#robotics Logs

Jul 31 2014

00:11 Hyratel1 OracleCarbon, pictures help with this kind of Q
00:12 OracleCarbon Hyratel1: It's a small brushed motor. Phone's dead so I can't get a picture of it
00:12 Hyratel1 dang
00:12 rue_mohr2 you want project ideas?
00:14 OracleCarbon I've got the project, it's an execution idea.
00:23 GargantuaSauce don't use a regulator
00:24 GargantuaSauce use an n-fet on the low side and limit the duty cycle if the supply voltage is higher than the motor's rating
00:24 OracleCarbon GargantuaSauce: Why should I not use a regulator?
00:24 GargantuaSauce there's a few reasons
00:25 GargantuaSauce one is that it's simply a waste of energy, they dissipate the difference in voltage as heat
00:25 GargantuaSauce another is that they're not designed to drive inductive loads, and can exhibit instability when they are used in such a manner
00:26 GargantuaSauce a third is presumably you want to use that regulator to also power the control electronics, and motors are very electrically noisy and that can cause all sorts of issues
00:27 OracleCarbon http://www.ti.com/product/ptn78020w The efficiency point is less relevant, but the others are quite valid.
00:27 GargantuaSauce ah ok a switching regulator is likely more stable too
00:27 GargantuaSauce but yeah there's no need if you're switching the motor anyway
00:28 OracleCarbon It seems cleaner to run everything at 5V. But maybe not.
00:28 Hyratel1 it isn't
00:28 Hyratel1 it's actually worse
00:28 GargantuaSauce for the motors, no way
00:28 Hyratel1 even though yoru switching reg can handle it
00:29 OracleCarbon So just drive the motors straight off the battery voltage, then?
00:29 GargantuaSauce yep
00:29 OracleCarbon What's the voltage on a fully-charged 2s lipo?
00:29 Hyratel1 7.4 i think
00:30 GargantuaSauce that's nominal. fully charged is notably higher
00:30 Hyratel1 low voltage motors are weirdy forgiving
00:30 GargantuaSauce yeah as I said, just reduce the duty cycle accordingly and it'll be just fine
00:30 Hyratel1 how long is your burst time
00:30 Hyratel1 the limiting factor will be motor heating
00:30 OracleCarbon Hyratel1: The drive motors are the lower voltage ones, those could be running for a few minutes at a time.
00:31 Hyratel1 yeah but I mean the pump motors
00:31 OracleCarbon That was on 6V and can fire for maybe 20 seconds before the supply's dry
00:31 Hyratel1 that's not what I'm asking
00:32 Hyratel1 how long will YOU be running them for at a stretch
00:32 OracleCarbon 3-5 seconds, probably
00:32 GargantuaSauce he just gave you the upper bound...
00:32 Hyratel1 try this
00:32 OracleCarbon But maybe up to that 20 if I decide it's necessary for the mission
00:32 Hyratel1 connect one of them to your batteries for that length of time
00:32 Hyratel1 see if it gets noticably warm
00:33 OracleCarbon Okay, so a 2s lipo's 8.4V full, which is above the range that my drive motors are good for.
00:33 OracleCarbon They're good for 1.5-8.2v by another user's experimentation
00:34 Hyratel1 they won't stay at that 8.4 for long
00:34 Hyratel1 will you be drivving with PWM
00:35 OracleCarbon I...think so? I've never played with driving motors before, but I think that's how the Arduino does these things.
00:35 GargantuaSauce if you're using fets to control them there's no reason not to
00:35 Hyratel1 you've been pretty vague how you're doing the main board
00:36 Hyratel1 you can NOT drive motors directly from arduino pins
00:37 Hyratel1 you'll kill the arduino
00:37 OracleCarbon Right, I've got a motor driver for the drive motors
00:37 OracleCarbon https://www.sparkfun.com/products/9457
00:38 Hyratel1 ok good
00:38 OracleCarbon Which...yeah, I guess it uses a PWM signal fro the Arduino
00:39 Hyratel1 you'll want to use the SoftPWM library
00:39 Hyratel1 using the hardware PWM is just annoying
00:40 OracleCarbon I can control a servo from the Arduino, right? Put the proper voltage on the power wires, put the signal wire on a pin on the Arduino?
00:41 rue_mohr2 yup
00:41 Hyratel1 OracleCarbon, yes, but you have to use the Servo library for that
00:41 orlock nah
00:41 orlock dont have to
00:42 Hyratel1 yyyeah, it's best to
00:42 orlock the built in libraries are good for testing
00:42 Hyratel1 not really
00:42 orlock but i find they are quite limiting
00:42 rue_mohr2 why is the hardware pwm annoying?
