A route calculation for unmanned vessel

Рассматривается проблема определения маршрута движения безэкипажного судна с учетом жестких требований контроля положения и курса судна. Современные электронно-картографические навигационно-информационные системы в режиме управления траекторией определяют точку поворота для выхода на новый участок маршрута, что недостаточно для управления безэкипажным судном в автономном режиме. Для повышения точности предложено проводить расчет траектории движения безэкипажного судна в географических координатах c учетом движения судна по радиусу поворота между участками траектории без перевода в прямоугольную систему координат. Показано, что при движении в свободной акватории проблема может быть сведена к решению обратной геодезической задачи. Предложен универсальный алгоритм расчета траектории в виде сегментов дуг большого круга, позволяющий получить путевые точки маршрута с любой заданной точностью. В случае возникновения ограничений на движение между двумя участками по внутреннему радиусу необходимо рассчитать альтернативный маршрут обхода препятствия. Для данного случая предложен расчетный маневр, полученный на основе решения задачи Дубинса. Альтернативный маршрут формируется в виде последовательности криволинейных сегментов, соответствующих заданному радиусу поворота. Алгоритм расчета путевых точек позволяет получить траекторию обхода препятствия с любой степенью детализации. A route calculation problem for unmanned vessels is investigated according to the control position and course high requirements. Present day electronic chart display and information systems (ECDIS) operating on the track control regime provide wheel-of-point calculation to course changing. It is not enough to control unmanned ship on the route in the autonomous mode. To increase control precision a new route calculation routine is suggested. The routine provides route calculation in the geodesic coordinates without Cartesian reference system mapping. It is shown that in the empty water the routine can be reduced to an inverse survey computation. A universal route calculation algorithm providing great circle arc segmentation with any given accuracy is suggested. In the case of course changing restricted area, it is needed to calculate an alternate route for obstacle or collision avoidance. The algorithm of alternate route calculation based on Dubins problem solution is applied. The route is found as a sequence of great circle arcs according to the ship turn radius. The shown algorithm allows finding avoidance route waypoints with any given resolution.

Assessment the collision risk level for an autonomous unmanned ship involving fuzzy logic and neural network technologies

В работе предлагается решение задачи по оценке степени опасности столкновения с надводными объектами на море для автономного безэкипажного судна. Такая оценка в предлагаемой модели основывается на двух параметрах: ожидаемая дистанция и время кратчайшего сближения автономного безэкипажного судна с другими объектами, которые могут встретиться на траектории его движения. Разработана и описана модель на базе теории нечётких множеств, демонстрирующая удовлетворительное качество оценки степени опасности. Также в работе представлена усовершенствованная модель с применением теории искусственных нейронных сетей – адаптивная нейро-нечеткая сеть, улучшающая качество оценки степени опасности более чем на два порядка. В работе показаны результаты оптимизации параметров адаптивной нейро-нечёткой сети, обеспечивающей качественную оценку степени опасности столкновения безэкипажного судна, также представлены рассчитанные оценки качества как для нечёткой модели, так и для наилучшей нейро-нечёткой модели. The paper proposes a solution of the problem of assessing the collision risk level with surface objects at sea for an autonomous unmanned ship. Such collision risk level asses in the proposed model is based on two parameters: the distance at closest point of approach and the time to closest point of approach for autonomous unmanned ship with other marine surface objects that may meet on the trajectory of its movement. In this work developed and described model based on the theory of fuzzy sets, which demonstrates the satisfactory quality of assessing the collision risk level. The paper also presents an improved model using the theory of artificial neural networks - an adaptive neuro-fuzzy network that improves the assessment quality of collision risk level by more than hundredfold. The paper shows the results of optimization of the parameters of an adaptive neuro-fuzzy network, which provides a qualitative assessment of collision risk level for an unmanned ship, and presents the calculated quality estimates for both a fuzzy and the neuro-fuzzy model.

Inertial Gyro Wave Energy Conversion Nonlinear Modeling and Power-Index Predictive Control for Autonomous Ship

The complex marine environment and the high energy consumption of shipboard equipment pose challenges to the long-term navigation of autonomous unmanned ships. In wave-induced motion, inertial gyro antirolling technology is used to offset the energy transmitted by waves, but the massive consumption of energy is not conducive to long-term navigation of the unmanned ships. This paper attempts to exploit the wave energy transmitted by the gyro to improve the power supply of the unmanned ship. Firstly, a nonlinear coupling model of the gyro antirolling device and the unmanned ship is established. Secondly, considering various model constraints and physical constraints of the equipment, the energy evaluation objective function of nonlinear model predictive control (NMPC) is designed. In the simulation, the proposed control method can effectively extract electric energy from different waves.

Automatic sampling of sea water quality based on electric propulsion unmanned ship

In many sea areas, toxic and harmful chemicals exceed the standard seriously, which not only has a very bad impact on the survival of marine organisms, but also makes the safety of edible groundwater damaged. With the continuous development of artificial intelligence and deep learning, it is the most efficient and safe method to detect seawater with unmanned ship. By processing and fusing the images transmitted by the two radars, the common advantages of the two sensors are integrated, and the comprehensiveness of the UAV's perception of the surrounding environment is improved. In order to improve the accuracy and safety of unmanned aerial vehicle (UAV) offshore operation, this study designs an electric propulsion unmanned ship and its automatic control system according to the requirements of water quality sampling. Based on the theory of small body, the model of unmanned ship with the least resistance and the best safety is designed. According to the requirements of water quality sampling in the sea area, the collection and analysis system of six elements of water quality is equipped. The Realizable k-e turbulence model is used to simulate the self recovery ability of unmanned ship under wave disturbance. Theoretically, the unmanned ship can realize self righting in 4.25 s. And in the actual navigation, the unmanned ship can effectively avoid obstacles, and the basic information of sea water quality is within the specified range. The unmanned ship constructed in this study can be used as an auxiliary tool for water quality detection. By comparing with various study method, the proposed method obtains better performance.

CFD Simulation of the Safety of Unmanned Ship Berthing under the Influence of Various Factors

The safety of unmanned ship berthing is of paramount importance. In order to explore the influence of wind and wave coupling, a berthing computational fluid dynamics (CFD) model was established, and the characteristics of speed field, pressure field, and vortex have been obtained under different speed, wind direction, and the quay wall distances. The results show that the total resistance of the hull against the current can be about 1.60 times higher compared to the downstream resistance, water flow resistance is the dominant factor, accounting for more than 80% of the total resistance. When changing the distance between ship and shore at fixed speed, the results found that the torque is small, but the growth rate is very large when driving below 2 m/s, and the torque growth rate is stable above 2 m/s. Based on the established coupling model, a multi-factor berthing safety study is carried out on an actual unmanned ship. The results show that when the speed increases from 4 m/s to 12 m/s, the curve slope is small, the resistance increases from 3666 N to 18,056 N, and the rear slope increases. The pressure increases with the speed, and when the speed is 24 m/s, the maximum pressure is up to 238,869 Pa. When the wind speed is fixed, the vertical force of the unmanned ship increases first and then decreases to zero and then reverses the same law change, and the maximum resistance is about 425 N at the wind angle of about 45 degrees; At 90 degrees, the maximum lateral force on an unmanned boat is about 638 N. The above results can provide control strategy for unmanned ship berthing safety, and provide theoretical basis for unmanned ship route planning and obstacle avoidance, safety design, etc.