#robotics Logs

Apr 29 2015

08:34 deshipu LiohAu: where?
08:40 LiohAu deshipu: few days ago you told me that there are few people in robotics here
08:41 LiohAu most of them are intested in 3d printing and stuff like that
08:41 LiohAu That's what you said right? or maybe it was someone else?
08:46 deshipu I believe it was me
08:49 LiohAu deshipu: so why are you there?
08:49 LiohAu robotics? or 3d printing? :D
08:52 verak se here because both of the to
08:53 LiohAu veverak: and you?
08:53 veverak both of them
08:53 veverak I've got 3d printer to create robotics thigns :)
08:53 veverak *things
08:53 LiohAu ok
08:54 LiohAu are you an hobbyist?
08:54 veverak yep
08:54 LiohAu do you have places to recommend where I could find robotics engineers to partner with ?
08:55 LiohAu by "places", I mean forums/websites
08:55 veverak here?
08:55 veverak :D
08:55 veverak letsmakerobots
08:55 LiohAu well here, everybody is "afk"
08:55 deshipu LiohAu: I'm here mostly because of robots
08:55 deshipu LiohAu: mostly interested in walking quadrupeds
08:56 deshipu but I'm also a hobbyist
08:56 LiohAu ok
08:56 deshipu LiohAu: there is letsmakerobots.com, there is also trossenrobotics.com
08:56 LiohAu I'm interested in finding people that can help me to build a robotic humanoid arm :P
08:57 deshipu and hackaday.io
08:57 deshipu like in Adams Family? ;)
08:57 LiohAu they have an arm?
08:57 LiohAu it's only the hand, no?
08:58 deshipu yes
08:58 deshipu but it's walking :)
08:58 LiohAu well, i'm not really looking for a walking arm :P
08:59 deshipu well, there are lots of such projects around, maybe you could join one of them
08:59 LiohAu just an arm that would be able to lift big payloads
08:59 LiohAu (by big, I mean few kgs, that's only too big for dynamixel servos for example ^^)
09:00 deshipu "just"
09:00 LiohAu Yeah "just" :P
09:00 deshipu https://hackaday.io/projects/tag/robot%20arm
09:00 LiohAu I don't think that it's really hard, it's only that informations are hard to find
09:01 LiohAu already saw the first one at least
09:01 LiohAu this one may be interesting : Open-Source 6-Axis Robotic Arm
09:01 deshipu there is a lot of information available
09:02 deshipu LiohAu: well, it's open source, so you don't need permission or anything, just take what they have and continue with it
09:03 LiohAu steppers :(
09:04 deshipu what about them?
09:04 deshipu rue_house has build several robot arms
09:05 deshipu I'm sure he will have a lot of information for you when he wakes up
09:24 rue_house if I ever wake up
09:25 rue_house LiohAu, you want to make an arm?
09:25 LiohAu rue_house: yes
09:26 LiohAu I would like to build one
09:26 rue_house what doyou want the arm to be on
09:26 LiohAu on a body :P
09:26 rue_house ah
09:26 deshipu a corpse?
09:26 LiohAu are you french?
09:26 rue_house no
09:27 LiohAu sounded like (the "ah")
09:27 LiohAu :)
09:27 rue_house well
09:27 LiohAu deshipu: yes
09:27 rue_house how big?
09:27 LiohAu 65cm long
09:28 e_house breaks out a r
09:28 e_house breaks out two ru
09:28 e_house breaks out 3.5 ru
09:28 LiohAu actually I want to teleoperate it with my own arm using sensors :D
09:28 LiohAu so I want to make it approximatelly as long as my own arm
09:28 rue_house why 65cm?
09:28 rue_house ah
09:29 LiohAu with the same degrees of freedom
09:29 rue_house is that to your wrist or fingertip?
09:29 deshipu human arm has a ridiculous number of degrees of freedom :/
09:29 LiohAu shoulder to fingertip
09:29 rue_house well you can make the arm small, but the control box will just get bigger
09:29 LiohAu it's really an approximate length
09:30 LiohAu deshipu: I read it has only 7
09:30 rue_house LiohAu, have you started making a bone structure for it yet?
