#robotics Logs
Aug 13 2013
#robotics Calendar
00:32 rue_more yay!
01:10 SleepersTide RifRaf: so I had an idea about that tiny hexapod I designed using servos that wouldn't be powerful enough
01:11 SleepersTide since it doesn't need to function upside-down, I think I could spring-load the leg joints so the servos don't have to lift the machine's whole weight
01:13 SleepersTide and then they would also have to push a bit of load when moving in the other direction
01:21 rue_more ooo I tried a bad-off battery on my capacity tester for a 10hr discharge and it tanked after 40 mins
01:25 rue_more ~1Ah
01:25 rue_more for an 8Ah battery
01:35 RifRaf SleepersTide, could help probably, rue can tell you aboult springs, he loves em
01:35 RifRaf signing off for now
01:59 rue_more rifraf didn't means springs so much
01:59 rue_more but COUNTERBALANCING
01:59 rue_more which means taking any part of your robot that aways has gravity forces on it, and balancing them out with weights or springs or whatever
02:02 SleepersTide oh, I see
02:03 SleepersTide well, the issue is basically that in this design: https://dl.dropboxusercontent.com/u/18030449/Hexa1.png
02:04 SleepersTide the servos will probably not have enough torque (they're 2.5g servos)
02:04 SleepersTide basically the smallest hexapod I could design with cheap actuators
02:04 rue_more if you COUNTERBALANCE, they dont have to hold the robot up, nomatter what it weighs
02:05 SleepersTide rue_more: well, I don't think I have room to counterbalance anything there
02:05 SleepersTide also increased armature mass would mean it moved slower
02:05 rue_more well counterbalancing is really complex, I dont think you can work it out
02:05 Jak_o_Shadows You generally don't see counterbalanced hexapod, cause the mechanics get hard
02:05 SleepersTide hence springs
02:06 rue_more I mean for every 10g you have at 10cm, you need 100g at 1cm, quite quite complex
02:06 SleepersTide indeed
02:06 rue_more levers and stuff, I dont think anyone does it in school
02:06 rue_more its university physics stuff
02:06 SleepersTide I don't think counterbalancing is feasible in a thing this size
02:06 SleepersTide maybe a much larger hexapod
02:07 SleepersTide but I think spring-loading the joints would work
02:07 rue_more yea, its for robots the size of a 10 story building, with freeway onramps for arms
02:07 rue_more and laser eyes
02:07 SleepersTide oh, I can fit laser eyes on this one
02:07 SleepersTide lasers are small
02:07 Jak_o_Shadows Springs are a bit of a pain, cause most are non-linear, so you have to pick where you want the most advantage
02:07 rue_more even tho laser eyes aren't cute
02:08 SleepersTide Jak_o_Shadows: yeah, my main concern would be the non-linearity
02:09 SleepersTide I will actually try it as-is and see how it goes
02:10 rue_more yea, the forces on a spring are F = d*k where d is stretched distance and k is the springs constant, F being the springs force, complex university algebra that only people who go to university know how to do
02:10 SleepersTide and also consider swapping out the motors in the servos
02:10 rue_more got letters in the formula and stuff
02:10 SleepersTide rue_more: I'll pretty much just use the TLAR method
02:11 Jak_o_Shadows Haha, all was good in the world, until satan said: Lets put letters in maths.
02:11 SleepersTide they'd be the lever-type springs, if you know what I'm talking about
02:12 SleepersTide I don't know the correct term
02:12 Faek Numbers in maths? What madness do you speak of?
02:14 SleepersTide anyway, I'm gonna go see if I have enough bits and pieces to put together a 3D printer
02:14 SleepersTide because that's more fun than spending an hour and a half on public transport to get to my local hackerspace
02:17 rue_more http://wikid.eu/images/9/9c/Springs_variety.jpg
02:18 rue_more http://www.woodcrestwebdesign.com/springdesign/images/EXT_END_TYPES2.jpg
02:18 Jak_o_Shadows Never seen german hooks
02:18 rue_more http://www.ridejbi.com/product_images/uploaded_images/spring-types.jpg
02:19 rue_more http://resortesyaccesorios.com.mx/imagesnew/5/5/5/8/6/Compression_Spring_Types.jpg
02:20 Jak_o_Shadows I suppose the variable rate one would be the ideal, but you'd have to run the maths, and then try to find one that matches.
