1 DOF swimming robot inspired by bacterial motion mechanism

Abstract

Living organisms have various kinds of flexibility and robustness which are realized by "yuragi," or biological fluctuations or noises. Bacterial motion is an example of the noise-based motion, since they can move towards higher concentration of some chemical which they prefer although they have only a limited 1 DOF for mobility using that flagella. Bacteria also have only a limited sensory device which cannot detect the spatial gradient of the chemical at a time. The simple strategies that bacteria take to realize chemotaxis are (1) to tumble (or turn) to change orientation randomly being hit by surrounding water molecules with Brownian motion, and (2) to change the frequency of tumbling according to the change overtime of chemical concentration. In this paper, we describe a quite small and simple, 1 DOF swimming robot developed by mimicking the bacterial motion generation mechanism. The robot only has a single motor and a single sensor (a photo detector). However by changing orientation due to various noises which exist in the environment, and by changing the frequency of turning, the robot can approach its target. Experimental results indicate that the robot statistically approaches the target (a light source) in two dimensional space with a 1 DOF actuator, which is impossible for the robot to achieve without the utilization of the noises in the environment.