00:42 Hyratel1 because changing the frequnecy requires messing with timers and that screws with so many other thigns
00:43 rue_mohr2 huh. glad I dont use the arduino libraies then
00:43 Hyratel1 rue_mohr2, that's a hardware thing, not an arduino thing
00:43 orlock Hyratel1: the duino libraries you give it an angle and thats it? or something similar?
00:43 OracleCarbon So I've got two servos (one for pitch control on the water gun, one for pitch control on the periscope for my phone which will give me vision from the bot), two drive motors, one pump motor, and I'm hoping to connect it out to the internet through a hotspot on my phone and a wifi module I bought for the Arduino.
00:44 rue_mohr2 no its an arduino thing
00:44 OracleCarbon So I can control it remotely.
00:44 Hyratel1 also you have to use the Servo liberry (one IS included) for driving servos or motor controllers
00:44 rue_mohr2 most people dont use pwm timers for things other than pwm
00:44 Hyratel1 the arduino libs take an angle 0-180 ctr 90
00:44 Hyratel1 and output the proper timing for a hobby servo
00:44 orlock Hyratel1: see, i used to calibrate my timing values per servo
00:44 rue_mohr2 "proper"
00:44 orlock and ignore the arduino libraries
00:44 rue_mohr2 I bet its jittery
00:45 Hyratel1 I've never used it for a servo
00:45 Hyratel1 https://dl.dropboxusercontent.com/u/33593534/images/Robot/DSCN2012.JPG
00:46 rue_mohr2 OracleCarbon, well, I'd suggest starting with getting the servo control working
00:46 rue_mohr2 Hyratel1, what were the motor drivers worth?
00:47 OracleCarbon rue_mohr2: I was going to start with the drivetrain, then move to the pump control, then the servos, then the wireless control of it
00:47 Hyratel1 these? $60/ea
00:47 rue_mohr2 huh, they look good
00:47 Hyratel1 1/2HP per 12v, up to 24v
00:47 rue_mohr2 OracleCarbon, ok, so have you used arduino stuffs before?
00:48 OracleCarbon rue_mohr2: A bit, none of this specific stuff
00:48 rue_mohr2 OracleCarbon, ok
00:49 OracleCarbon Odds of success?
00:49 rue_mohr2 OracleCarbon, so the drivetrain, do you want to do forward/reverse on each motor? variable speed?
00:49 OracleCarbon Variable speed would be best.
00:49 rue_mohr2 depends on all kinds of things
00:49 rue_mohr2 OracleCarbon, do you want to make mtoor drivers or buy them?
00:49 Hyratel1 rue_mohr2, why the observation on the drivers?
00:49 OracleCarbon I have...94 hours until I'd most ideally like it working. But that's a flexible deadline
00:49 rue_mohr2 Hyratel1, has some pretty good ones where
00:49 OracleCarbon rue_mohr2: I've bought the drive motor driver
00:50 rue_mohr2 OracleCarbon, ok, can I see?
00:50 Hyratel1 yeah, they're necessary for the size/scope I'm working with here
00:50 OracleCarbon https://www.sparkfun.com/products/9457
00:50 rue_mohr2 OracleCarbon, how large is your robot?
00:51 OracleCarbon rue_mohr2: About 5 inches by 12 inches by 3 inches
00:51 OracleCarbon W,L,H
00:51 rue_mohr2 ok, tracked?
00:51 OracleCarbon Yep
00:51 rue_mohr2 http://ruemohr.org/~ircjunk/robots/multibots/smokingprogress/dscn6164.jpg
00:51 rue_mohr2 so its a lot like that then?
00:52 OracleCarbon http://www.instructables.com/id/Tankbot-Internet-Controlled-Tank-Robot/ was the base I worked from
00:52 GargantuaSauce except with electronics made after 1990 :V
00:52 rue_mohr2 ok
00:52 OracleCarbon An instructable seemed like a good starting point.
00:52 Hyratel1 rue_mohr2, I want that chassis
00:53 rue_mohr2 :P
00:53 rue_mohr2 you might be pushing what that driver can do, but ok
00:54 rue_mohr2 so there are 3 driver inputs per mtor
00:54 rue_mohr2 PWM, IN1, IN2
00:55 rue_mohr2 hmmm
00:55 rue_mohr2 1W per amp...
00:56 Hyratel1 aha i see
00:56 OracleCarbon https://www.sparkfun.com/products/319 is driving the tracks
00:56 rue_mohr2 yea, just saying it looks close to its capability
00:57 OracleCarbon Each motor draws 0.35-0.75A, apparently
00:57 rue_mohr2 I bet they stall higher
00:57 rue_mohr2 :)
00:57 OracleCarbon We'll see.