02:20 rue_more http://www.keytometals.com/images/Articles/kts/Fig371_1.jpg
02:21 rue_more http://img.alibaba.com/photo/107510247/All_types_of_Springs.jpg
02:26 MrCurious that was fun
02:26 MrCurious got a bonus light show to let me know my license plate light was out
02:27 rue_more :
02:27 rue_more :/
02:37 MrCurious think tomorrow after work i am going to fix a light
02:39 RifRaf GuShH, the saw cut the hardened steel easy, the clamp locked onto the round rod well and the part was only just warm when cut, was a makita that looked like the one you posted, the blade was for 4400rpm but dunno what it was made from
03:32 RifRaf harmonic wats?
05:12 SleepersTide rue_more: torsion springs, then
07:59 KongfuPanda hello peoples
08:00 KongfuPanda I'm gonna work on my robot again, after loosing most of my code from a virus :(
08:00 KongfuPanda so, I'm gonna hand around here for a bit
08:02 KongfuPanda hmm, I was asking for some advice last time and there was a grumpy guy here, forgot his name
08:03 KongfuPanda it was about automating a system
08:03 KongfuPanda in the end I went for a stepper motor and a USB board
08:03 KongfuPanda it's working very well now :)
08:06 pythonsnake what's better for a rover? 2 treads or 4 wheels?
08:07 SleepersTide depends on what kind of terrain you want it to be able to handle
08:08 pythonsnake msot indoor obstacles
08:09 Hukka Chairs, tables, pets, people?
08:09 pythonsnake like a charger on the floor, legos
08:09 Hukka Stairs, maybe ladders, escalators
08:09 pythonsnake stuff like that
08:09 pythonsnake stairs would be hard i guess
08:10 pythonsnake http://www.robotshop.com/ca/dfrobot-4wd-arduino-platform-encoders-2.html maybe?
08:10 pythonsnake "The powerful motor performance, flexible and rapid movement is especially suitable for outdoor grass, gravel, sand, or slope pavement."
08:11 pythonsnake the other treads dont seem very flexible and durable
08:11 SleepersTide I think you'd be better-off with wheels, in that case
08:16 SquirrelCZECH god damn it
08:16 SquirrelCZECH it looks like servo that meets me req. is not obtainable
08:18 SleepersTide then change your requirements
08:19 SquirrelCZECH nope
08:19 SquirrelCZECH :D
08:19 uirrelCZECH will just modify some th
08:21 SquirrelCZECH and it would mean really complicated arduino code :-/
08:21 SquirrelCZECH god damn it
08:22 SquirrelCZECH that is not single one construction problem that could be name "unsolvable"
08:22 SquirrelCZECH *be named
08:39 rue_bed your gonna have to take a university program so you can counterbalance it
08:40 rue_bed thats gonna blow your project budget
08:41 SquirrelCZECH rue_bed: got google :D
08:41 SquirrelCZECH and IRC! :-)
08:46 KongfuPanda so, am I right to say that a microcontroller executes a loop of code that you program into it at maximum frequency (unless you ask it to pause)? Thanks
08:46 SleepersTide yeah, pretty much
08:48 KongfuPanda has anyone used this microcontroller called AXON 2?
08:51 KongfuPanda I guess not. Basically it is a microcontroller that can control many servos
08:55 SleepersTide I haven't heard of it
08:56 SleepersTide ah, it's an atmega640
08:57 SleepersTide KongfuPanda: there's a channel on here called #avr that is specifically about that manufacturer's microcontrollers
08:57 SleepersTide they may be able to help you, but I don't know if anyone is awake there
08:58 SquirrelCZECH nah
08:58 KongfuPanda well, I don't have any problem as of yet. I'm just re-installing AVR studio and webbotlib, since my computer got completely wiped by some virus. So, I have to start programming the controller and computer software from scratch
08:59 uirrelCZECH wanted "rotary encoder", but everyone he found uses "interrupts" of arduino
08:59 SquirrelCZECH god damn it
09:00 SleepersTide SquirrelCZECH: rotary encoders are a physical piece of hardware, interrupts are a software concept
09:00 SquirrelCZECH SleepersTide: I know that
09:01 SleepersTide okay
09:01 SquirrelCZECH it's more like I need solution to problem :-/
09:01 SquirrelCZECH and it feels like this is not the right way :-/
09:01 SleepersTide and interrupts are not an appropriate solution?
09:01 SquirrelCZECH SleepersTide: nope
09:01 SquirrelCZECH because I use them for different thing
09:01 SquirrelCZECH where they are needed
09:02 SleepersTide ok
09:04 uirrelCZECH wants to detect position of continuous rotation servo, that's all
09:04 SquirrelCZECH or, to be proper, mechanism after the servo...
