#robotics Logs
Jun 16 2017
#robotics Calendar
12:00 AM rue_house: there is no value in a not, tho maybe as an abort?
12:02 AM rue_house: how would that work
12:02 AM rue_house: so, like maybe if C is an inhibit
12:02 AM rue_house: go on,
12:02 AM rue_house: not sure, wouldn't you just .... say, ....
12:02 AM rue_house: well how about /C,(A|B)
12:02 AM rue_house: how does it unlock
12:02 AM rue_house: I dont know
12:02 AM Anniepoo_: there are notations for temporal logics
12:02 AM rue_house: please show me!
12:02 AM rue_house: me too
12:02 AM Anniepoo_: hang on
12:02 AM rue_house: TO WHAT!!! THE INSTRUCTIONS ARE UNCLEAR!!!!!
12:03 AM rue_house: OH GOD, OH GOD IS THERE A TIME LIMIT!?!?!?!
12:03 AM rue_house: WHAT HAPPENS IF I FAIL TO FIND SOMETHING TO HOLD ONTO!
12:03 AM Anniepoo_: https://en.wikipedia.org/wiki/Temporal_logic
12:03 AM * rue_house grabs his mug
12:04 AM Anniepoo_: @dmiles this is more your thing
12:05 AM Anniepoo_: (I was an RA in automata theory once)
12:06 AM rue_house: this is different
12:06 AM rue_house: I think
12:07 AM rue_house: I'm talking about impulse events
12:07 AM rue_house: I think this is different
12:10 AM Anniepoo_: impulse events are just events
12:10 AM Anniepoo_: seriously,dmiles is expert in this stuff, i am not
12:11 AM Anniepoo_: esp youre mixinging combinatorial logic w automata
12:12 AM rue_house: hmm, I'v never seen temporal logic in the context of state machines.
12:12 AM rue_house: why.
12:14 AM Anniepoo_: automata are, basically, state machines
12:15 AM rue_house: by the wiki article,t his dosn't seem well formed
12:15 AM rue_house: but nobody uses ( that I'v seen) formulas to dipict state machines as temporal logic devices
12:15 AM Anniepoo_: whats 'this'?
12:16 AM Anniepoo_: oh sure they do
12:17 AM rue_house: I'm also baffled by a temporal memory cell that goes beyond the memory of a state, it must go into memory of a sequence of states
12:17 AM Anniepoo_: see Bavel, Zamir, automata theory and finite machines
12:20 AM rue_house: is it on google books?
12:20 AM Anniepoo_: might be
12:20 AM Anniepoo_: its an 84 or so book
12:21 AM rue_house: https://www.amazon.ca/Introduction-Theory-Automata-Zamir-Bavel/dp/0835932710
12:21 AM rue_house: ?
12:22 AM Anniepoo_: thats it
12:26 AM Anniepoo_: hmm
12:26 AM Anniepoo_: hang on
12:27 AM Anniepoo_: yah, thats it
12:36 AM rue_house: god damnit I thought google digitized the world for us
12:37 AM rue_house: why do I have to be a free member of a library to get a book online?