00:57 rue_mohr2 http://bildr.org/2012/04/tb6612fng-arduino/
00:58 OracleCarbon I wonder if my phone's insurance covers fire
00:58 Hyratel1 pullin both IN# pins shorts both OUT# pins to ground
00:59 rue_mohr2 unfortunatly, I dont have the japanese language pack to try to read the datasheet properly
00:59 Hyratel1 rue_mohr2, check the comments. there's an all-english ver
00:59 rue_mohr2 there should eb a table that says what the IN combinations do
00:59 Hyratel1 there is
01:00 rue_mohr2 you want to use drive and coast, not drive and brake
01:00 Hyratel1 page 4 of the ENG datasheet
01:00 Hyratel1 I dont' think it has a coast mode unless you ... no
01:00 Hyratel1 it doens't have any coast mode
01:01 Hyratel1 all even the PWM mode alternates between DRIVE and BRAKE
01:01 rue_mohr2 its off via pwm
01:02 Hyratel1 no go look at the table
01:02 rue_mohr2 er
01:02 rue_mohr2 hmm
01:02 rue_mohr2 so you need to not use the pwm
01:02 Hyratel1 for all cases of PWM Low =Brake
01:02 Hyratel1 and for all cases of !Direction = brake
01:03 rue_mohr2 so tie pwm high and put your pwm on the IN1/IN2 lines
01:03 Hyratel1 it has no Coast mode
01:03 rue_mohr2 so your switching between stop and CW/CCW
01:03 rue_mohr2 stop is the coast mode
01:03 Hyratel1 oh i see
01:03 Hyratel1 high Imped.
01:03 Hyratel1 that's freaky
01:03 rue_mohr2 wait a sec, this is OracleCarbons project...
01:04 rue_mohr2 8|
01:04 Hyratel1 where'd he go
01:04 OracleCarbon I'm here.
01:04 OracleCarbon Just watching you two discuss the intricacies of the motor driver
01:04 Hyratel1 jsut letting us nerds hash it out while you much popcorn?
01:04 rue_mohr2 I need to go to bed, gnight
01:04 OracleCarbon Basically.
01:04 rue_mohr2 http://hackaday.io/project/2189-Robot-arm
01:05 rue_mohr2 :( I didn't update my had entry
01:05 Hyratel1 the brake mode does make it suitable for positional arms though
01:06 OracleCarbon Is brake mode good for making the world's least capable unmanned combat vehicle?
01:06 rue_mohr2 pwming motors between runa dn brake is almost as bad as using pwm to slam them between CW and CCW at 50% duty to make them not turn
01:06 e_mohr2 glares at Tom_
01:06 Hyratel1 rue_mohr2, why's that
01:06 rue_mohr2 seriously?
01:07 Hyratel1 yes
01:07 rue_mohr2 the current man! think of the current!
01:07 rue_mohr2 burning battery power, heating the driver and motor with the repeditive current spikes
01:08 Hyratel1 brake doesn't burn battery though
01:08 Hyratel1 wait
01:08 rue_mohr2 your dumping motor power
01:08 Hyratel1 I guess it would as a side effect
01:08 Hyratel1 i see now
01:08 rue_mohr2 if you let it coast between ... good
01:08 rue_mohr2 I cant really rant now, I have to go to bed!
01:08 Hyratel1 OracleCarbon, it will "work" but that chip is poorly designed from a practical point
01:09 rue_mohr2 thermally
01:09 OracleCarbon Hyratel1: That's all I need for now.
01:09 OracleCarbon "work" vs work is not worth $20 to me right now.
01:09 rue_mohr2 if it fails, get soemthing bigger
01:09 Hyratel1 it'll also eat much more battery than it needs to
01:09 OracleCarbon Even at balls-to-the-wall I can run the drivetrain for over an hour on my batteries
01:10 rue_mohr2 but honestly I think a $2.70 MOS stepper motor driver might be better
01:10 Hyratel1 https://www.sparkfun.com/products/9479
01:10 rue_mohr2 GOD NO!
01:10 OracleCarbon My design spec was 1 hour operating time
01:10 rue_mohr2 NEVER USE A 298 ON A BATTERY POWERED PROJECT
01:10 Hyratel1 woah what
01:10 rue_mohr2 there is a mos version, atleast use that
01:11 rue_mohr2 they are bipolar, they are a HUGE waste of energy
01:11 Hyratel1 oh!
01:11 rue_mohr2 there is a 14xxx that is a mosfet version
01:11 rue_mohr2 its not good, but its better
01:13 rue_mohr2 L6203?
01:13 OracleCarbon The goal was not ambitious in the least. 1 hour operating time, 10 foot water range, 10 second water capacity, internet-enabled operation, $100 cost.
01:13 Hyratel1 http://www.digikey.com/product-search/en?pv1664=11&pv16=8691&pv16=8692&pv16=8693&pv16=234&pv16=2673&FV=fff40027%2Cfff802d2&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25
01:14 rue_mohr2 pff, 6203 is .3Ron
01:16 OracleCarbon I'm pretty much in "make it work with what I've bought" mode now. I have 94 hours until the start of hostilities, and I want this in the field as quickly as possible.
