#robotics Logs

Feb 01 2014

00:28 Jak_o_Shadows Regarding repraps: http://www.ebay.com.au/itm/New-Mega2560-R3-Arduino-Compatible-ATmega2560-USB-Board-SYD-COMBINED-Postage-/271389178119?pt=LH_DefaultDomain_15&hash=item3f300e3907&_uhb=1 seems ok?
00:29 Jak_o_Shadows I'm wanting to slowly build up, while still being able to use the parts I have for other things.
02:02 rue_shop2 hmm I need a good proection circuit for this 20mA ammeter
03:24 rue_shop2 hmm jukebox has been going 24/7 for about 15 years
03:24 rue_shop2 they dont make hardware like they used to
05:22 SilentAssassin Hi im using Jacobian transpose to handle inverse kinematics, currently im calculating a plan to do the motion, what i would like to is to calculate it in real time and get an angular velocity
05:22 SilentAssassin So I was wondering I would do for example N at most iterations , sum up the deltas and that be the angular velocity, but i would like to validate this idea before waste time on it
07:49 GargantuaSauce SilentAssassin: I am under the impression that that approach works fine for simple kinematic chains but falls apart when there are local minima or you have to cross a singularity
07:51 GargantuaSauce i think motion planning needs to be a bit more complex in order to be robust
08:08 SilentAssassin What I do actually is at some time I calculate the angles of joints so that some end effector is in some desired position, then during some time I change the joint angles for example linear interpolation...
08:08 SilentAssassin The problem is that planning sucks if there are external effects...
09:41 robotustra_ morning
10:31 rue_bed void SimotaniouslyLinearlyInterpolateMultiAxis(axies_t * this) {
14:46 rue_house oh yea, I love that function name
14:46 rue_house and on a 6 axis robot is look SO COOOL
14:49 MrCurious ?
14:54 rue_house its my interpolation fucntion
15:22 e_house flips thru the tool catalog to think about what tool to make
15:23 rue_house I think I want to make a small mill
15:23 rue_house I was thinking about making a shaper, that could be entertaining
16:33 Technicus Hello, I am new to robotics, and trying to learn about visual tracking/sensing and how it is processed in the evaluation of autonamous decision making. What resources should I review to learn about this subject?
16:36 latemau5 What do you mean by "how it is processed in the evaluation of autonomous decision making"?
16:43 Technicus latemau5: I want to lean about the programming.
16:44 latemau5 Okay.
16:44 latemau5 I still don'#t understand your question, maybe it's the way you worded it.
16:44 Technicus Here is an example of what I mean: < http://www.youtube.com/watch?v=3BJFxnap0AI >
16:44 latemau5 okay great
16:44 Technicus I want to learn how to make something do that.
16:45 Technicus Or to recognize other object and do something else . . .
16:46 latemau5 http://www.youtube.com/watch?v=bSeFrPrqZ2A
16:46 latemau5 Well here's a video fo the creator of that robot describing some object tracking principles
19:30 GuShH_ rue_house: hmmm thermite reaction leaves liquid iron as a result, but is it pure iron? can you cast something with this method using just gravity?
19:53 armyofevilrobots Looks like it's been done: http://www.bladeforums.com/forums/showthread.php/560211-Thermite-Casting
20:02 rue_shop2 oo
20:02 e_shop2 ads to todo
20:02 rue_shop2 armyofevilrobots, whats opportunity look like for cutting that faceplate?
20:04 e_shop2 sits down for a long discussion with himself about power distribution on the hex
20:05 rue_shop2 we have reached our first conclusion, either the stool needs a backrest of the chair of doom needs a foot rest
20:06 Jak_o_Shadows footrest is easiest
20:07 rue_shop2 hmm, I rarely go the easy way...
20:07 rue_shop2 #14 15A
20:07 rue_shop2 delta 3 for 2x
20:08 rue_shop2 so #17 for 7.5A
20:08 Jak_o_Shadows Also, am I the only one that finds using a timing belt that you tension with a zip-tie incredibly dodgy?
20:08 rue_shop2 so #20 for 3.75A
20:08 rue_shop2 Jak_o_Shadows, I used a spring
20:09 Jak_o_Shadows Oh, good, someone has a brain.
20:09 rue_shop2 if you put a rubber jacket around the spring, it wont resonate
20:09 rue_shop2 where was I
20:09 Jak_o_Shadows Power distribution.
20:10 armyofevilrobots @rue_shop2; wife is a bit under the weather, but maybe tuesday?
20:10 rue_shop2 #23 for 1.875A
20:10 armyofevilrobots if you can make it in the afternoon?
