Search

Traditionally, bottom magnetic surveying is performed on towing the magnetometer by the ship with considerable length of the communication cable. This method is high costed and has significant limitations due to risks of equipment loss at poor weather conditions. At the same time, the magnetic field created by on-board equipments excludes possibility of installing a precision magnetometer in an underwater vehicle. To achieve the maximum accuracy of the magnetic survey, it is required to tow the measuring equipment at some distance from the vehicle, depending on its length. The article shows study results of effect of the towed magnetometer on the motion parameters of an autonomous underwater vehicle. The method developed by the authors for calculating the effect of towed equipment on the vehicle in cruising and maneuvering modes along standard trajectories is presented. The mathematical model of disturbances by towing of a magnetometer is determined. This model is based on an analytical representation of simulation results of steady-state motion. The structure of vehicle motion controller proposed in the article allows perturbations from a towed equipment to be effectively compensated. The simulation results of the underwater vehicle motion with a towed magnetometer are proposed. The usefulness of the method presented in the work was confirmed during the conduct preliminary magnetic survey of the area for underwater fiber-optic connection line in the Sea of Okhotsk.

The robotic complex for long-term mobile aqua monitoring is presented in this article. The complex consists of the underwater vehicle and the surface repeater. The main feature of the vehicle is a variable buoyancy system. The system allows buoyancy of the vehicle to be controlled in the wide range. We tried to combine mobility of classic AUVs and energy efficiency of static buoys. The technical implementation of the robotic complex and models of its using are presented. The results of the energy efficient hybrid method of depth control with the propulsion system and the VBS (Variable Buoyancy System) and long-term depth scanning by means of the VBS are showed.

Autonomous Underwater Vehicles (AUVs) are widespread and effective tool for oceanographic research. The main applications of AUVs are long-term missions for survey of wide area and patrolling. However the key issue for long term cruising range is energy storage. One of approaches to reduce energy consumption is using of the variable buoyancy system (VBS) on the AUV. This approach allows to compensate AUV's buoyancy and to reduce energy on hovering due to it. Two combined depth control methods based on cooperative work of propulsion system and variable buoyancy system has been presented in this paper. Estimation of the methods based on calculation of energy consumption and transient response time has been made. Comparison of ones with methods based on standalone work of propulsion system and VBS has been made. Provided methods was proved on simulation and water pool tests on variable buoyancy AUV “CH-2” designed at Institute of Marine Technology Problems FEB RAS year ago.