#robotics Logs
Sep 04 2017
#robotics Calendar
12:00 AM Snert: sg90 and other cheap ilk servos don't work well in rc helicopters.
12:02 AM Snert: jitter being the #1 bitch.
12:07 AM anonnumberanon: would you put an sg90 as a trigger actuator on a chainsaw? so why put it on an RC helicopter?
12:07 AM anonnumberanon: cause greed :)
12:42 AM Snert: another antijitter thing is to run the servos from 6v.
01:29 AM anonnumberanon: asking everyone: how would you power 3 laptops in the woods? gasoline powered generators not allowed
01:30 AM Snert: babbling brook available?
01:30 AM Snert: always be charging the spare battery. Then wap out.
01:30 AM Snert: swap, that is.
01:31 AM Snert: the brook may be capable of providing waterwheel power to run the charger.
01:32 AM anonnumberanon: yeah cause the spot would be picked to have some useful features such as that
01:33 AM Snert: water wheel is working 24/7/365 too.
01:33 AM Snert: not just sunny days like solar
01:35 AM Snert: I might try a hamster wheel on my gutter drain pipe.
01:35 AM Snert: it does a pretty good flow for sometimes all day long.
01:37 AM anonnumberanon: yeah i like that
01:37 AM anonnumberanon: so just bring in a mechanical generator for 100 watts?
01:39 AM Snert: why not. I've seen those - not expensive, really.
01:40 AM Snert: maybe just a car alternator and a belt over to the waterwheel.
01:40 AM anonnumberanon: yeah cause 12v
01:40 AM anonnumberanon: or 13.5
01:40 AM orlock: alternators are a bit special
01:41 AM Snert: alternator could be housed in the top of a metal box. The paddles are in the lower half. Just sit the metal box in the stream.
01:42 AM Snert: how much mcguyver you wanting to do?
01:43 AM anonnumberanon: as little as possible so that i can focus on enjoying the bonfires while programming
01:43 AM anonnumberanon: but any amount of preparation while before at home is okay4
01:46 AM Snert: I'd bring the weed and pay someone to pedal the generator to charge the batteries :)
01:49 AM anonnumberanon: weed makes me throw up
02:07 AM rue_shop3: I wonder if I should change up my amp/speakers in the shop for a bunch of singal-level self-powered speakers
02:18 AM rue_shop3: hmm I need an esp8266 expert
02:19 AM SpeedEvil: That was one of Tina Turners weaker songs.
02:20 AM SpeedEvil: ^Bonnie Tyler
02:20 AM SpeedEvil: sigh
02:23 AM anonnumberanon: ive never used one but what's the challenge?
02:24 AM SpeedEvil: First common mistake - what is your PSU, decoupling, and how have you attached this to the ESP
02:24 AM rue_shop3: dont know how to attack it yet
02:24 AM rue_shop3: I ahve a rov
02:24 AM rue_shop3: it take serial commands
02:24 AM rue_shop3: used to be over the wire
02:24 AM rue_shop3: but I ahve a esp8266
02:25 AM rue_shop3: I think I need custom firmware to open a port and shovel the data to the controller
02:25 AM rue_shop3: buuut
02:26 AM rue_shop3: the current controller firmware is pretty simple, and if I could do 2 pwm channels and 2 gpio channels, I could prolly ditch the current controller
02:30 AM SpeedEvil: https://spritesmods.com/?art=einkdisplay - possibly related
02:31 AM SpeedEvil: 100khz interrupt driving SPI GPIO port with 16 bits of data each interrupt
02:31 AM rue_shop3: you know
02:32 AM rue_shop3: I could use that pwm chip that anonnumberanon is using
02:32 AM rue_shop3: or Jak_o_Shadows
02:32 AM rue_shop3: anyhow, its just i2c
02:32 AM rue_shop3: I could use 0,100% for the reverser relays, and do the speed control with the other channels
02:32 AM rue_shop3: whats it? pc8395?
02:35 AM rue_shop3: PCA9685
02:37 AM rue_shop3: 1.70usd
02:37 AM rue_shop3: errrrr...
02:38 AM rue_shop3: or I could use a t13
02:39 AM SpeedEvil: Or just skip the ROV and go with a t1000
02:41 AM anonnumberanon: rue_shop3, can i ask you to do something?
