#robotics Logs

Jul 13 2014

02:01 MrCurious 18 minutes left in today! time to spare!
02:51 MrCurious it was a quiet night... too quiet
03:42 MrCurious guess i am the last one awake here... or sober....
03:44 Jak_o_Shadows I am here, bu silent
03:44 MrCurious working on anything Jak_o_Shadows
03:44 Jak_o_Shadows nope.
03:46 MrCurious tapping(threading) a bunch of holes tonight. i predict my wrists will scream tomorrow
03:46 MrCurious really wishing drills had a tap setting. 3/4 forward, 1/2 back, repeat
03:47 Jak_o_Shadows ha.
03:47 Jak_o_Shadows I cleaned the workbench today.
03:48 MrCurious i need to clean my garage tomorrow. got about 1cm of aluminum shavings, and 70% of tools are not in their homes
04:20 MrCurious all the tapping done. already regretting it
04:30 rue_mohr2 TIME FOR A NEW TAP?
04:30 MrCurious no, time for new wrists
04:31 MrCurious tomorrow i can assemble th delta structure and start the alignment process :)
04:31 MrCurious time to sleep, hate to miss the final game of the series
04:35 rue_mohr2 ah
04:59 rue_house I use the hand drill for tapping
04:59 rue_house good trigger finger and keep my hand on chuck as a brake
04:59 rue_house #6 min
05:02 rue_house its nice and cool out, now would be a greta time to do things
05:02 rue_house but I'm too tired
05:02 rue_house this sucks
05:02 rue_house its only 3am
06:09 orlock ok, i have buttons and switches and one stepper going nicely
06:10 orlock have problems figuring out the order for the 4 coils
11:00 rue_house orlock,
11:00 rue_house hook up any 1 coil
11:01 rue_house then hook up a second, look for it to alternate between two adjacent steps, back and forth
11:01 rue_house then hook up a third, it should go forward 2 steps then random
11:01 rue_house hooking up the last phase should result it rotation
11:02 rue_house A--mmmm--X--mmmm--B C--mmmm--Y--mmmm--D
11:02 rue_house A and B will never be on at the same time
11:02 rue_house C and D will never be on at the same time
11:02 rue_house so, A, C, B, D
11:03 rue_house otherwise
11:03 rue_house A = !B
11:04 rue_house C = !D
11:04 rue_house use a grey code count between B and D
11:04 rue_house 00
11:04 rue_house 01
11:04 rue_house 11
11:04 rue_house 10
11:05 rue_house half stepping A,C,B,D:
11:05 rue_house 1000
11:05 rue_house 1100
11:05 rue_house 0100
11:05 rue_house 0110
11:05 rue_house 0010
11:06 rue_house 0011
11:06 rue_house 0001
11:06 rue_house 1001
12:20 MrCurious threading holes is HELL on the wrists
13:19 Loshki MrCurious: makes them go limp?
13:56 MrCurious carpel tunnel syndrome
13:59 rue_mohr2 why dont you use a hand drill
13:59 rue_mohr2 get one with a good trigger
14:00 MrCurious i have one, but to tap, you need to go 2/4 forward, 1/2 rev, repeat
14:00 MrCurious 3/4
14:01 rue_mohr2 my drill has a reverse switch
14:01 MrCurious mine too
14:01 rue_mohr2 one thats easy to flip with a finger while not letting go fo the handle
14:02 MrCurious but that is a shit load of presses and trigger pulls
14:02 rue_mohr2 then stop complaining about your wrist :)
14:02 MrCurious needs to be automated to be workable
14:02 rue_mohr2 I was thinking of making one
14:02 rue_mohr2 geared more
14:02 MrCurious last night so was i. perfect AVR project
14:02 rue_mohr2 where did I just see a scrap drill chuck
14:03 rue_mohr2 oh thats right, I ahve a box of dead battery drills
14:03 Tom_itx on your bench?
14:03 rue_mohr2 storage tent
14:03 rue_mohr2 stuff I should have gotten rid of but cant bare to
14:03 Tom_itx how much you figure storing all that stuff is costing you?
14:04 rue_mohr2 so it'll rot till its garbage, then I'll get rid of it
14:04 rue_mohr2 nothing
14:04 Tom_itx what'd the shop construction cost you?
