#robotics Logs

Sep 17 2015

07:23 Jak_o_Shadows hi
08:04 knob hey yah Jak_o_Shadows
08:18 MisterX how does a 360* servo work? if the current position is 359* and you want it to be 1*, will it go backwards?
08:18 MisterX continous rotation
08:19 deshipu MisterX: in continous rotation servos you don't set the position, you set the speed
08:19 robopal but how you tell the direction?
08:19 robopal clockwise vs anti-clws
08:20 deshipu 1500µs is stop, lower than that is one direction, higher is the other
08:21 robopal ok its clear
08:34 Snert if uS only determines position, what determines when to stop?
08:34 rue_mohr 1.5ms is stop if its been set right
08:34 rue_mohr Snert, its been modified for continious rotation, right?
08:35 Snert oic...yes..
08:35 rue_mohr do you know how servos work?
08:35 Snert seems like you'd want it to rotate 175 degrees and then stop.
08:35 Snert or what have u.
08:36 rue_mohr do you know how those servos work tho?
08:36 Snert to rotate continously forever doesn't seem really useful.
08:36 rue_mohr http://ruemohr.org/~ircjunk/tutorials/elex/hobbyservo/servo101.html
08:36 rue_mohr do you know how those servos work tho?
08:37 Snert unless that's exactly what you want, as in a radar rotating thingy.
08:37 rue_mohr do you know how those servos work tho?
08:37 Snert I think there's just language/typing/explanation differences is all.
08:37 rue_mohr I should have said somehting about continious rotation
08:37 rue_mohr http://ruemohr.org/~ircjunk/tutorials/elex/hobbyservo/servo101.html
08:37 ert knows about t
08:38 rue_mohr ^ thats my info on servos, it has a bit more detail than most of the explinations
08:38 Snert my RC helis with 6 servos have taught me most of that I bet.
08:39 rue_mohr Snert, when does a servo turn the motor on?
08:39 Snert but great writeup!
08:39 Snert when you give it juice. I attempts to reach position.
08:39 rue_mohr when in relation to the control pulse does the motor get its power?
08:40 Snert if it's not on position according to pulse width then it attempts to reach position.
08:40 rue_mohr when in relation to the control pulse does the motor get its power?
08:40 Snert anytime it's not on position.
08:41 rue_mohr nope
08:41 Snert as determined by feedback, etc.
08:42 rue_mohr na, if you even looked at my webpage you would know
08:42 rue_mohr reading it would tell you even more
08:43 rue_mohr to make a servo continious rotation, the feedback is fixed to the 50% position
08:47 Snert anyways, thx for the info. I'll get to it after stepper motors and absolute position encoders.
08:50 rue_mohr you working on learning about position feedback systems?
08:53 Snert gray code absolute position encoders.
08:54 rue_mohr yup, to microcontrollers?
08:54 Snert yep.
08:54 rue_mohr using standard encoders?
08:54 Snert gray absolute position multi-turn encoders, yes.
08:55 rue_mohr yup, so do you know how to set up a state machine to decode and track positions?
08:55 Snert yep just never applied all that to an encoder....yet.
08:55 Snert I'm awaiting parts.
08:56 rue_mohr no dead HP printers eh?
08:56 Snert <--- goes straight for the herion.
08:56 rue_mohr come to think of it, even canon is using them now
08:56 rue_mohr how much did you spend on an encoder? $50? more?
08:57 Snert 40bux on one encoder, which will not be sufficient except to learn a few things with.
08:57 Snert I'll be spending much more.
08:57 rue_mohr you will
08:58 veverak nah
08:58 rue_mohr could have just grabbed an old printer tho
08:58 verak needs 1k/rotation enc
08:58 veverak but not absolute
08:58 Snert I see good graycode absolute position encoders from under $200.00 all the way up to a grand.
08:58 rue_mohr yup
08:59 rue_mohr funny to think they are thrown out by the hundreds every day eh?
08:59 Snert like I say..I don't mess around with toys except as a base learning thing.
09:00 veverak http://www.ebay.com/itm/Encoder-1000P-R-Incremental-Rotary-Encoder-AB-phase-encoder-6mm-Shaft-W-coupling-/231160065963?hash=item35d236afab
09:00 veverak what do you think about this?
09:00 veverak it suits my needs
09:00 veverak I just wonder about ebay quality :/
09:00 rue_mohr you should just buy an industrial encoder motor from me
09:01 Snert I have what looks exactly that encoder on the way.
