Type Of Autonomous Underwater Vehicle Research Articles

DESIGN AND ANALYSIS OF BUOYANCY ENGINE SYSTEMS ON CHANGES IN BUOYANCY FORCES IN UNDERWATER GLIDER

The vast and deep conditions of the ocean still contain many objects that have not been explored. Based on the type of autonomous underwater vehicle (AUV) device design, it consists of types that can drift, glide, and can propel itself in water. Types of AUV without propellers (nonpropelled, drifter). or glider), can float without thrusters or glide up and down the water by changing its buoyancy. This AUV uses little or no battery power compared to propeller-driven AUVs, but cannot perform as many maneuvers. Variable Buoyancy System used in different types of underwater craft, designed and built for specific rides and applications. Therefore, each system is completely different from the others. This research focuses on systems that raise and lower volume, using components such as diaphragms, bladders, and bellows. It is possible to use a diaphragm for a buoyancy engine to make the vehicle easier to fabricate. The aim of this research is to determine the magnitude of deformation of the diaphragm made from silicon rubber and EPDM (ethylene propylene diene monomer) with varying thickness of 0.5 mm; 1mm and 2mm. Through the Finite Element Method approach to obtain deformation analysis modeling, EPDM material provides higher deformation than using silicon material. However, for pressures of no more than 0.5 bar, using a rubber thickness of 0.5 mm is not suitable. So the appropriate application for Gliders is 1 mm thick.

Technical Design and Data Analysis of Autonomous Underwater Vehicle-Based Side-Scan Sonar Operations

In response to the absence of standardized work practices, work safety measures, efficient work procedures, and suitable line planning methods for exploring seabed topography using autonomous underwater vehicles (AUVs) equipped with side-scan sonar systems, this paper proposes a design framework for side-scan sonar measurement technology based on AUVs. Detailed research has been conducted on line planning methods that differ significantly from those used in shipborne operations. The new line planning method was developed based on the performance characteristics of AUV equipment, the principles of motion modes, and shipborne side-scan sonar operations. The validity of the line planning method was verified through actual sea experiments using different types of AUVs in various terrains. The experimental results demonstrate that the new survey line planning method is distinct from existing AUV path planning methods and is highly applicable for conducting seabed topography exploration operations. Furthermore, the technical design scheme studied in this article is applicable in different sea areas and ensures the safety, operational efficiency, and data quality of AUVs. It holds significant importance for marine science engineering and practical applications. The article also features an analysis of successful data collected from AUVs equipped with side-scan sonar for conducting seabed topography exploration operations.

Digital Twin-Driven Industrialization Development of Underwater Gliders

Underwater glider (UG) is the only marine equipment in the field of ocean observation that can realize unmanned autonomous, all-weather and wide-area continuous three-dimensional observation. The rapid individualized design (RID) and full lifecycle management (FLM) make two difficulties to be solved in the industrialization development of UGs since the UG system involves interdisciplinary multiphysics and there exists multi-source uncertainties in complex ocean environment. With the application of new information technologies in industry, the above problems can be effectively solved by the digital twin (DT)-driven methodology. In this paper, an architecture of DT-driven RID and FLM for UGs is first put forward based on our previous theoretical research and technique development. Then, the proposed architecture of DT-driven methodology is researched in detail in terms of its digital modeling, design optimization, virtual verification and practical application. Finally, Petrel developed by China is introduced, and a typical preliminary application of DT-driven methodology is presented based on Petrel to verify its feasibility. The architecture proposed in this paper is also appropriate for other types of autonomous underwater vehicles.

