#robotics Logs

Mar 29 2014

00:15 Mr_Sheesh Wrong Mr?
00:16 rue_more yup
13:58 TELunus|2 I'm thinking of making a laser cnc with a friend. It looks like laser cutting is usually done with a CO2 laser in industry, but steel is almost 1 reflective to the main CO2 frequency band. Anyone know how they get the laser to not cut their factories with reflected beams?
14:02 TELunus|2 Oh, right. Focusing.
14:25 rue_more if you make anything with laser, make sure you get soem proper goggles, and keep the laser under a lid
14:25 rue_more I'v never heard of it happening, but a strong beam and burst your eye before you know what happened
14:45 BelgaradAtlantis Is inverse kinematics worth learning or am I just fine by trial-and-error until I get it right?
18:57 i-make-robots hey, robotics.
18:57 i-make-robots http://www.marginallyclever.com/blog/2014/03/building-an-open-source-3dof-palletizing-robot-part-4-repeatability-test/
18:57 i-make-robots what tool should I put on the robot next?
19:00 MrCurious lazer
19:00 MrCurious but get eye protection
19:01 GargantuaSauce_ you should put software on it that supports curved motion
19:02 MrCurious closed loop positioning
19:05 silicio how does it work? do you use a microcontroller?
19:07 silicio or arduino, o raspberry, o some board of that kind?
19:09 MrCurious all questions start with google
19:16 silicio MrCurious, you mean I should have googled instead of asking here?
19:16 silicio maybe you're right, I'm kind of a newbie...
19:17 MrCurious its a good life resource
19:19 GargantuaSauce_ fwiw his second blog post on the arm mentions the controller
19:22 silicio oh, I see, he uses an Arduino
19:28 silicio has anyone worked with AVR microcontrollers? I mean, not Arduino but bare microcontrollers. I'm looking for the right mcu and programmer to buy for the first time.
19:36 GargantuaSauce_ i use one of these http://www.dx.com/p/148046
19:37 i-make-robots GargantuaSauce_: already has it, G02, G03.
19:37 GargantuaSauce_ well why doesnt hello world have nice round letters then? :(
19:37 i-make-robots muCurious - laser? like, cat nuissance laser?
19:37 i-make-robots GargantuaSauce_: because I wrote the gcode by hand. Do you want to write me some gcode?
19:38 GargantuaSauce_ there's gotta be a ttf to gcode converter
19:38 i-make-robots silicio: arduino based RUMBA controller. it's like a MEGA and a RAMPS board put together. i send it gcode.
19:38 i-make-robots GargantuaSauce_: if you can find one please let me know.
19:39 GargantuaSauce_ http://timeguy.com/cradek/truetype
19:45 i-make-robots hrm. I'll have to give that a try. Thanks!
19:45 i-make-robots GargantuaSauce_: do you have a website? I will mention you in the next blog post and I can link to it if you like.
19:56 GargantuaSauce_ http://workman-industries.net
19:56 GargantuaSauce_ not a lot there
19:57 i-make-robots nice hex! what control board do you use to drive 18 servos?
19:57 GargantuaSauce_ a perfboard with shift registers
19:57 i-make-robots you might be interested in my old hex code: http://visualhexapod.sourceforge.net/
19:58 i-make-robots I wrote a windows opengl app to simulate my robot, that's how i taught it to walk. then I copide the code into the arduino and it worked great. you can drive both at the same time so the real one matches the simulation.
19:58 i-make-robots I'm doing the same thing again with my robot arm.
19:59 GargantuaSauce_ i am using my pc application to control it directly at the moment
19:59 i-make-robots hand-rolled? Nice.
19:59 i-make-robots respect.
19:59 i-make-robots what gaits does it understand?
19:59 GargantuaSauce_ tripod and 2-stepping
20:00 GargantuaSauce_ keep meaning to add ripple
20:00 i-make-robots cool.
20:00 i-make-robots ripple looks so arachnid.
20:00 GargantuaSauce_ going to do the 4dof kinematics "properly" first though
20:00 i-make-robots ?
20:00 GargantuaSauce_ like with an iterative solver. currently it's an analytical solution designed for 3dof
20:01 GargantuaSauce_ fixing that will allow me to tilt the body, etc
20:01 GargantuaSauce_ in fact that's what i'll do tonight, was gonna work on the stewart platform but eh
20:01 i-make-robots not sure I follow. my method I can tell it where I want the toes to be and the orientation of the body, then it solves for all elbows and calculates joint angles. is that what you mean?
