#robotics Logs

Jan 07 2015

01:29 rue_house heh, that guy PLAYS the wav header
01:29 rue_house hahah
01:56 rue_house I'm guessing that means he dosn't check the sample rate
01:57 rue_house hahah $600
01:57 rue_house wow is frc becomming a money grab?
02:02 RifRaf first robotics?
02:04 rue_house FIRST
02:05 rue_house its an organization that does robotic competitions
02:05 rue_house you have to buy their parts to make your robot
02:06 rue_house schools put togethor teams of kids that sell cookies and their souls to get the money to buy the kit and enter the compoetition
02:12 RifRaf does sounds like a money grab if you have to use all thier stuff
02:15 rue_house yes and no, they want to keep eveyone on the same level, but if they have inflated prices for the stuff...
02:26 rue_house damnm, its midnight
02:26 rue_house this is becomming a bad habit
02:36 Hyratel rue_house, I'd like to see you do the parts cheaper (after accounting for economies of scale in manufacturing)
03:00 LiohAu any french people here?
03:01 LiohAu I'm looking for french partners for a robotics project, if anybody is interested => pm
03:38 deshipu https://www.youtube.com/watch?v=Ocyhbij9JYQ
03:38 deshipu big robots :)
09:32 rue_house titanboa is larger now
10:36 Mister one need a voltage regulator to reduce and increase speed on electrical motors right?
10:36 Mister what happens if one use a current regulator?
11:24 Mister anyone know a good gyroscope and accelerometer for a self-balansing vehicle?
11:27 deshipu mpu6050 is popular
11:30 Mister what is a breakout board?
11:31 Mister deshipu: can't find a produkt called that on arduinos website
11:31 Mister did find this however
11:31 Mister http://playground.arduino.cc/Main/MPU-6050
11:31 deshipu a breakout board is a board for a chip with its inputs/outputs "borken out" to convenient pins
11:33 deshipu http://www.aliexpress.com/item/GY-521-MPU-6050-MPU6050-Module-3-Axis-analog-gyro-sensors-3-Axis-Accelerometer-Module/641898763.html
11:34 Mister deshipu: Aha cool! what are bords such as a motherboard from amd called?
11:34 Mister closed board?
11:35 deshipu no idea what you mean
11:36 Mister what's the opposite of a breakout board? x-D
11:37 deshipu I don't think there is an opposite
11:42 Mister deshipu: is it possible to use that gyro you linked without using accelerometer?
11:42 Mister i tihnki know the answer but i have to make sure x-D
11:42 deshipu yes
11:42 Mister i'm planning on buying two of them and only use the accelerometer on one of them
11:43 deshipu well, you get all the values, you just ignore the ones you don't need
11:43 Mister aha k, thanx for the help btw =)
11:43 deshipu it also has a thermometer
11:43 deshipu no idea why
11:43 Mister for 2 dollars thats so silly lol
11:44 deshipu it will take 2-3 weeks to ship
11:44 deshipu from china
11:44 Mister mount it inside the battry compartment so heat the battery in cold weather conditions
11:44 Mister to*
11:44 armyofevilrobots thermometer because it is probably supposed to go in a phone.
11:44 armyofevilrobots and for some reason, phones need thermometers :)
11:45 deshipu or maybe it adjusts its operation to the temperature
11:45 Mister does galaxy note 3 have thermometer?
11:46 Mister it's very cold up in the sky, and batteries lose their power very quickly when they are cold :-S
12:14 armyofevilrobots Yes, it does.
17:03 GuShH rue_house: Hmm I think I found a very simple way to align tailstocks without having to do a series of test cuts, but I've yet to fully test this
17:03 GuShH I got it within under 1 thou now and you can tell the difference
17:05 Tom_itx yay! got my new boards today
17:06 veinofstars Tom_itx: what did ya get
17:06 Veverak nah
17:06 Veverak have to finally finish the gerabox
17:06 Veverak but..
17:06 Veverak more questions than answers as usual
17:07 Tom_itx boards for my cnc
17:11 GuShH Tom_itx: don't burn these!
17:11 ShH h
19:28 rue_house I think they are gonna blow up like the other one
19:29 rue_house casue I think its an intermittent bad neutral connection somewhere that tom wont try to find
19:40 rue_house maybe I should build the agc amp today
19:41 Tom_itx i am gonna go thru the whole box again
20:06 rue_house I dont think its in the box
20:20 Tom_itx where would it be then?
20:20 Tom_itx and why if it isn't in the box would it take out the box and nothing else?
20:29 rue_house it could be at the outlet everything is plugged into
20:29 rue_house it could be in the power bar
20:29 rue_house it could be in the computers power supply
20:30 Tom_itx i seriously don't see how it could be the computer
20:30 Tom_itx the two are isolated except for the parallel port
20:31 rue_house no, they are linked by the grounds
20:32 rue_house measure the resistance btween ground and neutral on the suppling outlet
20:32 Tom_itx ok
20:32 rue_house should be less than an ohm
20:32 Tom_itx power on?
20:32 rue_house dosn't matter
20:32 rue_house at the panel the ground and neutral are connected
20:32 rue_house visitors!
20:33 Tom_itx aww
22:32 codepython777 Hyratel: how does one accurately move a gearmotor to say 60 degree angle? From what I understand, it seems like doing one rotation is easy, but not angles?
22:32 Hyratel what do you mean?
