Depth Control for a Dual Profiler-Sampler System for Water Sampling at Predefined Depths

Abstract

The environmental degradation of the Mar Menor has promoted the development of autonomous platforms for the continuous monitoring of shallow marine ecosystems. During critical events or situations in which manual sampling campaigns cannot be carried out, autonomous systems capable of collecting water samples for subsequent laboratory analysis are required. This work presents the integration of an automatic water collection system into an autonomous profiler. The main objective is to validate the profiler’s ability to maintain a stable depth during the water collection process. For this purpose, a cascaded control strategy based on PID controllers and a variable ballast system was implemented. Experimental tests demonstrated that the integrated system is able to maintain different depth setpoints for periods of 60 and 120 seconds, obtaining depth errors generally below ±10 cm, validating the feasibility of the platform for autonomous monitoring and water collection applications.