14:04 rue_mohr2 tent out back
14:04 Tom_itx taxes
14:04 Tom_itx heat
14:04 Tom_itx loss of use space
14:04 rue_mohr2 unheated tent
14:04 Tom_itx cost of tent
14:04 rue_mohr2 I was given the tent
14:05 rue_mohr2 I stuffed the tent in an otherwise unusable spot in the yard
14:06 rue_mohr2 a narrow sliver with banks on 2 sides and a neighbours fence on the other
14:07 rue_mohr2 hmm which I can build up and fill in now that the yard is all torn up
14:07 rue_mohr2 but its too hot to do anything
14:10 Tom_itx how hot is too hot?
14:17 rue_shop3 32c
14:55 rue_mohr2 well, I suppose if I want to do that data link project I need to make a ir link
14:55 Tom_itx i got a pair you can use
14:55 Tom_itx Lynx iirc
14:56 rue_mohr2 I have lots of ir stuffs
14:56 Tom_itx FCC approved
14:56 rue_mohr2 just have to do it
14:56 rue_mohr2 think i can get 115200 baud?
14:56 Tom_itx err not IR rather radio
14:56 rue_mohr2 er its 16Mhz
14:56 Tom_itx from these i know you can
14:56 rue_mohr2 no, i only have to go 3mm off the end of a shaft
14:58 Tom_itx http://tom-itx.no-ip.biz:81/~webpage/old_misc_files/Linx_tx.jpg
14:58 rue_mohr2 looks like at 16Mhz the highest I wanna go is 76800
14:58 rue_mohr2 38400 for a standard rate
14:58 Tom_itx those are FCC approved
14:59 rue_mohr2 I dont want radio for this
14:59 rue_mohr2 its 3mm
14:59 m_itx takes his toys and stomps
14:59 rue_mohr2 the ir link will sit on the end of the castor shaft
14:59 rue_mohr2 but thanks :)
15:00 rue_mohr2 what the range on those things?
15:00 rue_mohr2 they look like they are like 500mw or something
15:00 rue_mohr2 4 lines?
15:00 rue_mohr2 er miles
15:00 rue_mohr2 hmm, the heat is effecting my wordage lookup table
15:02 Tom_itx i dunno
15:02 rue_mohr2 I suspect even 9600 baud would be just fine
15:03 rue_mohr2 low res encoder on a not so fast turning wheel
15:03 rue_mohr2 I'm gonna have lots of fun with the encoder that needs to work out the angle of the caster tho
15:04 rue_mohr2 maybe if I do sine/cosine potentiometers
15:05 rue_mohr2 hmm but I cant be off the end of the shaft... hmm
15:06 rue_mohr2 I need to work out code
15:06 rue_mohr2 tractor drive
15:06 rue_mohr2 with a castor that provides direction feedback
15:06 rue_mohr2 the idea is to balance the drive on the motors to keep the bot going int he right direction
15:06 rue_mohr2 I cant just do master/slave wheel
15:07 rue_mohr2 there is direction and speed
15:07 rue_mohr2 so, you need to work out the balance of them to get the right speed, and the ratio to get the right direction
15:09 rue_mohr2 once upon a time I worked otu the math to get your heading from your wheel speeds
15:09 rue_mohr2 I think
15:13 rue_mohr2 Tom_itx, how do you work out trajectoy based on the speed of two wheels in a tractor drive?
15:13 rue_mohr2 there is a pivot point along the axle line
15:14 rue_mohr2 that goes from 0 between the axles, to infinity where your going straight forward
15:16 rue_mohr2 hmm
15:17 rue_mohr2 I suppose the distance traveled it D1+D2/2
15:17 rue_mohr2 where d1 and d2 are the distances traveled by each wheel
15:17 rue_mohr2 if you phrase the turning angle as rise/run
15:18 rue_mohr2 your run is the width of the bot, your rise is the d1-d2
15:19 rue_mohr2 because run is never 0, your dont have to worry about the division
15:20 rue_mohr2 because there is castor feedback
15:20 rue_mohr2 I suppose the veocity becomes a general velocity numbers that used by the two motors, and the direction is used to determine the split of that number
15:21 rue_mohr2 which means the robots velocity is determined by the speed of the castor, but whatever
15:22 rue_mohr2 the only time that might be a problem is if the castor is spinning in place around its axis
16:08 raleigh are there industrial/faster grippers like this being used? http://www.youtube.com/watch?v=h5I9AZsZPwo
16:09 raleigh i don't even know the term to search for
16:28 rue_mohr2 yes, made by
16:29 rue_mohr2 festo I think
16:29 rue_mohr2 make sure you have about a million dollar budget
16:29 rue_mohr2 or make your own for like $15
16:29 rue_mohr2 but alot of people are opposed to making their own things
16:36 MrCurious rue_mohr2: i think for some of those people, it could be a coordination/planning issue
16:42 raleigh what type of gripping is it called?