02:41 AM anonnumberanon: power the servos without pwm lines connected and tell me what happens
02:47 AM rue_shop3: you get one twitch
02:49 AM rue_shop3: what I'll do is modify the firmware to bring up the 4017 one at a time with delays, then atleast everyone wont be pulling at the same time
02:50 AM rue_shop3: I dont think I can even simulate not feeding a signal to individual servos
02:50 AM rue_shop3: THO, I could start them up in sequnce by playing with the reset line
02:51 AM rue_shop3: another feature, one of my buddies suggested I save the last position on powerdown, and use those as the defaults on startup
02:51 AM anonnumberanon: so you dont get the crazy stuff anymore? thats good that means you know what you can improve on
02:52 AM anonnumberanon: nah defaults should be 50% imo
02:52 AM rue_shop3: its the servos freaking out and overshooting trying to get to their initial position
02:52 AM rue_shop3: I have two servo channels not working
02:52 AM rue_shop3: need to sort that out
02:53 AM rue_shop3: then work out the directions and positions for each axis
02:55 AM rue_shop3: anonnumberanon, did I show you the servo order?
02:56 AM anonnumberanon: maybe rue_shop3
02:56 AM anonnumberanon: these past few days i read a code that had a bunch of servo ordering
02:56 AM rue_shop3: https://paste.debian.net/984329/
02:56 AM anonnumberanon: yeah that one
02:57 AM rue_shop3: i = y*sz*sx + x*sz + z; where x is the side 0,1 right, left; y is the position, 0 front, 1 middle, 2 back, and z is the joint of that leg [0-2, with 3 being a skip]
02:58 AM rue_shop3: that way, I have 18 of the 24 axies used, and 2 channels on each 4017 skipped
02:58 AM rue_shop3: each bank of 8 servos has a switching power converter
02:58 AM rue_shop3: so it evens out the load
02:58 AM rue_shop3: sx = 2; sy = 3; sz = 4;
02:59 AM anonnumberanon: slow down
02:59 AM anonnumberanon: what are you doing
02:59 AM rue_shop3: I have a servo controller for 24 servos
02:59 AM anonnumberanon: what is i
03:00 AM rue_shop3: I have a 3 dimentional array of servos = the side its on, the leg row (front-back) and the joint of the leg
03:00 AM rue_shop3: I need to convert the 3 dimentional address to a linear servo number
03:00 AM rue_shop3: [x][y][z] -> i
03:00 AM anonnumberanon: ah ok
03:01 AM rue_shop3: I still cant think, it took everything I could monkey today to get that formula right
03:02 AM rue_shop3: you see, if I make a robot with more legs and joints, there is a formula to work out the order nicely
03:03 AM rue_shop3: the battlebot is supposed to be 8 legs with 4 axies per leg
03:03 AM rue_shop3: (the tv show ended, so the project did too)
03:03 AM rue_shop3: pneumatic jumping ... pile of danger
03:19 AM anonnumberanon: bed
03:56 AM Jak_o_Shadows: anonnumberanon, stuff you and your 4 channel oscope :(
03:58 AM Jak_o_Shadows: PCA9865
06:13 AM Jak_o_Shadows: Or is it 9685
12:04 PM rue_house: was looking at the price and its not worth it
12:04 PM rue_house: for what I want
12:04 PM rue_house: I can just do a avr of some kind
12:28 PM rue_house: I'd like to know wy, when I came up with a generic servo library I did not put a provision in for limits
02:08 PM tumdedum_ is now known as tumdedum
02:12 PM Atomsk is now known as ace4016
02:13 PM rue_shop3: 0x800 is 12 bits
02:57 PM rue_shop3: THERE ARE 11 BITS!, SEE!!! 1 2 3 4 5 6 7 8 9 10 11!....(12...)...
03:41 PM jandor: рш
03:41 PM jandor: hi
03:41 PM jandor: rue?
03:42 PM jandor: anybody here?
03:42 PM jandor: anyone?
03:44 PM rue_shop3: yea
03:48 PM jandor: hooray
03:48 PM jandor: how goes it?
