Maritime Data Transfer Protocol (MDTP): A Proposal for a Data Transmission Protocol in Resource-Constrained Underwater Environments Involving Cyber-Physical Systems

The utilization of autonomous maritime vehicles is becoming widespread in operations that are deemed too hazardous for humans to be directly involved in them. One of the ways to increase the productivity of the tools used during missions is the deployment of several vehicles with the same objective regarding data collection and transfer, both for the benefit of human staff and policy makers. However, the interchange of data in such an environment poses major challenges, such as a low bandwidth and the unreliability of the environment where transmissions take place. Furthermore, the relevant information that must be sent, as well as the exact size that will allow understanding it, is usually not clearly established, as standardization works are scarce in this domain. Under these conditions, establishing a way to interchange information at the data level among autonomous maritime vehicles becomes of critical importance since the needed information, along with the size of the transferred data, will have to be defined. This manuscript puts forward the Maritime Data Transfer Protocol, (MDTP) a way to interchange standardized pieces of information at the data level for maritime autonomous maritime vehicles, as well as the procedures that are required for information interchange.SWARMs (Smart and Networking Underwater Robots in Cooperation Meshes) 1034 European research project. It is under Grant Agreement 1035 n.662107-SWARMs-ECSEL-2014-1 and is being partially supported by the Spanish Ministry of Economy and Competitiveness (Ref: PCIN-2014-022-C02-02) and the ECSEL JU

Are object detection assessment criteria ready for maritime computer vision?

Maritime vessels equipped with visible and infrared cameras can complement other conventional sensors for object detection. However, application of computer vision techniques in maritime domain received attention only recently. The maritime environment offers its own unique requirements and challenges. Assessment of the quality of detections is a fundamental need in computer vision. However, the conventional assessment metrics suitable for usual object detection are deficient in the maritime setting. Thus, a large body of related work in computer vision appears inapplicable to the maritime setting at the first sight. We discuss the problem of defining assessment metrics suitable for maritime computer vision. We consider new bottom edge proximity metrics as assessment metrics for maritime computer vision. These metrics indicate that existing computer vision approaches are indeed promising for maritime computer vision and can play a foundational role in the emerging field of maritime computer vision

Modeling of Performance of a AUV Vehicle Towards Limiting the Hydro-acoustic Field

Some results of research devoted to the modeling of a AUV-Stealth vehicle performance towards limiting its hydro-acoustic field are presented in the paper. At the beginning the AUV-Stealth autonomous underwater vehicle concept is described. Then the method of research is introduced. Next the key design drivers of the AUV-Stealth vehicle are presented. Between them are the AUV-Stealth hull form, arrangement of internal spaces, materials, hull covers, energy supply and propulsion system, etc. Some results of the hydrodynamic and stealth characteristics of the AUV-Stealth vehicle are briefly described. It is presented in the paper that the hull form, construction materials including the covers may affect the AUV-Stealth vehicle boundary layer and wake. This may create some problems of identification of the AUV-Stealth vehicle using a sonar or hydrophone. The final conclusions are presented

LiDAR Buoy Detection for Autonomous Marine Vessel Using Pointnet Classification

Maritime autonomy, specifically the use of autonomous and semi-autonomous maritime vessels, is a key enabling technology supporting a set of diverse and critical research areas, including coastal and environmental resilience, assessment of waterway health, ecosystem/asset monitoring and maritime port security. Critical to the safe, efficient and reliable operation of an autonomous maritime vessel is its ability to perceive on-the-fly the external environment through onboard sensors. In this paper, buoy detection for LiDAR images is explored by using several tools and techniques: machine learning methods, Unity Game Engine (herein referred to as Unity) simulation, and traditional image processing. The Unity Game Engine (herein referred to as Unity) simulation data was used for the training and testing of a Pointnet neural network model while the labeled real-world maritime environment point cloud data was used for the model validation. Fitting the Pointnet model on the simulation data, after some data alignment with the LiDAR images allowed for accurate classification of buoys on the real-world data with the 93% of accuracy. A traditional image processing approach using 2D occupancy maps to detect the buoys by shape was used as well and is outlined in the paper

Dynamic Task Allocation in Partially Defined Environments Using A* with Bounded Costs

