Tag Archives: hexapod

hexacon. well, hexapod jewelry and then someday a post about hexacon

i wanted to make jewelry
i also need prizes for saturday’s hexacon
hexacon2013.mit.edu
hexacon2013.eventbrite.com

bought some supplies from http://www.yelp.com/biz/artist-and-craftsman-supply-cambridge, then lasercut some hexapods from a vector SVG file of my hexapod CAD files

I added some lock washers and made them asymmetrical, because I miss the ones that +Hanna Lin made for me a while back that look like this, but prettier and more functional.

lock washer source, MITERS.mit.edu
Fatal flaw of acrylic jewelry: it only wants to face one direction, sideways, by default (I twisted it around to take this picture). Ah well. A puntly-hour’s worth of work.

I made a video about hexapods.

I made a video about hexapods! yay. I’d estimate it was a full 4 or 5 days working on it, learning final cut pro along the way. It basically covers my journey through 2.007 two years ago, and is meant to be a resource for students in the class.

Note to self: shortcuts: < > ctrl-= alt-w

Meanwhile, I think an instructable a week sounds like an excellent plan for Spring semester senior year.

recap (maker faire, hackaday and hexarideablepod, emergency nyanpancake)


I guess now is as good a time as any to reflect on my years of building things (years now?!). Hello, crackaday.
Quick note: hexarideablepod is run off of two A123 magic 12v batteries and is actually controlled by drill triggers. @__@

First, a brief interlude.

Back in the day I made some nyancakes for MAS.863. That was cut out on the shopbot from pink foam, around which I poured a full pound of easymold two-part silicone mix, aka $26.52 1lb Easymold Silicone Rubber (price has gone up since then).

one of the earlier tries. turns out it’s sad without a mold release agent, aka vegetable oil.

Kind of pricey for a single cake. Most of the silicone goes into the areas around the nyancake which can’t really be hollowed out without doing a two-part mold process. Being utterly lazy, I didn’t do that.

Well, lately I’ve been thinking that a better idea is to make cute little nyancupcake molds. So Saturday around 3 am when we were packing up getting ready to leave for maker faire, I decided to emergency nyancake.

  • 3:19am

Nancy R. Ouyang
hi charles, can i 3d print a tiny nyancake right now?
like 1” x .5 ”
if not that’s okay!
i recognize i am slightly crazily procrastinative

  • 3:21am

Charles Guan
squee squee squee
0_0 do you have the stl?
it’s gonna take like 15 minutes just to heat the machine up
i somehow think this is a bad idea 0___0
if you’re really down i’ll go heat it up right now

This actually turned out pretty well!

Files: https://github.com/nouyang/orangenarwhals-nouyang-blog-files

So then I was staying over at Dane Kouttron-wrote-own-software-for-giant-robot-arm-turned-3d-printer-currently-printing-[transportation to be disclosed] person. After getting home from maker faire I took my 1 lb Easymold Silicone Putty ($20) (putty, because since this is way smaller I don’t need to pour in the silicone) and mashed the two parts (white and purple putties) together and then stuck it into the mold. The only issue is I lost one of the eyes which wouldn’t come out of the 3d print.

The next morning, I pancaked! Using box pancake batter. This turned out surprisingly well — the pancake batter resulted in lots of holes yet it held the shape pretty well. We vegetable oiled the interior, spooned a bit of batter in, used the spatula to speed flip everything over, and let it sit for a few minutes, and then took it off the burner and let it cool to medium hot (this is a theory, that letting it cool a bit = contracts and better shape retention, and cooling too much = well idk).

ahhh one-eyed cat pancakes

Then once we got to maker faire I had this awesome idea of getting someone to 3d print me a slightly larger cake mold and ask the pancake printer people to make some pancakes for me.

Some helpful people in the 3d printer pavilion printed this out, although it finished after we left so no pancakes :'( Ah well, good shot at emergency maker faire project.

Note spider webs, sphincter compared to earlier print; need more drool control πŸ™‚ Appears to be branch from MTM snap

Okay, so back to existential crisis.

(I am totally doing this to intro all my projects so far, because I’m shameless. Also I made a portfolio recently and realized I should actually organize things).

