Showing papers on "Rudder published in 2023"

MPC-Based Collaborative Control of Sail and Rudder for Unmanned Sailboat

Abstract: In the traditional motion control method of an unmanned sailboat, the sail and rudder are divided into two independent controllers. The sail is used to obtain the thrust and the rudder is used to adjust the yaw angle. The traditional control method does not consider the synergy between the two controllers and ignores the influence of the roll angle on sailing. It is easy for these methods to cause an excessive roll angle and large yaw angle error, which will weaken the safe navigation and accurate path tracking of an unmanned sailboat. This paper presents a collaborative control method of sail and rudder based on model predictive control. A four-degree-of-freedom kinematics and dynamics model of the unmanned sailboat considering roll angle was established, with the yaw angle and roll angle as the control objectives at the same time. The collaborative control method outputs sail angle and rudder angle simultaneously. By comparing the motion of this method and the separation control of sail and rudder under the same wind field conditions, it is verified that the collaborative control has better effects of yaw angle control and roll angle limitation and can obtain a more accurate path tracking effect.

Further Study on One of the Numerical Methods for Pure Loss of Stability in Stern Quartering Waves

Abstract: The International Maritime Organization (IMO) finalized the second-generation intact stability criteria in 2022. However, an accurate and practical numerical method for stability loss has yet to be established. Therefore, a 6 DOF numerical model is further improved based on the previous study. Firstly, the rolling motion is simulated using a seakeeping model instead of the previous maneuvering mathematical model. Secondly, the roll-restoring variation is calculated directly considering the instantaneous wet hull instead of the previous pre-calculated method. Thirdly, transferring frequency to time is used to obtain heave and pitch motions, further considering yaw angle and sway velocity. Fourthly, the dynamic forces for sway, roll, and yaw motions are calculated, further considering the effect of the speed variation. Fifthly, the 6 DOF motions are used to determine the instantaneous wet hull, and the FK force and the hydrostatic force are calculated by the body’s exact method. Finally, a new conclusion is obtained that the sway and yaw motions’ effect on the ship speed loss, the relative longitudinal wave profile by the speed loss, the rudder angles, and the accompanying rudder forces in the rolling direction are significant, and much more than their centrifugal force or coupled force in the rolling direction.

Optimal Route Generation and Route-Following Control for Autonomous Vessel

Abstract: In this study, basic research was conducted regarding the era of autonomous vessels and artificial intelligence (deep learning, big data, etc.). When a vessel is navigating autonomously, it must determine the optimal route by itself and accurately follow the designated route using route-following control technology. First, the optimal route should be generated in a manner that ensures safety and reduces fuel consumption by the vessel. To satisfy safety requirements, sea depth, under-keel clearance, and navigation charts are used; algorithms capable of determining and shortening the distance of travel and removing unnecessary waypoints are used to satisfy the requirements for reducing fuel consumption. In this study, a reinforcement-learning algorithm-based machine learning technique was used to generate an optimal route while satisfying these two sets of requirements. Second, when an optimal route is generated, the vessel must have a route-following controller that can accurately follow the set route without deviation. To accurately follow the route, a velocity-type fuzzy proportional–integral–derivative (PID) controller was established. This controller can prevent deviation from the route because overshoot rarely occurs, compared with a proportional derivative (PD) controller. Additionally, because the change in rudder angle is smooth, energy loss by the vessel can be reduced. Here, a method for determining the presence of environmental disturbance using the characteristics of the Kalman filter innovation process and estimating environmental disturbance with a fuzzy disturbance estimator is presented, which allows the route to be accurately maintained even under conditions involving environmental disturbance. The proposed approach can automatically set the vessel’s optimal route and accurately follow the route without human intervention, which is useful and can contribute to maritime safety and efficiency improvement.

Simulator Evaluation of Flightpath-oriented Control Allocation for the Flying-V

Abstract: A novel aircraft configuration, the tailless Flying-V, is examined for its longitudinal handling qualities in cruise by means of piloted simulations. The Flying-V is controlled by two aileron/elevator (elevon) surfaces on each side, and rudders on each wingtip. Two control allocation schemes were created: a conventional one where both inboard and outboard elevons deflect in the same direction, and one where the change in lift the elevons generate is countered by deploying the inboard and outboard elevons in opposite directions, allowing more direct control of the resulting flight path. The longitudinal handling qualities in cruise conditions were investigated by pilot opinion in a moving base simulator. Three experiments were conducted: a traditional pitch tracking experiment with the conventional control allocation, and a new flight-path-angle tracking experiment, using both the conventional and the flight-path-oriented control allocation. The pilots indicated the conventional pitch attitude control to have Level 1 handling qualities for the pitch control task, and Level 2 for the flight path control task. The flight-path-oriented control allocation improved the performance of the pilots during the flight-part tracking experiment, but the perceived control authority was considered too small for most pilots to consistently rate it at Level 1.

