DIY Walkers: TrotBot using EV3

In my previous post, I shared some of my exploration of walking mechanisms using mainly LEGO Technic.

Here is a MINDSTORMS EV3 version I have just built.

The challenge with this build was maximizing performance while working with the heavy EV3 brick. I found that I could improve performance by adding “retractable toes” that increase foot-contact with the ground, but I had to saw 32 LEGO parts in half to make them. Instead, I looked at video of the gait in slow motion where it was obvious that the plastic LEGO axles were twisting a lot, and delaying the leg motion. I replaced the plastic LEGO axles with steel axles that I bought from Brick Machine Shop, resulting in the performance seen in the above video.

To get an idea of how much LEGO plastic axles twist under torque I set up this simple experiment:LEGO plastic axles:

Stainless steel axles:

I posted instructions on how I built my EV3-based TrotBot here.  I hope you find this useful!

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Ben Vagle

Ben Vagle is a high school senior in Colorado. His childhood was spent observing animals in nature and building with LEGO, and these passions are alive and well in his role as a young maker.