#robotics Logs

Aug 19 2015

08:36 rue_school often its good to put a second limit on the loop
08:45 deshipu yeah, dwpends what you do
10:02 veverak also
10:02 veverak while loops are ones you definetly want to keep simple :)
11:15 mbrumlow Howdy.
11:17 password2 hi
11:27 mbrumlow How is it going password2 ?
11:27 mbrumlow Want to control my bot at http://pluto.brumtopia.com:8080/indexl.html ?
11:27 password2 good and you?
11:27 mbrumlow I am doing good, just got an upgrade to my rbotot control.
11:27 password2 wil it stream video?
11:27 mbrumlow yes
11:27 password2 then I'm out
11:27 mbrumlow using websockets.
11:27 mbrumlow oh okay.
11:27 mbrumlow :(
11:27 password2 got the worst internet ever
11:27 password2 2gig/month
11:28 mbrumlow Oh wow.
11:28 password2 so 60Meg a day
11:28 password2 i need to do something about that sometime
11:28 mbrumlow yeah, a few min on that and you would be done :(
11:30 password2 a few hours
11:30 password2 its slow too
11:30 password2 i've had irc timeout on me
11:30 password2 :]
16:49 rue_school mbrumlow, did you put it back in range of the wifi base station?
16:49 rue_school mbrumlow, are there ANY mirrors for the robot to look at?
16:51 rue_school mbrumlow, it needs a 'chat' window
16:52 rue_school that echos the text to a display on the orbot
16:55 rue_school mbrumlow, and add a second robot
16:55 rue_school this is what happens when everyone is driving
17:45 mbrumlow hmm
19:02 rue_school mbrumlow, yes?
19:20 Solifugus What's the best thing for controlling a large number of two-direction DC motors from a computer?
19:21 rue_school avr
19:22 rue_school mind blower today, 1/sqrt(3) = sqrt(3)/3
19:26 jason__ that's not that crazy
19:26 jason__ it's basically the same thing as 1/3 is the same as 3/9
19:30 deshipu Solifugus: or, if the computer already happens to have gpio, just a h-bridge
19:31 deshipu well, one per motor
19:31 deshipu Solifugus: what are you making?
19:32 Solifugus a humanoid robot
19:32 rue_school you need to speed control each?
19:32 Solifugus deshipu, pvc injection molded..
19:32 rue_school the atmega328 has a good few pwm channels
19:32 rue_school 6 iirc
19:33 rue_school if you want to run LOTS of pwm channels, use soemthign like
19:34 Solifugus hmm..
19:34 rue_school TM1809 or...
19:34 Solifugus what is dc motors are of much higher voltage
19:34 rue_school TLC4950
19:34 Solifugus 24vdc
19:34 rue_school yea, you have to use bridge drivers
19:35 rue_school full or half depending
19:35 rue_school Solifugus, how many channels, more than 18?
19:35 rue_school are they real motors or hobby servos?
19:35 rue_school what is the meaning of life?
19:35 deshipu or robotic servos...
19:35 rue_school how many watts are the motors?
19:35 deshipu rue_school: how many roads a man has to walk?
19:36 Solifugus I am a software developer and can do mechanical engineering.. but not good with electronics.
19:36 Solifugus need to lift about 250 pounds.
19:36 zhanx Solifugus, soungs like me
19:36 Solifugus but not too fast..
19:36 zhanx sounds
19:36 deshipu that's fine, you will learn
19:37 rue_school still dont know how many axies
19:37 deshipu Solifugus: how fast is not too fast?
19:37 Solifugus well.. I hope for something simple.. was at first thinking of a usb relay array with 32 relays..
19:37 rue_school sounds like he has a LARGE budget tho
19:37 rue_school no speed control?
19:37 Solifugus I was thinking of off/on frequency for speed control..
19:37 deshipu for 250lbs I would consider hydraulics
19:37 Solifugus gearing by threading of a rod
19:37 rue_school you wont get it with relays
19:38 Solifugus you mean relays tend to be slow?
19:38 rue_school yea
19:38 deshipu they also tend to break if you switch them a lot
19:38 Solifugus h-bridges are fast though.. i assume
19:38 rue_school yup
19:39 Solifugus I don't see any h-bridge array product that to buy anywhere.. that I could connect to a computer... just instructions using breadboards and such..
19:40 Solifugus btw: I don't have a huge budget.. hoping for under $2K.. but do have FreeCAD, an ABS 3d Printer, and a CNC machine..
