#robotics Logs

Mar 19 2017

12:08 AM Jak_o_Shadows: Delta IK?
12:17 AM anniepoo_: Roger bravo seven, you are go for delta ik on charlie three
12:19 AM Snert: :)
12:20 AM anniepoo_: 8cD
12:22 AM Jak_o_Shadows: aha
12:23 AM anniepoo_: I've been using blender to figure out where everything goes in the snail
12:23 AM anniepoo_: the internal morphology
12:25 AM Jak_o_Shadows: Pics?
12:25 AM anniepoo_: hang on
12:25 AM Jak_o_Shadows: Gotta say, blender is good for quick thinking
12:26 AM anniepoo_: http://partyserver.rocks/anniepoo/snailxray.png
12:27 AM anniepoo_: yes, when i know where everything goes, I'll make a proper set of CAD drawings, mostly illustrator files for the laser
12:28 AM anniepoo_: anybody have opinions about how to articulate the neck and head?
12:28 AM Jak_o_Shadows: Robot arm
12:29 AM anniepoo_: ??
12:29 AM anniepoo_: what about robot arm?
12:29 AM Jak_o_Shadows: Just build a 3-4 DOF robot arm and shove it in the neck.
12:30 AM Jak_o_Shadows: I'd suggest a stewart platform, but you sorta want a lower neck and upper neck
12:30 AM anniepoo_: Hmm...
12:32 AM anniepoo_: instinctively I was thinking something spine-like
12:33 AM anniepoo_: stewart platform --> parallel manipulator --> spine-ish thing
12:35 AM Jak_o_Shadows: The thing about stewart platforms, is thtat unless you use linear actuators, it's hard to make them small
12:35 AM anniepoo_: well, I can think of twisted string actuators and cable mechanism
12:35 AM anniepoo_: it's such a confined area, and I have lots of space in the shell
12:36 AM anniepoo_: that remoting to servos elsewhere makes sense
12:36 AM anniepoo_: though introducing a raft of their own problems
12:36 AM Jak_o_Shadows: I wonder if using https://www.aliexpress.com/item/HiSKY-HFP100-WLtoys-V944-RC-Helicopter-Parts-LS90-Linear-Servo/32556738951.html?spm=2114.01010208.3.37.4ymk3X&ws_ab_test=searchweb0_0,
12:36 AM Jak_o_Shadows: searchweb201602_4_10065_10130_10068_433_434_10136_10137_10138_10060_10131_10132_10062_10133_10141_10056_10140_126_10055_10054_10059_10099_10103_10102_10096_10052_10053_10050_10107_10142_10051_10106_10084_10083_10080_10082_10081_10110_10111_10112_10113_10114_10078_10079_10073_10070_10122_10123_10124-10051,searchweb201603_5,afswitch_1,ppcSwitch_7,single_sort_0_price_asc&btsid=b1f0cff6-bbe1-460b-a569-f3cc62ada21a&algo_expid=ba0a15a5
12:36 AM Jak_o_Shadows: -531d-4061-a01a-192eae3d7f62-4&algo_pvid=ba0a15a5-531d-4061-a01a-192eae3d7f62 would get you enough
12:36 AM anniepoo_: (mechanical complexity, rigidity/hysteresis issues, ....
12:37 AM Jak_o_Shadows: I mean, if you're stacking stewart platforms anyway.
12:37 AM anniepoo_: you know, I should build a prototype
12:38 AM Jak_o_Shadows: I'm 12 M4 bolts, and half a dozen hours of 3D printing away from my stewart platform
12:38 AM anniepoo_: I can use the laser and make a lot of these options pretty quick
12:39 AM Jak_o_Shadows: If you need help/anything for the FK side of things (or IK), I can help with stewart platform
12:39 AM Jak_o_Shadows: I have code for both
12:39 AM anniepoo_: oh, thanks
12:39 AM Jak_o_Shadows: Even for rotary stewart platforms - albeit my own weird kind
12:45 AM anniepoo_: imagine a spine - a series of disks in the horizontal plane, cross sections of the neck
12:45 AM anniepoo_: at the back the actual spine - a flexible but incompressible support
12:46 AM Jak_o_Shadows: and then have tendons and muscles attached?
