Research on the dynamic positioning of remotely operated vehicles applied to underwater inspection and repair of hydraulic structures

Abstract

Hydraulic structures (such as dams and aqueducts) can suffer from damages, such as cracks and collapse due to natural aging as well as the impact of natural disasters (such as earthquakes and floods). Determining underwater damage is generally not easy because of significant concealment and safety hazards. Remotely operated vehicles (ROVs) have gradually become capable assistants for the regular underwater maintenance of hydraulic structures. With disturbances from undercurrents and propeller reactions, achieving precise positioning of ROVs has always been a complicated technical problem, and it is also one of the important factors affecting underwater inspections and repair accuracy. To address the environmental disturbances during ROV dynamic positioning, a fuzzy predictive control algorithm combining fuzzy control and model predictive control is proposed in this paper. This algorithm can dynamically adjust the power output of propellers in real-time according to the undercurrent data measured by sensors and carry out differential correction until the ROV reaches the predetermined position. Moreover, the aim of this paper is to analyze disturbances in the longitudinal (X), lateral (Y), and depth (Z) directions during the motion of the ROV. The parameters are adjusted through the algorithm to simulate the dynamic positioning of the ROV's spatial movements. By setting different external environmental conditions, the power adjustment strategy and different dynamic positioning performances of ROVs can be obtained to enhance the adaptability of ROVs in complex environments and their stability in underwater inspection and repair and improve their underwater operation quality and efficiency.