12:37 AM * rue_house grumbles
12:37 AM Anniepoo_: honestely, tlak to dmiles
12:37 AM rue_house: dmiles, your answer sometime soon would help
12:38 AM Anniepoo_: dmiles, you're very handsome and we love you
12:38 AM theBear: rue_house, you probly got too much sensible security between you and google, and they're punishing you for not just letting them have free access to every tiny bit of everything about you without even trying :)
12:38 AM Anniepoo_: hang on
12:42 AM * rue_house grips his mug tight ... "I hope I'm doing this right"
12:42 AM rue_house: VPL dosn't have it
12:42 AM rue_house: I wonder if I ahve access to , say the ubc library
12:43 AM rue_house: oh maybe bcit
12:45 AM Anniepoo_: gimme 24 hours
12:45 AM * rue_house tries not to grip the mug so hard, as to conserve strength
12:46 AM rue_house: I found a few of zamirs books in the bcit lirabry
12:46 AM rue_house: but this peter linz book keeps comming up
12:46 AM rue_house: An introduction to formal languages and automata, fifth edition
12:47 AM Anniepoo_: hmm
12:48 AM Anniepoo_: thats avctualluy just as g9oood
12:48 AM rue_house: huh, my bcit password isn't good anymore
12:50 AM theBear: dagnabbit... was gonna go past the lectronics local store on my way somewhere real soon, but can't remember wtf i need... something real small and simple i think, ya know, like a specific dc jack or particularly unusual spec transistor or something tiny and worth nothing, but i sure remember feeling i really needed one for something yesterdAY
12:51 AM Anniepoo_: carry a small notebook
12:52 AM rue_house: theBear, you should have wandered thru, then halfway between there and home, you would have remembered
12:53 AM theBear: i do, yesterday was a rare day that i was a bit more social and less on top of things like putting it in my pocket instead of my bag when i left the house or got outta the car, as i do most of the time these days
12:53 AM rue_house: I think my bcit membership is only good for a month or so after finishing a course
12:53 AM theBear: rue_house, you speak like i'm already too late.. that's not the attitude that might win me this mental battle with my own mindtank before the working week is over
12:53 AM rue_house: no, no, you see, then you would know what it is
12:54 AM rue_house: you wouldn't have it, but you would know
12:54 AM rue_house: and you would probably have some things you dont need, which can be fun
12:54 AM theBear: rue_house, i could probly make you an honorary member of the fcit if you think it will help... probly not tho, we certainly don't have any libaries, or outside of members personal posessions, i don't think we even own a single book
12:54 AM * rue_house looks at the bookshelf bordering collapse behind him
12:57 AM theBear: rue_house, it can, but i been getting carried away a bit doing exactly that recently, plus i spoiled myself at the variety/$2 store yesterday, sure it was still only $22.5 or something, and i got a ton of bits and pieces i needed (i like this particular one, right near where i love, nice lady, and everything from my favourite indian incense flavour to teeny anodized carabiner thingies, teeny weeny little seethru jars that are great for teeny screws
12:57 AM theBear: etc, and you get maybe 12 for under $2, and the best bit that first got me in the door, $3 for a full strip of any coin/hearingaid batt you can think of, a fyull strip, that's err, 10 or 12 individual cells in most sizes, and not varta or anything like that, but i been using em in various sizes for a few years now, all kinds of low/high current apps, and they sure don't seem much less-good than namebrand cells... i mean, coin cells are small, you'd
12:57 AM theBear: have to work hard to mess em up
01:06 AM rue_house: yup
01:17 AM mun_: anyone know how small rc helicopters like this work? http://ecx.images-amazon.com/images/I/41lrrI-fkdL._SX355_.jpg
01:18 AM mun_: how does it go forward/backward?
01:18 AM mun_ is now known as mun
01:18 AM mun: bigger copters use swashplates, but how about small ones like this?
01:20 AM Anniepoo_: tilts the whole mast & motors
01:21 AM mun: Anniepoo_, hmm how come there're two blades?
01:22 AM Anniepoo_: prevent countertorque
01:22 AM mun: Anniepoo_, so this guy has opened one up https://youtu.be/worMycPCN5s?t=2m39s
01:22 AM mun: how is the mast tilted though?
01:22 AM mun: is there a servo in there?
01:22 AM Anniepoo_: real helicopters have a tail rotor, or some of them do have the counerrotating propes
01:23 AM Anniepoo_: I have one of these tiny helicopters, tats how mine works
01:23 AM Anniepoo_: mine you turn by varying speeds of two props
01:23 AM mun: if my reading is correct, there's just a single DC motor in there
01:24 AM Anniepoo_: this one I don't know
01:25 AM mun: Anniepoo_, but how does changing speeds of the two props change direction?