01:17 Hyratel1 your current drive will work* but you'll want to keep an eye on your battery voltage
01:17 rue_mohr2 yea, do you have the driver yet?
01:17 OracleCarbon Yeah, the one I linked.
01:17 Hyratel1 and give it a stress test to see if the chip gets dangerously warm
01:17 OracleCarbon How warm is dangerous?
01:17 rue_mohr2 burning your finger
01:17 orlock yeah, about thwn its dangerous
01:17 Hyratel1 ^
01:17 orlock if it hurts or sizzles
01:17 rue_mohr2 if you cant hold your finger on it, its way too hot
01:17 OracleCarbon Is there a good way to monitor battery voltage in the field?
01:18 Hyratel1 it should never get hotter than "mildly uncomfortable" - surface temp 110F
01:18 rue_mohr2 use the arduino :)
01:18 Hyratel1 ^ build a voltage divider
01:18 OracleCarbon Analog read?
01:18 rue_mohr2 if you have an analog input with a votlage divider, you cant monitor it
01:18 Hyratel1 can*
01:18 Hyratel1 yeah
01:18 OracleCarbon The Arduino can handle 8.4 V on the analog pin can't it?
01:18 Hyratel1 no
01:18 OracleCarbon Oh
01:18 Hyratel1 Vcc
01:19 Hyratel1 you use the divider to proportion the voltage down to something safe
01:19 OracleCarbon So...keep it under 5?
01:19 Hyratel1 yes
01:19 Hyratel1 it'll give you a % of maximum
01:19 Hyratel1 but size it to 2:1
01:19 Hyratel1 this will give you a safe overhead
01:19 OracleCarbon Yeah, that was my thinking
01:20 rue_mohr2 http://www.digikey.com/product-detail/en/CSD87588N/296-35792-6-ND/4027411
01:20 rue_mohr2 is dk selling dies now?
01:20 OracleCarbon I'll have to loot the lab for parts tomorrow
01:20 Hyratel1 Gnd --[ 10kR ]-- AIN1 --[10kR]-- Vbatt
01:20 orlock rue_mohr2: oh wow
01:20 OracleCarbon Is there a decent way to drive the pump motor with things I can buy cheaply at Radio Shack?
01:20 rue_mohr2 *bklink* its not, thats the belly of a smt part...
01:21 Hyratel1 OracleCarbon, we've told you a FET
01:21 rue_mohr2 OracleCarbon, your want a mosfet
01:21 rue_mohr2 trying to think where you could scrounge one
01:21 OracleCarbon Oh, right.
01:21 acleCarbon makes a
01:21 rue_mohr2 ah, old power amp
01:21 orlock OracleCarbon: do you have your servos moving? that should not take more than 5 minutes
01:21 rue_mohr2 from a car, like a base drive, shot is ok
01:21 rue_mohr2 or an old multisync crt monitor
01:22 rue_mohr2 or a 12V to 120V AC inverter for a car
01:22 rue_mohr2 some old motherboards
01:22 Hyratel1 rue_mohr2, really>
01:22 OracleCarbon orlock: Not yet, no. I'm thinking saving those for later
01:22 Hyratel1 i'll have to check that
01:22 Hyratel1 OracleCarbon, you really should
01:23 orlock OracleCarbon: ok... theres a basic arduino sketch to make them move, you just need the wires to hook them up to your IO - but anymore than one moving at a time and you will want to run them from an external power source
01:23 rue_mohr2 some computer power supplies use fets, they aren't good ones tho
01:24 OracleCarbon My thinking was drivetrain, then pump, which would make a workable system for the most basic uses, then pitch on the gun and periscope, then wireless connectivity.
01:24 Hyratel1 do you have all your radio hardware?
01:24 OracleCarbon Yeah
01:24 rue_mohr2 maybe do the servos first, then the drive train
01:24 Hyratel1 man, it is SO tempting to bash together a sketch that'll do everything you need but...
01:24 rue_mohr2 SLEEEEEEP!
01:25 ratel1 shoos rue_mohr2 off to
01:25 OracleCarbon Hyratel1: If you want to give in to the temptation, I won't mind a bit!
01:25 Hyratel1 link me to your radio set / libs
01:25 OracleCarbon https://www.sparkfun.com/products/10822
01:26 OracleCarbon And I'm going to hopefully get it able to communicate over a phone-made hotspot so I can sit in wifi and let it do its thing while I cower inside
01:26 Hyratel1 have you figureed out how to reinforce the antenna/ looks a little flimsy
01:27 OracleCarbon I wasn't planning to.
01:27 Hyratel1 is your robot's topshell metal?
01:27 OracleCarbon Acrylic
01:27 Hyratel1 mmk
01:27 Hyratel1 dop you have a shield for it for arduino
01:28 rue_bed ok I made it to bed
01:28 OracleCarbon Just a breakout board
01:28 OracleCarbon The shield was $70
01:29 Hyratel1 O_o
01:29 OracleCarbon Yeah
01:29 rue_bed 8|
01:29 OracleCarbon Not worth it.