09:04 SquirrelCZECH (there is "gearbox")
09:10 SquirrelCZECH I think I can use the gearbox for that! :-)
09:11 SquirrelCZECH but... not sure if attaching "potenciometer" on 3 meters long cable is right
09:14 rue_more depends on the cable
09:14 SquirrelCZECH should be lightweight :-/
09:14 rue_more there are smaller signals that go thru up to 100m of cable and come out ok
09:18 R0b0t1 SquirrelCZECH: If you can't use interrupts
09:18 R0b0t1 you suck
09:18 R0b0t1 learn to use interrupts
09:19 SquirrelCZECH R0b0t1: I said
09:19 SquirrelCZECH that I can't use them
09:19 SquirrelCZECH BECAUSE I USE THEM FOR SOMETHING DIFFERENT
09:19 SquirrelCZECH :-)
09:20 R0b0t1 o
09:20 R0b0t1 you got me
09:20 R0b0t1 You know you have pin change interrupts per port
09:21 SquirrelCZECH R0b0t1: for arduino mega?
09:21 SquirrelCZECH I found library that could do so for UNO
09:21 SquirrelCZECH but mega wasn't really supported
09:22 R0b0t1 My god! You might need to read the datasheet.
09:22 R0b0t1 Anyhow default libs should at least support one or two ports.
09:23 R0b0t1 Registers should be called PCICR and PCMSK[0..numport]
09:25 uirrelCZECH is using "arduino" language...
09:25 SquirrelCZECH and that thingy gives me 6 interrupt ports on arduino mega
09:25 SquirrelCZECH all af them - used
09:40 R0b0t1 ...
09:40 R0b0t1 wtf u doin
09:40 R0b0t1 also each interrupt serves a port
09:40 R0b0t1 but you can differentiate the pins
09:41 uirrelCZECH just does what documentation said
09:43 SquirrelCZECH and by documation I mean reference on arduino.cc
17:24 GuShH RifRaf: yeah figured it would cut just fine, the blade was either carbide tipped or diamond coated (of which I've got no plans to buy, since they cost about half as much as the whole unit) ran some cuts with the abrasive wheel today, after it got "dressed" it began to cut better, but I'm still not happy with it. I'll try a thinner one, if that doesn't work out I'll get the carbide tipped and slow the speed down, otherwise It'll
17:24 GuShH end up in a corner wasting space as I've no use for something that won't cut straight and fast. I did finish cutting the lathe stand parts in a 10th of the time though, I just wasn't happy with the results. 40x40mm square tubing, I cut 3 faces at once, then flipped it 90° to cut the remaining face (as I would've done with an angle grinder) there's some deviation here and there, I don't mind the burrs that's expected with an abra
17:24 GuShH sive cut but it's still not good enough... maybe I'm asking way too much for what it is?, I'd like a bandsaw but I can't afford it, and I don't have the space for one anyway plus I bet the cheap ones cut just as bad.
17:25 GuShH if I had the clamping accessories I wouldn't have to flip the work, I could mount it at 45° and run a straight cut across, but with the regular vise you can't do that safely. I might make some of those clamp addons myself, after all they were not an option when I bought the saw.
21:23 pythonsnake where do you guys buy stuff from?
21:23 pythonsnake dx?
21:23 MrCurious ebay
21:24 MrCurious its an addiction
21:24 MrCurious should ask what "stuff" you are looking for?
21:24 pythonsnake shipping cost so much over there
21:26 MrCurious i suppose this is "like" a conversation
21:27 Tom_itx buy what stuff?
21:27 MrCurious he wont say
21:30 pythonsnake robotics stuff
21:30 thonsnake is looking for a solid wheels cha
21:32 R0b0t1 http://www.greenarraychips.com/
21:32 R0b0t1 heard those were pretty old
21:32 R0b0t1 anyone know?
21:32 R0b0t1 GuShH, ever heard of http://www.greenarraychips.com/ ?
21:33 GuShH R0b0t1: nope
21:33 R0b0t1 Hm, heard they were kinda old
21:33 R0b0t1 all I can find is a bunch of russians dicking around with the
21:33 GuShH and I'm old?
