#robotics Logs

Feb 23 2017

06:46 AM Tom_itx is now known as Tom_L
10:19 AM rcc is now known as jadew`
05:14 PM veverak: I wonder
05:14 PM veverak: is ther some nice UBEC schematic available?
05:14 PM * veverak is googling but not exactly success
05:15 PM Snert__: generally not, if it comes out of the RC UBEC world.
05:15 PM veverak: yep
05:16 PM Snert__: I have seen schematics on hobbyking under the docs tab but it's few and far between
05:17 PM Snert__: I mean.... a 5v regulator is a 5v regulator.
05:17 PM Snert__: gets strange when they go and combine it with an ESC too.
05:23 PM * veverak uses it for various projects with lipo inside
05:23 PM veverak: ie. electric poi now
05:23 PM veverak: Snert__: where on hobbyking?
05:24 PM veverak: we have some PCB manufacturing capabilities in hackerspace
05:24 PM veverak: would like to make everything singleboard
05:24 PM veverak: UBEC + 3.3V->5V shift + esp8266
05:25 PM veverak: (esp8266 soldered on the boarD)
05:31 PM Snert__: well...on the ubec/esc page of choice, there's usually a files tab.
05:31 PM Snert__: if there is anything, it's there.
05:31 PM anniepoo_: whats UBEC?
05:31 PM Snert__: even so...it's always crappy docs...sometimes better than nuthin' tho'.
05:32 PM Snert__: universal battery eliminator circuit.
05:32 PM Snert__: a 5v regulator.
05:32 PM anniepoo_: thanks
05:32 PM Snert__: it's RC world jargon.
05:32 PM Snert__: and it misses the point....but ph well :)
05:33 PM anniepoo_: 8cD
05:36 PM Maya-sama is now known as hackkitten
05:38 PM Snert__: it eliminates the 2nd, receiver battery pack by making the receiver run off the same main pack that powers the motor.
05:38 PM Snert__: which some do and don't agree with but to each their own
05:47 PM z64555: UBEC's mentioned
05:48 PM z64555: veverak: whats your goal with the UBEC?
05:48 PM z64555: As Snert__ mentioned, it's just a voltage regulator
05:49 PM z64555: I think all, or almost all, modern ESC's provide that capability
05:50 PM z64555: Since the controller itself needs 5V, so why not grab it off of the engine battery
05:51 PM z64555: If you have multiple ESC's (like with a multirotor), each of their UBEC's add to the available current
05:51 PM z64555: for the controllers, radios, and misc. electronics that you want to run
05:51 PM z64555: Still, it's 5V
05:52 PM veverak: z64555: have power source for projects that needs 5V/3.3V and battery
05:52 PM veverak: nothing RC related
05:52 PM veverak: :)
05:52 PM z64555: so you'll need another regulator for the 3.3v
05:52 PM z64555: or you can try getting the 3.3v directly off of a cell in the battery, if it's a lipo
05:53 PM orlock: veverak: have you seen the bradboard PSU's?
05:53 PM orlock: breadboard, even
05:53 PM veverak: nope?
05:53 PM orlock: take USB or barrel jack in
05:53 PM veverak: z64555: want 2s+ battery
05:53 PM orlock: they plug into a breadboard and line up with the standard voltage rail positions
05:53 PM z64555: veverak: point being?
05:54 PM orlock: and have a switch for 5v/3.3v out
05:54 PM Snert__: I was just defining it for someone elses's benefit. I use castle creations seperate regulators always anyways.
05:54 PM veverak: z64555: I would need to take 3.3v fromm all cells
05:54 PM orlock: https://core-electronics.com.au/3-3v-5v-black-wings-breadboard-power-supply-module-adaptor.html
05:54 PM veverak: make thinks complicated?
05:54 PM veverak: or?
05:54 PM z64555: why would you need 3.3v from all cells?
05:54 PM veverak: I mean
05:55 PM veverak: it's not wise to discharge only one cell with 3.3v
05:55 PM orlock: veverak: that
05:55 PM z64555: It's only a problem if you don't have a good charger
05:55 PM veverak: orlock: seems interesting
05:55 PM veverak: z64555: no, it's a problem
05:55 PM orlock: veverak: they are handy and cheap if you do any breadboarding
05:55 PM veverak: or, you should make voltage cutoff for each cell ;)
05:55 PM z64555: why is it a problem?