01:29 rue_bed whats it got on it?
01:30 OracleCarbon https://www.sparkfun.com/products/9954
01:30 Hyratel1 https://www.sparkfun.com/products/12847
01:31 Hyratel1 you'll need to match your breakout pins to the pins of the arduino shield there
01:31 Hyratel1 to make your interconnects
01:31 OracleCarbon Shouldn't be too hard?
01:31 Hyratel1 well, check anyway
01:32 Hyratel1 the radio is a mission-critical part of the build. you need it to WORK before anything else happens
01:32 rue_bed pff
01:32 rue_bed smartphone with otg usb port?
01:32 Hyratel1 what are you scoffing at, rue_bed
01:32 rue_bed android perhapps?
01:33 Hyratel1 I mean he needs to be able to talk to the arduino first
01:33 Hyratel1 through the radio
01:33 rue_bed what arduino is it?
01:33 OracleCarbon rue_bed: I do plan to have a phone onboard
01:33 OracleCarbon Uno
01:33 rue_bed android phone?
01:33 OracleCarbon Yup
01:33 OracleCarbon Moto Droid 4
01:33 rue_bed otg usb port?
01:34 Hyratel1 I think what rue_bed is getting at is you might be able to omit the arduino radio and tether to the phone
01:34 rue_bed tho iv never written apps for android...
01:34 rue_bed yea
01:34 OracleCarbon Hyratel1: Yeah, that wouldn't be a bad plan. Though it would limit endurance
01:34 Hyratel1 why
01:34 rue_bed but the phone has to be there anyhow
01:35 OracleCarbon If I'm using the USB port for the comms, I can't use it to charge the phone
01:35 Hyratel1 you're removing the draw of the radio
01:35 rue_bed yes you can
01:35 OracleCarbon So my phone's battery becomes limiting
01:35 Hyratel1 ...
01:35 rue_bed no, the robot can power the phone
01:35 rue_bed while the phone controls it
01:35 Hyratel1 the arduino becomes the 5v source
01:35 rue_bed no the robot becomes a 5V charger
01:36 OracleCarbon Oh. So I plug the battery into the barrel jack on the Arduino at its 7-8V voltage, and then the USB puts out 5V to the phone?
01:36 Hyratel1 yep
01:36 e_bed gets a facefull of a bug that found its way into the wrong end of his
01:36 OracleCarbon The Arduino steps down by a linear regulator, though, which would increase my waste.
01:37 rue_bed use a dc-dc to convert the battery to 5V, have it power the arduino and the phone
01:37 Hyratel1 OracleCarbon, you're feeding the arduino from clean 5v, right?
01:37 rue_bed (skips the arduino regulator)
01:37 OracleCarbon I think the Arduino needs 7V on the straight pin
01:37 Hyratel1 through a switching regulator
01:37 Hyratel1 OracleCarbon,
01:37 Hyratel1 no
01:37 Hyratel1 it needs 5v on the 5v pin
01:37 OracleCarbon Oh. Am I misinformed?
01:37 rue_bed the arduino can run fine if injected with 5V to its vcc rail
01:37 Hyratel1 this can come from plugging a 5v feed into that pin
01:38 OracleCarbon Oh okay
01:38 Hyratel1 thus eliminating the onboard 5v regulator
01:38 rue_bed battery->dc-dc->phone+arduino
01:39 rue_bed whats your battery voltage?
01:39 rue_bed 12?
01:39 OracleCarbon My phone's not the fastest in the world. I'm wanting to use a G+ Hangout or a Skype call to get steering video and 2-way voice comms. Will controling the Arduino give me issues?
01:39 rue_bed 24?
01:39 OracleCarbon rue_bed: 7.4 nominal
01:39 rue_bed hmm
01:40 rue_bed I wonder if the car cigerette converters can go that low
01:40 Hyratel1 what
01:40 rue_bed they are really cheap
01:40 rue_bed the usb chargers for car power jacks
01:40 rue_bed look like a little rocket
01:40 Hyratel1 OracleCarbon, didn' you say you already have the DC-DC converter
01:40 rue_bed they can go up to 30V
01:41 rue_bed oh
01:41 OracleCarbon Hyratel1: Yeah
01:41 rue_bed k
01:41 OracleCarbon http://www.ti.com/product/ptn78020w
01:41 rue_bed thats a chip...
01:41 OracleCarbon From a previous lipo-phone charger project
01:41 rue_bed its not a board with all the inductors etc you need tho...
01:42 OracleCarbon It's on a board as I have it.
01:42 rue_bed oh module
01:42 OracleCarbon I connect a capacitor, a resistor, and a high-side supply voltage, and it puts out the low-side voltage I want.