The sector of maritime robotics has seen a boom in operations in areas such as surveying and mapping, clean-up, inspections, search and rescue, law enforcement, and national defense. As this sector has continued to grow, there has been an increased need for single unmanned systems to be able to undertake more complex and greater numbers of tasks. As the maritime domain can be particularly difficult for autonomous vehicles to operate in due to the partially defined nature of the environment, it is crucial that a method exists which is capable of dynamically accomplishing tasks within this operational domain. By considering the task allocation problem as a graph search problem, Minion Task, is not only capable of finding and executing tasks, but is also capable of optimizing costs across a range of parameters and of considering constraints on the order that tasks may be completed in. Minion task consists of four key phases that allow it to accomplish dynamic tasking in partially defined environments. These phases are a search space updater that is capable of evaluating the regions the vehicle has effectively perceived, a task evaluator that is capable of ascertaining which tasks in the mission set need to be searched for and which can be executed, a task allocation process that utilizes a modified version of the A* with Bounded Costs (ABC) algorithm to select the best ordering of task for execution based on an optimization routing, and, finally, a task executor that handles transiting to and executing tasks orders received from the task allocator. To evaluate Minion Task’s performance, the modified ABC algorithm used by the task allocator was compared to a greedy and a random allocation scheme. Additionally, to show the full capabilities of the system, a partial simulation of the 2018 Maritime RobotX competition was utilized to evaluate the performance of the Minion Task algorithm. Comparing the modified ABC algorithm to the greedy and random allocation algorithms, the ABC method was found to always achieve a score that was as good, if not better than the scores of the greedy and random allocation schemes. At best, ABC could achieve an up to 2 times improvement in the score achieved compared to the other two methods when the ranges for the score and execution times for each tasks in the task set as well as the space where these tasks could exists was sufficiently large. Finally, using two scenarios, it was shown that Minion Task was capable of completing missions in a dynamic environment. The first scenario showed that Minion Task was capable of handling dynamic switching between searching for and executing tasks. The second scenario showed the algorithm was capable of handling constraints on the ordering of the tasks despite the environment and arrangement of tasks not changing otherwise. This paper succeeded in proving a method, Minion Task, that is capable of performing missions in dynamic maritime environments

Safety Risk Analysis of Unmanned Ships in Inland Rivers Based on a Fuzzy Bayesian Network

Risk factor identification is the basis for risk assessment. To quantify the safety risks of unmanned vessels in inland rivers, through analysis of previous studies, the safety risk impact factor framework of unmanned vessels in inland rivers is established based on three aspects: the ship aspect, the environmental aspect, and the management and control aspect. Relying on Yangtze River, a fuzzy Bayesian network of the sailing safety risk of unmanned ships in inland rivers is constructed. The proposed safety risk model has considered different operational and environmental factors that affect shipping operations. Based on the fuzzy set theory, historical data, and expert judgments and on previous works are used to estimate the base value (prior values) of various risk factors. The case study assessed the safety risk probabilities of unmanned vessels in Yangtze River. By running uncertainty and sensitivity analyses of the model, a significant change in the likelihood of the occurrence of safety risk is identified, and suggests a dominant factor in risk causation. The research results can provide effective information for analyzing the current safety status for navigation systems of unmanned ships in inland rivers. The estimated safety risk provides early warning to take appropriate preventive and mitigative measures to enhance the overall safety of shipping operations. Document type: Articl

Justification for the Body Construction Selection of the Unmanned Uninhabited Underwater Apparatus

The paper explores the possibility of creating an underwater apparatus in the form of a body of rotation. The form of the device will allow to effectively examine the found underwater objects, the bottom topography, measurement of other parameters of the underwater environment or objects. The devices of a different streamlined body form are considered. The apparatus in the form of a rotation body is proposed. The geometric shape of the proposed apparatus, the system of motion and control are investigated. Methods for calculating the motion parameters, methods for the vehicle positioning in the flow and the underwater vehicle movement in the vertical plane are proposed. The study confirms the ability of the underwater vehicle to move under water in a horizontal and vertical directions. The study confirms that the device possess stability at rectilinear motion, good turning ability and at the same time it is able to position itself during the flow

