#robotics Logs

Jun 11 2015

01:11 orlock clear skies it looks like
02:30 wolfmanjm deshipu: this looks closer, but it doesn't actually move much when set on the ground... https://flic.kr/p/ucEKWm so i guess there is some other magic number somewhere I need to play with ;)
03:16 deshipu wolfmanjm: well, most likely you need to shift the body more, since it's larger
03:18 veverak wolfmanjm: yep
03:18 wolfmanjm ok which parameter is that? SHIFT
03:18 wolfmanjm or STRIDE?
03:21 Triffid_Hunter wolfmanjm: how long have you been hanging out in here/
03:21 wolfmanjm Triffid_Hunter: a while now :)
03:21 wolfmanjm every since I started playing with a quadruped
03:22 wolfmanjm I'm using deshipus code to drive it
03:22 Triffid_Hunter oh neat
03:22 Triffid_Hunter I'm thinking about making one at some point
03:22 Triffid_Hunter slap a cortex-m4f on it and do kinematics
03:25 wolfmanjm Triffid_Hunter: I'm running min eoff an edison
03:26 wolfmanjm but i think I'm going to convert to a hexapod I have the servos and bearings on order
03:26 wolfmanjm I think hexapod gaits are much easier to code
03:26 wolfmanjm this quadruped is giving me heartburn
03:26 Triffid_Hunter the boring ones perhaps
03:27 Triffid_Hunter dynamic gaits are the only sort I'd be interested in, and afaik they're just as hard with 1 leg or 8
03:27 wolfmanjm yea that is true
03:27 Triffid_Hunter with a quad you need to have the CoM well centered, and either in the stable triangle or heading into it when you lift each leg
03:28 Triffid_Hunter I'd really love to write some code that would lift diagonally opposite legs simultaneously without the thing falling over
03:28 Triffid_Hunter make it skip like those fancy horses do
03:29 deshipu wolfmanjm: SHIFT, STRIDE is the length of a step
03:30 deshipu Triffid_Hunter: I have that
03:30 Triffid_Hunter teach 'em a drunken sailor walk where they translate laterally to shift the COM from one stable triangle to the other
03:31 wolfmanjm so SHIFT is to shift the center of gravity so it doesn;t fall over? that seems to be ok it doesn;t fall over, but it seems to not move is a consistent direction if at all
03:31 deshipu Triffid_Hunter: basically it switches from creep to trot at certain speed
03:31 deshipu wolfmanjm: well, fall over or fall on the legs that were supposed to be on the ground
03:31 Triffid_Hunter deshipu: next step is to teach it the spin-run like the observer biots from rendezvous with ram
03:31 Triffid_Hunter rama*
03:31 deshipu wolfmanjm: it's too wide to really fall over
03:32 deshipu Triffid_Hunter: that would be doable, actually
03:32 wolfmanjm the leg it is lifting seems to clear the ground ok and move. but the other legs don't seem to move the body very much in the forward direction
03:33 deshipu Triffid_Hunter: you mean http://www-arailab.sys.es.osaka-u.ac.jp/index.php?option=com_content&view=article&id=79&Itemid=112&lang=en ?
03:33 Triffid_Hunter wolfmanjm: they can't, or the CoM would move outside the stable triangle and it'd fall onto the leg it's moving. have to establish a new triangle then shift into it first
03:33 wolfmanjm Triffid_Hunter: I think it is doing that part ok
03:34 wolfmanjm one leg lifts and moves then drops that seems to work
03:34 wolfmanjm but I'm not getting overall forward motion
03:34 Triffid_Hunter deshipu: heh is that thing doing cartwheels?
03:35 deshipu wolfmanjm: well, the initial speed is set quite low
03:35 deshipu Triffid_Hunter: yup
03:35 deshipu Triffid_Hunter: there was a video somewhere too
03:35 Triffid_Hunter well it's not quite what I had in mind, but that would be awesome too
03:35 Triffid_Hunter the gait I was thinking of is similar to when ballet dancers pirouette across the stage
03:36 deshipu https://youtu.be/kMF83m8lNrw?t=98
03:36 deshipu the Asterisk robot is one of my favorites, shame most information is only in Japanese
03:37 deshipu and there hasn't been many updates since 2011
03:37 Triffid_Hunter have you seen the ones that skate?
03:37 deshipu yeah, that's stupid :P
03:37 Triffid_Hunter that's awesome
03:37 Triffid_Hunter high speed movement on flat terrain, can still walk up stairs by locking the wheels
03:37 deshipu well, doesn't make sense when you can simply put a motor on the wheels
03:38 deshipu if you look at that video, by the way, that robot does that too
03:38 deshipu and it climbs on vertical nets
03:39 deshipu I agree that wheels at the ends of the legs are probably the best locomotion method for a small robot in buildings
03:39 deshipu I have an idea for a logicoma-like robot
03:41 deshipu with only 12 servos (4 converted to continous rotation)
03:42 Triffid_Hunter logicoma? is that like tachikoma?
03:42 deshipu yes, only simpler
03:43 deshipu Shirow keeps on changing those bots
03:43 deshipu first it was Fuchikoma, then Tachikoma, now Logicoma
03:43 deshipu logikoma?
03:43 deshipu no idea how it's spelled
03:45 deshipu http://itakon.it/giapponesi/ghost-in-the-shell-arise-logicoma-124-plastic-model-di-wave-in-preordine.html
03:45 deshipu I could have two servos per leg and make it walk dog-like (without sideways movement of the legs)
03:46 deshipu and then put 4 servos on the ends with wheels
03:47 deshipu if I connected them pairwise to the same signal, I could even use one servo for the eye and one for the hands
08:26 deshipu http://i.imgur.com/VPdJTDE.gif
08:26 deshipu turobo-turtle
23:30 zhanx Evening