01:42 OracleCarbon I tried to rig a low-voltage cutoff to it before, but that didn't work so well.
01:43 OracleCarbon Mostly because I suck at electronics projects
01:49 rue_bed tell us what you tried
01:50 OracleCarbon Oh, it was a while back.
01:51 OracleCarbon I think I had a voltage divider from the battery voltage and the regulated 5V going into an opamp, and the output from the opamp going to the gate of a transistor between the battery and the regulator
01:52 OracleCarbon So when the battery voltage fell below 11v or something, it would stop powering the gate pin
01:52 rue_bed the trick would have been to divide down the 5V to say 2.5
01:52 rue_bed the op-amps dont work well close to their + or - rails
01:52 rue_bed depending on the chip, it can screw up as much as 1V near a rail
01:53 OracleCarbon Could be that, could be I wired it up wrong.
01:53 Hyratel1 OracleCarbon, another way would be to use a Zener diode of proper Vrb to turn off a transistor
01:53 rue_bed the idea was right
01:53 OracleCarbon I made one run at it, then tabled it for another day and never got around to making it work
01:53 Hyratel1 fewer components
01:53 OracleCarbon I stopped playing Ingress so I didn't need to charge my phone every 15 minutes
01:53 Hyratel1 but sourcing suitable zeners can be tricky
01:53 rue_bed how about a relay with the right dropout voltage :)
01:53 OracleCarbon Hyratel1: Yeah that's the right way
01:54 rue_bed the op-amp provides a nice quick, sharp cutoff
01:54 OracleCarbon Digikey has a good variety
01:55 rue_bed tho remmeber to do filtering, nothing like having the power kick out because you just hard enguaged a motor
01:55 OracleCarbon I think I'll not put the cutoff on the bot
01:55 rue_bed I have 18 overload protectors on a hexapod I have to adjust
01:56 OracleCarbon And just either monitor it myself or have the Arduino turn off the regulator when the power drops below a software-defined threshold
01:56 rue_bed if you have the arduino monitoring the voltage, you can also just use that
01:56 Hyratel1 if it drops below threshold, disable all motor drives
01:57 Hyratel1 that's all you should have to do
01:57 OracleCarbon I wish I had a GPS antenna around. Then I could savenge up the sonar sensor I've got and maybe give it a return-to-home under a certain voltage.
01:57 OracleCarbon So when it gets in danger of dying in the field, it retreats and I don't have to enter the combat zone to get it.
01:58 rue_bed arg I have to charge up my wireless bot batteries agian
01:59 rue_bed the voltage monitor runs down the batteries
01:59 rue_bed should have used larger resistors
02:02 rue_bed its also got problems, when I slam the motors on, they pull the grounds up so hard the avr reboots
02:03 rue_bed but they are 48V motors
02:03 OracleCarbon That sounds problematic
02:03 Hyratel1 how big a robot is it
02:03 rue_bed yea, esp cause the avr is controlling the motors
02:03 rue_bed 12x12inch or so, maybe 18
02:03 Hyratel1 got pix?
02:03 rue_bed microatx + linksys wireless router
02:03 Hyratel1 what weight class
02:03 rue_bed hah, weight class
02:04 OracleCarbon Maybe some capacitors or something to smooth that voltage shift?
02:04 Hyratel1 70 lb with battery -> https://dl.dropboxusercontent.com/u/33593534/images/Robot/DSCN2011.JPG
02:04 rue_bed its got big ones, and inductors
02:05 rue_bed http://ruemohr.org/~ircjunk/robots/buddy_II/p1040837.jpg
02:05 OracleCarbon Hyratel1: You like showing that off, don't you?
02:05 rue_bed http://ruemohr.org/~ircjunk/robots/buddy_II/p1040836.jpg
02:05 rue_bed 48V to 12V, then 12 to 5
02:05 Hyratel1 ooh
02:06 rue_bed http://ruemohr.org/~ircjunk/robots/buddy_II/
02:06 rue_bed I suggest last images first
02:08 rue_bed http://ruemohr.org/~ircjunk/robots/buddy_II/assembly.html
02:09 Hyratel1 what are your logic electronics?
02:09 rue_bed its an avr
02:10 rue_bed or you mean the relays?
02:10 rue_bed those are motor drivers
02:10 Hyratel1 oh, just bang-bang drive?
02:10 rue_bed I use a relay for reverse and a fet for power
02:10 rue_bed then I dont have 2x the fet loss to the mtoors
02:10 Hyratel1 oh, mechanical direction, FET PWM?
