#robotics Logs

Dec 28 2015

03:08 Jak_o_Shadows quite a bit? What do you know
03:09 cheetah2 i know computer science
03:09 cheetah2 nothing about electrical engineering
03:09 Jak_o_Shadows comp. sci is a good start
03:09 cheetah2 ok well what else do i need
03:09 cheetah2 i want to build a walking robot that has arms
03:10 cheetah2 can be on wheels
03:10 cheetah2 do i have to have a microcontroller for that?
03:10 Jak_o_Shadows Yes. A micro-controller will be needed to control your hardware (most likely)
03:11 Casper a microcontroller or something more powerfull
03:11 cheetah2 could i use a raspberry pi instead or not
03:11 cheetah2 thing is microcontroller has no networking right?
03:11 Casper I beleive so, the rpi have some gpio, so most likelly usable with other glue chips
03:12 Casper and µC do not by itself, but you can connect some modules, but then... the ressources become an issue
03:12 Casper mainly ram
03:12 Jak_o_Shadows I generally don't like that idea though: The RPi uses a decent amount of power, but it'd work.
03:12 Casper µC may only have 2k of ram, yes, 2048 bytes
03:12 cheetah2 ok so should i use a pi or a phone?
03:13 cheetah2 i guess i would need a pie for the gpio
03:13 cheetah2 phone has no gpio
03:13 Jak_o_Shadows A phone complicates connecting to things, but it does come with an accelerometer, gyro, compass, gps, which is nice
03:14 cheetah2 yea
03:14 cheetah2 how would i connect a phone?
03:15 Jak_o_Shadows If the phone is newish, it could act as a USB host - then you could connect via serial to a uC
03:15 Jak_o_Shadows If it's older, serial over bluetooth
03:15 cheetah2 usb to serial?
03:16 theBear not even that new for otg/host
03:16 Jak_o_Shadows a lot of uC's can implement a serial port over USB
03:16 Jak_o_Shadows theBear, i'm still on Android 2.3 :P
03:16 theBear and a lot can, what he said, like actual ttl level raw serial
03:16 theBear Jak_o_Shadows, i was till i spilt a drink a few days ago :(
03:17 Jak_o_Shadows haha
03:18 Jak_o_Shadows That's one way to need an upgrade
03:18 cheetah2 whats a uC ?
03:18 cheetah2 controller?
03:18 Jak_o_Shadows More properly µC , but I am lazy
03:19 cheetah2 controller?
03:22 Jak_o_Shadows micro-controller
03:24 theBear samsung s1 and s2 are available literally for nothing if you mention it to everyone you know, and pretty sure both of them just need a certain resistor on the 5th micro usb pin to set them to serial port mode on the little mux just inside them
03:25 Jak_o_Shadows That's handy.
03:28 theBear totally, they got all kinds of analog AND digital (fake usb "soundcard", not sure if oldest do that,) and various button/car kinda modes too, other brands have varying amount of things outside of just usb normal and (often, more as time passes) usb otg (aka usb host if you short the 5th micro pin)
03:29 theBear i got a cute little doubel-ended micro usb/regular memory stick recently that does normal or usb-otg straight to a fone, been surprised how many it works on, anad apparently it's rare to seea fone that won't do hid keyboard or mouse without blinking these days, tho normal people do upgrade oh so quickly
03:30 Jak_o_Shadows That's cool
03:31 Jak_o_Shadows I have an old android phone with a half broken touch screen & no wifi, I wonder if I oculd do something useful with it
03:31 theBear totally, me AND the guy that gifted it to me were quite shocked while i was idly fingering it and the mini-end cap popped off :)
03:31 theBear you can make it into a err, bluetooth connected wireless cam
03:32 theBear or a a2dp/handsfree bt adaptey thing for something, so your good fones can play music on yer hifi for exampple
03:32 theBear or just a heavy duty mini-linux for a robot if yer workout some io
03:34 Jak_o_Shadows I was thinking the latter tbh
03:34 Jak_o_Shadows No wifi is a pain
09:05 robotustra btw
09:05 robotustra how to make linux to shut down correctly on BBB on power off
09:05 robotustra without corrupting eMMC
09:19 robopal what is bbb?
09:20 Tom_itx beable bone black
09:20 Tom_itx better business bureau
09:20 Tom_itx take your pick
09:22 hackkitten busty black... bushes?
09:22 hackkitten :P
09:26 theBear boegois brown bushes ?
09:26 theBear boegoisie ?
09:27 theBear hot damn that's hard to spell, i even read it earlier today
09:27 hackkitten bourgois?
09:29 theBear you askin me ? you crazy mang, you're all 'woohoo' and shit ;-)
09:30 hackkitten :D
09:31 theBear lets just say that the politariat ALWAYS loses, and that in an 'egalitarian communist utopia' the governing committee that rises to power is ultimately more oppressive than the <insert french here> it vilifies
09:31 theBear if nothing else, has history not shown THAT ?