20:02 GargantuaSauce_ yes and that works fine for 3dof because there is a unique solution (well sometimes two)
20:02 i-make-robots oh well, if you want to talk stewart platforms… http://www.marginallyclever.com/shop/stewart-platforms/rotary-stewart-platform-v2
20:02 GargantuaSauce_ but with four degrees of freedom in the leg there becomes infinite solutions
20:02 GargantuaSauce_ mine's gonna use leadscrews
20:02 i-make-robots open source so it may give you ideas.
20:02 i-make-robots where do you get the leadscrews?
20:03 GargantuaSauce_ shitty threaded rod from the hardware store
20:03 i-make-robots DIY linear actuator?
20:03 GargantuaSauce_ basically
20:03 GargantuaSauce_ this is a prototype of a prototype. it's gonna be quite small and slow but will let me develop the software for a better one with ballscrews
20:03 i-make-robots I wanted to try mounting a leadscrew on an RC u-joint on the shaft of the motor. all 6 motors would be under the base plate, facing straight up.
20:04 GargantuaSauce_ i am going to put the motors on gimbals, universal joints are a bit wonky
20:04 GargantuaSauce_ since the torque is not constant
20:04 i-make-robots they have a bit of play, it's true.
20:04 i-make-robots I can buy them off the shelf. I have to make my own gimbals.
20:05 GargantuaSauce_ anyway https://www.youtube.com/watch?v=nebJ59TcYlQ this is sort of my target for that project
20:05 GargantuaSauce_ down the road.
20:05 GargantuaSauce_ that one has 400W ac servos driving ballscrews, a bit on the pricy side i think
20:06 i-make-robots that is a great video.
20:06 i-make-robots https://www.youtube.com/watch?v=yLKR6RrhGJs&list=PLB010AA8788EA52C1 my playlist for Stewart Platforms
20:07 GargantuaSauce_ sweet
20:08 i-make-robots I do my homework ;)
20:08 i-make-robots if you know of any not on there, let me know and I'll grow the collection.
20:10 GargantuaSauce_ you definitely have all the good ones i can remember
20:10 GargantuaSauce_ the okuma one gives me a rager
20:12 i-make-robots which one? url.
20:13 GargantuaSauce_ https://www.youtube.com/watch?v=kS9oxp0mlw8
20:14 GargantuaSauce_ i cant even guess how much money that is
20:14 GargantuaSauce_ 750K?
20:14 i-make-robots if you like that you'll love the one that mills a whole helmet.
20:14 i-make-robots a dirt bike helmet milled on a 6 axis cnc machine from a single block of aluminum.
20:15 i-make-robots and they buff the name fo the company into the back of the helmet. Buff! it's maybe 1thou difference.
20:17 i-make-robots my bad, it's only 5 axis. https://www.youtube.com/watch?v=RnIvhlKT7SY
20:19 GargantuaSauce_ oh man the way the arm moves with the turntable
20:22 i-make-robots yep. robot porn.
22:17 GargantuaSauce_ i've made a habit of mixing CFL and incandescent bulbs in my multi-light fixtures
22:17 GargantuaSauce_ and it always seems to be the fluorescents that die first...
22:18 GargantuaSauce_ these aren't some offbrand pieces of shit either, they're GE
22:33 armyofevilrobots @gargantua; I have tons of problems with cooling on anything that isn't incandescent. Fluorescents seem to require a pretty open cage to live. :(
22:37 GargantuaSauce_ yeah i guess there's an electrolytic cap in there, probably the point of failure
22:37 GargantuaSauce_ they certainly don't like being hot
23:17 MrCurious seems my odroid-u2 is haaving a bad day. wont light hdmi displays
23:18 GargantuaSauce_ uboot configured correctly?
23:20 MrCurious flakey vid cable i think
23:21 GargantuaSauce_ ah
23:25 MrCurious seems to be a power issue...
23:28 GargantuaSauce_ it was earth all along
23:30 MrCurious yeah, cant parasiticaly power it
23:42 GargantuaSauce_ man i never have enough workbench space
23:43 GargantuaSauce_ should really ditch the whole idea of doing more than one project at a time
23:54 i-make-robots I keep each project in a clear shoebox I got from Home Depot. a piece of paper stands up in the front of the box with the last year I touched it. anything sits for more than a year gets recycled in some way.
23:55 i-make-robots also it means I can work on them as opportunity presents itself.