I would count 2.007 as the first time I really started building things (which is an interesting thing in itself — does this mean I only count electromechanical things I built mostly by myself?). As usual I’m plagued by my sense of inadequacy. Because I try to point out to my friends how awesome they are when they talk about their failures and envies, I can recognize the symptoms of this cognitive distortion. And at maker faire — I got a hackaday post off of what I would call a ripoff design, when all my friends have made such awesome projects. Just at maker faire, there was Bayley and Kramnik‘s oneTesla (soon to be kickstarted), Nick’s wholly unique forging-his-own-path-at-MITERS musical instruments and tricopter, Charles’s chibikarts, Shane’s crazy motor controllers, tinykart, and quadrotor, also Ben Katz’s I’m-a-crazy-freshman (okay Kramnik is too but he’s not new to MITERS) awesome!scooter, dgonz‘s scooter and robot arm, Hunter Bank’s let-me-almost-make-an-entire-scooter-in-two-days (designed beforehand), Dane‘s crazy death scooter (pics not up yet), Ted‘s bike-scooter, and a ton of projects

oh robot hexalord all the projects

Anyway, you see what I mean? Here I’ll list out how I think about my projects. I’ll roughly list my projects in my scale of rather inadequate to completely inadequate. Mostly it’s a combination of two axis — how much engineering I put into it and whether it actually worked or not.

1) hexapod 18 servo
— failure because I never built controls / even sensors for it. Also now dead in the water because after several plane trips, I appear to have killed the pololu serial servo controller – a whopping $50 — which goes to teach me a lesson, buy things with the bare minimum I need because I’ll likely destroy it ;___; . To become legit: need to make actual (3d printed?) case for it, also figure out servo calcs instead of beast-it-and-hope-it-works as I’ve been doing. Figure out how to write inverse kinematics controls, make a GUI interface, make it dance.

2) hexaridaeblepod
— failure because I did very little engineering — almost entirely a ripoff of the epic rpalanteo instructables. Also I don’t think I’ll be working on anything other than maintenance for a long time. Well, maybe add some LED strip lights and a speaker playing nyancat, because I am apparently hexapod nyancat project person.

fewer kids than last year, also no rides the second day because I didn’t have batteries because other people’s projects ate them… ;__; the whole reason I brought hexarideablepod was to give kids rides
Also it runs much faster / scarier at 24v but I seem to be on a blowing-up-controllers spree right now.

3) Nyancake
— failure because zero engineering involved besides CADing the model.

4) persistence of vision yoyo
Failure because I never actually carried through on it and got it working (display text) with rotation, and got it to work as a yoyo. Although I did learn about charlieplexing, wrote terrible pov yoyo code which only worked when you waved the yoyo in a straight line.

5) 24v motor controller (h-bridge)
Well, I attempted to make this in 48 hours. That was a fail. I am most sad that I failed to even get to test it because I had issues with routing tiny traces under components, which the mill didn’t cut out, and also soldered the caps on top instead of poking out the bottom so I couldn’t reach the leads to solder them down. Derr. Fail. It was a simple H-bridge controller and I couldn’t even manage that despite lots of help from the thorough documentation on Charles‘s and Shane’s blog. Also it played into the pattern (yay cognitive distortion) of me not finishing final projects. -___-;;

6) Electronics vending machine
— failure because oh yea, speaking of not-finished final projects, this was for MAS.863, I made this over 48 hours — CAD’d and lasercut over 24 hrs — and I skipped the entire final class for it and only brought the half-working thing to the open house. Professor Gersheneld, I’m super sorry for taking up a spot in the class and not doing my fair share of work, although I guess in the end I am the only who lost out.

7) Random lasercutter stuff
(lab glass, business cards, clock)
— failure because, well actually I really like the lab glass present for Dan Fourie (found glass of reuse = free gift for putz cruftmas), but for the most part, no engineering involved.

gift for my friend, alice chung
clock face for what was actually supposed to be a waterjet-marble class, but I wimped out.
Cathy Wu! and anodized aluminum laser-etched..
yay fuzzy pictures. “MIT 2013, Meche (2-A), ~dream it. build it. ~ orangenarwhals.blogpsot.com”

8) Nyanweight
— failure because I intended to make a 3d nyancat, but ended up making an engraving only because I spent countless hours and couldn’t get masterworks to overlap the cuts in the right order (yay pixels = many paths ending on the same point).

speaking of which, I don’t know where i put this. oops.

