Characteristic function–based trial-and-error control of underwater profilers for vertical-column observation

Abstract

This article proposes a novel trial-and-error control strategy for buoyancy-driven underwater profilers that can be used for water column observation. The proposed strategy is based on the design of a characteristic function utilizing the profiler’s buoyancy adjustment components by automatically triggering a pump and a valve. To facilitate the elaboration of the proposed control strategy, a Bottom Ocean Stationing Ocean Profiler and its buoyancy adjustment system are introduced. Based on this buoyancy adjustment system, a characteristic function uses the difference between the current depth and the desired depth to determine a target velocity. Then, the trial-and-error control strategy based on error in velocity is implemented on the control of the buoyancy engine by determining whether positive or negative buoyancy adjustment is needed and by how much. This method has been applied to the depth control for our profilers resulting in field application results to validate the analysis.