#robotics Logs

Dec 13 2012

18:28 Tom_itx http://www2.electronicproducts.com/MIT_creates_mini_reconfigurable_robots_that_can_transform_into_anything-article-FANE_MIT_tiny_robots_Dec2012-html.aspx
19:02 Centauri Tom_itx: the 2nd link is interesing work.. 1st time I have seen new motors designs to do this.. the older designs I remember were interlocked servos (and far larger)
19:10 home hmmmmmmmmmmmmmmmmmmm
20:02 rue_mohr hmmm
21:21 rue_mohr man, there are some nice android tablets out there for like $60
21:25 Tom_itx google won over imap
21:31 rue_mohr nobody was ever preferential to imap
21:31 rue_mohr people dont know where there data is
21:31 Tom_itx it kinda sucked
21:31 rue_mohr most people dont care
21:32 rue_mohr most people dont even care if they loe it caue they throw it out every year or so
21:32 rue_mohr sss
21:33 Tom_itx i'm betting early next week
21:33 rue_mohr end of the world?
21:33 Tom_itx but then i don't win many bets
21:33 rue_mohr do you usually?
21:33 Tom_itx for your mailbox to be stuffed
21:35 Tom_itx i was gonna wire up the encoder tonight but i'm bushed
21:36 rue_mohr wire it up to what?>
21:36 Tom_itx the menu
21:36 rue_mohr ah
21:36 rue_mohr do you have to make an adapter?
21:37 Tom_itx i was just gonna stick some wires on one
21:37 Tom_itx i made an eagle footprint for it
21:37 Tom_itx the adapter will fit my lcd, encoder, sd and a couple other things
21:38 rue_mohr not using a cable adapter then
21:38 Tom_itx i dunno yet, i might
21:39 Tom_itx i'm just tossin stuff in the schematic right now
21:43 Tom_itx that would mean 2 boards then instead of one
21:50 Guest61271 +?
21:51 Tom_itx -�
21:51 Guest61271 hi sorry guys but what short of robotics is this room about?
21:51 Guest61271 arduino, atmel, microchip?
21:51 Centauri ;)
21:52 rue_mohr not microchip, we dont like that one
21:52 Guest61271 ok, smart man
21:52 rue_mohr all other kinds
21:52 Tom_itx most
21:52 Guest61271 ok, nice I hit the right spot then
21:52 Centauri rue_bed: given microchip is a closed system, I would assume the same fort BASIC stamps?
21:52 rue_mohr we also do mechanics and electronics
21:52 rue_mohr I dont mind basic stamps for people starting out
21:53 Tom_itx i have a stamp 2 somewhere
21:53 Tom_itx didn't do much with it
21:53 Centauri expensive as they are ;) but yes, there are many choices out there
21:53 Guest61271 :), lol I have one of those
21:53 Guest61271 I'm trying to get some experience with ethernet based chips
21:54 Centauri Tom_itx: I too, have one of each, tho I cant re-program them on unix, at this point, they are just taking up space.. as are my 5 jackrabbit boards
21:54 Guest61271 no sure which one to choose I want something not so expensive and basic starting point
21:54 Tom_itx i got 5 of those too
21:54 Tom_itx some kind of rabbit thing
21:54 Guest61271 rabbit?
21:55 Tom_itx http://tom-itx.dyndns.org:81/~webpage/SBC/sbc1.jpg
21:55 Tom_itx on the left
21:55 Guest61271 any recomend. on a net based chip? as a starting point
21:55 Centauri I can tell you this: I am duely impressed with my little Arduino Uno.. I have 2800 lines of C code, using some 22k of program space.. and I am using only some 500 bytes of ram, to run a whole robot (so far)
21:56 Tom_itx http://tom-itx.dyndns.org:81/~webpage/SBC/rabbit.jpg
21:56 Jak_o_Shadows Centauri: I'm probably going to use several hundred megabytes, i'm going to offload a lot onto a netbook
21:56 Centauri Tom_itx: Mine were in that class as well (from 8 years ago) - when I dropped WinBlows.. I lost the ability to use those
21:57 Tom_itx i've never used em
21:57 Centauri Jak_o_Shadows: Megs? what the heck are you doing? video processing?
21:58 Centauri -- only using ultrasonic, IR, light gyro, compass and such, no vid at this point
21:58 Jak_o_Shadows Video proccessing, in python, as well as a web server for android control, as well other stuff.
21:58 Jak_o_Shadows Was talking about RAM though
21:58 Centauri ahh ok, vid is "hungry"
21:59 Centauri Jak_o_Shadows: one thing I considered in video ram, was first of all, converting to greyscale, then the processing for edge detection, to get it down to something managable
22:00 Centauri the raw image format is truely far too much for something with 2k of RAM
22:00 Jak_o_Shadows aye
22:00 Centauri I even considered a pi just for that.. even transmitting the data serially thru an RF link would take a while
22:01 Centauri so far, vid is completely off the table, given what it would take
22:01 Jak_o_Shadows I'm just gonna build my robot around my netbook
22:02 rue_mohr I should finish mine
22:02 Jak_o_Shadows If i had a jigsaw, i'd be much more motivated
22:03 Centauri Jak_o_Shadows: in general, that might work quite well, you can interface thru the USB and talk to many devices.. or a sub-processor to do all the lower level work. I have pondered multiple CPU design in my work all the time, including my unix server, which has the capacity, but the weakest link is the comm between the 2
22:04 Centauri our own minds are a bunch of processors, each given a specific task (based on the specialty of that brain area) and conceptually, this is not a bad idea
22:04 Jak_o_Shadows I'm planning on initally very little communication, eg: go forward, go back, turn right, turn left, don't turn.