09:31 theBear yeah that's right, theBear is a dirty red bastard, and occasionally turns on his mindtank
09:32 theBear usually by thinking about bbb's <grin>
09:32 ckkitten is just a kit
09:32 ckkitten does kitten st
09:35 theBear one of my current favourite "artists" has an album called "we do jeff goldblum things" ... i find this very funny, but am not sure i have any idea what it could mean
09:39 hackkitten :D
09:54 akem2 hi
09:56 deshipu akem: so what did you do to the poor servos?
09:57 akem2 deshipu i did not harassed them
09:57 deshipu they always say that
09:58 deshipu how did you feed them?
10:04 veverak lol
10:39 akem deshipu i try to send raw signal directly to mg995 and mg90
10:40 akem i got them turning 180, found some example online for the pulse
10:40 akem but i think its not optimal for the mg995
10:41 akem do you know about that
10:41 akem ?
10:44 akem that is turning 180 back and forth is ok, now switching instantly to another position is not so good, plus is not very acurrate
11:06 anonnumberanon akem not accurate?
11:07 anonnumberanon do you have a potentiometer to control the servo?
11:09 akem anon no, i'm waiting them, i just try signals positionning from code based on one online example wait
11:15 akem http://www.linuxcircle.com/2013/07/04/servo-manual-control-without-arduino-servo-library-on-raspberry-pi-and-gertboard/
11:15 anonnumberanon akem servos take a PWM signal. Their value can be hardcoded with Arduino Sweep or controlled live with Arduino knob. Knob takes a potentiometer to work.
11:15 akem anonnumberanon you control them with a lib or manually?
11:16 anonnumberanon mg995 likes 5 to 5.5V. Not less and not more.
11:17 anonnumberanon akem I started with a potentiometer and that's still how I test them before putting them in my robot. Then I had to write a program that would signal to ten of them at a time which is very hard to do.
11:21 anonnumberanon thearduino servo lib is good for less servos. 6 servos i think.
11:23 akem i see, i have the datasheets also, but i was looking at the fast positionning, 'peak' like effetcs that i had randomly while testing a bit like doing reverse engineering. not so fast
11:24 akem i got mg90 micro ones they are good also
11:24 akem anon so you are sending signal yourself then, you use 25ms pulse?
11:27 anonnumberanon I send pulses ranging from 500 to 2400 microseconds, with a refresh period of 20 milliseconds.
11:30 anonnumberanon That gives me an agle range of a bit more than 180°
11:33 akem ok yea , sort of the same
11:41 akem anon you re in USA?
11:43 anonnumberanon yeah . you in France?
11:44 akem yes
11:44 anonnumberanon I'm French too.
11:45 akem just because i usually get my electronic stuff from china dx mainly, i know about sparkfun and few other
11:46 akem anon ok bonjour, so you work in usa?
11:46 akem expatriate
11:47 akem lots of french, keukpa also
11:52 anonnumberanon no job yet I'm looking for one just got out of school
11:52 anonnumberanon ahh yeah keukpa
11:53 akem you got in school in usa but you french? ok.
11:57 Snert_ anonnumberanon: do any interviews yet?
11:59 anonnumberanon Snert_, not yet
12:02 Snert_ taking a break from school :) I did that for 3 months after techschool.
12:03 anonnumberanon I did that and worked small jobs a bit, then I went back in and finished electrical and computer engineering
14:08 rue_bed dx didnt work out for me
14:08 rue_bed iirc I couldn't buy what I got, they coul;dn't take payment
14:09 rue_bed which was prolly good, I had like 100usd in stuff
15:00 Tom_itx they don't like canuckian money?
15:01 rue_house I was up till 4am last night, thats pretty good
15:02 Tom_itx i wasn't
15:02 Tom_itx however i was up at 6
15:02 Tom_itx went to the doc
15:51 adv_ when should i use forward and when inverse kinematics? which cases?
16:05 veverak hmm
16:05 veverak servo description says that it should do 0.1s/60degree
16:05 veverak that seems way too fast compared to reality
17:52 rue_house adv_, forward kinematics are when you want to sowrk out your xyz position from the joint angles,
17:53 dpg_ t
17:53 rue_house inverse kinematics are when you want to know what your joint angles should be when your at your xyz position
17:53 rue_house dpg_, yea, I'll have some T, thanks
18:18 dpg_ I could go for some green tea right now as well.
19:23 adv_ rue_house: can you give some practical example for FK?
19:37 Hyratel yay! my micro SD cards came in today. 3x 8GB
19:39 mrdata good!
19:40 Hyratel need 'em for Orange Pi asperimenting
22:29 rue_house adv_, plase stand by while I post that project on my site
22:30 adv_ rue_house: which one?
22:30 adv_ FK example?
23:06 rue_house yup