Project Information

Little Walker

A biped made with only three hobby servos
Created by jwatte | Forum Thread Link | External Link
5 hours
< 500 grams/ 1 pound
12 in x 3 in x 5 in
30-60 minutes
Powersource: LiPO / LiON

My current LiPo is way too heavy -- the target is a 1300 mAh 7.4V 2S cell.

Locomotion: Biped

This project was inspired by the "Twitch" walker, but uses just two feet instead of six. Locomotion is a wagging gait.

Controller/CPU: Arduino Uno

Very simple walk cycle. Goal is to add nRF24L01+ based radio control.


No current sensors


EXI D226F "digital" hobby servos, for $15 each.


This is a proof of concept I decided to build on a lark after I had smoked my other robot motor controller by mashing an aluminum bar on it to short it out :-D

It came together beautifully for what it is. I drew the parts in Inkscape, laser-cut them from 1/4" MDF at Tech Shop, and screwed together with simple machine screws. Right now, the entire twisting torque is put on the axle of the servo; I'm thinking about adding a hinge of some sort to help with that.

If I can get it to carry the weight of the entire package, and walk a little faster than the video, and add remote control, I may attempt to enter this as a biped in the Mech Warfare for 2013, although my plan to enter the Magellan rover is likely to overrule that for time reasons anyway. (Perhaps I can enter my youngest son, who's pretty interested in being a mech pilot?)

Right now, it's using an Arduino, but I intend to use a Raspberry Pi for the real deal. That will let me use a USB webcam, which means it can do image processing, and I can use the same WiFi for controlling the robot as I use for viewing.