Acoustic receiving on glider-type autonomous underwater vehicles: Advantages and challenges

An ocean glider is a specific type of Autonomous Underwater Vehicle (AUV) that operates using a buoyancy engine rather than traditional propellors or thrusters. This method of propulsion enables a glider to be deployed for weeks or months and is relatively quiet, making the ocean glider a desirable platform for persistent acoustic monitoring. A glider typically remains submerged for several hours, during which time it can be challenging to localize the vehicle precisely. Gliders are low-power platforms that operate in the mid-water column, and therefore subsea navigation technologies implemented on other types of AUVs, such as inertial navigation systems aided by Doppler velocity logs, may not be suitable. Acoustic signals from fixed broadband sources have been used for subsea localization of Seaglider, a commercially available glider platform. Measurements of the multipath acoustic arrival structure received on Seagliders at ranges up to hundreds of kilometers from transmitting sources were used for vehicle localization in both temperate and polar underwater sound propagation environments. Methodology and results for subsea localization of the Seaglider platform will be presented and placed in the context of a broader discussion of the advantages and challenges specific to the glider as a moving acoustic receiving platform.

Resistance Evaluation for the Submerged Glider System using CFD Modelling

The underwater gliders are type of autonomous underwater vehicles, which are in their way to be used instead of traditional propellers or thrusters. They are used as submerged gliders or as a part connected to floating hull which is propelled by it. The underwater system depends on different number of hydrofoils (underwater wings) that allow it to glide forward while descending through the water. This paper concentrates on three critical design details: profile of the wings, multiple flapping wings and their angle of attack (AoA), and a method is focused on the mesh generation to predict calm water resistance for the submerged glider system while considering the profile and the maximum rotating angle of the wings and rudder. Flow around submerged wing system model has been calculated at different Froude numbers ranging from 0.1 to 0.6. The grid generator is established for meshing the computational domain with structured hexahedral and unstructured tetrahedral grid. Simulations are carried out using commercial CFD code ANSYS Fluent 19 to calculate calm water resistance of the submerged glider system with different number of hydrofoils. The results conclude that the cambered plate was chosen to design the rudder at 19o AOA and the hydrofoil NACA0012 can be practically applied in the design of the wings at 15o AOA from the resistance point of view. In addition, this investigation introduces a new application for CFD calculations in estimating the resistance of the submerged glider system.

추력편향방식 AUV의 직진안정성 개선을 위한 고정핀 설계

AUVs (Autonomous Underwater Vehicles) have been widely used for various underwater survey missions. In general, cruising type AUVs have torpedo-shaped hull forms for minimizing the hull resistances. It is necessary to ensure there are sufficient straight-line stabilities for a cruising type AUV in order to maintain its desired courses and depths with minimum controls during operations. In this study, vertical and horizontal plane straight-line stabilities of a designed AUV are analyzed based on the captive model tests. VPMM (Vertical Planar Motion Mechanism) tests are carried out to obtain hydrodynamic coefficients of the designed AUV. The AUV shows both vertical and horizontal plane instabilities, its stability margin indices are unsatisfying when compared with the recommended values. But the recommended vertical plane stability margins are subject to very high-speed conditions, so the characteristic equations of the AUV are reconsidered to investigate low-speed vertical plane stabilities in more detail. Next, a pair of horizontal and vertical fins are respectively designed to improve the vertical and horizontal plane stabilities of the AUV. The AUV with fixed fins shows improved stability margin indices within the recommended levels. In addition, the shape of the horizontal fins is properly modified for safe operations. The AUV with the designed vertical fins shows good horizontal plane stability in straight run simulations with step disturbances. And the effects of the horizontal fins are investigated through depth control simulations with biased random disturbances.

Estimating DVL Velocity in Complete Beam Measurement Outage Scenarios

Autonomous underwater vehicles (AUVs) commonly employ a Doppler velocity log (DVL) to achieve an accurate navigation solution. In real-world scenarios, like when operating in complex environments, situations of complete DVL outages may occur, leading to rapid degradation in the navigation solution. To circumvent such situations, this article proposes an approach to estimate the platform’s velocity vector based on past DVL measurements and a motion model, for short time periods. At-sea experiments were conducted using two types of AUVs, each with a different DVL, to collect data for a total time duration of 90 min. This dataset was employed to show the benefits of using the proposed approach.