09:30 deshipu LiohAu: depends how you count
09:30 deshipu LiohAu: also, fingers
09:30 LiohAu rue_house: not yet
09:31 LiohAu At the begining I was thinking to use homemade pneumatic muscle, but the latency suck..
09:31 LiohAu so I wanted to 3D print human bones
09:32 rue_house LiohAu, hmm
09:32 rue_house cable operate it
09:32 rue_house you can use whatever you want to drive the cables
09:32 LiohAu I know that dynema rope is used sometimes for fingers
09:33 LiohAu but I don't know if that would be a good idea in that case
09:33 LiohAu (I mean fingers are lighter than arms)
09:35 LiohAu rue_house: also with the cables/rope how do you shorten them? using DC motors?
09:36 rue_house if you want
09:36 LiohAu In the end I need something like a winch
09:36 rue_house if you break it all down to cables, you can use anything
09:36 rue_house hydraulics, pneumatics
09:36 rue_house the drive becomes abstracted
09:37 LiohAu hm actually with pneumatics, the pneumatic muscle IS the cable
09:37 LiohAu I don't know how that works for hydraulics though
09:37 rue_house hydraulics can pull or push
09:37 rue_house tho pushing on rope wont get you much
09:38 rue_house or cable
09:39 rue_house the largest arm done here used electric lifters
09:40 rue_house http://ruemohr.org/~ircjunk/robots/arm5/p1030984.jpg
09:41 rue_house gtg!
09:41 LiohAu rue_house: "pushing on rope wont get you much" antagonist muscles
09:41 LiohAu solves the problem
09:46 LiohAu rue_house: there's an other option which is the elastic series actuator, but I can't find enough details on them
09:46 LiohAu I only know that there are 2 motors and a spring..
09:50 deshipu do you really need that whole arm to have exact same position as your arm, or do you only need the manipulator at the end to be where your hand is?
09:50 deshipu the latter is much easier
09:58 LiohAu deshipu: 1st case
09:58 LiohAu else you have to check collisions with objects
10:00 LiohAu because as I said i'll use it to teleoperate it with my arm, so if I see an obstacle, I can move my arm to avoid it. If the robotic arm is different from my arm it cannot reproduce that and has to check for collisions itself.
11:03 malinus I'm trying to print a pretty simple object on a makerbot (replicator X2). Their slicing tool seems however to be very bugged. It can't even draw proper supports. Is that normal? Do you guys usually use other slicing tools?
11:26 veverak slic3r
11:27 malinus veverak: can it generate the .3xg or w/e format the makerBot uses?
11:27 veverak ouch, that maybe not :)
11:28 verak nevernow that replicator didn't used gcode which should be stan
11:28 malinus veverak: I think you can feed it gcode trough a usb-cabel, I however can only access it using a SD-card.
11:29 veverak sucks
11:29 malinus on which you need to place their own file format. I think it also tells it about temperaturs and such
11:30 veverak which also tells gcode
11:32 malinus Oh I see
11:39 malinus veverak: it just won't generate supports for the half-empty cube http://i.imgur.com/4mwCUPO.png
11:39 malinus shouldn't it just fill the cube with supports?
11:41 veverak not really
11:41 veverak bridges here
11:42 malinus bridges?
11:42 malinus isn't that the same thing?
11:49 zaxxon support material is "stuff you need to cut away after printing", bridging is spanning an air gap, your print will likely bridge
11:50 malinus how would something that long be able to bridge? How can in print in thin air :P?
11:55 zaxxon how long is it?
11:56 malinus zaxxon: about 3.5cm X 3cm
11:57 zaxxon https://www.youtube.com/watch?v=wK2APNwEoSk
11:57 malinus h-how
11:58 zaxxon if it's sagging, perhaps you have an option somewhere to set the max bridge length
11:58 zaxxon i don't know the makerbot stack
11:59 zaxxon (admittedly that youtube one is a little extreme for my setup tho)
11:59 malinus and I was under the impression it was impossible, haha
20:19 JEntrep what happened to sauce?