03:55 PM rue_shop3: making a remote control
07:19 PM rue_shop3: ok, I have a tiny13 based IR tx/rx set
07:30 PM rue_shop3: but it took the day
10:32 PM rue_shop3: ok, I worked out how to mount the pipe bender, put the mounts on, and built a stand
10:32 PM rue_shop3: but its too heavy for me to put on the stand (about a 40% chance of horridly gashing myself)
10:36 PM Tom_itx: so what's gonna happen when you start climbing around on a 12' mech putting pieces into place?
10:37 PM rue_shop3: its an interesting topic
10:37 PM rue_shop3: I'v come to a partial conclusion that the only way I can build the damn thing is with a 12' mecha
10:37 PM rue_shop3: so, the logical conclusion is to bootstrap it
10:38 PM rue_shop3: use it to build itself
10:38 PM rue_shop3: so, arms and upper body have to be the first parts
10:42 PM Tom_itx: it needs a base to support the upper body or it will fall
10:42 PM rue_shop3: kinda
11:31 PM Tom_itx: rue_shop3, any MB with M.2 on them?
11:43 PM rue_house: M.2?
11:43 PM Tom_itx: ssd interface
11:43 PM rue_house: sata
11:43 PM Tom_itx: form factor i guess
11:44 PM orlock: rue_house: M2's faster, looks like a mini-PCIe
11:44 PM rue_house: ?
11:44 PM Tom_itx: https://arstechnica.com/gadgets/2015/02/understanding-m-2-the-interface-that-will-speed-up-your-next-ssd/
11:44 PM orlock: same sorta form factor as little wireless cards, but for fast SSD's
11:44 PM rue_house: why do they need something faster than pcie?
11:45 PM orlock: sata isnt as far as PCIe
11:45 PM Tom_itx: Max Sequential Read
11:45 PM Tom_itx: Up to 2500 MBps
11:45 PM rue_house: I think that one of my ssd's is that with an adapter
11:45 PM Tom_itx: Max Sequential Write
11:45 PM Tom_itx: Up to 1500 MBps
11:46 PM rue_house: an OS should not need to transfer that much data to bring up a webpage in less than 2 seconds
11:46 PM rue_house: after I click the link
11:46 PM Tom_itx: renderings
11:46 PM rue_house: besides, speed vs latency
11:47 PM rue_house: today is all about terrabit speeds and nobody cares that there's 5 seconds latency
11:47 PM Tom_itx: Max Sequential Read
11:47 PM Tom_itx: Up to 3200 MBps
11:47 PM rue_house: how much LATENCY tho
11:48 PM Tom_itx: 1G cache
11:48 PM rue_house: not important, its just my rant
11:48 PM rue_house: ok, so
11:48 PM orlock: i like them because theres no worries about cables or power
11:48 PM rue_house: this weekend I mounted the controller to the hexapod
11:48 PM Tom_itx: orlock what kind have you tried?
11:49 PM rue_house: I did up lots of the pipe bender for the mecha
11:49 PM rue_house: (control cage)
11:49 PM rue_house: played a bit with an ROV
11:49 PM rue_house: (land)
11:49 PM Tom_itx: i thought you already did the cage
11:50 PM Tom_itx: round hoops
11:50 PM rue_house: nope, have to bend pipe
11:50 PM rue_house: and thats with the pipe bender thats getting RELLY heavy
11:50 PM rue_house: I need to keep working on hands and arms
11:50 PM rue_house: and pneumatics
11:50 PM Tom_itx: you should have considered your limitations
11:51 PM rue_house: I would say it'll all be fixed when I'm a 12' mecha, but we all know the problems always outscale the hero
11:52 PM rue_house: at this rate I'll be getting old, will need the mecha for things I CAN do now
11:52 PM Tom_itx: you should be working on a submarine
11:52 PM rue_house: I need to make a really smart AI that can operate on an stm32
11:52 PM rue_house: I have a sub project
11:52 PM rue_house: its in a bucket in the back of the shop
11:53 PM rue_house: cause I'm the only one in the world who apparently thought of pressure compensation
11:56 PM Tom_itx: http://www.deepseanews.com/2014/05/how-to-shrink-a-styrofoam-cup-and-other-side-effects-of-deep-ocean-pressure/