Depinning and activated motion of chiral self-propelled robots

TL;DR

This paper investigates the complex motion of chiral self-propelled robots, revealing a depinning transition and creep behavior, and provides a comprehensive model that matches experimental and simulation data without fitting parameters.

Contribution

It introduces a simple yet accurate model for chiral active particles, linking experimental, numerical, and analytical results to advance understanding of chiral active matter dynamics.

Findings

Identification of a rotational depinning transition in chiral active particles.

Exact computation of steady-state distributions and escape times.

Validation of the model against experiments and simulations without fitting parameters.

Abstract

We study experimentally, numerically and analytically, the dynamics of a chiral active particle (cm-sized robots), pulled at a constant translational velocity. We show that the system can be mapped to a Brownian particle driven across a periodic potential landscape, and thus exhibits a rotational depinning transition in the noiseless limit, giving rise to a creep regime in the presence of rotational diffusion. We show that a simple model of chiral, self-aligning, active particles accurately describes such dynamics. The steady-state distribution and escape times from local potential barriers, corresponding to long-lived orientations of the particles, can be computed exactly within the model and is in excellent agreement with both experiments and particle-based simulations, with no fitting parameters. Our work thus consolidates such self-propelled robots as a model system for the study of chiral active matter, and highlights the interesting dynamics arising from the interplay between external and internal driving forces in the presence of a self-aligning torque.