Adaptive neural networks trajectory tracking control for autonomous underwater helicopters with prescribed performance

An autonomous underwater helicopter (AUH) is a type of autonomous underwater vehicle (AUV) that is capable of fixed-point hovering, precise and free take-off, and landing. It is effective for underwater ultra-mobile tasks, including mobile observation networks, resource exploration, and data connection. This paper aims to investigate an AUH trajectory tracking controller based on the prescribed performance method, considering the influence factors such as current disturbance, modeling uncertainty and thruster faults. A novel preset time performance function is designed in which the stable terminal time of the system can be specified explicitly, and the convergence rate of the system's dynamic process may be altered by adjusting the parameters, making it more intuitive for the designer. A speed observer was introduced to address this problem of measuring the required state information from the AUH's sensors in practice, which was enhanced using a radial basis function neural network (RBFNN) to approximate external perturbations and uncertainties. The stability of the closed-loop AUH system is proved by using Lyapunov theory. The feasibility and effectiveness of the proposed algorithm proposed approach were eventually verified by two sets of simulations for different thruster fault forms.

Simulation and control of a novel hovering type autonomous underwater vehicle (HAUV) with ballast tanks

Simulation and control of a novel hovering type autonomous underwater vehicle (HAUV) with ballast tanks

Investigation of a New Hovering Autonomous Underwater Vehicle for Underwater Missions

It is impossible to implement very tasks by diver, because of complexity of underwater environment and high pressure in the deep sea. These tasks can just be done by a vehicle that includes all special requirements such as: high maneuverability, precise controllability, and especially hovering capability. Underwater robots are integral parts of the industry and marine science. The application of the underwater vehicles has increased with the development of the activities in deep sea. This paper presents a special Hovering type Autonomous Underwater Vehicle (HAUV) for underwater missions. To provide the most suitable and efficient formation of vehicle thrusters for reduction of complexity of control strategies and control of the most degrees of freedom, in this paper, a new thrusters' configuration is investigated, in terms of number of the thrusters, position and the thrust direction of the thrusters. The state feedback controller is designed according to the linear dynamic model and then applied to the non-linear model to validate the controller performance. Designed controller consists of three controllers: horizontal plane controller, vertical plane controller and surge controller. The last controller is developed to control the forward speed. For examination of the system behavior in presence of environmental disturbance and hydrodynamic coefficients uncertainty, the robustness of controller is also investigated.

Visual navigation and docking for a planar type AUV docking and charging system

As being increasingly used for underwater explorations, Autonomous Underwater Vehicles (AUVs) are diversified in their structures and outlines to match up with various mission requirements, which brings challenges to the design of customized submerged docking stations. Aiming at providing a generalized solution, this paper proposes an omnidirectional and positioning-tolerant planar type AUV docking and charging platform, which has no constraints on AUV structures. In order to solve the planar-type docking issues, an integrated visual navigation and docking algorithm is developed for the miniaturized prototype AUV. The adopted monocular Simultaneous Localization and Mapping (SLAM) program takes charge of the wide-range underwater locationing, and handles practical problems such as scale drift and tracking failure. A combined control strategy of horizontal dynamic positioning and vertical visual servo docking is developed for the terminal docking process. The strategy is robust against constant water flow disturbance and performs stable docking using a roll motion adjustment. The visual navigation and docking performances and other system functions are successfully validated in simulation, water pool experiment, and sea trial.

Dynamic modelling of a hovering type autonomous underwater vehicle with ballast tank

Dynamic modelling of a hovering type autonomous underwater vehicle with ballast tank

Dynamic modelling of a hovering type autonomous underwater vehicle with ballast tank

Dynamic modelling of a hovering type autonomous underwater vehicle with ballast tank

Parameters Identification of the Flexible Fin Kinematics Model Using Vision and Genetic Algorithms

