Modeling and Characterization of Bi-flagellated Robot with Tumbling

Multi-flagellated bacteria locomote due to the interaction between two or more filamentary tails in low Reynolds number flow, i.e., bundling and tumbling. One of the fundamental goals of robots inspired by bacterial locomotion is to develop an effective and steerable robot based on the interplay of filamentary structure and hydrodynamics. In this work, we build a macroscopic bio-inspired robot with two rigid flagella (right-handed helices) connected to a cylindrical head. The robot body can reorient with repeatable and controllable tumbling when two flagella rotate in the opposite direction. We model this bi-flagellated mechanism interacting with the low Reynold fluid by coupling rigid body dynamics and the method of Regularized Stokeslet Segments. We further explore the parameter space of the simulation and the experiment to maximize the rate of change of reorientation. Moreover, we propose a run-and-tumble control scheme by modulating the rotation speed and direction of two flagella so that the locomotion gait is analytically tractable. We expect our framework to encourage more study and application on the mobility and controllability of micro-scale bacterial robots.