9) hexapod reading group
Katy Gero took charge and spearheaded the lasercutter – bristol board – doube-sided tape replica of berkeley biomimetic millisystem’s hexapods. Cool linkage design. So again I had nothing to do with the design, although I’m happy I inspired people to make things.

credit: katy gero

10) nyantart
— failure because it is entirely a derivative of lvl1 work. Zero engineering! Yay GIMP trace of bitmap on internet!

hi lasercutter <3>

11) Metrify wireless sensors
— failure because I didn’t do any board design (all by mark spatz) — I was more business “cofounder” (no, we didn’t pursue the project as a startup, but it did help me get a job my amazing internship at fitbit). also uber thanks to startlabs for funding us and redstar ventures for hosting us.

daww generic chinese nrf24l01+ knockoff of nordic breakout board.

12) 2.008 project
— failure due to my terrible grade in that class, also I don’t feel like I contributed much to my team. I didn’t pay enough attention to lecture even though I am fascinated by manufacturing, I didn’t learn all the ins and outs of the magical mold-making process since I worked on the thermoform mold.

does it say MIT? or hell?
Hmmkay. Look, all the dumb projects I have done.

fixing the hexarideablepod shaft slipping issue

I’ve had this recurring problem where the set screws on hexarideablepod prevent the aluminum torque transmission bar from slipping radially on the shaft, but have issues preventing it from slipping axially.
Today I learned today courtesy of Mars, regarding ways to prevent axial slippage:
  • Retaining rings (clips, e-clips, c-clips, circlips) are more for axial alignment, not very load-bearing
    • E-clips are “Side-Mount External Retaining Rings” 
    • the middle part of the E isn’t supposed to go inside a keyway.
      Yea, that retaining ring I put on earlier (sticking the middle part in the keyway and dremeling an imprecise groove for the other “ear” parts of the e) wasn’t actually being that useful, although it did seem to help. 
  • Cotter pin + washer is a good solution, 
    • can probably take a hand drill even and drill a small diameter hole through the shaft
  • Even a small divot instead of a flat channel will go a long way to helping the set screws not slip around the shaft
  • I could mount a steel plate to my aluminum linkage and weld the linkage permanently to the motor shaft steel, 
And then finally the “duh” easiest solution, since I’m only concerned about inward slippage, is make a PVC standoff. 
This is super exciting, since I can finish this in 15 minutes (wellllll. If our bandsaw wasn’t out of service…. a long story… oh MITERS) and then the hexarideablepod will be mostly mechanically robust.
The electricals will be a piece of cake because I found drill triggers that are 24V 16A and make me happier than my 15V triggers. (yea, yea, I should make my own dumb motor controllers, but the packaging is just so convenient. People will even sit on turned-off hexarideablepod and play with the triggers just because). So I just need to rewire that, and make a more permanent battery mounting solution, and I’m all set.
Oh, and find another tennis ball, I lost one of my floor protectors.
Also add some 12V rgb LED strip lighting.
Next for NYC Maker Faire: 
  • hexadancingpod
    • model & print new body
    • buy new pololu serial servo controller because I am too lazy to make my own
    • build battery pack
    • buy accelerometer and ultrasound (or find)
    • write software
  • nyancat singing poptart
    • arduino + speaker
    • arduino + piezo
    • attiny + piezo -> buy surfacemount attiny’s, scrounge up piezos (get digikey account)
  • vending machine
    • add buttons
    • if time, add ir led sensors
    • ??? payment ???
  • pov poi
    • buy rgb LEDs
    • route board
    • packaging?
Other notes:

My shaft measured about 43/64” (672 mil) , so it seems like the standard given motor shaft diameters, in this case 3/4” (725 mil), is larger than the actual shaft size (? check this with someone).