19:41 Solifugus suggest I find an electrical engineering student who will work for free pizza and a modest sum of money?
19:50 deshipu Solifugus: strong motors are expensive
19:56 Solifugus deshipu, Yes.. but it seems to me there are a few for under $35 at decent strength when geared down from 81 rotations per minute (in one case I found).
19:57 Solifugus My software works on 1/3rd of a second cycles... each 1/3rd of a second, it reads sensors, processess, and will provide signals to actuators.
19:59 deshipu and that allows walking?
19:59 Hyratel http://hackaday.com/2015/08/19/steam-powered-machine-shop/
19:59 deshipu by the way, how many motors?
19:59 Hyratel 3Hz updating? that's awful slow
20:04 Solifugus deshipu, allows walking because it's not balancing.. This design is to use counter-rotating fly-wheels for stability.
20:04 Solifugus 20+ motors
20:04 Solifugus I have good software.. and am currently working on the CAD design.. trying to learn on the electronics, side..
20:04 deshipu do you have a prototype?
20:05 Solifugus I will use threaded rods to gear this as necessary..
20:05 Hyratel Solifugus, why such a low update frequency?
20:05 deshipu flywheels are going to be a pain when moving
20:05 Solifugus just drawings... working on translating those to cad, currently.. then will 3d print in abs to see how they work together..
20:06 Solifugus Hyratel, fluid dynamics..
20:06 deshipu maybe you should start with a small-scale prototype
20:06 Hyratel Solifugus, I don't understand
20:06 deshipu you know, one that fits on your desk
20:06 Hyratel it takes that long to parse the new update?
20:07 Solifugus Hyratel, I have two programs actually.. but I built a framework (kinda like an operating system--an abstraction layer based on 1/3rd of second cycles).
20:07 Hyratel but why that timing?
20:07 Hyratel are you running on a microcontroller?
20:07 Solifugus I based on this because that's similar to the human brain.. 1/3rd of a second to get a message from one end to the other.. boxers, for example, cannot react in less time.
20:07 Hyratel but what are you doing
20:08 Solifugus well.. building a platform.. i have many things I'd like to do.. one is a boxing robot.
20:08 Solifugus more so, a platform to test software on.
20:09 deshipu of course you can react in less time, it takes very precise timing to hit a ball with a baseball bat, for instance
20:09 Hyratel so your 1/3 sec is arbitrary BS
20:09 Hyratel maybe that's the REACTION time, but it's not the update frequency
20:09 Hyratel the update frequency is much higher
20:10 Solifugus deshipu, yes... but the cognitive reaction is 1/3rd of a second in terms on picking an action sequence that might do things within that same cycle time.
20:10 Solifugus the human brain is limited to that time frame.... it's peripheral nervous circuitry that can do more within it.
20:11 Solifugus most of walking, for example, is actually encoded in the nervous system of the legs themselves..
20:11 Solifugus and the spine
20:11 deshipu you have no idea how much experience you are missing to do that project
20:11 deshipu start with something smaller
20:11 Hyratel Solifugus, have you made a motor turn?
20:11 deshipu make a Bob robot
20:11 deshipu seriously
20:11 Solifugus in terms of electronics.. yes.. that's why i am here.. to learn.. but i have a good handle on theory, software, and mechanics.
20:11 deshipu you will get there, just do it step by step
20:12 deshipu start with a Bob, 4 servos, arduino and battery
20:12 Hyratel Solifugus, table your Big Ideas and break them down into principles and do projects that learn and apply each principle separeately or in 2 or 3 at a time
20:12 Hyratel you have too many variables. listen to deshipu
20:12 deshipu and maybe a distance sensor
20:13 Solifugus yes.. i have an adruino, a sonic sensor, etc.. and a stepper with stepper controller..
20:13 Solifugus (it slips easily)
20:13 Solifugus I mostly like my raspberri pi
20:14 deshipu then make a bob robot
20:15 deshipu once you have that walking, make your own servo, maybe
20:15 Solifugus The hard part has always been making a computer actuate something. I bet if there was a decent solution in terms of an array of some sort.. we'd already be in a huge robotics revolution. making software meet mechanics is the hugely weak link.. difficult.
20:16 deshipu outvof a motor, an arduino and a h-bridge
20:16 deshipu start with hobby servos
20:16 deshipu arduino has a ready library for those
20:17 deshipu sg90 are cheap, so it won't hurt your budget
20:31 rue_school I think he wants to go big
21:44 blockh34d whats up