01:25 AM Anniepoo_: each one exerts a torque on the body
01:25 AM Anniepoo_: if you unbalance the torques, the bodyturns
01:25 AM mun: Anniepoo_, even forward?
01:26 AM Anniepoo_: dnno - I'd have to go get mine, it's at the shop
01:27 AM mun: i wonder how something like that with just one motor can change direction
01:27 AM mun: similarly, this one https://i.ytimg.com/vi/X6GBfPSyuuo/maxresdefault.jpg
01:29 AM Anniepoo_: i think the copper color thing in between batt and pcb is a coil
01:29 AM Anniepoo_: bet its a galvo setup
01:29 AM mun: Anniepoo_, you mean the one in the photo?
01:30 AM Anniepoo_: in video
01:31 AM mun: Anniepoo_, hmm what might the coil do?
01:32 AM Anniepoo_: tilt the whole pcb and mast assy
01:32 AM Anniepoo_: https://www.youtube.com/watch?v=m6mJclTF4CI
01:32 AM Anniepoo_: mine
01:33 AM mun: Anniepoo_, hmm so the coil produces enough torque to tilt the whole setup?
01:34 AM Anniepoo_: guessing yes
01:34 AM Anniepoo_: its just changing angle of attack
01:34 AM mun: Anniepoo_, but the coil is fixed to the helicopter's frame though
01:34 AM mun: how does it tilt?
01:35 AM Anniepoo_: https://www.youtube.com/watch?v=VtnVSoupqyk
01:36 AM Anniepoo_: oh, hm - has servos and swash plate
01:36 AM Anniepoo_: thats clear
01:37 AM Anniepoo_: takes a bit of practice
01:37 AM mun: but this one has a swash plate
01:37 AM mun: yeah
01:37 AM Anniepoo_: mine the batt died, i wasnt using enuf to replace it
01:37 AM mun: but the one i linked to doesn't, right?
01:38 AM Anniepoo_: you assume i know
01:38 AM Anniepoo_: i don't
01:38 AM mun: Anniepoo_, but you can't see the swash plate rods there, right
01:39 AM mun: which usually connect to servos
01:39 AM Anniepoo_: not sure what u want from me
01:39 AM Anniepoo_: i don't know
01:39 AM mun: thanks. i'll keep looking
01:43 AM Anniepoo_: thanks - my heli's dead, wondering if i can salvage servos for snail
03:29 AM mun: anniepoo, those seem to be linear servos
06:04 AM Jak_o_Shadows: You can get small linear servos for cheap
06:04 AM Jak_o_Shadows: Apparently because helicopters
06:07 AM deshipu: well, relatively cheap
06:08 AM deshipu: you can also get the stepper motors from camera lens, with worm drive
06:08 AM Jak_o_Shadows: My issue has always been that the range of motion is so small.
06:08 AM Jak_o_Shadows: They might, potentially, be good for moving a head around? But nothing more
06:09 AM deshipu: depends on the mechanics
06:10 AM deshipu: you can always add a lever
06:12 AM Jak_o_Shadows: eh. If you're chucking levers in, just use a rotary one.
06:13 AM Jak_o_Shadows: The point about linear ones is that they make the maths easier, and simplify the mechanics.
06:13 AM Jak_o_Shadows: Like, I don't even want to think about trying to figure out working space if you have to consider actuator collisions
06:19 AM deshipu: you only do math once
06:19 AM deshipu: and with levers it's a simple proportion anyways
06:19 AM Jak_o_Shadows: true
06:20 AM Jak_o_Shadows: to me, it is about the actuator collisions
06:22 AM Jak_o_Shadows: and what are you gaining anyway. Just use rotary actuators
07:07 AM goppo: hi
07:07 AM goppo: i'm planning to power a hobby servo that operates between 4.8V and 6V with a 9V power supply. my device has two usage modes: low torque and high torque. to save battery, would it be a good idea to regulate the voltage to 4.8V during low torque mode and 6V during high torque mode?
