#qi-hardware IRC log for Thursday, 2014-11-13

wpwrakzrafa: btw, did you get somewhere with the simulator now ?11:47
wpwrakhmm, nouveau driver acting up, it seems. or maybe it's the hardware that went klingon12:44
wpwraklet's see if i can close the xchat connect dialog ...12:45
wpwrakphew. this time it worked12:45
wpwrakwell, for a few seconds at least12:48
wpwrakhmm, strange error patterns13:02
wpwrake.g., start mocp in xterm on the nividia -> system freezes13:03
wpwrakweirder: switched primary to ati, and that one had a hang, too13:04
eintopfmocp :o16:25
whitequarkwpwrak: testing the limits of my camera. https://i.imgur.com/kF6JRVq.png17:23
wpwrakwhitequark: is this a new one ? or the SLR you bought already a good while (> 1 year ?) ago18:23
whitequarkwpwrak: actually that's even a bad pic, let me upload a new one in a moment18:36
whitequarksame camera though18:36
whitequarkwpwrak: http://lab.whitequark.org/notes/2014-11-13/photographing-pcd8544/19:03
wpwraknice :) now, on to reverse-synthesizing the netlist :)19:06
whitequarkwell, resolution's not high enough19:07
whitequarkI'm going to get an optical microscope.19:07
wpwrakDocScrutinizer05: i guess that's the sort of camera you should have :)19:27
DocScrutinizer05yes, I know19:33
eintopfwhats the correct word for a potentiometer which doesn't block19:36
eintopfnewbie question :-)19:36
eintopfI mean I want to measure the angle of a 360 degree stick mounted at the end at the potentiometer - like this http://walter.bislins.ch/physik/media/Pendel.png19:39
wpwrak"rotary encoder" ? ;-)19:39
wpwrak(but such an encoder has has discrete positions)19:39
DocScrutinizer05such thing doesn't exist19:40
DocScrutinizer05yes, you can get encoders, but they rarely ever use the potentiometer approach19:41
eintopfah okay, so no potentiometer19:41
DocScrutinizer05rather two 90° phase skewed adjustable capacitors, or recently rather digital encoders19:42
eintopfbut I need more granularity than 8 bit19:42
DocScrutinizer05when you need more resolution than 8 bit, then how about using a laser mouse looking on a ring mounted to the axis, and have an index marker of some sort (e.g. a hole in ring and a light path sensor) to keep track of the absolute position19:44
eintopfthis sounds too complicated for me19:45
whitequarkthat's actually a very high-resolution method19:46
whitequarkyou have mice upwards to 8000dpip19:46
DocScrutinizer05of course you also can do a binary encoder, but that's for sure even more complicated. BTW usual potentiometers have a resolution quite a bit less than the requested 9 bits19:46
whitequarkand you can make radius as high as you can possibly want19:46
DocScrutinizer05whitequark: exactly19:46
whitequarki.e. it essentially offers unlimited resolution19:47
DocScrutinizer05and shouldn't be any complicated to build either19:47
whitequarkthough at some point accumulating error will be a big problem19:47
DocScrutinizer05optical mice afaik have no systemic accumulating error19:47
eintopfwhat the hell is a light path sensor19:47
whitequarkDocScrutinizer05: of course they do19:48
DocScrutinizer05a thing made of an LED and a light sensor, both form a gap19:48
whitequarkit traverses 1mm, it says it traverses 1.1mm19:48
DocScrutinizer05that's not systemic accumulating error, that's maybe a calibration factor19:48
DocScrutinizer05afaik the sensor works with pattern recognition and that has no _error_19:49
whitequarkwell, there are two concerns19:49
DocScrutinizer05when you move the target a million times back and forth for 10mm, it should still shop position:0.000000019:49
whitequarkthat'd be a different kind of error19:50
DocScrutinizer05everything else is not error but calibration19:50
DocScrutinizer05or error introduces by noise/jitter, but that's still not accumulating in this concept afaik19:51
DocScrutinizer05iow once you calibrated the ting to show 10000cm as 10000cm, it's as accurate as it gets: 1/8000 inch19:52
whitequarkyeah, that makes sense19:53
DocScrutinizer05the rest are non-linearities but no accumulating errors19:53
eintopfyou mean with index marker some point like 0 degree's and the mouse detects all movements?19:55
eintopfthis really working on long distance?19:56
eintopfs/this/do this/19:56
DocScrutinizer05such concept obviously needs a setup procedure after power up19:56
DocScrutinizer05where's a long distance in this design?19:56
DocScrutinizer05the mouse sensor should hove a 0.5mm over your ring19:57
eintopfah, yes19:57
DocScrutinizer05or even glide on it19:57
eintopfI understand19:57
DocScrutinizer05after poer up you need one full turn of axis to make sure the index marker passed by19:58
eintopfs/I understand/I see19:58
DocScrutinizer05a second turn can auto-calibrate the mouse data, you know it's been 360.000° when index marker passing by a second time19:59
DocScrutinizer05when your mouse reported 36000 clicks until that 2nd index event, you know it has a resolution of 1/10 degree20:00
DocScrutinizer05err 1/10020:00
DocScrutinizer05such sensor would be *very* fine grained and accurate20:01
DocScrutinizer05and you can build it for 25 bucks from material you got in your garage ;-)20:03
whitequark25 bucks? how about zero20:04
eintopfokay, okay. This sounds like a nice solution. Thanks20:15
eintopfnow I need to figure out how I can control the motor of my old scanner device and place a stick on it with some mass at the end. But maybe the motor control is too slow20:16
eintopfI am sure I could do that with libusb and some control messages20:17
eintopffor controlling a inverted pendelum...20:18
eintopfs/a inverted/an inverted20:18
kristianpaulhttps://www.indiegogo.com/projects/lantern-one-device-free-data-from-space-forever 21:15
kristianpaulWhat that thing have to no need a dish at all..21:15
wpwrakgrmbl. spamprobe started to hang. i don't like the possible pattern. new database, new luck ... for now ...23:35
wpwrakhmm. nvidia degradation killed xclock. no update to small to potentially cause a hang. i guess i'll go shopping tomorrow ...23:52
zearkristianpaul, your gps device also doesn't need a dish :)23:59
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