02:10 rue_bed yea
02:10 rue_bed and I dont ahve to deal with high side fet drivers
02:11 rue_bed I just cant use that for fine servo control
02:11 rue_bed its good for robot driving tho
02:12 Hyratel1 why 48 v though
02:12 Hyratel1 and wth are those gearboxes out of
02:12 rue_bed they are 108V motors
02:12 rue_bed I think they are for meat gridners
02:12 rue_bed sunbeam
02:13 rue_bed or power skylights
02:13 Hyratel1 why them though
02:13 rue_bed good ratio
02:13 rue_bed and the 90 degree thing worked
02:14 rue_bed I origionally wanted to use them for a large tank like robot for spying on deer in the bush
02:14 rue_bed hmm, I should restate that project
02:14 Hyratel1 5600 RPM motor into 4.6:1 gearbox into 4:1 chain into 10" wheels
02:14 rue_bed Ihave more tech now
02:14 Hyratel1 https://dl.dropboxusercontent.com/u/33593534/images/Robot/DSCN2015.JPG
02:15 rue_bed fast mover
02:15 rue_bed wow, gigapixel image
02:15 Hyratel1 yep. clocked at 10mph
02:15 rue_bed (not on this laptop)
02:15 Hyratel1 sorry ;<.< brother's camera is 16MP
02:15 rue_bed there is a menu for dialing it down to, say 3mp
02:16 Hyratel1 yes, but the pics were already taken
02:16 rue_bed which is still crazy high for a basic image
02:16 rue_bed I post scale the standard images to 640x480
02:17 rue_bed some I leave higher, but there just isn't any requiremet for the extra detail
02:17 rue_bed the old webcam images are 640x480, but with only like 240x120 pixels
02:17 rue_bed ugly as all sin
02:20 rue_bed you ahve remote video on yours?
02:20 Hyratel1 I can't get to sparkfun.com anyone else?
02:20 Hyratel1 nope
02:20 Hyratel1 but just because we haven't had need for
02:20 OracleCarbon Sparkfun works for me
02:20 rue_bed so no spying on wildlife for yo
02:20 Hyratel1 weird
02:20 OracleCarbon Hyratel1: I don't think I saw an answer the other day, what do you use that thing for?
02:20 rue_bed Hyratel1, they blocked you, your buying too much
02:21 Hyratel1 I have all the necessary hardware to do so
02:21 Hyratel1 just for funsies
02:22 OracleCarbon You should chainsaw equip it and use it for remote-operated logging.
02:23 Hyratel1 yeahno
02:23 OracleCarbon I don't see any way that could end badly.
02:27 OracleCarbon Turn it into a robot backhoe?
02:30 Hyratel1 not enough weight
02:30 OracleCarbon Yeah, you couldn't lift much before it tipped I guess.
02:30 OracleCarbon I imagine you could scale it up easily enough, maybe switch to gas power. But you may not need a backhoe.
02:31 Hyratel1 we upgraded to an 18AH battery from 10AH
02:31 OracleCarbon Lawnmower engine and an onboard alternator?
02:32 Hyratel1 it's too small for that
02:33 OracleCarbon Lawn trimmer engine?
02:33 Hyratel1 it's still too small
02:33 Hyratel1 the frame footprint is 12x18 between the frame rails
02:34 OracleCarbon Ah, yeah, that's RC plane engine levels
02:35 Hyratel1 but it weighs 70 lbs
02:35 OracleCarbon You could probably get 40 kW of generating power on there reasonably
02:37 OracleCarbon Oh wow. Our engine sponsor gives us a hell of a deal.
02:39 OracleCarbon I was going to suggest throwing a DA-60 on it.
02:39 OracleCarbon But...that's a $650 engine
02:39 Hyratel1 all extant hardwrae cost-to-buy is $600
02:40 OracleCarbon Yeah, they basically gave us our DA-50 we run, so I never saw it as an expensive item.
02:43 Hyratel1 http://www.hobbyking.com/hobbyking/store/__28238__NGH_GT9_9cc_Gas_Engine_With_Rcexl_CDI_Ignition.html
02:43 Hyratel1 so what I'd want with that is a brushless motor and a regen ECU
02:46 OracleCarbon I don't know that I'd trust a Hobby King engine.
02:46 Hyratel1 why not
02:46 OracleCarbon HK's products are, in my experience, of a quality I don't feel comfortable mixing with flammable liquids.
02:47 Hyratel1 whyso?
02:47 OracleCarbon Hobby King is the Harbor Freight of RC supplies
02:49 OracleCarbon I'd be concerned about an engine fire.
02:52 OracleCarbon That said, they do have the Beercopter contest. The UAV team has been throwing around the idea for years now of making a kegcopter
02:52 OracleCarbon Because why not go big, right?
02:56 Hyratel1 OracleCarbon, 20cc gas mated to a brushless motor with regen
02:56 Hyratel1 not sure how well it'd work though
02:57 OracleCarbon Is it enough power?
02:57 Hyratel1 2.2 HP I think so
02:58 Hyratel1 acutally hmm
02:58 Hyratel1 Hormes runs 2x 1/2 HP motors
02:58 OracleCarbon We get 170 shaft horsepower out of 50cc on our system.
