Rolling Helix Locomotion: A New Mode of Self-Propulsion for Limbless Robots

Inspired by snakes, engineers have developed snake-like limbless robots (SLRs) for confined space inspections. More traditional SLRs rely on body undulation for locomotion, which relies heavily on anisotropic ground friction and fails to produce effective motion on isotropic surfaces like smooth floors. Recent 3D motions like sidewinding enable the SLRs to move on isotropic surfaces, but they are less efficient than limbed robots of similar size and cannot achieve forward motion.

To address these limitations, we propose a new locomotion method where the SLR curls into a 3D helix and propels itself forward by spinning the helix, similar to a rolling spring. We used a least-square optimizer in MATLAB to identify joint angles sequences that yield the same 3D helix curve. Sequencing these angles produces a gait that generates self-propulsion through continuous spinning. This self-propulsion without shape changes preserves momentum and achieves near-unity wave efficiency. Our framework advances toward high-speed rolling, load carrying, and pipe traversal, extending capabilities beyond those of current snake robots.