Abstract Recently a new type of autonomous underwater vehicle uses artificial fins to imitate the movements of marine animals, e.g. fish. These vehicles are biomimetic and their driving system is an undulating propulsion. There are two main methods of reproducing undulating motion. The first method uses a flexible tail fin, which is connected to a rigid hull by a movable axis. The second method is based on the synchronised operation of several mechanical joints to imitate the tail movement that can be observed among real marine animals such as fish. This paper will examine the first method of reproducing tail fin movement. The goal of the research presented in the paper is to identify the parameters of the one-piece flexible fin kinematics model. The model needs further analysis, e.g. using it with Computational Fluid Dynamics (CFD) in order to select the most suitable prototype for a Biomimetic Underwater Vehicle (BUV). The background of the work is explained in the first section of the paper and the kinematic model for the flexible fin is described in the next section. The following section is entitled Materials and Methods, and includes a description of a laboratory test of a water tunnel, a description of a Vision Algorithm (VA)which was used to determine the positions of the fin, and a Genetic Algorithm (GA) which was used to find the parameters of the kinematic fin. In the next section, the results of the research are presented and discussed. At the end of the paper, the summary including main conclusions and a schedule of the future research is inserted.

Sensitivity Analysis of Bias in Satellite Sea Surface Temperature Measurements

The satellite sea surface temperature (SST) measurement is based on the detection of ocean radiation using microwave or infrared wavelengths within the electromagnetic spectrum. The radiance of individual wavelengths can be converted into brightness temperatures for using in SST determination. The calibration and validation of the determined SST data require reference measurements from in-situ observations. These in-situ observations are from various platforms such as ships, drifters, floats and mooring buoys and require a high measurement accuracy. This paper presents an investigation about the possibility of using a glider as in-situ platform. A glider is a type of autonomous underwater vehicle (AUV) which can log oceanographic data over a period of up to one year by following predetermined routes. In contrast to buoys, a glider allows a targeted investigation of regional anomalies in SST circulations. To assess the quality of SST observations from a glider, logged data from a glider mission in the Atlantic Ocean from 2018 to 2019 and corresponding satellite SST data were used. The influence of variables (e.g. measurement depth, latitude, view zenith angle, local solar time) of the bias between satellite and glider SST data was investigated using sensitivity analysis. A new and efficient distribution-based method for global sensitivity analyzes, called PAWN, was used successfully. Interested readers will find information about its operation principle and the usage for passive observations where only “given-data” are available.

Mathematical modeling of autonomous underwater vehicle propulsion and steering complex operation in oblique (beveled) water flow

The research of nonlinear hydrodynamic characteristics of the propulsion and steering complex (PSC), which influence the accuracy of the plane trajectory motion of an autonomous underwater vehicle (AUV), is carried out. During the underwater vehicle curvilinear motion, its PSC operates in an oblique incident water flow. This leads to a decrease in the PSC thrust force and negatively affects the controlled trajectory motion of the underwater vehicle. The research was conducted for a specific type of AUV for the plane curvilinear motion mode. The mathematical modeling method was chosen as the research method. To this end, the well-known AUV motion mathematical model is supplemented by the control system that simulates (mimics) its trajectory motion. The developed model consists of four main units: an AUV improved model; the vehicle speed setting unit; the nozzle rotation angle control unit; the unit containing the AUV pre-prepared motion trajectories. The research results of the AUV hydrodynamic parameters for several typical trajectories of its motion are presented. The investigated parameters include the following: the required nozzle rotation angle; the vehicle actual motion trajectory; the vehicle velocity; the propeller shaft moment; the propeller thrust force. As a result of the conducted researches, the dependence diagram of the propeller thrust force on the AUV nozzle rotation angle in the speed range from 0.2 m/s to 1 m/s and during the nozzle rotation in the range of up to 35° was constructed. A three-dimensional matrix, which describes the dependence of the propeller thrust force on the incident water flow angle and velocity of the vehicle, was created. The obtained dependence can be used in the synthesis of automatic control systems regulators of AUV plane manoeuvering (shunting) motion of increased accuracy.