07:07 AM Jak_o_Shadows: Remember power = volts*current.
07:07 AM goppo: my reading is that the current draw is lower when the supply voltage is lower. but will the result be effectively the same? e.g., even if the power is lower, it takes longer to reach the final position
07:07 AM Jak_o_Shadows: So, erm, without knowing what the two modes are...
07:08 AM goppo: Jak_o_Shadows, well it's just that the servo may turn a small load or a large load
07:08 AM Jak_o_Shadows: But how?
07:08 AM goppo: when the load is small (i.e. low torque), i wonder if it'd be a good idea to lower the voltage
07:08 AM goppo: Jak_o_Shadows, i manually make the switch
07:08 AM Jak_o_Shadows: oh.
07:10 AM goppo: yeah, power = volts*current, but work = power*time. so even if i have low voltage and current (= low power), i wonder if time will take longer and wipes out any power saving (per time unit)
07:10 AM Jak_o_Shadows: Well. torque is torque.
07:10 AM Jak_o_Shadows: I might lean towards that
07:11 AM goppo: Jak_o_Shadows, i wonder if there's such a thing as "wasted" torque
07:12 AM Jak_o_Shadows: Well. If you're rotating it faster than you need?
07:12 AM goppo: Jak_o_Shadows, yeah
07:12 AM goppo: and thus wasting power
07:14 AM Jak_o_Shadows: But just like, rotate it slower?
07:15 AM goppo: Jak_o_Shadows, so do you think there's no benefit in switching voltage for low and high torque use?
07:16 AM Jak_o_Shadows: I have some questions on how effective it'll be. Like, motors still thirsty.
07:16 AM Jak_o_Shadows: I don't know you rproblem though
07:19 AM goppo: Jak_o_Shadows, in my setup, the horn pulls on two pulleys: one on the right and one on the left. the load on the right is 3x heavier than the one on the left
07:19 AM goppo: so i was thinking if i should get an IC regulator and lower the voltage to 4.8V when the lighter one needs pulling
09:25 AM rue_house: no
09:25 AM rue_house: linear regualtors will just dissipate power as heat
09:25 AM rue_house: you would be better off not dropping the voltage
09:26 AM deshipu: they should make a LED regulator, that would dissipate power as light
09:48 AM rue_house: is 12cmx8cm a big enough screen for google cardboard?
09:52 AM deshipu: 5.5" seems a bit small
09:52 AM rue_house: so I should go with 7"
09:52 AM deshipu: don't they have any documentation on that?
09:52 AM rue_house: hard to find dimentions for google cardboard
09:52 AM rue_house: usable ones
09:54 AM z64555: goppo: as rue_house said, linear voltage regulators dissapate heat, so the net conservation is probably close to nil
09:55 AM deshipu: Fits phone up to 6" screen size. Works with iPhones and Android devices.
09:55 AM deshipu: rue_house: so sounds like that screen would actually be fine
09:56 AM z64555: goppo: motors only consume power when acting against a load. Rotor momenta of inertia is usually ignored, but that does factor in as a load.
09:56 AM deshipu: "Securely fits any size phone with or without most cases."
09:56 AM deshipu: any size, so you should be good with anything ;)
09:56 AM rue_house: yea but I'm trying to work out an lcd monitor
09:56 AM rue_house: its not a phone
09:57 AM rue_house: https://www.aliexpress.com/item/234-x-480-7-Inch-Color-LCD-Car-Monitor-7-Inch-TFT-LCD-Screen-Car-Rear/32325670599.html
09:57 AM z64555: rue_house: phone screen, then? or a screen of similar size?
09:57 AM deshipu: they said any size
09:57 AM rue_house: sweet, I can use my 21" lcd
09:57 AM z64555: <.<
09:57 AM z64555: good luck strapping that to your face
09:58 AM rue_house: and it'll fit in V1 google cardboard right?