22:04 Centauri I hear ya
22:05 Centauri I finally got that far without crashing into every wall, just this weekend, my bot finally exacaped the office, and wandered half the house this past weekend
22:06 Centauri I can certainly tell you the strength and weaknesses of various sensors, given what I have learned in 7 months
22:06 Centauri especially ultrasonic, VS IR, vs bumpers, etc
22:06 Jak_o_Shadows I gotta figure out how to steer. I'd prefer differential steering, but i don't have 2 identical motors that i can attach wheels to
22:07 Centauri Jak_o_Shadows: mine are not matched either., if I set each motor to 75.. the REAL settings for each motor are typically 75 and 84 for steer straight
22:08 Jak_o_Shadows Yeah, but i don't even have two motors that are similar enough. I have a drill motor, and a bunch of other motors, but the drill is best
22:09 Centauri Jak_o_Shadows: I do this: set each motor forward at 75 each, read the gyro, if the course is steering either left or right.. speed up one wheel to correct.. keep track of the last correction, I use this to avoid what I call "fish-tailing" so if the last correction WAS left, and now right.. dont speed the other wheel, but back off the last wheel I sped up
22:10 Centauri this works well, and keeps from maxxing out both wheels
22:10 Centauri you cant even SEE the correction, because it happens so fast
22:11 Centauri it just looks like its trtacking straight right from the beginning
22:11 Centauri even when they are off by says 40 points of a max of 127
22:11 Centauri I have a routine to say correction = correction / 2 if correction > 2
22:12 Centauri this also helps prevent oversteer
22:12 Centauri but it can correct the total amount within 2 correction calls
22:12 Centauri and this happens within 10-100 milliseconds at worst
22:14 Centauri Jak_o_Shadows: I have a pair of geared motors, but without correction.. I have a "curve" that is say 20 degrees every 5 feet
22:15 Centauri correction is always necessary.. one drive train has more drag in it, etc.. I read a compass, gyro, and soon wheel encoders (to account for slip) all of it is important, and matters in a cascade sort of way
22:16 Centauri you do need a way of detecting that slight curve to the left or right, so you can correct it
22:17 Jak_o_Shadows Yeah. Might be able to use the netbook for that.
22:17 Centauri Jak_o_Shadows: as long as you have sensors.. the math and code is easy
22:18 Centauri bots need a LOT of sensors, unless they are running blind
22:19 Centauri I have been trying to avoid bumpers or whiskers myself, but my poor bot still runs into things that escape detection of things like chair legs.. a physical bumper or whisker would catch this
22:20 Centauri the longer I work on robotics, the more I appreciate our biological systems
22:20 Centauri its a tough ting to do well
22:24 Jak_o_Shadows With your gyro, how do you tell if it's going left/right? Wouldn't a gryo just give a tilt direction/angle in the 3 axis?
22:34 Centauri Jak_o_Shadows: I read the Z axis ( rotation horizontal to the floor) and I can see within a degree per second)
22:34 Centauri in aircraft terms, this is YAW
22:34 Centauri I also check pitch and roll to know he he is runing over crap
22:34 Centauri bu tthe Z -a xis is the one I use for course correction
22:38 Jak_o_Shadows Hmm, i should check if my laptop has those sensors
22:39 Centauri laptop typically doesnt, smmart phone does
22:40 Jak_o_Shadows For some reason my netbook has sensors, that you can get to under linux
22:40 Centauri in fact, a single android smart phone typically contains many of the needed sensors
22:41 Jak_o_Shadows Yeah, i've got an app mostly done, but untested, that uses that for laptiming for racing vehicles
22:44 Centauri ;) - we have a lot of choices these days, how to implement a solution
22:44 Jak_o_Shadows Yep.
22:45 Centauri my friend at work keeps bugging me with "you should just hack a roomba" well that not where I am going
22:46 Jak_o_Shadows well, that's one option, but not the only one.
22:46 Centauri I need to understand each and every part of movement, navigtion, and sensors. not build on something that is fuzzy or black box
22:47 Centauri my bots have a goal in which I really need to know these details, so I can implement in any hardware
23:07 DagoRed hey orlok
23:08 orlok hey
23:08 orlok 41 days till we move
23:08 orlok well
23:08 orlok get the keys
23:08 orlok start moving
23:08 DagoRed damn
23:08 DagoRed Were you living with your mother during this time?
23:08 DagoRed I remember you lost the old place due to the land lord fucking up.
23:09 orlok well, owner sold due to us asking for too much stuff to be fixed
23:10 orlok well, thats what we assume due to the timing
23:10 orlok yeah, living with my mother for the past.. 18 months or so
23:10 DagoRed that has to be fun with the kid
23:10 DagoRed nice at times, baby sitter!