attempt to walk


update 7/12/11

At last got enough code together to get a painfully slow actively balancing crawl to work, but must be able to do better than this ? Servos holding up ok so far, but bought some spares as they seem to be pretty much at their limit. Still if they werent as cheap as they are, I couldnt have even attempted this bot, they are amazing good for the price.Next couple of weeks will try to get the walk easier and then turning left right. Beginning to think that solving one will solve the other.


Hi, for 2 years I've wanted to, but chickened out of, build a quad with foot 'pressure' sensors. With cost and time as excuses for not.

 But with the very cheap 8g servos and the good-looks and convenience of the spider contoller I felt I had no excuses left and had better get on with it.

 Should stress here that I have no expectation of success, but do feel the need to get it out of my system and put the idea to rest one way or another.

 Have gone for the simplest build I could think of for a 12 servo quad and tried not to use anything other than stuff i had laying around. ( except for the servos and board of course).


 from blank sheet of paper to the finished physical build took around 42 hours spread over about 3 weeks of evenings and weekends.



cutting out the first leg took about 6 hrs of jigsawing, drilling etc

the other 3 only half the time once i knew what i was doing (kind of)

the final version of the very crude foot sensor, just took everything except the pot + the gears on the pot shaft out of a servo and used that. It seemed an easy way to mount a tiny pot.

Finally added a little sub-board to the controller, with some simple filtering for the foot pots and a genral purpose 10k preset to help with the calibration and debugging. The more I look at this thing the more flaws I see in it and the less likely it will ever walk at all. But fingers crossed I will get on with the programming and post vids if anything does happen.


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That is wild!!!

Can't wait to see the video!


Let's hear those 8g servos hummin!

Awesome  ,be nice to see it in action :)

Wohooo, that's an impressive walker. With this in LMR others will look ugly....I am talking about my quadruped ;-) However, can't wait to see the video of it#s first walk...I missed this for my quadruped when he was fell over after one step ;-) Hopefully yours will not do that. well done inkling

Fantastic! Very great job!

Your quad looks very promising. Love the fact that you have taken your time building the parts and not just a blob of hot glue. Like all the rest in here am I looking forward to see it moving.
One question. The two servos on the top that is linked to the center piece, are they there to shift the center of gravity? If so, couldn’t it be just one servo in the center and links to either side?

very very cool and sleek design

Looks great, very impressive jigsaw skills! Can't wait to see it run around.

Hey ! thx for the kind words

lumi: re; the looks
I had really thought when i started out with 2 chopping boards a tin can and a coat hanger that i would get the "LMR look", which i love. But newbie caution took hold early and the whole thing just got neater and neater. Ended up with something that looks to me like plastic star-wars toy. Not cool.

Geir: good point ! will probally though have to use those two hip servos to spread the legs when it starts toppling. think i only have have a very slim chance of it balancing at all.

RichardInVA: Did you base the positions and angles for the servos on a cat's muscles?
No, i wish i had thought of that though.

Anyway, did the servo calibration on Monday night and Tues got a simple walk cycle going (+posted awfull quality vid).
Planned to try and layer the balancing on top of that. Although the first attempt at that just made it throw itself to the ground quicker than the usual falling.

Very nice build!!  Can't wait to see it in action.  The walk cycle vid looks very promising.