09:58 AM deshipu: https://www.aliexpress.com/item/Original-LONG-CZ-J8-bluetooth-dialer-FM-radio-mini-bluetooth-3-0-earphone-Magic-voice-long/32798642529.html
09:58 AM deshipu: rue_house: they said so
09:58 AM rue_house: rembeber, all images of things from china look better than they really are (and usually bigger)
09:58 AM deshipu: they wouldn't lie, would they?
09:58 AM rue_house: well its google
09:59 AM deshipu: don't be evil
09:59 AM deshipu: oh, they removed that a few years ago
09:59 AM deshipu: nevermind then
09:59 AM z64555: well, "alphabet" is a pretty evil sounding name for a corporation...
10:00 AM rue_house: its sad whent hey drop their goals
10:00 AM rue_house: like motorola "deep in the heat of the state of the art"
10:01 AM deshipu: you're in heat only once a month
10:01 AM rue_house: maybe I should just get the 7" lcd, and make what I need
10:01 AM deshipu: and if it doesn't fit, sue them
10:05 AM rue_house: well I already have a case then, my 7" tablet dosn't fit
10:07 AM deshipu: litigate :)
10:22 AM z64555: found a sheet of aluminum just laying out in the yard yestarday, 1/4" thick or so
10:22 AM z64555: along with a large aluminum heatsink
10:23 AM deshipu: that must have been a glin fairy
10:24 AM z64555: it's been there for awhile, it was covered with leaves and dirt
10:54 AM goppo: rue_house, z64555 thanks
10:54 AM goppo: z64555, but i'd need to step down from 9V to an operating voltage anyway though
10:54 AM goppo: so there'd still be heat dissipation anyway?
10:55 AM deshipu: buck converters have up to 90% efficiency
10:59 AM goppo: yeah
11:34 AM z64555: lol...
11:34 AM z64555: the head connector for this radio is a set of round headers cast in a plastic plug
11:38 AM z64555: hm, coin cell only has 0.5V on it
11:38 AM z64555: wonder if that's for the memory
11:44 AM z64555: oh bollocks, they used crown nuts on the knobs
11:44 AM z64555: (taking apart a VHF/UHF radio, for those that are wondering)
11:52 AM deshipu: Turns out that those fidget cubes do have a calming effect on me after all, I was just using them wrong. Taking them apart is so satisfying!
11:53 AM z64555: rubix cubes? :P
11:53 AM z64555: and good news, the lights are diodes. bad news, the lights are diodes
11:54 AM z64555: so need to figure out why the backlight in the LCD isn't turning on
11:55 AM deshipu: maybe wear some sexy lingerie, that should help
11:55 AM deshipu: to turn it on
11:56 AM z64555: hm, theres burn marks on the umbilical
11:57 AM Snert__ is now known as Snert_
12:09 PM z64555: hm, the lights for the LCD are actually lamps
12:24 PM z64555: mkay
12:24 PM z64555: One burnt out, one shorted out, and one wasn't soldering on good enough
12:24 PM z64555: the last one is perfectly fine
12:32 PM z64555: yup. definitely lamps
12:53 PM z64555: well, shoot. they're in series
01:00 PM z64555: are a pair of series
01:01 PM z64555: I could solder a jumper across them or solder in a 220 ohm resistor across them
01:02 PM deshipu: those don't shine as brightly, in my experience
01:04 PM z64555: they also last longer
01:08 PM z64555: oh, just a 22 oh. ok.
01:09 PM mumptai: hi
01:09 PM z64555: hi
01:50 PM z64555: erm. ok...
