2.007 Hexapod Design Process
Channel: Rui Ouyang (Nancy)
Date: 12/02/2013

An overview of my journey through 2.007 in spring 2011. Disclaimer: I was a distinctly average student in 2.007. You should build better robots than me! ^__^ 
It can be watched in HD :) and sped up: youtube.com/html5 
A rough transcript follows:
Caution: This video contains hexapods, like the dancing one shown here from the university of applied sciences in upper austria, and may lead to endless hours of staring at pretty hexapods online.

Hexapod, or six-footed, in this case refers to a six-legged walking robot. Other use cases include  in nature studies, where hexapoda is a group of arthropods including the insects. In fact, robot hexapods are inspired by these critters. In the arduino code for my robot hexapod, you can find references to the coxa, femur, and tibia segments of an insect leg. Hexapod can also refer to a type of robotics platform called the Stewart platform, which uses six servos. a video of a DIY one can be seen here.

Spring term of 2011 begins, and I decide to build a hexapod.

I email out to my friends to ask about how I might build a hexapod. 

Hello,
Has anyone built a hexapod? I want to build a simple one for 2.007, but I'm unsure where to start."
It's february 1st, and I get plenty of replies, some of them talking about "inverted bicores" and other things I don't understand. 

I learn about klann and jensen linkages, which I won't go into here, 


n particular I end up staring at this picture of a parallax boebot. It's not at all clear to me how the leg mechanism works, so I decide to build a foamcore version. Foamcore is a fast way to prototype ideas you have in mind, as it can be "machined" in a sense with just a razor, and I highly recommend prototyping any ideas you have with it.

I also build a 2d version in solidworks to play with, or try to, but since I'm completely new to solidworks at this point, I end up not trying to figure out the optimal leg lengths and I just go ahead and  build it. 

Two years later, I'm much better at solidworks. Here is a quick video of me making a model of the mechanism, it took me a few tries. You can try implementing this and there's no need to copy what I did here since solidworks is definitely a many-ways-to-the-same-result language, but it's a bit tricky if you're new to solidworks. Note the use of the "add relations" tool, making things Fixed, constraining them with dimensions, and the use of equations and global variables. Also, for the love of hexapods, don't be fooled by this throwaway sketch and in your real solidworks parts. make sure all your lines are black rather than blue, meaning they are fully defined,

Thus, I spend an entire weekend building a small prototype hexapod that uses just two servos. Here are some pictures of the build process, including turning aluminum and plastic spaces on the lathe and milling out a slots. The aluminum was cut out on the sheet metal shear and bent on the brake. I did this at a student-run shop called MITERS, but actually the pappalardo shop guys are really awesome and friendly s

n the end, my very janky robot walks with the help of a giant weight on the front in the form of a screw to counteract the arduino carrier board weight in the back. It is wobbly as heck, but still immensely satisfying to get something done Speaking as a jaded senior, never underestimate the importance of morale in going through your studies at MIT.

About 1.5 months have passed and it is now March 15th. Following small 2 dof hexapod, I spend a while doing more research on designing hexapods, basically staring at lots of pretty pics of hexapods online. and then decide to just go for the 18 servo version, cos why not. Right around spring break, I build a prototype of a single leg based off of this CAD model I found online.

[Cut because too long. See in full, along with a links list: https://docs.google.com/document/d/1ayg5M3y8zFRW-KeicfUK6T43--W70nlX2NfGhoWANLg/edit]