812-R7 Biped

*Update 2010 Jan. 26* 
I figured out one of the problems with R7 was there was too much flexibility in its feet. I added several polymorph goobers around the edge and against the brackets to strengthen them up a bit. Now it doesn't fall flat on its face anymore! I even managed to get some (crappy cellphone) video so you can have a look at R7 taking its first (mostly) successful steps. Definitely got quite a bit of work to do on the programming...

I've been wanting a biped for quite some time now. With the holiday acquisition of half-a-dozen micro servos and a kilogram of polymorph I've finally got this project underway. I won't write a whole helluva lot here right now, y'all will have to mostly settle for a few captioned photos.

Most of the polymorph is rolled flat using ~1/16 inch thick tongue depressors as guides. Then cut, sliced, bent, melted, rebent and stuck in a U shape. The pivots are 22g copper wire, not the most robust choice for hinge material.

Currently there are ten micro servos. I only had 8 of the Dagu servos, so the two black ones (shoulder rotate) are pirated from my helicopter.

The brain is an ATMega168 @ 16MHz running the Arduino bootloader for easy programming. The board is a Gadget Gangster half-size project board. 12 of the 'mega's digital pins are brought out to three-pin "servo style" headers, with a strip of female headers above. Obviously only ten are currently in use by servos. D13 has a bright blue LED for debugging just plugged into the female headers. None of the analog pins are brought out yet. Top left is a 1x6 right-angle header for the programming cable. There's a 5V LDO regulator to provide power to the chip from 4 AA or AAA batteries (alkaline, totalling ~6V). The servos get their power straight from the batteries.

In all the whole thing is quite wobbly. Combined with the fact that I don't have a clue what I'm doing, R7 manages to get about 1.5 steps before tipping over on its face. I'm fairly certain a redesign of the feet and ankles is my next step before working very hard on a walking sequence. I have managed to get it to move to standing on one foot though. That felt like at least a small win ;)

For now I need to get back to working on LMR again, so it may be a little bit before I do more on this. Hopefully I'll come up with a proper name for it too.

Hips and Knees - front

Right knee and ankle - front

closer view of right ankle - front

knees - front

hips - front

left shoulder and elbow - front

left elbow

back

legs - back

left ankle

left leg. Also shows a little bit of the Erector stand I knocked together to hang the bot for programming

Brain "backpack"