02:58 Hyratel1 O_o
02:58 Hyratel1 how the
02:58 Hyratel1 how
02:58 OracleCarbon If I remember the figure right.
02:59 OracleCarbon Nope, that's wrong. I thought it was quite high.
02:59 Hyratel1 hell...
02:59 OracleCarbon Google has confused two things that have the same model number
02:59 Hyratel1 a 9cc engine would be enough for a small gokart
02:59 OracleCarbon But are very different machines
03:00 acleCarbon needs to click links before treating the bolded things on Google as relevant
03:01 OracleCarbon I would have been amazed at that feat of engineering, but was not about to question the almight First Google Result
03:05 Hyratel1 OracleCarbon, if not hobbyking, then where should I look for engines
03:06 OracleCarbon I think we use Horizon Hobby
03:06 OracleCarbon And Tower Hobby
03:07 OracleCarbon Pricier, though
03:07 OracleCarbon So you could roll the dice on the HK engine
03:13 OracleCarbon Save $200, risk $600, or spend the extra $200 and quite possibly not have needed it.
03:14 OracleCarbon Are you generally nearby the bot while it's running?
03:16 OracleCarbon I wonder if you could rig an automatic fire suppression system from a car extenguisher.
03:16 Hyratel1 yeah i am
03:16 Hyratel1 but if I put a dynamo on it it'll have the range to go farther
03:17 Hyratel1 that would be part of a much larger design though i think
03:17 Hyratel1 maybe 120 lb curb weight
03:19 OracleCarbon You're operating an a whole different scale than my designs, man.
03:20 OracleCarbon I guess the UAV could fly at 60 or so, at the upper end. But that's not my project so much as a project I'm on
03:21 OracleCarbon http://aerialroboticsclub.com/system.html
03:22 OracleCarbon Yeah, 5 HP. That's what I thought I remembered
03:22 OracleCarbon But I had to Google and question my entire reference base for engine power vs displacement
03:25 OracleCarbon Anyways, I'm off for the night.
03:25 Hyratel1 later tater
06:20 SquirrelCZECH_ nah
06:20 SquirrelCZECH_ for that feeling when you got little bit bored on google
06:20 SquirrelCZECH_ and you try to scout which CNC get
06:20 SquirrelCZECH_ nah :/
08:21 iveevue o/
08:21 Jak_o_Shadows hi
09:08 rue_mohr2 hi
15:05 OracleCarbon Oh these parts are so well made.
15:05 OracleCarbon The axle turns freely in the wheel
18:27 OracleCarbon Hrm. That's fun.
18:27 OracleCarbon Someone mishandled the waste container for PCB etchant. It burst in the cabinet
18:27 OracleCarbon Everything is rusted now.
18:28 Tom_itx shouldn't be in a cabinet
18:29 OracleCarbon Due to fun administrative situations, there's actually not a way to remove hazardous waste from the lab, so we accumulate it in the flam cabinet.
18:29 Tom_itx so now you must call in HAZMAT
18:30 OracleCarbon I'm not 100% sure there's a way to interact with environmental services at all for non-emergency situations from this lab.
18:32 OracleCarbon There's no professor who actually manages the lab beacuse it's shared between two groups under different professors, and neither professor will sign off on environmental and safety documents while the other has a group in the lab, and all requests to deal with waste go through the managing professor
18:33 Tom_itx so everybody just points fingers and nothing happens
18:33 OracleCarbon Yep
18:33 OracleCarbon And nobody who uses the lab can request any university services
18:33 OracleCarbon Like waste removal, hazmat cleanup, or maintenance
18:34 Tom_itx so just dump it down the stool
18:35 OracleCarbon I'm not going to improperly dispose of waste.
18:35 OracleCarbon Though in the past people have just poured it in the grass out back
18:35 Tom_itx you just did... it's all over the cabinet
18:35 OracleCarbon No, it's still in the cabinet.
18:35 Tom_itx and nobody want's to claim responsibility
18:35 OracleCarbon I'm going to embrace the culture of the department over here and declare it not my problem.
18:35 Tom_itx typical
18:36 Tom_itx i have no use for that mentality
18:36 OracleCarbon If these people want to run their organization poorly, I'll let them.
18:36 Tom_itx or you could be the one that made a difference
18:37 OracleCarbon I've seen how the sausage doesn't get made in this department.
18:37 OracleCarbon There's so much inertia in the direction of malice and apathy that there's no recovering it.
18:37 OracleCarbon I jumped ship to a functional department, but the aerial robotics group is under this hole-filled, dysfunctional umbrella
18:47 rue_mohr2 ok
18:50 rue_mohr2 so I worked out how to operate a 4x4 keyboard matrix with 4 analog channels, which on the tiny85 leaves me 1 serial out channel to say what button was pushed