========
Some notes I was taking:


Common ways of preventing axial slippage in the inward direction:
  • cotter pin
    • requires drilling a thin hole all the way through the motor shaft
  • retaining ring http://www.mcmaster.com/#retaining-rings/=jcg38v
    • requires machining a precise groove all around the motor shaft
    • which means if I lamely do it with a dremel (how do people do it anyway? build a fixture with a cutting edge, apply power to the motor, in a temporary lathe sort of way?) then the retaining ring isn’t going to be very strong (it’ll pop out).
    • I’m not sure about installing it since I have keyways on both sides of the shaft so it’s hard to not have one of the ends of the “e” dig into a keyway instead of a groove.

emergency motor controller fail

just an update to say no, i did not successfully make a motor controller in 48 hours πŸ™‚
(see previous post for schematic: http://www.orangenarwhals.com/?p=152)
what was it? a 6.131 final project / motor controller for hexarideablepod (derived off of an instructables):

which works, but uses an arduino and two victor speed controllers — total overkill. also, terrible UI: it uses a hard to reach switch for fwd/bwd and foot pedals, which little kids have issues reaching even with the awesome!adjustable-car-seat.

block diagrams! ewww.

https://github.com/nouyang/hexapodtroller for the eagle sch/brd. You can see terrible routing here:

power board (4 FETs to make a full H-bridge)
sig board — attiny44 and four FET drivers (21844s). also, chain voltage regulators from 24v battery to 15v for drivers to 5v for attiny logic.

speed routing and my inexperience led to use of 24 zero ohm resistors and I still used a jumper πŸ™‚

hai zero ohm resistor friends
If you look closely, you can see some of the trace fails (compare IRL to board layout) which were probably due to too high error allowances when the fab module was creating the roland modela machine code. See: pins 8 and 9 on the top right side of the topmost IC, the attiny44. They’re connected on the board but not on the schematic. I used eagle’s erc/drc and it didn’t point out a warning so I’m going to assume it was mill code generation settings, not limits of mill capability.
I discovered how useful eagle layers are, even in the interface is terribly clunky.

I create zero-ohm resistors a dumb way that actually turns out to be helpful when populating a lot of them. Since they each have an air wire, I can set air wires to a nice contrasting color and see where they all are:

Another note, I milled out the moles CNC-ly too using GIMP to get the traces I needed, but :/ milled them out too small and had difficulty getting the 3.5mm spacing power connectors to go through the board — had to carefully use a vise.

This is what the final half-populated boards looked like:

Summer: Rideable hexapod, check

teaser pic

Ah, where’ve I been all summer?

Having lots of fun, actually, but I’ve been hiding in my codefail cave and then I went and lost my camera.

Poof, hundreds of meticulous documentation pictures. Serves me right for not documenting as I go along / backing up my pictures.

Above is a pic of hexapod before I added the foot controls. Which are now being demoted in favor of joystick controls. But I did finish it in time for dorm rush / hall rush and gave lots of froshlings rides! And discovered some serious issues πŸ™‚

Hexarideablepod is based off of a very detailed instructables called Hexabot. I’m slightly embarrassed by this fact, for whatever reason, and even though hexarideablepod only deserves my love (it already has my blood, sweat, and tears…)

Yea, that’s a racecar seat that my fellow MITERSians helped me recycle from an old unfinished vehicle πŸ™‚

Strange and Beautiful Hexapods (Spider Robots), A Gallery

Hexahelicopter: ridiculousness.

 http://www.youtube.com/watch?v=4Wy0s0S8eZQ

Q: How many species of hexapods (six-legged robots) are there in the world? Oh, oh dear.
A: A mind-boggling awesomespectacular amount.

Here’s a compilation of some of the hexapod craziness out there. The sheer number of different hexapod designs out there is mind-blowing.

(p.s. for ideas of simple ways to build one, see my build post: http://www.orangenarwhals.com/?p=202)

Infinity Degrees-of-Freedom Style

To start off with, you guys have all watched the dancing hexapods, right?

http://www.youtube.com/watch?v=msaWXY3OuQQ

Chopsticks (yes, the robot frame was made of snapped-in-half bamboo chopsticks o.o)

 http://letsmakerobots.com/node/26107

[update 8 dec 2011] Cheaply, out of wood:

http://forums.trossenrobotics.com/showthread.php?4102-Low-Cost-Hexapod

Ant-like A-Pod

http://forums.trossenrobotics.com/showthread.php?t=2762

Hexapod that learns to walk using machine-learning algorithms! shiny shiny, and good music too:

http://www.youtube.com/watch?v=O3ovrT8pWww
http://hplusmagazine.com/2010/02/15/can-he-make-dancing-hexapod-robot-happy/