05:56 PM veverak: OR for the cell you use 3.3v from and entire baterry pack -> two cutoffs
05:56 PM veverak: and you will definetly discharge the one cell faster
05:56 PM z64555: You still haven't explained the problem :P
05:56 PM veverak: z64555: it's just that it seems more practical for me, to make IN BATERRY -> cutoff -> 5V/3.3V
05:56 PM veverak: z64555: powering 3.3V/5V circuits and electronics with li-po baterry, 2s+
05:57 PM veverak: I need proper voltage regulation AND battery cut off
05:57 PM veverak: hmm, I think I will just find schematics for both circuits and use them then? :)
05:58 PM z64555: use a pair of voltage regulators, one for 5V, and one for 3.3V, then design a cutoff circuit that disables the output to both should the input voltage from the battery get too low
05:58 PM z64555: done
05:58 PM veverak: yeah
05:59 PM veverak: one question
05:59 PM veverak: how can voltage cutoff detect number of cells in battery
05:59 PM veverak: because, most of them do
05:59 PM veverak: somehow
05:59 PM z64555: probably a % of its max voltage
06:04 PM deshipu: veverak: well, they check the voltage
06:04 PM deshipu: veverak: it has to be between 3.2 and 4.2 times the number of cells
06:05 PM veverak: so multiple voltage comparators
06:06 PM z64555: or a voltage comparator after a modulus
06:07 PM veverak: voltage can be moduled O_o
06:07 PM veverak: ok, thanks
06:07 PM veverak: !
06:07 PM veverak: :)
06:07 PM z64555: it can be divided, pretty sure it can be moduled
06:31 PM z64555: hm, nope, a modulo won't work
06:31 PM z64555: so, scratch that idea before trying to make a circuit that you won't use :(
07:05 PM Snert__: it's 7.2v ... therefore it cannot be a 1s lipo.
07:05 PM Snert__: it's 7.2v, therefore it cannot be a 3s lipo.
07:05 PM Snert__: so it has to be a 2s lipo.
07:06 PM Snert__: the logic can figure it out as opposed to straight detecting how many cells.
07:08 PM Snert__: so given "full charge knowledge of voltage" ... it does the math on the low cutoff point.
07:08 PM Snert__: there's no real black magic going on there.
07:09 PM Snert__: rc stuff is stoopid.
07:11 PM Snert__: ESCs are made for a known number of lipo cells per case at hand. So the situation has some preknowledge of what it's gonnabe.
07:12 PM Snert__: (and I'm prolly wrong somewhat - it might have changed in the past 5 years or so._
07:14 PM justan0theruser: Is there a minimal program where I can define a part and how I want it machined? Right now I draw isometric sketches and I'm not a fan of the 3d modeling software I've used. Is there something that assists with drawing 2d sketches and labeling dimensions?
07:56 PM rue_shop3: justan0theruser, do you know of openscad?
08:04 PM justan0theruser: I've dealt with it briefly using python a while ago
08:04 PM justan0theruser: maybe that is the solution
08:50 PM peeps[lappy]: are there any rovers that people have made that use optical flow of the ground for dead reckoning?
08:51 PM peeps[lappy]: like optical flow sensor from a computer mouse
09:02 PM z64555: unreliable for ground travel
09:02 PM z64555: highly variable terrain
09:17 PM peeps[lappy]: well, say an indoor rover
09:18 PM peeps[lappy]: carpet at worst
09:19 PM peeps[lappy]: and maybe it could do some sensor fusion with sonar or something to double check what's going on
09:56 PM z64555: should be OK, but you should consider using other positioning methods, as well
10:33 PM justanotheruser: is it possible to use openscad to manipulate step files, or can it only work with objects defined in openscad
10:35 PM justanotheruser: oh they have a channel
10:35 PM justanotheruser: I'll ask there
11:49 PM stanford_ai: I'm looking for a GENIUS to work with us on the most promising drone AI company. Do you know any geniuses here?
11:57 PM zhanx-: Nope not one