18:28 deshipu hmm, I wonder, if I get one of those laptop camera spare parts, they are basically USB cameras and I should be able to solder an usb plug to them, right?
18:29 Hyratel deshipu, should be able to yes
18:29 Hyratel if it works, let us know!
19:35 MrCurious deshipu: i have salvaged about 8 laptop cameras to make usb cameras. easy peasie
19:35 deshipu MrCurious: how did you figure out the pinouts?
19:35 MrCurious half of the time they color code the wires for your usb convienence
19:36 MrCurious sometimes trial and error
19:36 MrCurious other times using http://pinouts.ru/Slots/USB_pinout.shtml
19:38 deshipu any safety precautions for the trial and error?
19:39 MrCurious uhm, it would be an error to try with an expensive computer
19:39 MrCurious i used a raspberry pi
19:39 MrCurious and did a dmesg
19:39 MrCurious if it announces a usb device, you nailed it
19:40 MrCurious usually + and - are easy to spot
19:40 MrCurious then its a 50 50 crapshoot for usb +/-
19:40 MrCurious almost always there is a shielding ground
19:40 deshipu yeah, for data it should be relatively safe
19:40 MrCurious i just tie that tou ground
19:41 MrCurious look at the wires coming off. should be red white green black
19:41 MrCurious if you see that its a slam dunk
19:41 deshipu it's just a socket
19:41 MrCurious you didnt saslvage th matching cable?
19:42 MrCurious picture?
19:43 deshipu I don't have the module yet, I'm looking at what is available from the salvagers :)
19:43 MrCurious just put the word out to friends you are looking for dead laptops
19:43 MrCurious then harvest the cameras yourself
19:44 deshipu hmm
19:45 MrCurious however.... if you can tolerate a bigger camera... the usb ps2 eye cam is the BEST i have seen for robotics and can be had for under $20
19:45 MrCurious sorry, ps3
19:45 MrCurious http://www.ebay.com/itm/PS3-OFFICIAL-EYE-USB-CAMERA-PLAYSTATION-3-CAM-BRAND-NEW-GENUINE-/171324930604?pt=US_Video_Game_Motion_Sensors_Cameras&hash=item27e3c2fa2c
19:46 MrCurious has a great framerate, and i think multiple directional microphones, but not sure
19:46 MrCurious and its fast enough to do pretty well on the test where you bounce the camera and see if you get anything other than a blur
19:47 deshipu well, I actually don't want too big a framerate or resolution, as this is a raspberry pi and it won't be able to process it all
19:48 MrCurious will the camera move at all?
19:48 MrCurious or be firmly fixed in position
19:48 MrCurious and $10 cant be beat for a cheap camera that works well
19:48 deshipu it will be firmly fixed in position on the moving robot
19:48 MrCurious the moving robot will be the problem
19:48 deshipu it can stop to look
19:49 MrCurious most cameras have a shit frame rate, and as such, give useless images while they are bouncing
19:49 MrCurious advice rendered... you are now free to make mistakes and learn :D
19:52 Tom_itx worth every penny
19:52 deshipu advice appreciated, thank you very much
20:01 MrCurious yes. free advice is worth what you paid for it...
20:01 MrCurious gimme a dollar...
20:17 robotustra lunney
20:17 robotustra or dunney
20:18 robotustra or better 2
20:18 robotustra about to print a holer tor my minitesla coil
20:29 MrCurious wonder if anyone has done work embedding a fine wire fillament inside of an extrusion.
20:32 Tom_itx very doubtful
20:32 Tom_itx the ratio of the filament to nozzle hole would prevent it
20:33 Tom_itx or do you mean imbedding it in the print?
20:33 MrCurious embedding it in th print
20:34 MrCurious suppose it could be deposited below the print and entoumbed
20:34 MrCurious if possible it turns into an engineering problem of "work out a use/need" for this
20:35 Tom_itx i've heard of ppl adding bridges etc to prints
23:59 MrCurious i think i will need to make a set of 120 deg story blocks to tune this delta