Getting four legs to step in a coordinated way is one of the classic headaches in hobby robotics: with several joints per limb, keeping every foot exactly where the code wants it gets tricky fast, and adding a rhythm on top makes it harder still. That is the problem this project takes on: a small Arduino quadruped that walks, performs several different moves, and even dances in time with music.
The maker built it around an Arduino Uno, with eight Mg90s micro servos running at the same time to drive the four legs. The legs are multi-bar linkages assembled from flat link plates, and the body combines 3D-printed pieces with a chassis of clear laser-cut transparent plastic plates, stacked as top and bottom tiers joined by cylindrical standoffs. An RGB LED strip wraps around the frame, and the whole machine comes out at 700 grams.
What stands out to me is the math: the maker derived the inverse kinematic formulas with nothing beyond high school math, and that model is what positions the feet precisely. A video series explaining the construction and the programming is in the works, which I think many of us here will appreciate.
Two things deserve mention as open threads. Syncing the dance moves to the beat reportedly took real effort, and the competition story has an unfinished edge: the maker won the first round of the German youth science competition, but the second round was cancelled as Coronavirus spread.
Project by Vanessa Weiß. Watch it on their YouTube channel: