autonomous robotics.
20:02 rue_house will you make a beer robot?
20:02 katsmeow-afk designing or building?
20:02 rue_house we need somone to finish a beer robot
20:02 katsmeow-afk Rif's beer bot?
20:02 rue_house yea
20:02 katsmeow-afk i need something heavier,, several somethings, and i keep getting distr.. oh look at that!
20:03 haryv I would like to skip the idea of learning robotics that barly lift a pencil, and put a system together that can do real work. Example, build two or three robotic wheel barrels that move dirt from one part of a property to another using gps and so on.
20:03 rue_house ok
20:03 rue_house I suggest piling the following parts
20:03 katsmeow-afk ok, it's not "wheel barrel"
20:03 rue_house 4 to 6 18Ah, 12V batteries
20:04 rue_house a computer, 200Mhz or better, prefably a small case
20:04 katsmeow-afk http://en.wiktionary.org/wiki/wheelbarrow
20:04 haryv Servo or liniar motor for power driven wheel
20:04 haryv wheels
20:04 rue_house yea
20:04 rue_house drivers are hard to do for large motors
20:05 katsmeow-afk heh
20:05 haryv Is there a site that sells lots of parts to build robotic assemblies from small systems to more industrial usage?
20:05 rue_house haryv, use vector drive, its a snark to control but I think it would be less trouble
20:05 loanshark hello
20:05 rue_house haryv, how much did you want to spend?
20:06 katsmeow-afk no, there's hobby sites to make weak robots, some battlebot sites, and those for millionaires
20:06 haryv rue_house 500 or less. I can weld up the metal to make the housing.
20:06 loanshark I am trying to decide on electrical or electronics engineering…
20:07 rue_house electrical currently isn't being sent overseas
20:07 katsmeow-afk loanshark , you should have a clue what your interests are before this point
20:07 rue_house haryv, you can spend 500 easy on a large motor controller
20:07 haryv DC-Dc power engineers pay well here in canada
20:07 rue_house they do?
20:07 loanshark I'm interested in hexapods verymuch!
20:07 loanshark also bioengineering and genetics
20:07 rue_house !assist robots/buddy_III/
20:07 tobbor Possibly http://eds.dyndns.org/~ircjunk/robots/buddy_III/
20:08 loanshark but i need to do a bachelors that i can do online.
20:08 haryv if your company you work for, is directly releated to petro industry, expect to be paid well
20:08 rue_house http://eds.dyndns.org/~ircjunk/robots/buddy_III/p1020058.jpg
20:08 rue_house I'm sorry I'm going to eat and sleep
20:08 haryv rue, thats impressie
20:08 haryv :)
20:09 haryv but would not be of any use in the real world.
20:09 loanshark katsmeow-afk: is there any issue with online electronics engineering degrees?
20:09 haryv loan, you mean teleconferance
20:09 haryv Loan, it would be really difficult to do, unless you had the lab equipment
20:09 loanshark haryv: do i?
20:10 tsmeow-afk is rapidly running out of ways to cram this psu into the
20:10 loanshark haryv: the university i am looking at does 'virtual' labs
20:10 haryv where teacher sees you and you see teacher via teleconferance
20:11 loanshark ahh
20:11 haryv btw, I asume a number of you know c programming?
20:11 loanshark I'm not sure if grantham university does that
20:11 katsmeow-afk i suspect there's 3 tiers of schooling as emloyers see them: the top 10, the rest of the bricks-and-mortar, and anything online
20:12 loanshark :/
20:12 haryv DONT look for the program that is online or what the career counsolor shows you "ASK THE EMPLOYER who they hire grads from. This is my mistake 15 years ago.
20:12 loanshark o.o
20:12 loanshark I want to go to MIT for bioengineering
20:13 loanshark but I want that to be a masters
20:13 haryv IF the training is crap...and the employer says so, avoid that program.
20:13 orlok Only a masters? Why not a phd?
20:13 orlok </bigbangtheory>
20:13 katsmeow-afk time, cost
20:13 loanshark orlok: baby steps xD
20:13 haryv Better to get masters...THEN experiance, then PHD
20:13 loanshark orlok: i will if i can
20:14 orlok loanshark: heh, my father actually just skipped the masters step and went straight from ba to phd
20:14 haryv im outa here
20:14 loanshark but i am in the military and have 4 years left and can start using tuition assistance next month
20:14 orlok loanshark: ahh. which branch?
20:14 loanshark and electronics is my job, and i am interested in it on a component level
20:14 loanshark Navy
20:14 loanshark Sonat Tech
20:14 loanshark Sonar*
20:14 haryv loan,....you are doing a smart thing. Service covers 50 percent of tuition while serving
20:15 haryv navy best training in the world for technoligy
20:15 loanshark haryv: actually only $4000 a year now, but some online schools offer scholarships to make up the difference
20:16 loanshark but i will get 75k when i leave plus 1800$ every month just to live in boston ($_$) if i go to MIT and i would really like that to go towards my masters
20:16 katsmeow-afk damn
20:17 loanshark but i want a degree that I can use to peruse that bioengineering masters
20:18 loanshark :/
20:18 orlok navy.. bioengineering..
20:18 orlok sharks
20:18 orlok with
20:18 orlok frigging
20:18 orlok LASERS
20:18 loanshark would it be a better idea just to do courses related to bioengineering so i can get most of the undergraduate part done
20:19 orlok LAAAAAAAAAAAAASERS
20:19 loanshark orlok: bioengineering is more engineering life than it is interfacing life with electronics.
20:34 katsmeow-afk i can't hear this, but the video of the robots is good : http://www.wetware.co.nz/2011/05/very-good-ai-clip-about-naturally-evolving-artificial-intelligence/
20:59 katsmeow-afk hmm, Srinagar is located on the banks of river Jhelum
21:36 rue_livingrm falling asleep makes it so hard to be productive