Tiny

http://www.custobots.com/products/pre-built-mini-hexapodinno-kc01001
http://www.youtube.com/watch?v=glNS81Kgk7g

Sexy

http://www.hexapodrobot.com/forum/viewtopic..php?f=5&t=389

Sheer Giant Awesomeness Style

Spider Tank (An entire series on Youtube!)

http://www.wired.com/magazine/2011/02/st_obsessed_robot/
The cute prototype: http://www.youtube.com/watch?v=_6qpSOjtB2E

How it works: http://www.youtube.com/watch?v=is7x_atNl94 (someone attempts to explain it here: http://www.youtube.com/watch?v=NJjX_YbqTC4)

The series: http://www.youtube.com/watch?v=86Krv3gE-c4

Walking House-style (by MITERs alum Sam Kronick!) (yes, the scale of this is where humans fit inside easily)

http://www.youtube.com/watch?v=gkb6jfEwe0g
http://www.n55.dk/MANUALS/WALKINGHOUSE/walkinghouse.html

Simple Linkage Style
General idea: Cant one side up and move legs forward.

3D printed

http://www.thingiverse.com/thing:5156

Rideable

http://www.instructables.com/id/Hexabot-Build-a-heavy-duty-six-legged-robot/

[update 8 dec 2011]
Look it’s bicycle powered

http://www.youtube.com/watch?v=jJY1fqzuqL0

Tiny (Pololu)

Simple Hexapod Walker: http://www.pololu.com/docs/0J42
Knexapod

http://robotics.hobbizine.com/knexapod.html

Even simpler lego one:
http://www.youtube.com/watch?v=MZ9QOjx-7FQ

Boebots parallax:

Lego Pneumatics-style
Mondo Spider– Hydraulic, electric

Jensen / Klann Linkage style “hexapods”

(for a comparison of the linkages: http://www.youtube.com/watch?v=WsRVu8BoSN4)

Uh… more like infinity legs. But same order of magnitude πŸ™‚
Knex: http://robotics.hobbizine.com/knexabeast.html

http://www.youtube.com/watch?v=hz4mflE2foM

Steam Powered! Wow.

http://www.crabfu.com/steamtoys/rc_steam_spider/ The Crabfu site has many other wonders as well.

And semi-relatedly, cute mini-windbeest. D’awww…

http://crabfuartworks.blogspot.com/2011/01/gakken-otona-no-kagaku-strandbeest.html

Holy cow that’s robots on speed. This just has to be watched, no image will do it justice:
Hyper fast robot line following  http://www.youtube.com/watch?v=4XiRxNkZleY
(more closeups here: http://www.youtube.com/watch?v=-Soq9qpK5Ac)

[update 8 dec 2011]
Rideable
okay, not simple-linkage-style, but rideable! yay

http://www.orangenarwhals.com/wp-content/uploads/2011/07/uak5f.gif

http://www.youtube.com/watch?v=eE9HqGas7FM&feature=fvst

Research Hexapods

(theses are an excellent source of juicy details!)
DASH Resilient High-Speed 16-gram Hexapedal Robot 
By “resilient”, they mean “let me drop this robot off a the roof of a ten-story building and have it walk away perfectly fine”…. o___O (28 meters, actually)

http://www.youtube.com/watch?v=LsTKAtBBkfU
Thesis: http://www.eecs.berkeley.edu/~paulb/IROS09_DASH_submitted.pdf

Origami hexapod?

http://robotics.eecs.berkeley.edu/~ronf/Prototype/index.html
Climbing robot, DIGbot (awesome site!): http://biorobots.case.edu/projects/climbing/digbot/

About halfway through this vid, it climbs up a tree trunk! http://biorobots.case.edu/projects/climbing/digbot/natural_1.wmv
The thesis: http://biorobots.case.edu/projects/climbing/digbot/thesis_Diller.pdf