09:01 veverak Snert: nice
09:01 verak would like to be info
09:01 veverak still not sure if I want it or not :)
09:01 veverak http://uk.farnell.com/productimages/large/en_GB/2447891-40.jpg local shop got this
09:01 Snert I also have a 32 position mechanical graycode switch which I will use to generate position so I can work on the circuit and programming.
09:02 veverak and I am lees concerned about quality
09:02 veverak it's just big pain as I look at it
09:03 Snert a mechanical switch generating graycode is the stationary equivalent of an absolute position encoder.
09:04 Snert at least that's the way I'm looking at the subject for proof of concept and initial build purposes.
09:05 Snert I won't deal with homing after a power outage, except as a learning thing.
09:05 Snert I want it to pick up exactly where it left off after an outage.
09:07 Snert verak that looks like fun stuff @ franell.
09:07 veverak yeah
09:07 veverak /me wants encoder on his 3d printer
09:07 Snert so I'll prolly pick up a set and learn with it.
09:07 veverak sad thing is that it needs to be 1k/step :/
09:07 Snert can't do scaling/divisor factors?
09:08 veverak resolution
09:08 veverak on my X/Y axis
09:08 veverak I've got 40mm per turn
09:08 Snert only the best :)
09:08 veverak 40/1000 is around 0.04
09:09 veverak which is OK
09:10 veverak means that when I will finish the devel. I should have system that won't hold me back for a long time
09:10 Snert I'm doing a proof of concept stepper motor and absolute position encoder mountd with a belt in between the 2.
09:11 veverak that's something I thought of
09:11 Snert just to see if I can gain control and repeatability and deal with the C code.
09:11 veverak I thought about replacing idler on my axis
09:11 veverak with the encoder
09:11 veverak no problem to put proper gear for belt on the idler and make it happen
09:11 veverak :)
09:12 Snert yes, I figure a mismatched condition won't really matter as long as you can deal with it.
09:12 Snert pulley sizes, you know.
09:13 Snert or gear sizes
09:32 Snert is there a such thing as an encoder with an ip addy? Sits on your ethernet network, graycode absolute is what I'd be looking for.
09:32 Snert or stepper motors with an ip addy?
09:59 veverak make one
09:59 veverak :)
10:00 deshipu veverak: build a clock!
10:00 deshipu http://hackaday.com/2015/09/16/why-you-should-build-a-clock-for-social-good-this-week/
10:01 veverak I won't debate on the fack that I read cock instaed of clock
10:01 veverak nah
10:01 veverak too many "computers" for this day, afk! :)
10:02 deshipu make it water-powered
10:02 deshipu or beer
10:06 Snert veverak: I dunno if you're being facetious or one actually doesn't exist.
10:06 Snert if they exist it may just bee too spensive to afford :(
10:10 knob Snert, why don't you build it? rPi?
10:13 Snert might end up doing that. Just like to know what exists for options.
10:14 Snert I suppose an arduino with an ip addy controlling a motor amounts to the same thing. Not nearly as compact though.
10:15 deshipu an esp8266
10:19 Snert it's an option and a good one. Though I lean toward an edison with wireless built on. Ethernet/wireless as an afterthought is what I'd seek to avoid.
10:20 Snert I'll go get me an esp8266 on payday. It may be the only option at this point in time.
10:21 Snert I'm sure the next generation of devices such as arduinos will have wireless built on.
10:42 SpeedEvil ESP8266 has in principle extreme diming resolution and is quite awesome
10:42 SpeedEvil ^timing
10:42 SpeedEvil https://spritesmods.com/?art=einkdisplay - for example.
10:42 SpeedEvil this uses an ISR running at 100khz - and every tick it posts new content to a SPI GPIO chip
10:43 SpeedEvil While doing wifi
10:43 SpeedEvil That can instead be running 16 servos
12:23 deshipu shame you only get 8 usable gpios
12:23 deshipu so you'd need to multiplex it
12:37 SpeedEvil http://www.digikey.com/product-detail/en/MCP23S17T-E%2FSS/MCP23S17T-E%2FSSCT-ND/4307901
12:37 SpeedEvil <deshipu> so you'd need to multiplex it
12:57 deshipu still an extra chip
12:57 SpeedEvil true
12:57 deshipu and for the combined price, you could instead get a EMW3165
17:13 rue_mohr why woulnd't you just do it on the avr?
18:18 Tom_itx rue_mohr appears to be home now
20:08 rue_mohr I'm back