#robotics Logs

Aug 09 2017

12:01 AM rue_room: zlog
12:04 AM rue_room: ? rly?
12:04 AM rue_more: https://www.youtube.com/watch?v=u5OCyOfTdnQ
12:19 AM rue_more: huh, I didn't have to fight to get that into an mp3
06:05 AM veverak: anniepoo: ros.org + RVIZ
07:17 AM Jak_o_Shadows: veverak: what software is that!
07:17 AM Jak_o_Shadows: Does it have rigid body
07:17 AM Jak_o_Shadows: oh, it's ROS
07:18 AM veverak: yeah, it's ros :)
07:21 AM Jak_o_Shadows: I recently gave up on blender rigid body for simulations
07:21 AM Jak_o_Shadows: I just want it to work. Making the rigid body simulation work is NOT what I want to psent time on
07:23 AM veverak: :D
07:23 AM veverak: Jak_o_Shadows: it's just visualizer
07:23 AM veverak: not simulation
07:23 AM Jak_o_Shadows: ah, ok.
07:23 AM Jak_o_Shadows: Yeah, I should learn a visualiser
07:23 AM Jak_o_Shadows: my other option is blender at the moment - which is fairly easily doable, but meh
09:16 AM ib0t: Jak_o_Shadows: if you want a simulation tool have a look to VREP or gazeebo
09:17 AM ib0t: not gazeebo its gazebo
11:42 AM anniepoo: Jak, why'd you give up on blender? I'm thinking of using blender, don't want to go down wrong path
12:09 PM Maya-sama is now known as hackkitten
02:10 PM SpeedEvil: Blender is excellenent, but it's like using an artists brush to do 2d cad.
02:10 PM SpeedEvil: It has way too many off-target features optimised for if you want your robot to sprout semi-realistic fur.
03:24 PM BeautiCode: I have this old RC tank that I took apart and am programming to drive autonomously.It has 2 motors, and of-course to turn I'm making one motor go forward and the other go backwards...But when that happens, there's a loud clicking sound that occurs and it starts going to slow that it won't even turn successfully
03:24 PM BeautiCode: anyone know what that coul dbe?
03:26 PM SpeedEvil: the tracks coming off
03:26 PM SpeedEvil: or rubbing as they're torqued badly
03:27 PM BeautiCode: the sound only occurs when its trying to turn though
03:27 PM BeautiCode: its fine when the motors are going in the same direction
03:32 PM anniepoo: It could be that there's a ratchet in the drive
03:32 PM anniepoo: so if you drive in reverse it's the ratchet slipping
03:32 PM anniepoo: can you drive straight back?
03:33 PM BeautiCode: yeah it can drive straight backwards and straight forwards. but they cant go in different directions without struggling
03:33 PM anniepoo: if so, it's some issue with side forces (eg SpeedEvil's solution)
03:33 PM anniepoo: pick it up
03:33 PM anniepoo: will one tread go backwards in the air?
03:34 PM anniepoo: run it forwards on the ground, and twist it with your hand - does it do it?
03:34 PM anniepoo: try turning the tank on the ground with the power off
03:34 PM anniepoo: and look at what the treads do
03:35 PM BeautiCode: one track keeps going forward, while the other one stops (when its in air)
03:35 PM BeautiCode: i can turn it on the ground with the power off
03:36 PM anniepoo: ok, that tends to make me think a ratchet of some sort
03:36 PM anniepoo: look at the mechanism
03:37 PM BeautiCode: the whole motor/gear system is encased, and it's hard to get the case off without damaging the tank
03:38 PM anniepoo: can you see if the sides are independent?
03:38 PM anniepoo: turn the power off, turn the tread each direction
03:38 PM anniepoo: (that is, manually pull the tread back and forth)
03:39 PM anniepoo: did it do this before you started the mods?
03:40 PM BeautiCode: yeah theyre independent
03:41 PM BeautiCode: i bought the tank like 5 years ago and its been sitting in my garage for a while. so i dont remember exactly how it performed, and i couldnt test it since I had lost the controller
03:41 PM BeautiCode: this is it: https://www.youtube.com/watch?v=RvzT46YMsbg
03:43 PM anniepoo: try running it forwards into a wall.
03:43 PM anniepoo: does it make the clicking noise?
03:45 PM BeautiCode: nope it just stops
04:05 PM anniepoo: hmm
04:06 PM anniepoo: what happens if you manually move the tread with power off?
04:11 PM BeautiCode: weird...but, i push it forward and it sort of clicks every once in a while, while its moving forward. if i pull it backwards, it comes back smoothly
04:11 PM anniepoo: yes
04:11 PM anniepoo: you have a directional ratchet in the mechanism
04:12 PM anniepoo: 'push it forward'
04:12 PM anniepoo: you mean the tread, or 'make the tread move as if the tank is moving forward'?
04:13 PM anniepoo: in normal forward operation, the tread flows towards the back of the tank
04:14 PM BeautiCode: make the tread move as if the tank is going forward
04:15 PM anniepoo: ok, you're driving the drive train in reverse
04:15 PM anniepoo: so it looks then to the ratchet that you're backing up
04:16 PM anniepoo: you're 'overruning'
04:17 PM anniepoo: eg if the tank were to drive down a steep slope
04:17 PM anniepoo: it might be going fast, you don't want the treads driving the motor
04:18 PM anniepoo: if you can find the ratchet in the mechanism, you can probably disable it
04:18 PM anniepoo: post a pic of the mechanism, as disassembled as you can get it
04:23 PM BeautiCode: argh, i hope i dont break anything trying to open this little case where the 'mechanisms' should be
04:24 PM anniepoo: don't open anything you're uncomfortable opening
04:24 PM anniepoo: lets just get as much pic as we can
04:35 PM BeautiCode: 0http://imgur.com/a/DL64y
04:35 PM BeautiCode: http://imgur.com/a/DL64y
04:44 PM anniepoo: cool
04:44 PM anniepoo: ok, possibly the ratchet is inside the drive wheel?