22:32 Tom_itx encoder feedback
22:32 Hyratel why are you trying to turn a gearmotor 60 degrees
22:32 codepython777 I'm just trying to understand.
22:33 codepython777 Tom_itx: If an encoder told you that its turned 60 degree, how do you stop the motor at that particular point?
22:33 Hyratel you don't
22:33 Hyratel or you use closed-loop feedback to anticipate how far it'll coast once you remove power
22:34 codepython777 do motor controllers that take quadrature input support such things? can one tell them that i want the motor to turn only 90 degrees?
22:34 Hyratel no you can't
22:35 codepython777 so if you want precise angles, steppers?
22:35 Hyratel encoders are more commonly used as odometers and tachometers
22:35 Hyratel yes
22:36 codepython777 for steppers, if one has a 200 step stepper, how do i calculate -> how fast can i go from step 0 to step 100 ?
22:44 Hyratel don't use steppers as drive motors
22:44 Hyratel what exactly are you wanting to do?
22:45 codepython777 Hyratel: Was trying to figure out how to build a pan tilt system
22:45 Hyratel you don't use spinmotors for pantilt
22:45 Hyratel you use servos
22:45 mrdata the stepper consumes max power while holding
22:45 armyofevilrobots You can probably figure it out with some calculus and the torque/(steps/s) chart, but I would suggest experimenting to get the acceleration values.
22:45 mrdata do you want to maintain a particular angle?
22:45 codepython777 mrdata: yes
22:45 mrdata ok
22:45 armyofevilrobots and you can drop the duty cycle when holding, so steppers are valid, just cheap and higher power :)
22:46 codepython777 goto theta = 90 degree , phi = 57 degree
22:46 mrdata there is a max step rate
22:46 Hyratel codepython777, use 4 wire steppers
22:46 mrdata i always just had to discover it by tests
22:46 Hyratel actually no don't
22:46 codepython777 seems like some people use gearmotors for pantilt! https://www.servocity.com/html/mpt1100-ss_pan___tilt_system.html#.VK4GHStDGSo
22:47 codepython777 gearmotors! how do they control angle with tat
22:47 Hyratel "open loop"
22:48 Hyratel they just turn a system that can travel in full 360 in both axes and it's up to the operator to avoid crashing it
22:48 codepython777 interesting
22:48 Hyratel all it's doing is running the spin motors
22:49 Hyratel there is no feedback
22:49 Hyratel it's you watch it, learn the speed and don't crash your camera
22:49 Hyratel https://www.sparkfun.com/products/10335
22:49 codepython777 Can steppers be fast? The last pan tilt i played with was really slow.
22:49 Hyratel stopsign
22:50 codepython777 Hyratel: already looked at that
22:50 Hyratel you're doing it again
22:50 Hyratel you're putting the details of structure in front of determining your constraints
22:50 codepython777 k - lets do constraints?
22:52 Hyratel this is for your forward vision, correct?
22:53 codepython777 Hyratel: nope, for a separate project.
22:53 Hyratel ok
22:53 Hyratel state what it needs to do
22:54 codepython777 Hyratel: it needs to point a light weight camera in a particular direction (theta, phi), fast and precisely.
22:54 Hyratel define fast. define accurate
22:55 Triffid_Hunter codepython777: you want digital hobby servos for that
22:55 codepython777 accurate = < 1 degree error. Preferably < 0.01 degree error
22:56 codepython777 fast = 360 degree rotations in a second
22:56 Triffid_Hunter codepython777: 0.01°? that's gonna be some expensive servos
22:56 Triffid_Hunter 360° too? might need a winch servo
22:57 Hyratel http://www.hobbyking.com/hobbyking/store/__6314__Hobby_King_Digital_Servo_2_2kg_12_5g_11sec.html
22:57 Hyratel codepython777, what's your required range of motion?
22:58 codepython777 theta = 360, phi >= 100 degree
22:59 Hyratel say pan and tilt
22:59 codepython777 Hyratel: can you tell that servo -> Move to 60 degrees and stay there?
22:59 codepython777 k
22:59 Hyratel codepython777, do your own datasheet reading
22:59 Hyratel I am quite tired of having to handhold you through every step of the process
23:00 codepython777 thanks :)
23:06 codepython777 Hyratel: seems like the motor you pointed to will fit in the sparkfun kit. Any suggestions for a good controller ?
23:06 Hyratel C_C
23:09 codepython777 reading PWM
23:09 Hyratel that's a digital controller
23:10 Hyratel did you read the spec sheet?
23:10 Hyratel er, digital servo
23:12 codepython777 Could not find the spec sheet on that page.
23:13 codepython777 Nice -> Digital servos have an internal microcontroller that allows the servo designers much more flexibility in how servos react.
23:16 Hyratel codepython777, critical thinking/reading
23:16 Hyratel PRODUCT ID: DS-929MG
23:20 rue_house codepython777, not the cheap ones
23:21 rue_house codepython777, http://ruemohr.org/~ircjunk/tutorials/elex/hobbyservo/servo101.html
23:26 codepython777 rue_house: so what is the cheap version of digital servos?
23:27 rue_house Tom_itx, basically measure the resistance of all the neutral paths in your power train
23:27 rue_house codepython777, motor + avr+potentiometer
23:27 Hyratel codepython777, again, why do you need full 360 degree travel
23:31 codepython777 Sorry - 180 degrees should be fine
23:58 rue_bed codepython777, you know a normal hobby servo will do 180