Application of the Tecnomatix Plant Simulation Program to Modelling the Handling of Ocean Containers using the AGV System

AGV systems, gradually making their way into individual logistics processes, represent an important tool for handling different types of cargo. Since their initial start in the domain of small handling units, their use has been incrementally finding its application in the area of large handling units, too, such as different types of containers. That is why an ever increasing number of them can be encountered at the range of land and sea reloading sites. Thus, there are many opportunities for them to be deployed in different types of logistics processes at maritime reloading sites. For the AGV system and the logistics processes to function correctly at each maritime reloading site, they need to be thoroughly fine-tuned. One of the methods that can be used effectively to that end is the method of computer simulation. The paper will describe how to create a simple simulation model using Tecnomatix Plant Simulation

Математичне моделювання роботи рушійно-стернового комплексу автономного ненаселеного підводного апарату у косому потоці води

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.Проводится исследование нелинейных гидродинамических характеристик движительно-рулевого комплекса (ДРК), которые влияют на точность плоского траекторного движения автономного необитаемого подводного аппарата (АНПА). При криволинейном движении подводного аппарата его ДРК работает в косом потоке воды набегает. Это приводит к снижению силы упора ДРК и негативно влияет на управляемый траекторных движение подводного аппарата. Исследования в работе проведено для конкретного типа АНПА для режима криволинейного движения.В качестве метода исследования был избран метод математического моделирования. С этой целью известная математическая модель движения АНПА дополнена системой уравнений, которые имитируют его траекторное движение. Разработанная модель состоит из четырех основных блоков: усовершенствованной модели АНПА; блока задания скорости движения апарата; блока управления углом поворота насадки; блока, который содержит заранее подготовленные траектории движения АНПА. Представлены результаты исследования гидродинамических параметров АНПА для нескольких типичных траекторий его движения. К исследуемым параметрам отнесены следующие: необходимый угол поворота насадки; действительная траектория движения аппарата; скорость движения аппарата; момент на валу гребного электродвигателя; упор гребного винта.В результате проведенных исследований построено диаграмму зависимости упора гребного винта от угла поворота насадки АНПА в диапазоне скорости от 0,2 м/с до 1 м/с и при повороте насадки в диапазоне до 35°. Создано трехмерную матрицу, которая описывает зависимость упора гребного винта от угла потока набегающей воды и скорости движения аппарата. Полученная зависимость может быть использована при синтезе регуляторов систем автоматического управления плоским маневровым движением АНПА повышенной точностиПроводиться дослідження нелінійних гідродинамічних характеристик рушійно-стернового комплексу (РСК), які вливають на точність плоского траєкторного руху автономного ненаселеного підводного апарата (АНПА). При криволінійному русі підводного апарата його РСК працює у косому потоці води, що набігає. Це призводить до зниження сили упору РСК і негативно впливає на керований траєкторний рух підводного апарату. Дослідження було проведено для конкретного типу АНПА для режиму плоского криволінійного руху.У якості методу дослідження було обрано метод математичного моделювання. З цією метою відому математичну модель руху АНПА доповнено системою керування, що імітує траєкторний рух АНПА. Розроблена модель складається з чотирьох основних блоків: удосконаленої моделі АНПА; блоку завдання швидкості руху апарату; блоку керування кутом повороту насадки; блоку, який містить заздалегідь підготовлені траєкторії руху АНПА.Представлено результати дослідження гідродинамічних параметрів АНПА для декількох типових траєкторій його руху. До досліджуваних параметрів належать наступні: необхідний кут повороту насадки; дійсна траєкторія руху апарату; швидкість руху апарату; момент на валу гребного електродвигуна; упор гребного гвинта.В результаті проведених досліджень побудовано діаграму залежності упору гребного гвинта від кута повороту насадки АНПА в діапазоні швидкості від 0,2 м/с до 1 м/с та при повороті насадки в діапазоні до 35°. Сформовано трьохвимірну матрицю, яка описує залежність упору гребного гвинта від кута потоку води, що набігає, та швидкості руху апарату. Отримана залежність може бути використана при синтезі регуляторів систем автоматичного керування плоским маневровим рухом АНПА підвищеної точност