12:46 AM anniepoo_: a cord wraps helically around the periphery of the disks.
12:47 AM anniepoo_: yes, I have these cords, clockwise and counterclockwise, and
12:47 AM anniepoo_: they go up a varying number of disks
12:48 AM anniepoo_: I'm being a bit vague and cloud shaped here
12:48 AM Jak_o_Shadows: It's interesting
12:48 AM Jak_o_Shadows: good luck
12:50 AM anniepoo_: yah, I think I'll try making a prototype
12:50 AM anniepoo_: I'm spending too much time trying to design when I'm guessing
12:51 AM anniepoo_: probably not even electric, just lasered scraps and string
01:15 AM anniepoo_: thakns for the pointer towards parallel manipulators
01:15 AM anniepoo_: I think that's what I need to be thinking aboujt
01:21 AM Jak_o_Shadows: No worries
01:21 AM Jak_o_Shadows: parallel manipulators are fun
03:34 AM rue_shop3: I'm building another arm
03:34 AM rue_shop3: arm10
03:45 AM Jak_o_Shadows: My light-up alarm clock is theoretically working
03:45 AM Jak_o_Shadows: and I just designed this - http://pasteall.org/pic/show.php?id=113686 It's a base for ahttps://www.amazon.com/NEEWER-Microphone-Suspension-Scissor-Stand/dp/B00DY1F2CS/ref=sr_1_1?ie=UTF8&qid=1489911368&sr=8-1-spons&keywords=microphone+stand&psc=1&smid=A2L2IBCOJNQSLR that I put bearings on the base, to let it spin
03:46 AM Jak_o_Shadows: https://www.amazon.com/NEEWER-Microphone-Suspension-Scissor-Stand/dp/B00DY1F2CS/ref=sr_1_1?ie=UTF8&qid=1489911368&sr=8-1-spons&keywords=microphone+stand&psc=1&smid=A2L2IBCOJNQSLR oops
03:46 AM Jak_o_Shadows: It's not going to clamp on, it'll just screw into the table.
03:49 AM rue_shop3: test1; can a robot assemble itself or another robot: Can the robot turn a screw?
04:04 AM Jak_o_Shadows: I am a little concerned about delamination. That is how most of the foce is.
04:05 AM Jak_o_Shadows: But I don't really want to print it sideways.
04:05 AM Jak_o_Shadows: and well, I'm going to pretend I have a lathe, and just print it like this.
04:14 AM rue_shop3: whats it?
04:15 AM rue_shop3: almost 2am, dont think I can stay awake
04:17 AM Jak_o_Shadows: The second link - I want it to more freely rotate
04:18 AM Jak_o_Shadows: SO I designed something to hold two 608 bearings
04:36 AM Poltergiest: hi Jak_o_Shadows
04:36 AM Jak_o_Shadows: hiya
04:37 AM Poltergiest: how are you ?
04:37 AM Jak_o_Shadows: good. You?
04:37 AM Poltergiest: yeah im good thanks
04:38 AM Poltergiest: how long you been playing around robotics?>
04:38 AM Jak_o_Shadows: Vaguely a few years?
04:38 AM Poltergiest: cool
04:38 AM Jak_o_Shadows: Haven't achieved a heck of a lot.
04:38 AM Poltergiest: oh
04:38 AM Poltergiest: i havent done any yet, however ive always been interested. just never knew where to start
04:39 AM Jak_o_Shadows: To be honest, at the moment, it seems that anniepoo_ is the closest to actually have a new robot.
04:39 AM Jak_o_Shadows: (Rue's got another arm coming though)
04:39 AM Poltergiest: cool
04:40 AM Poltergiest: what software do they program in ?
04:41 AM Jak_o_Shadows: WSell, embedded is all in C
04:42 AM Poltergiest: ok cool
04:42 AM Jak_o_Shadows: If i'm just doing some quick calculations, quick plotting, quick proof of concept stuff, I'll often use matlab.
