Modeling, Characterization, and Control of Bacteria-inspired Bi-flagellated Mechanism with Tumbling

TL;DR

This paper presents a bio-inspired bi-flagellated robot model that uses hydrodynamic interactions for controlled tumbling and reorientation, employing advanced modeling techniques to optimize its propulsion and control.

Contribution

The study introduces a macroscopic bi-flagellated robot with a novel control scheme based on hydrodynamic interactions modeled by Regularized Stokeslet Segments, advancing bacterial-inspired robotic design.

Findings

The robot can reorient itself through controlled flagella rotation.

RSS modeling captures hydrodynamic interactions more accurately than RFT.

A simplified control scheme with two inputs effectively achieves reorientation.

Abstract

Multi-flagellated bacteria utilize the hydrodynamic interaction between their filamentary tails, known as flagella, to swim and change their swimming direction in low Reynolds number flow. This interaction, referred to as bundling and tumbling, is often overlooked in simplified hydrodynamic models such as Resistive Force Theories (RFT). However, for the development of efficient and steerable robots inspired by bacteria, it becomes crucial to exploit this interaction. In this paper, we present the construction of a macroscopic bio-inspired robot featuring two rigid flagella arranged as right-handed helices, along with a cylindrical head. By rotating the flagella in opposite directions, the robot's body can reorient itself through repeatable and controllable tumbling. To accurately model this bi-flagellated mechanism in low Reynolds flow, we employ a coupling of rigid body dynamics and the method of Regularized Stokeslet Segments (RSS). Unlike RFT, RSS takes into account the hydrodynamic interaction between distant filamentary structures. Furthermore, we delve into the exploration of the parameter space to optimize the propulsion and torque of the system. To achieve the desired reorientation of the robot, we propose a tumble control scheme that involves modulating the rotation direction and speed of the two flagella. By implementing this scheme, the robot can effectively reorient itself to attain the desired attitude. Notably, the overall scheme boasts a simplified design and control as it only requires two control inputs. With our macroscopic framework serving as a foundation, we envision the eventual miniaturization of this technology to construct mobile and controllable micro-scale bacterial robots.