Another climbing robot, RiSE:
http://kodlab.seas.upenn.edu/~rise/newsite/

Pneumaticals and FAST and cute -^-^- Stanford Sprawl and iSprawl: (esp. see 0:43 mark)

http://www.youtube.com/watch?v=GC4vWKenA7Y
The website: http://www-cdr.stanford.edu/biomimetics/ (click on “Robots”: http://www-cdr.stanford.edu/biomimetics/documents/sprawl/)
Thesis: http://bdml.stanford.edu/twiki/pub/Rise/IndependentSprawl/Kim_A038_CLAWAR04.pdf

Rhex, http://en.wikipedia.org/wiki/Rhex, http://kodlab.seas.upenn.edu/RHex/Home

Stiquito,  http://en.wikipedia.org/wiki/Stiquito, http://www.era.lib.ed.ac.uk/bitstream/1842/2574/1/Rosano%20PhD%20Thesis.pdf

Random thesis with a lot of theory and less building: http://poisson.me.dal.ca/~dp_08_02/Site/Documentation_files/Build_Report.pdf

Controls Thesis nom nom: http://www.sigada.org/ada_letters/march2002/thirion.pdf

MIT Leg Lab Controls thesis: http://www.ai.mit.edu/projects/leglab/robots/robots.html

(pdf at http://www.ihmc.us/users/jpratt/publications/jpratt_masters_thesis1995.pdf)

Thesis-y youtube vid, background on hexapods:
http://www.youtube.com/watch?v=eunuHrTPS1o

Old-school 18 motor hexapod, back in the 1980s: Odex I

http://www.theoldrobots.com/odex.html
Schematic: http://www.genomicon.com/2009/09/the-functionoids-are-coming/

NASA GIANT hexapod, wheeled hybrid “ATHLETE”

http://www.youtube.com/watch?v=vwFrCpYavt4

What the…

Oh, and then you can use your robot as a platform and attach weird things to it. πŸ˜€
18 servo planter (Farmbot) — lynxmotion body

http://www.youtube.com/watch?v=ACtihXjq2B0

18 servo CNC Hexapod Router

 Video: http://www.youtube.com/watch?v=quN37YskoaM
Construction details: http://www.hexapodrobot.com/forum/viewtopic.php?f=14&t=12

Toys
ELEKIT MR-9722, aka Avoider III http://www.youtube.com/watch?v=nc-viPoI1iY

Hexbugs, which seem like toy rip-offs of research robots / the internet (Jamie, of Spider Tank / Wired fame, was a bit upset about this):

http://en.wikipedia.org/wiki/Hexbug

And that’s all for today folks. Whew.
Hope that gives some inspiration for building hexapod / spider / legged / AWESOME robots πŸ™‚

Appendix


Sellers: (product datasheets are an excellent source of information for advice on how to build your own)

Misc. Documentation:

My main aids in this search: (I mirrored the images, because I hate seeing beautiful image collections destroyed by dead links)

I mirrored the images here:
https://picasaweb.google.com/nancy.ouyang/StrangeAndBeautifulHexapodsMirroringImagesFromTheWeb

And, in closing, lego shrimp climbing! An entirely different way of solving “how to climb over obstacles.”
Lego Technic SHRIMP http://www.youtube.com/watch?v=mW4LJW6j05E

Puaghhhh. Who knew compiling images would eat 6 hours of my life???

====
edit 10/13/2010: more hexapods, don’t think they’re mobile but so pretty!

http://www.microbotic.org/singer.htm

=====
edit 17 dec 2011:

http://www.hizook.com/blog/2011/11/28/jambots-soft-robots-based-particle-jamming-hexapod-irobot
eeeee particle jamming hexapod! hehe. soft hexapod~~

hexapods / summer status update

hexapod: IK, preprogrammed dancing+lilypad controls ETA end of August (2 months, pure software development)
electronics working, now apply programming
(look at trossen robotics code, implement IK)
buy things: xbee tx and rx, two lilypads, some battery male plugs + femfem servo cables, maybe a sensor or two?, maybe a ps2 controller? or accel for lilypads?, el wire, [conductive thread]
vision: sound-reactive EL wire’d body, movements depend on real-time sound input processing. lilypad
buy them soon. spend money, you can do it. o__o
mechanical: upgrade to laserjet acrylic, 3d printed, or waterjet+Al body. Put HITECs on shoulders. double-sided support. (ETA New Year ish)

hexarideablepod: ETA end of July (1 month), ideally by next week…
order steel monday or tuesday
learn welding tuesday or wednesday
CAD slightly larger version, possibly with gearing to avoid undervolting and provide more torque/power. probs not for first version… check for bolts etc.

