Category Archives: Hardware

Hexapod conference? how to plan a conference budget?

caution: hexapods ahead. cc0

I applied to the deFlorez Fund for Humor at MIT. The application deadline for grants over $1000 was due at midnight, and at around 10pm I decided to apply for funds for a hexapod conference.

I should hear back by the end of MIT spring break (the 30th).

Funding decisions will be made approximately two weeks following the application deadline. If an award is made, disbursement of the award will take place once sufficient funds have been secured to hold the event.

 If they fund this, it will be hilariously awesome. However, the application is so hilariously rushed and badly written that I am actually really embarrassed. It was so much fun writing it though. The coherent parts were written by the lovely +Julia Hopkins (http://fluidarchive.blogspot.com/), including this beautiful part:

Please explain in one or two paragraphs how exactly this event fits the de Florez Humor Fund mission of “impressing students with the importance of humor in all aspects of life, both personal and business.”

Let’s face it. An MIT student’s personal life is their work life. Too few are prepared to find the humor in this, or prepared to acknowledge such humor exists. This conference epitomizes silliness in research, silliness in personal projects, and silliness in how we envision the technical world around us evolving. Moreover, it highlights the importance of this silliness in a student’s daily life. The concept of a hexapod, the concept of investing time and resources into something that, in the end, probably won’t change the world (unless you build it several stories tall and figure out how to give it a Godzilla complex), resonates with many an MIT student. This conference is to help them both acknowledge and celebrate all of the things in their research, classes, personal lives (for those that persist in imagining they have one, in any case), and business which have not gone the direction they anticipated, or which did not provide as much of an impactful result as they were envisioning.

I would try and explain the humor of wrapping all of this up in a metaphor of hexapods and then go on to wax eloquently (or perhaps just wax) about the philosophical implications of how a project which has gone nowhere can still impart necessary skills and life lessons, but that’d be spoiling the fun of it. You should come see for yourself the wonders of dancing hexapods, the hours of toil put into this utterly silly contraption, and experience your nervous laughter as this parody evolves into genuine humor acknowledging all of the ridiculous things humans do which, somehow, make the world a better place. We’re just not sure how yet.

Well, anyway.  How do you plan a conference?

Well, you decide on a mission (yes, conferences have missions) and then make a budget. This is a most excellent guide on missions and general conference thoughts: http://ctb.ku.edu/en/tablecontents/sub_section_main_125.aspx

e.g.

 The field needs a conference.  There are several possible reasons for this:
  • The field may be a new one, and still lack a clear identity.  A conference could bring together the people who are building it, and help to define it.
  • The field may not be cohesive.  People in it may not know one another, may disagree on methods or other issues, or may simply not realize how many others have similar interests.  A conference could bring them together and create networks that would expand and improve the work.

The mission of this conference would be to promote silliness at MIT.

Here is the budget I ended up with:

.
Item Cost Comments
.
venue rental fee connections (held in the N52 IDC space, using equpiment there)
.
food and beverage fee 300 (can be acquired from dumpsters but kind of sketchy)
.
transportation & lodging scholarships 500 to help people make it here
.
A&V, recording, livecasting equipment 150
.
speaker fee bribe with cookies
.
activity fee 100 (lasercut hexapod material – bristol board)
.
miscellaneous fee 100
.
prizes from reuse
.
.
Total 1150

(budget table in neater formatting here)

And here is my (rambling because I had no time) proposal:
https://docs.google.com/document/d/1rq3cIFy9j1FjbIYA67gpZCksZKgtXzLZrxkLw93_v2s/edit

The conference schedule (tentatively planned for May 4th) would be

9 – 9:30 registration, breakfast
9:30 – 10 keynote speaker
10:15 – 11:15, break, 11:30 – 12 five-minute lightning talks (+ 5 minutes questions), nine total
12 – 13 eat food and make hexapods (invite general public, including kids)
13 – 14 hexapod dance-off, other hexapod competitions (e.g. fastest?)
14 – 17 conference talks about specific topics (e.g. the use of hexapods in educational kits, in adaptive terrain traversing (climbing trees, over rough ground), in millirobotics)
17 – 18 pm Poster session and demonstrations, appetizers

For reference, prior work:

http://youtu.be/pXMnbNoccgA?t=49s


http://ieee.scripts.mit.edu/urgewiki/index.php?title=S2012_-_Hexapods_and_Other_Cool_Things
An extracurricular undergraduate reading group I led last year.

http://katygero.wordpress.com/2012/07/17/hexapods/
The rapid fabrication hexapods we made during the last reading group session.


Hexapod Demonstration II from Katy Gero on Vimeo.

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 🙂 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.

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 🙂

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 🙂