04:42 AM Jak_o_Shadows: If I want more serious calculations, stuff that's meant to tie together, I'll use python (and numpy & scipy)
04:42 AM Jak_o_Shadows: If I want to 3d visualise things, i'll use Blender
04:42 AM Poltergiest: any c++?
04:42 AM Jak_o_Shadows: If I want to design things, I'll use autodesk inventor
04:42 AM Jak_o_Shadows: Not for me
04:43 AM Poltergiest: ok cool
04:43 AM Poltergiest: anyone in here from sydney ?
04:43 AM Jak_o_Shadows: Um. I think there is.
04:44 AM Jak_o_Shadows: I'm south australia myself
04:44 AM Poltergiest: nice
04:45 AM Jak_o_Shadows: At a guess, you're a student?
04:45 AM Poltergiest: noooo
04:45 AM Poltergiest: lol
04:45 AM Poltergiest: just someone thats always been interested in robotics
04:45 AM Poltergiest: im a psychologist
04:48 AM Jak_o_Shadows: aha.
04:48 AM Jak_o_Shadows: Fair enough
04:48 AM Snert: if one of our bots goes crazy we'll know who to consult :)
04:48 AM Poltergiest: :)
04:49 AM Jak_o_Shadows: We're a generally friendly enough bunch
04:50 AM Poltergiest: lol
04:50 AM Poltergiest: cool
04:51 AM Poltergiest: that always makes it easier
04:52 AM Poltergiest: Jak_o_Shadows, r u a student ?>
04:53 AM Jak_o_Shadows: Nup
04:55 AM Poltergiest: ahh
04:55 AM Poltergiest: what u do ?
04:59 AM Jak_o_Shadows: Dunno what the technical term is.
04:59 AM Jak_o_Shadows: Works out to sitting at a computer, reading things, little bit of boding together code, and some reports
05:01 AM Poltergiest: ahhh
05:01 AM Poltergiest: sounds exciting
05:01 AM Poltergiest: :)
05:07 AM Poltergiest: anyways time to get some dinner ready. ill come back again thanks for chatting
05:08 AM Jak_o_Shadows: No worries
05:08 AM Jak_o_Shadows: Nowadays, apart from 4-4:20am (South Australia time) I'm always online.
05:08 AM Jak_o_Shadows: ie. I get messages. I do sleep though
06:26 AM Jak_o_Shadows: You know that feeling, when you design something to be 3D printed,then decide that you'd be better off cutting it out of a block of wood?
06:26 AM Jak_o_Shadows: Yeah.
06:27 AM SpeedEvil: :)
06:27 AM SpeedEvil: yeah - sometimes it's eleven hours of 3d printing, or two minutes with a saw.
06:27 AM Jak_o_Shadows: It started off with these somewhat nice features. But it was gonna take 4 hours of printing. So I kept siimplifying.
06:28 AM Jak_o_Shadows: Then realised It's literally 6 holes, two counterboes with a spade bit.
06:29 AM SpeedEvil: Quite
06:29 AM SpeedEvil: If you have literally no other tools, it can often be a real ame-changer.
06:30 AM SpeedEvil: With even a drill and a handful of bits, hacksaw, ... -
06:30 AM Jak_o_Shadows: I mean, if I had a drill press, this piece would literally take me 10 minutes.
06:30 AM Jak_o_Shadows: Wihtout one, I'll have to be a bit more careful drilling one of the holes.
06:31 AM SpeedEvil: drill guides are pretty good.
06:31 AM Jak_o_Shadows: Drill guide?
06:31 AM SpeedEvil: Block of wood, drill hole in, oil hole.
06:31 AM SpeedEvil: Lasts nearly forever
06:31 AM Jak_o_Shadows: To keep it nice and perpendicular?
06:34 AM SpeedEvil: yes
06:34 AM SpeedEvil: Not for spade bits, as simply though
06:35 AM Jak_o_Shadows: The spade bit is just to counterbore, for a 608 bearing
06:37 AM Jak_o_Shadows: The tricky bit is because they're on both sides, concentric.