laser-cutter: ETA end of IAP (next January)
make spreadsheet of options and commercial cost
e.g.
bed size, laser wattage, commercial price & URL, laser commercial price & URL.
Then email out to MITERS.

direct-to-pcb/garment printing: requires just a weekend. maybe with Rush funding?

MITERS, lights automation and RFID keyholding, ETA last two weeks of August (begin after GSoC end).
*go ahead and order parts


Timeline:
hexarideablepod, until Monday July 11th (intense build during week off from CfA).

hexapod w/ IK and bluetooth, 2 weeks. w/ EL wire, 1 week. (aug 1st). w/ lilypad, 1 week (aug 8th).

Then 3 weeks left…
Plan A: MITERS personality core, 1 week, RFID keyholding, 1 weekend, rotary phone Putz, 1 week.
Plan B: make a scooter (hate walking). Last week = rush.
Plan C: start on hexaawesomepod

mysekritproject, 1 weekend sometime.

how to set up arduino + pololu mini maestro (for an 18 servo hexapod)

EDIT 4 Dec 2012:
As of august 2012-ish (I haven’t tried to run hexapod since then, because I ate my pololu controller sometime while dragging my hexapod all around the country this summer >__< Ugh I fail at taking care of expensive electronic things), there are some syntax changes if you’re using the latest version of arduino because newsoftserial is now built into arduino, not a separate library.

This version of the code is also slightly better organized…
https://github.com/nouyang/18-servo-hexapod/blob/master/pololu_aug17-2012.pde

[updated because i saw a link from http://forum.pololu.com/viewtopic.php?f=16&t=6188&p=29520#p29520]

EDIT 18 March 2013:
I made a video about my hexapod.

Also, a diagram to explain what is going on in the August 17th revision of the code:

[updated because I saw a link from hexy forums]

=====

this post because pololu has awesome documentation but dear lord is it long and difficult to wade through when I’m fairly new to this stuff. Also, I finally figured out the sad-servo problem that was plaguing me for a week.

Fig. 1

My current setup: eighteen servos on maestro pins 1-18 (pin 0 left empty), VSRV=VIN jumper has been removed. 8.4V battery pack fed through 5V linear regulator on carrier board. The servo wire with with masking tape comes from PIN2 of the carrier board/arduino setup and is supplying the pololu controller with GND, VIN, and the serial signal. Red and black wires going from breadboard on carrier board to VSRV on maestro.

If all that didn’t make sense…

Steps

a. Hardware
  1. Look at labeled picture http://www.pololu.com/docs/0J40/1.b
  2. What you need on pololu-side: serial going through to RX pin on pololu, power to VSRV and VIN, ground to GND, and lots of servos
  3. According to our eventual code:
    #include <NewSoftSerial.h>
    #define txPin 2
    NewSoftSerial mySerial(rxPin, txPin);
    void setup(){
    mySerial.begin(9600);
    delay(1000);
    }
  4. we should take a servo female-female wire, put one end on servo male header pins for pin 2 of Arduino.

  5. RX/TX and Microntroller power: Put other end white wire (or yellow or whatever wire is SIG) on RX on maestro, and red (VIN) and black (GND). Should look like pic above, the wire-with-masking-tape, with black facing “out” toward the USB port.
  6. Servo power: see pic above, the two non-servo cables (the red wire and black wire going to the breadboard) are screwed into the blue terminal block on the maestro. The breadboard has 5V and GND from the 8.4V battery going through the linear regulator on the carrier board. I’m actually stealing 5V from a servo pin. See the black wire soldered to Dig9Output, 5V in the upper left of this pic (which is actually carrying 5V, not GND) (via a female header pin so I wasn’t soldering straight to the carrier board pins) (ignore the gazillion extraneous wires)
  7. Remove VSRV=VIN jumper

Why remove the jumper? Well, a. Makes the pololu RX pin happier (compare to setup below) b. Setting that jumper seems to current-limit the power going to the servos, leading to my sad-servo symptoms. aka unable-to-walk hexapod.

the single pin (pololu RX) inside the masking-tape-servo-cable is a sad pin. The cable also falls off often.

I used the jumper originally because I was thinking I would need two batteries (one for VSRV one for VIN) or something otherwise. But hey look, it’s setup to be neater without the jumper, I’m still only dealing with one battery, and my hexapod doesn’t work with the jumper on. u___u

b. Software
[edit 27 Jun 2011 I fixed the many errors in my post, as pointed out on the pololu forums: Pololu maestro and arduino again]

1) newsoftserial should be downloaded from the internet and the folder inside the zip put in (path to where you unzipped arduino)/arduino/libraries/ (e.g. for ubuntu 10.10 via the repository, /usr/share/arduino/libraries)

And the code from http://www.pololu.com/docs/0J40/5.e or from above means:
a. BYTE is a parameter that pecifies the base (format) to us http://www.arduino.cc/en/Serial/Print
b. target is a non-negative integer less than 8192 (it can be written in binary notation with 14 or fewer digits)
e.g. 6000, or in binary: 01011101110000 
c. 0x7F is 01111111 in binary, which infinity zeros to the left, so “&”ing (bitwise AND) it masks out all the digits in target (when target is written in binary) except the last 7 digits (only 1 AND 1 == 1. all other combinations == 0)

  01011101110000
& 00000001111111
= 00000001110000

d. right shift operator, shifts last seven digits (numbers 7 through 13) in target off into empty space and so now the “new” last seven digits were originally bits #0 to 6 (see color-coded pololu doc). Mask with 0x7F again, just to be sure.

  01011101110000,>>7 to:
00000000101110, then:
& 00000001111111
= 00000000101110

You can see the code I used with Fig. 1 here: https://github.com/nouyang/18-servo-hexapod/blob/036271da7e66b80ff7ea732ea13b7028b43d28ac/pololu_jun17a.pde

The main difference from the default code is that I mapped the values so that I could mindlessly port code from arduino-“Servo.write()”-style to pololu-“settarget()”-style.

void settarget(unsigned char servo, unsigned int target)
{
target = map(target, 0, 180, 2400, 9500);

Also feel free to compare to original arduino version: https://github.com/nouyang/18-servo-hexapod/blob/master/arduino_may13_2011.pde

hexarideablepod

Rideable Hexapod (aka spiderbot or hexabot or whatever). Anyway, I want.

Step A. KISS. Clone someone else’s work on a linkage hexapod.

~$ git clone git@instructables.com:Hexabot-Build-a-heavy-duty-six-legged-robot/

haha I wish hardware was as easy as software to duplicate.

Substeps:

  1. Acquire materials
    1. Steel stock
      1. Turner Steel (carpool with someone)
        1. 60 feet of 1″ square steel tubing, 0.065″ wall ~$72
        2. 20 feet of 2″ x 1″ square rectangular steel tubing, 0.065″ wall ~$37
        3. Directions
        4. (508) 583-7800 –inquire about cost for delivery to MIT, also hours
      2. Inquire from the Central Machine Shop, bldg 38-001
  2. Apply CAD (scale up, can motors handle? torque calcs?)
  3. Apply controller to motors (make original one? probably stick with relays)
    1. schematic
  4. Learn welding (MIG or TIG)
  5. Build build build
Oh, right, youtube research: (specifically for this kind of linkage-based rideable hexapod)
Look it’s bicycle powered http://www.youtube.com/watch?v=jJY1fqzuqL0
Look it’s wheelchair motor x2 powered http://www.youtube.com/watch?v=xuRT9gC0CGs

in the meantime, I learned a bit of serial by asking Leighton, a hallmate, so now I understand the pololu code. But I still don’t understand why it’s sad. Yay I kept thinking it was something with the code, and I couldn’t find my cute tiny 2.007 battery to try . But I tried something I knew wouldn’t work, and it worked! yay. will post in pololu forums to make it more findable.
http://forum.pololu.com/viewtopic.php?f=16&t=3944&p=19496#p19496