Optimal crawling: from mechanical to chemical actuation

TL;DR

This paper explores a physical model of self-propulsion inspired by biological cells, demonstrating how combining mechanical and chemical actuation can enhance the performance and control of biomimetic crawling robots.

Contribution

It introduces a novel framework for integrating mechanical and chemical actuation in crawling robots, showing how their interplay affects propulsion efficiency and control strategies.

Findings

Traveling wave actuation yields maximum velocity at low chemical turnover.

Chemical dominance shifts control from traveling to standing wave patterns.

Combining actuation modalities broadens the performance capabilities of biomimetic crawlers.

Abstract

Taking inspiration from the crawling motion of biological cells on a substrate, we consider a physical model of self-propulsion where the spatio-temporal driving can involve both, a mechanical actuation by active force couples, and a chemical actuation through controlled mass turnover. We show that the competition and cooperation between these two modalities of active driving can drastically broaden the performance repertoire of the crawler. When the material turnover is slow and the mechanical driving dominates, we find that the highest velocity at a given energetic cost is reached when actuation takes the form of an active force configuration propagating as a traveling wave. As the rate of material turnover increases, and the chemical driving starts to dominate the mechanical one, such a peristalsis-type control progressively loses its efficacy, yielding to a standing wave type driving which involves an interplay between the mechanical and chemical actuation. Our analysis suggests a new paradigm for the optimal design of crawling biomimetic robots where the conventional purely mechanical driving through distributed force actuators is complemented by a distributed chemical control of the material remodeling inside the force-transmitting machinery.