01:50 PM z64555: That's interesting. the coil cell holder is welded to the cell
02:25 PM z64555: anybody know a suitable replacement for a 22ohm lamp? I don't know the voltage or wattage for it
02:26 PM z64555: thinking it's 5V
02:26 PM anniepoo: the resistance of an incandescent depends on the current flowing thru it
02:26 PM anniepoo: it's R goes up as I goes up
02:27 PM anniepoo: so the cold resistance isn't very meaningful
02:29 PM z64555: I was afraid of that :(
02:38 PM SpeedEvil: 22 ohm means hot resistance is about 22*7
02:39 PM SpeedEvil: Or 150 ohm, so 0.16W. Sounds unlikelyly low
02:39 PM SpeedEvil: why do you think it's 5V?
02:39 PM SpeedEvil: At 12V, that works out pretty much exactly to 1W
02:43 PM z64555: it's a little bitty lamp, about 2.5mm in diameter and about 3 or 4mm tall
02:43 PM z64555: I'm used to seeing 12V lamps for something thats the size of my thumb
02:47 PM SpeedEvil: go to digikey
02:47 PM SpeedEvil: find out if 5V/0.16W bulbs exist
03:17 PM Sol is now known as Guest53261
03:48 PM Guest53261 is now known as Solgriffin
04:44 PM anniepoo: z, what you probably have is a 'grain of wheat' lamp
04:45 PM anniepoo: they start glowing about 4v and are good to about 14v
04:46 PM anniepoo: stop in a hobby shop that caters to model railroaders
04:46 PM anniepoo: they have an assortment of tiny incandescents
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07:02 PM cherryh.freenode.net changed topic of #robotics to: If you ask a question, you must wait for the answer. | http://tom-itx.no-ip.biz:81/~webpage/index.php | K is for kilobite (which megahurts!)
07:04 PM Elleo__ is now known as Elleo
08:12 PM rue_house: for gain control of sine wave oscillators
08:12 PM Tom_itx: grass can try to catch up again...
08:14 PM * Tom_itx sits down to cool off a bit
08:51 PM z64555: picked up an alchohol lamp for $1 today
08:52 PM z64555: Tiki was selling them as a cheap tabletop torch for mosquito fuel
08:53 PM z64555: the snuffer is a wooden cap made from a 1.5" wood dowel
08:58 PM z64555: I need to come up with some sort of blowpipe for it
09:06 PM zhanx: for?
09:12 PM z64555: glass lampwork
09:13 PM z64555: popular nowadays with those that want to make their own beads for jewelry, but you can also make figurines
09:13 PM z64555: ...and test tubes and some small scientific glasswares
09:16 PM z64555: I'd like to see at some point if I'm able to make a miniture glass furnace that's alchohol fueled
09:26 PM z64555: I also grabbed a spool of waxed thread, so now I can repair my shoe
09:27 PM * z64555 wonders if he can make a glassblowing robot
09:31 PM anniepoo: nice!
09:32 PM * z64555 remembers that he has a neon power supply
09:32 PM z64555: if I had a tank of neon, I could also make a neon sign
09:38 PM z64555: there's also the slim /slim/ possibility of making homebrew vacuum tubes
09:53 PM rue_shop3: vacuum
09:53 PM rue_shop3: not neon, vacuum
09:57 PM anniepoo: need a good vacuum system for that
09:57 PM anniepoo: diffusion pump, the whole works
09:59 PM zhanx: or wing it and flood it after vacuum and a ready torch
10:58 PM logicmoo is now known as dmiles
11:57 PM rue_house: or build it in an ion cloud
11:57 PM rue_house: like the flame of a candle
11:58 PM rue_house: but preferably something cleaner
11:58 PM z64555: vacuum pump and some soft heat to the piece should do
11:58 PM rue_house: nothing like your emitter and plate shorting because of SOOT
11:59 PM z64555: I was thinking, for the lamp I could use some 1/4" copper tubing soldered to the side of the can
11:59 PM rue_house: cathode and plate!?
11:59 PM rue_house: memory failing
11:59 PM z64555: and then attach vinyl or rubber tubing to the blowpipe and an aquarium bubbler