Zippy: The smallest power-autonomous bipedal robot

TL;DR

Zippy is the smallest autonomous bipedal robot, demonstrating stable walking, turning, and stepping with a simple design and achieving the highest leg-length-based speed among bipeds.

Contribution

This paper introduces Zippy, the smallest self-contained bipedal robot, showcasing novel miniaturization and control strategies for stable locomotion at a tiny scale.

Findings

Achieves 25 cm/s walking speed, the fastest among bipeds by leg length.

Utilizes simple mechanisms and open-loop control for stable locomotion.

Demonstrates versatile movements including turning and stepping.

Abstract

Miniaturizing legged robot platforms is challenging due to hardware limitations that constrain the number, power density, and precision of actuators at that size. By leveraging design principles of quasi-passive walking robots at any scale, stable locomotion and steering can be achieved with simple mechanisms and open-loop control. Here, we present the design and control of "Zippy", the smallest self-contained bipedal walking robot at only 3.6 cm tall. Zippy has rounded feet, a single motor without feedback control, and is capable of turning, skipping, and ascending steps. At its fastest pace, the robot achieves a forward walking speed of 25 cm/s, which is 10 leg lengths per second, the fastest biped robot of any size by that metric. This work explores the design and performance of the robot and compares it to similar dynamic walking robots at larger scales.