06:37 AM Jak_o_Shadows: So I'll drill the spade, swap to a smaller bit, drill all the way through, swap to spade, counterbore, swap to 9mm, drill out the centre
06:38 AM Jak_o_Shadows: Cause spade bits don't like not having that starting point
01:21 PM Ahti_ is now known as Ahti
01:28 PM rue_bed: Jak_o_Shadows, its happened to me lots, when I go thte lathe too
01:28 PM rue_bed: I was like, wait a min, I can just _____ instead
01:31 PM veverak: rue_bed: was thinking
01:31 PM veverak: that it should be doable, to pake PCB port with <some> microcontroller
01:32 PM veverak: for controlling 4 servos with load feedback
01:32 PM veverak: and feedback from soldering wire to ponteiometer inside servo
01:39 PM rue_house: sounds like your starting to think of modular reusable generic technology
01:40 PM z64555: replacible parts!
01:40 PM rue_house: I was thinking, if you tap one side of the motor, you can know the polarity as well as the amplitude of the force
01:41 PM rue_house: I was also thinking, if you know the position, you can control the size of the motor pulse by knowing the controllers pulse characteristic
01:41 PM z64555: sensor across one of the stator coils?
01:41 PM rue_house: no
01:41 PM rue_house: the current tells you the force on the motor
01:41 PM rue_house: tapping one side of the motor tells you the polaity its running
01:42 PM rue_house: if you also tap the pot, you know position too
01:42 PM z64555: not sure what you mean by "tapping" then
01:42 PM rue_house: to solder a wire to
01:42 PM z64555: oh. huh.
01:42 PM rue_house: you take-off from 3 points to know everything
01:42 PM z64555: yeah
01:43 PM rue_house: maybe today I should write servo 201
01:44 PM rue_house: https://en.wikipedia.org/wiki/101_%28number%29
01:44 PM rue_house: dear god, really!?
01:44 PM rue_house: I know the wikipedia is full of useless informatoin, but really?!
02:09 PM Snert_: I think it's 101st.
02:09 PM Snert_: as in 101st Airborne.
02:10 PM Snert_: so they got something right :)
02:12 PM Snert_: brought to you by the number 101, of course
02:22 PM justan0theruser: I'm making an elbow joint for a robot arm. The bicep is made of t-slotted framing. Do you think I should have bearings mounted to the ends of the t-slotted framing? Or is there a better way to allow a shaft to rotate freely while attached to the framing
02:27 PM justan0theruser: Also, how much of the cost of t-slotted framing is the raw materials and how much is the manufacturing
02:46 PM rue_house: I'v has quite a fight with that part of the design for my 12' mecha
02:47 PM rue_house: the conclusion I came to was to use a thick threaded bolt, long, and put the forearm on a big-ass nut, it will not pull off, but will rotate within 180 degrees just fine, with the only disde effect a slight change in length
02:48 PM justan0theruser: Do you have a picture? I'm having trouble visualizing what you're describing
02:51 PM rue_house: nut and bolt
02:51 PM rue_house: they turn, but do not slip off each other
02:56 PM justan0theruser: oh, your'e saying the shaft itself is a nut?
02:56 PM justan0theruser: bolt*
02:58 PM rue_house: so that it can turn axialy with out having to make connections that are too fancy to deal with pull
03:17 PM justan0theruser: this is my current design blob:https://imgur.com/a4ae048a-27bb-4364-bb1f-546d2b4bfc4e
03:17 PM justan0theruser: woops
03:17 PM justan0theruser: https://i.imgur.com/So4VXVm.png
03:17 PM justan0theruser: I think I'll stick with it for now
06:45 PM anniepoo_: Anniepoo's a long ways from having a new robot
06:45 PM anniepoo_: 8cD
06:45 PM anniepoo_: but thanks for the vote of confidence
06:45 PM anniepoo_: life's caught up with me the last few weeks
07:31 PM veverak: rue_house: I am getting into phase, where each module can be module connected to main body
07:32 PM veverak: *each leg can be module
07:32 PM veverak: and you can freely replace 3DOF leg for 5DOF and it will still walk
07:32 PM veverak: #wetDream
09:22 PM anniepoo_: Can it do that without breaking stride? ;-)