21:33 R0b0t1 the,
21:33 R0b0t1 no, figured someone in here may've seen it
21:34 GuShH ask the russian
21:34 GuShH robotustra
21:34 R0b0t1 imo suffers from same flaw as the parallax propeller, cores too limited
21:34 GuShH "belarussian"
21:34 R0b0t1 I wanna see something like that on an fpga routing matrix
21:34 GuShH how much a pop
21:35 R0b0t1 $20 I think, gotta buy like 10
21:35 R0b0t1 so I am particularly dissuaded
21:35 ShH sh
21:36 Tom_itx " i bought an adafruit programmer and it won't work on my 128. would you please send me your code so i can put it on my programmer"
21:36 Tom_itx FARK NO!
21:36 GuShH heh
21:36 Tom_itx an email i got
21:36 GuShH I got a similar weasel poking in my mail a few days ago
21:37 GuShH he wanted free advise so he could engineer and sell a device for a small fortune.
21:37 Tom_itx well, i was nice about it
21:37 GuShH I didn't answer.
21:37 Tom_itx i wouldn't be surprised if he got one of mine
21:37 GuShH Instead I poked around and found out he's part of the competition.
21:38 ShH idly winches his middle finge
21:39 R0b0t1 Competition in what?
21:39 Tom_itx i wish i could compress all these audio files and still have them work with rhapsody
21:39 pythonsnake as a all terrain chassis any car toy would work?
21:40 R0b0t1 NO
21:40 Tom_itx it would work within it's limits
21:40 R0b0t1 you'd need an all-terrain chassis
21:40 Tom_itx if the toy won't do it, the µC controlled one won't either
21:41 GuShH pythonsnake: did you meet with the ##electronics guys yet?
21:44 pythonsnake GuShH: a bit
21:45 GuShH and
21:45 GuShH how about #arduino
21:46 R0b0t1 GuShH, shh
21:46 GuShH R0b0t1: what?
21:46 R0b0t1 I went into #arduino, heh. Was talk about commercializing a product and hackerspace franchises
21:47 GuShH ...
21:47 GuShH hipsters with mom and dad money?
21:47 pythonsnake GuShH: same
21:47 GuShH trustfund hipsters (tm)
21:47 pythonsnake #arduino is voidish
21:47 GuShH THE Trustfund Hipster Enterprises
21:48 GuShH pythonsnake: you are still going around in circles
21:48 GuShH finalize your design already
21:48 GuShH otherwise you'll grow old looking at all the options
21:48 GuShH and have nothing in return
21:49 pythonsnake GuShH: yeah :/
21:50 pythonsnake maybe i should just go with that 4wd pirate
21:50 GuShH how come you were talking about arms and now a 4 wheel vehicle
21:51 pythonsnake GuShH: mount the arm on the vehicle?
21:51 GuShH and a chicken coop too
21:51 GuShH use the arm to throw the unlimited supply of eggs toward people
21:53 pythonsnake or a plane with the chicken poop
21:53 GuShH there's a movie...
21:53 GuShH wallace and grommit
21:54 GuShH I think.
21:54 GuShH yeah, they escape on a flying coop from the chicken pie factory
21:54 pythonsnake lol
21:56 Faek GuShH knows where it's at
21:58 MrCurious wife said she wanted to do woodworking and make little animal stools
21:59 MrCurious i asked if she meant the round kind or the 2" long kind
22:00 GuShH MrCurious: and the response was?
22:00 MrCurious not positive
22:01 GuShH buy her some brown and white paint so she can paint the stools
22:01 ShH bl
22:01 MrCurious thought you just painted em black, and they turned white on their own
22:02 GuShH I got a dry-ish can of Bondo you could use to sculpt a stool!
22:02 GuShH black is bad... on any animal or person.
22:02 MrCurious sculpt'ed stool....
22:02 GuShH stoolbend stools
22:02 MrCurious sounds like the product of a 3rd world starving artist
22:03 GuShH it could just as easily come from a hipster in san francisco
22:03 GuShH except the stool would also be a marihuana dispensery
22:04 GuShH MrCurious: don't you have woodworking tools?
22:05 GuShH here's a way to support her, say they have to be made with a CNC and for that to happen, more money needs to be allocated toward the CNC project!
22:17 rue_more the alkaline 9V lasted 66442 seconds
22:17 rue_more 18 hours, at 20hr rate
22:18 rue_more I thik thats almost .4Ah
22:26 R0b0t1 http://papilio.cc/
22:26 R0b0t1 arduino for fpga
23:09 MrCurious BAM!
23:10 MrCurious bit-angle modulation BRILLIANT!
23:37 MrCurious big bang theory is killing me tonight
23:37 MrCurious "you brought a catholic girl home to mother? why dont i write you a prescription for xanax"