20:10 Jak_o_Shadows Strictly speaking, could you probably make the wires thinner as you move down the leg
20:10 rue_shop2 armyofevilrobots, np, I'm really in no hurry
20:10 rue_shop2 I'v not even finished the frame
20:10 armyofevilrobots The CNC has been _busy_ the last week.
20:10 rue_shop2 armyofevilrobots, I'm mainly really curious about your cad->cam software
20:10 armyofevilrobots I use rhino with rhinocam.
20:11 armyofevilrobots and solidworks for design.
20:11 rue_shop2 yea, I'v only ever used mastercam
20:11 rue_shop2 I'm wondering if its at all similar
20:11 rue_shop2 hmm, my goal was 3A
20:11 rue_shop2 when did I pass that...
20:11 rue_shop2 #20
20:12 Jak_o_Shadows Strictly speaking, half the 3D printed reprap parts look like it'd be just as easy to make by hand.
20:12 e_shop2 checks the assorted bits of wire d
20:12 rue_shop2 Jak_o_Shadows, if you make the peices by hand out of metal, you will have a sturdier machine
20:12 rue_shop2 look er up, cant remmeber who did it
20:13 rue_shop2 folded sheet metal
20:13 Jak_o_Shadows I don't have that capability at home, but the parts arn't what I imagine when I think of 3D printing.
20:13 Jak_o_Shadows I think of stuff that's difficult to make conventionally, not an L shaped bit with holes in it.
20:15 Jak_o_Shadows Also, a bloody bit of plastic tubing for a motor coupling...
20:16 Jak_o_Shadows Then more cable ties as hose clamps.
20:16 Triffid_Hunter GuShH_: it has a lot of aluminium oxide mixed in with it
20:17 rue_shop2 Jak_o_Shadows, isn't it amazing anyone can get it to work?
20:17 Jak_o_Shadows Absolutely.
20:17 rue_shop2 Jak_o_Shadows, try not to be like me, spend $300 on parts and come to a slow grinding halt trying to upgrade everything before you ever get it working
20:18 GuShH_ Triffid_Hunter: I thought most of it burns off
20:18 GuShH_ and iron having higher mass..
20:18 Triffid_Hunter GuShH_: well thermite works because the oxygen jumps from the iron to the aluminium or copper, which have higher binding energies and thus energy is released mostly as heat
20:18 rue_shop2 hahahahaha, this robot has no 5V distribution!
20:19 e_shop2 cu
20:19 ShH_ wonders what's funny about
20:19 Jak_o_Shadows I'm looking up cheap stuff for the electronics, but the rods, bearings/bolts, 3D printed bracket thingos, extruder I don't think i'll be able to skimp on too much
20:19 Triffid_Hunter GuShH_: armyofevilrobots' link is a good one, esp down the bottom from the guys who've tried it and said it can work but the consistency is rubbish
20:19 GuShH_ Triffid_Hunter: mostly for art eh
20:20 Triffid_Hunter Jak_o_Shadows: https://picasaweb.google.com/114006544968779005866/Mendel?noredirect=1 :P
20:20 Jak_o_Shadows Also, Triffid_Hunter, your idea of cooling the stepper drivers with an old fan is good.
20:20 Triffid_Hunter GuShH_: sure
20:20 rue_shop2 hahaha the new baord require it too... hahahahahaa
20:20 e_shop2 curses
20:21 Triffid_Hunter GuShH_: they do indicate that the slag (Al or Cu oxide) will float on top of the iron, but they have to stay liquid long enough to separate
20:21 Triffid_Hunter and you never know how much simply didn't come out of solution
20:22 e_shop2 sits down infront of the out-of-control wire pile with some cutter
20:23 Triffid_Hunter Jak_o_Shadows: re cooling the drivers, the fan and 'sink actually don't do much at all
20:23 Triffid_Hunter Jak_o_Shadows: A4988s' heatsink is on the *bottom* of the chip, gets soldered to the pcb so the pcb itself acts as the heatsink. the thermal resistance from die to top of chip is high enough that putting a sink on top does almost nothing except restrict airflow
20:24 e_shop2 squeaks a little as he's enveloped by the wire
20:24 Triffid_Hunter the pololu boards are simply not physically large enough to provide adequate heatsinking. you'd get best results blowing air *under* them.
20:25 ShH_ takes his survival knife and saves rue_shop2 from certain d
20:25 Triffid_Hunter these days I'm working with smoothieboard which has all the drivers on-board with proper thermal management. I have driven them at 1.8A for an hour without overheating, whereas pololus struggle to hit 1.2A
20:27 Jak_o_Shadows In that case I'll just blow air under them.
