Active chemical sampling system for underwater chemical source localization

Abstract

This paper investigates the effect of active water sampling to enhance chemical reception for small underwater robots. The search for a chemical source in a stagnant water environment is not an easy task because the chemical solution released from the source stays in the close vicinity of the source. No signal is obtained even if a robot with chemical sensors is placed a few centimeters from the chemical source. In the system under study, four electrochemical sensors are aligned in front of a suction pipe that draws water samples from the surroundings. Owing to the smooth laminar flow converging to the suction port, the streak of the chemical solution drawn to the sensors is shaped into a thin filamentous form. To prevent the chemical solution from passing between the sensors without touching their surfaces, slits are placed in front of the sensors to guide the incoming chemical solution from different directions to the corresponding sensors. A chemical source can be located by moving the system in the direction of the sensor showing the largest response. It is also shown that the chemical reception at the sensors can be significantly enhanced when the system is wobbled to introduce disturbances.