Shape optimisation of blended-wing-body underwater gliders based on free-form deformation

ABSTRACTAs a type of Autonomous Underwater Vehicles (AUV), blended-wing-body underwater gliders (BWBUGs) have drawn much attention due to their unique performance advantages in long-distance navigation missions. Because the configuration is the direct component to influence the navigation efficiency, it is significant to perform shape optimisation of BWBUGs. In this paper, an optimisation framework is presented, where Free-Form Deformation (FFD) is adopted for geometric parameterisation. Besides, an Euler-based CFD solver with a discrete adjoint method is applied for numerical simulation and gradients calculation, and Sequential Quadratic Programming (SQP) is employed as the optimiser. With the help of the proposed framework, an optimised BWBUG is regarded as the initial shape and four shape optimisation cases are carried out for different design purposes. All the objective functions aim to increase the lift-drag ratio under the thickness and volume constraints. The simulation results show that all the cases achieve a higher lift-drag ratio.

Rendezvous Planning for Multiple AUVs With Mobile Charging Stations in Dynamic Currents

Operation of autonomous underwater vehicles (AUVs) in large spatiotemporal missions is currently challenged by onboard energy resources requiring manned support. With current methods, AUVs are programmed to return to a static charging station based on a threshold in their energy level. Although this approach has shown success in extending the operational life, it becomes impractical due to interruption of AUV operation and loss of energy needed to return to charging station. It is also not practical for large networks due to shortage of charging stations. We introduce mobile onsite power delivery, which will fundamentally change the range and duration of underwater operations. This letter presents a mission planning method to generate mobile charger trajectories, given pre-defined working AUV trajectories, considering environmental constraints such as currents and obstacles. The problem is formulated as a multiple generalized traveling salesman problem, which is then transformed into a traveling salesman problem. Energy cost in dynamic currents is integrated with a path planning algorithm using a grid-based environment model. A scheduling strategy extends the problem over multiple charging cycles. Simulation results show that the planning method significantly improves mission success and energy expenditure. Field experiments in Lake Superior using two types of AUVs, an unmanned surface vessel, and a manned support vessel validate the feasibility of the planned trajectories for long-term marine missions.

Computational fluid dynamics study of the motion stability of an autonomous underwater helicopter

In this study, the motion stability of a new type of autonomous underwater vehicle (AUV) named an “autonomous underwater helicopter (AUH)” with a disk-shaped hull was analyzed to better accomplish the complex tasks under the sea, namely, pipeline maintenance, mobile observation network, resources exploration, and isodepth navigation. A Reynolds Averaged Navier-Stokes (RANS) grid for the AUH was created with an ICEM mesh generation tool. The RANS-based computational fluid dynamics (CFD) technique, ANSYS-CFX, was adopted to analyze the AUH's behavior, including its motion stability and maneuverability in the horizontal and vertical planes. Pivotal hydrodynamic technical issues including configurations selection and a trade-off study of the AUH were analyzed with the RANS solver, including computed pressure distribution and comparison of different lengths of aquatic transducers mounted on the AUH for enhanced hydrodynamic performance. The Routh motion stability criterion based on the 6-DOF equations of motion consisting of linear hydrodynamic derivatives was implemented by the RANS solver for the optimized AUH with a service speed in the range of 1–3 knots. The simulation results and experimental tests show that the AUH has ample motion stability for enhanced maneuverability in translational and rotatory motion during under-sea navigation. The results suggest that design configurations of the appended hull can be used on AUVs.

Research on Dynamic Characteristics of Glider Hydrofoil by Finite Element Models Analysis

The underwater glider is a new type of autonomous underwater vehicle driven by buoyancy. The glider hydrofoil is the key driving element of the glider, it works under complex alternative load and determines the safety of navigation of the underwater glider. This paper takes the hydrofoil as the research object, a finite element model of hydrofoil has been established and the dynamic load of hydrofoil has been calculated. Finite element model analysis was conducted to the glider hydrofoil in free and restrained states, and the preceding few orders natural frequency of the glider hydrofoil and the corresponding vibration model and the vibration amplitude in the conditions were conducted respectively. The dangerous area of the glider hydrofoil was found out, which could provide data for optimal dynamic design and dynamic modification of hydrofoil.