04:45 PM anniepoo: I see a little shaft (white) going into drive wheel (green)
04:51 PM BeautiCode: yeah probably
04:52 PM anniepoo: try running it, see if you can get the white shaft to turn and the tread not
04:52 PM anniepoo: or vice versa
04:52 PM anniepoo: if so, the ratchet's in there
04:53 PM anniepoo: you can also try sticking a piece of tubing or a stick in your ear and putting it in contact ith various places on the mechanism to try to localize the ratchet
04:54 PM anniepoo: might also try holding it up to a really bright light
04:54 PM anniepoo: (don't melt it)
10:47 PM AltJesteR: http://a.co/8ppgV6z
10:47 PM rue_more: ...
10:48 PM rue_more: ms-windows-store://pdp/?productid=9nrrbgttm4j2
10:49 PM rue_more: https://hexchat.github.io/downloads.html
11:23 PM rue_more: I'v had anohter discovery about the human mind, and like a few others, its sparked (once again) that "is that all we are" moments
11:24 PM rue_more: ?
11:24 PM orlock: we may just be a long-running chemical reaction, but it's a really really complicated one!
11:25 PM rue_more: I'v been focusing on how learning works
11:25 PM orlock: rue_more: http://en.crypt.net.au/Controller/IMG_2134.JPG http://en.crypt.net.au/Controller/IMG_2135.JPG
11:25 PM rue_more: I have an idea I'm thinking thru
11:26 PM rue_more: k
11:26 PM rue_more: whats it?
11:26 PM orlock: IP based wireless controller
11:26 PM rue_more: are the boards interrupters?
11:26 PM orlock: you should be able to make out a pot shaft with a trigger attached roughly in the middle of the mess
11:26 PM orlock: the two red ones, yes
11:27 PM rue_more: yup I see that
11:27 PM rue_more: what resolution did you get on the encoder?
11:27 PM orlock: 144 pulses per revolution
11:27 PM rue_more: interesting number
11:27 PM orlock: 36 slots
11:28 PM orlock: 2 edges per sensor, 2 sensors
11:28 PM rue_more: ah, k, thats quad then
11:28 PM orlock: sorry, not 144 pulses - 144 edges.
11:28 PM rue_more: yea, still good
11:28 PM rue_more: esp for its size
11:28 PM rue_more: is the disc printed?
11:28 PM orlock: yup!
11:29 PM orlock: so one of the photo inturruptors is mounted at an offset of 50% of slot width
11:29 PM rue_more: http://www.bushytails.net/~randyg/encoder/encoderwheel.html
11:29 PM rue_more: ^^ you didn't forget about hsi encoder generator right?
11:30 PM orlock: to gt the right pulse geometry for the software quadrature encoding to work
11:30 PM rue_more: was it hard to dial in the phase?
11:30 PM orlock: nope
11:31 PM orlock: got it first try - it was just basic maths
11:31 PM rue_more: haha did you use those connectors as distribution bars?
11:31 PM orlock: just had to calculate it off the slot count of the disk
11:31 PM orlock: yes hahahah
11:31 PM rue_more: hah nice idea
11:31 PM rue_more: just needs a 3d printed holder...
11:32 PM rue_more: 0.1"...
11:32 PM orlock: ahh, i just realised the wires in the way
11:32 PM orlock: so you cant see the extra pin soldered across them all
11:32 PM orlock: arduino does the quad encoder and the pot, then talks serial to the ESP8266
11:35 PM rue_more: did you use my state machine for the decoder?
11:35 PM rue_more: I stress tested it once, its damn fast
11:36 PM orlock: voltage divider to take the 5v down to 3.3v for the arduino, and it only needs unidirectional comms
11:36 PM orlock: decoder for what?
11:36 PM orlock: this all just spews data via serial, then UDP
11:39 PM rue_more: for the quadrature decoder
11:40 PM orlock: I doubt it (unbless you wrote the one that google turned up)
11:40 PM orlock: It's only going to have a human spinning it
11:42 PM rue_more: http://paste.debian.net/980712/
11:42 PM rue_more: please note that like 50% of that is comments
11:45 PM rue_more: since I came up with it in 1997, I'v used it in almost every encoder app I'v made
11:45 PM rue_more: hah, its 20 years old
11:45 PM orlock: The interesting bit will be turning the inturruptor data into steering values
11:45 PM orlock: so the power for the left and right wheels
11:45 PM orlock: total power available will come from the pot
11:45 PM rue_more: tractor?
11:45 PM orlock: and then i'll use the timing between pulses to determine the split
11:46 PM orlock: yeah, close enough - sumo bot
11:46 PM * rue_more looks for code
11:46 PM orlock: so the closer together the quad pulses, the more power goes to that side
11:47 PM rue_more: // Tractor mixing:
11:47 PM rue_more: // SpeedL = X + Y;
11:47 PM rue_more: // SpeedR = Y - X;
11:48 PM rue_more: http://paste.debian.net/980713/
11:49 PM orlock: snarfed, cheers
11:49 PM orlock: the last comp, there was only one oerson with a human-controlled bot
11:49 PM rue_more: I was amused its that easy
11:50 PM orlock: and they were using a nintendo wii "chuck"/joystick
11:50 PM rue_more: hahah that code is from 2007 :)
11:55 PM rue_more: do you know how those balancers work in cd's?
11:56 PM rue_more: the little disk with the bits in it?
11:56 PM rue_more: disc