20:31 Jak_o_Shadows Hmm, I have one of http://www.xbitlabs.com/images/mainboards/asus-p5e/fan.jpg fans, but It has 3 wires. I suppose the white (yellow for mine) would be sense?
20:32 e_shop2 climbs out of the pile clutching a 12" peice of #20 orange
20:32 rue_shop2 GOT ONE!
20:32 e_shop2 puts it aside and goes back in for the grey
20:35 e_shop2 climbs out with a piece of b
20:35 rue_shop2 its damn elevator cable!
20:35 e_shop2 goes over to the wire rack and get the rest of what he needs off the elevator cable s
20:36 rue_shop2 its out of grey
20:36 e_shop2 looks at the wire
20:37 e_shop2 looks at the spool of elevator cable and the hac
20:37 rue_shop2 ooo tough call...
20:39 zap0 you'll need a red wire and a green wire
20:39 zap0 and some LED's counting down
20:41 Jak_o_Shadows Don't most sensors work off 5V?
20:43 rue_shop2 black is getting rare, I need to stop using grounds on my systems
20:46 Jak_o_Shadows I found a BOM!
20:47 Jak_o_Shadows and good instructions! http://botbuilder.net/documentation/
20:51 rue_shop2 ok I think i have all the wire I need
20:52 e_shop2 tries to unhook his foot from a few of the piles lo
20:55 rue_shop2 so, I have to rebuilt the few bits of the power backplane I was gonna leave in tact
20:55 rue_shop2 Jak_o_Shadows, when did you start your machine?
20:55 Jak_o_Shadows I've been wanting one for a while. Currently I have bought thermistors.
20:56 Jak_o_Shadows I'm working it in a spreadsheet atm
20:57 rue_shop2 ooo, tell me if you are able to work out their table genorator, I have a copier thermister that I need to build a calibration table for
20:57 rue_shop2 I know the real-world paramiters
20:57 Jak_o_Shadows Well, I put the thermistor in the freezer a little while ago, to check it.
20:59 Jak_o_Shadows https://docs.google.com/spreadsheet/ccc?key=0Ao2vkRrCrZOsdHFxYVc5ZmtEcWV4Z21aUFBPbENzaFE&usp=sharing is where I'm at.
20:59 rue_shop2 remember your freezer is lower than 0c
20:59 Jak_o_Shadows Yep. It sits at around 60K at current room temp
20:59 rue_shop2 an salt/ice slurry is closer
20:59 Jak_o_Shadows Which is a bit hotter than normal room temp atm
21:00 rue_shop2 heh
21:12 rue_shop2 so, on the ganged set I supposadly have 6A
21:13 rue_shop2 #17
21:13 rue_shop2 was 7.5A
21:14 rue_shop2 #20 was 3.75
21:14 rue_shop2 so I can go #18
21:17 rue_shop2 ok I think I have a workable plan
21:17 rue_shop2 now to throw it out and do what works
21:25 Jak_o_Shadows I have little idea of what a good price for stuff is.
21:27 Jak_o_Shadows For example: the LM8UU bearings. Local stores seem to be at around the 1.20 mark, but ebay is cheaper
21:35 robotustra_ finish working day
21:38 Jak_o_Shadows Hmph, the extruder bit isn't cheap is it.
21:39 rue_shop2 ... he left?
22:06 rue_shop2 I need a large bundle of brightly coloured zap straps
22:06 Jak_o_Shadows Ok, that's a new term for me.
22:07 rue_shop2 zipties?
22:07 Jak_o_Shadows that's more australian
22:07 rue_shop2 or brightly coloured?
22:07 Jak_o_Shadows No, brightly coloured is ok
22:07 Jak_o_Shadows cable organization?
22:07 rue_shop2 how about stuffing strips?
22:07 rue_shop2 :) yea
22:08 rue_shop2 "organization" sure...
22:12 Jak_o_Shadows ha
23:10 Jak_o_Shadows Do you trust threads tapped into aluminum or not? Not particularly
23:11 Tom_itx why not?
23:11 Jak_o_Shadows The one experience I have had with it, it's come loose
23:11 Jak_o_Shadows Admittedly this was about 38 pounds of force
23:11 Tom_itx then it wasn't engineered right
23:12 Jak_o_Shadows nope :D I just had to pick it up
23:22 rue_house yes, double the leds, is quite nice and bright
23:36 Jak_o_Shadows Hmm. I was hoping to do the box frame one, but the sheet frame seems more common, and easier to get the printed parts for
23:38 rue_shop2 I was thinking about colour-coding nuts/bolts/screws on robots so that, as they fall off, you can know what they were from, it just occurred to me that structural and nonstructural might be two good starting catagories