Design and Depth Tracking of a Robotic Quadrotor-Float for Ocean Exploration Tasks

This paper presents an end-to-end design and de-velopment of an underwater robotic quadrotor-float specifically aimed at observing seafloor methane seeps. The mechanical structure of the robotic float adopts a modular design that combines a 3D-printed body frame and a commercially available water-tight enclosure to house the electronics. Utilizing four propeller-based thrusters and a pressure-based depth sensor feedback, the underwater quadrotor robot achieves precise depth tracking via a PID controller. Unlike traditional pure depth-tuning Lagrangian profilers, our design incorporates selective actuation along the heave direction and limited horizontal motion, crucial for maneuverability in the proximity of methane seeps and enhancing the reliability and success rate of data and sample collection. Physical experiments were conducted in a water tank to validate the mobility and depth control capability of the robotic quadrotor-float.