November 2008


Finally! I’ve built a version of Disney-Pixar’s Wall-E robot from the movie. There are a lot of great versions of Wall-E on the net already, and they inspired me to build my own. The version you see here is my third or fourth attempt at a working Wall-E: previous versions were very weak and soon fell apart under their own weight. Getting the center of gravity over the tracks is important so that Wall-E doesn’t topple over when he drives across obstacles.

I decided to articulate the arms and hands individually. Each arm is raised and lowered using a XL power functions motor through a worm gear. I went through many arm designs over time before realising that I should Keep it Simple, Stupid! and mounted a basic arm on the end of an axle! The small PF motor opens and closes the grippers.

The tracks are driven using an XL PF motor each. Originally I had geared the drive to power both rotation wheels, but that led to a lot of gear friction, so I used the simple direct-drive design you see in the pictures below.

The neck rotates on a turntable using a small power functions motor, and the belly door opens and closes also using a small power-functions motor.

Finally Wall-E’s head, the most recognisable robot face out there! I went through many designs for this, attempting to replicate the real Wall-E before settling on the NXT motor to raise and lower the head, and a micro-motor to power the eyes. I debated using a small PF motor to power the eyes but the cable would not reach from the motor into the body!

In total Wall-E uses 2 XL PF motors for the tracks, 2 XL PF motors to raise and lower the arms, 2 small PF motors for the grippers, a small PF motor to open and close his belly door, a small PF motor to rotate the neck, a NXT servo motor to raise and lower the neck and a micro-motor to wiggle his eyes. There are 4 PF IR receivers to control all those motors, and the NXT controls the neck and eyes directly. That's a lot of weight - he weighs in at 2kg which doesn’t sound like a lot, but puts a lot of stress on the LEGO chassis!

I had to go through a number of designs for the tracks as the weight was causing them to splay and drag on the ground. This version is based on a modified base from the new Excavator (8294) set.


Most of these videos are hosted on my channel at YouTube:

Last updated 21 November, 2008

All content © 2008 Mark Crosbie

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Wall-E has a NXT microphone and will say his name when he hears a loud noise. There seems to be an issue where he ends up saying his name over and over..

Test driving Wall-E around the kitchen floor. The previous version of the tracks were buckling under the weight of the robot. This track chassis in version is based on the LEGO Excavator and is much stronger than my previous design.


To give Wall-E some personality I downloaded a wav file containing a clip from the movie of Wall-E saying his name, and I also got a wav file of the Mac startup chime which Wall-E plays when he wakes up. I converted them to .rso files using wav2rso and you can download them:

  1. Wall-E saying his name as an .rso file: wall-e.rso (28k)

  2. Mac startup chime as an .rso file: macstartup.rso (28k)


My goal is to give Wall-E some of that loveable personality we see in the movie. I will be using a subsumption architecture to encode behaviours for Wall-E. So far he has a very basic wake-up and wiggle his eyes behaviour. More will be added here over time.