Constrained Aerodynamic Shape Optimisation of the Flying V Outer Wing

Abstract: The Flying V is a flying wing aircraft consisting of two pressurized passenger cabins placed in a V shape. Its longitudinal and lateral control is ensured via elevons and split flaps on the outboard wing, and rudders on the tip-mounted winglets. The goal of this study is to devise a design for the outboard wing of the Flying V through a constrained aerodynamic shape optimization at cruise conditions. The design process is divided into a geometry preparation phase in which the existing parametrization is adjusted, followed by a planform design optimization guided by the Differential Evolution algorithm making use of a vortex-lattice method and an Euler flow analysis. The cross-sectional shape of the wing is subsequently optimized through a Free-Form Deformation (FFD) shape optimization based on the Euler equations. Two FFD optimizations are conducted to evaluate the effect of the integration of the elevons. The highest lift-to-drag ratio is obtained by neglecting the control surface integration and amounts to 20.3. While the constraints related to this elevon integration reduce the efficiency to 19.4. The overall efficiency gain compared to the original aircraft design is equivalent to 13% and 8%, respectively. A further increase is expected once the inefficient outboard wing is optimized in more detail.

Numerical simulation of a gear

Abstract: To navigate safely, the ship must be manoeuvrable and have good stability. The steering of the ship depends on a number of factors such as: the means of steering used, the geometric shapes of the hull (stern area), the ratios between the main dimensions (LCWL/B and B/T), the number, position and direction of rotation of the engine. and the hydro-meteorological conditions in which they sail (water, air, wind, waves). Every ship, with the exception of barges, must have a robust and safe steering system to ensure manoeuvrability and sea stability. These installations can be: rudder with hydrodynamic profile, installation with adjustable nozzles and other installations approved by the Classification Societies. In this particular study an analysis on a gear pump fitted in the azimuth system of a chemical tanker is being made, using a CFD technology. The main aim is to study the efficiency of this pump by comparing the CFD analysis results with the results in real operational condition. Main parameters focused on are outlet flow, suction column, power and pump efficiency. There are several differences registered in the case of suction column and power, but they are not that high, while parameters outlet flow and pump efficiency are almost identical.

Study on the Model Tests of Cavitation Erosion Occurring in Navy Ship’s Flat-Type Rudder

Abstract: In the present study, a method of performing cavitation erosion test directly on the anodized surface of the rudder model is proposed, not applying ink or paint on its surface. An image processing technique is newly developed to quantitatively evaluate the erosion damages on the rudder model surface after erosion test. The preprocessing saturation image, image smoothing, adaptive hysteresis thresholding and eroded area detection algorithms are in the image processing program. The rudder cavitation erosion tests are conducted in the rudder deflection angle range of 0SUPo/SUP to -4SUPo/SUP, which is used to maintain a straight course at the highest speed of the targeted navy ship. In the case of the conventional flat-type full-spade rudder currently being used in the target ship, surface erosion can occur on the model rudder surface in the above rudder deflection angle range. The bubble type of cavitation occurs on rudder surface, which is estimated to be the main reason of erosion damage on the rudder surface.

Application of fuzzy controllers in automatic ship motion control systems

Abstract: Automatic ship heading control is a part of the automatic navigation system. It is charged with the task of maintaining the actual ship’s course angle or actual ship’s course without human intervention in accordance with the set course or setting parameter and maintaining this condition under the effect of disturbing influences. Thus, the corrective influence on deviations from a course can be rendered by the position of a rudder or controlling influence that leads to the rotary movement of a vessel around a vertical axis that represents a problem, which can be solved with the use of fuzzy logic. In this paper, we propose to consider the estimation of the efficiency of fuzzy controllers in systems of automatic control of ship movement, obtained by analysis of a method of the formalized record of a logic conclusion and structure of the fuzzy controller. The realization of this allows to carry out effective stabilization of a course angle of a vessel taking into account existing restrictions.

Research on trajectory tracking control algorithm in 4WS mode

Abstract: In indoor shooting training, most of targets are fixed targets or tracked target vehicles that move on a fixed track,while in actual combat, most of targets are moving targets with uncertain orientation.This paper designs a four-rudder wheel moving target vehicles chassis and proposes chassis kinematics model in view of the omnidirectional moving targets,and achieves four-rudder wheel chassis trajectory tracking control model by using model predictive control algorithm,and deduces the mobile chassis trajectory tracking control algorithm according to the technical performance indicators and constraints of the vehicle motion,and proves that applying the model predictive control algorithm to the four- rudder wheel chassis to realize trajectory tracking has feasibility in the locomotion mode of 4WS according to the simulation experimental results,and conducts trajectory tracking comparative simulation experiments by selecting different prediction time domain,control time domain and sampling time.The experimental results shows that the model predictive controller with less sampling time and lower control time domain has better effect on target path tracking.

Numerical Investigation of the Rudder–Propeller Interaction in Open Water with and without Duct

Abstract: The propulsive performance of a ship depends mainly on the interaction between the rudder and propeller. Hence, it is essential to understand the interaction between the rudder and propeller to design an improved energy-efficient propulsor for ships. Rudder performance is significantly affected by the flow of the propeller slip stream, and propeller performance is also affected by the presence of a rudder. With the advancement of computational fluid dynamics, it is now widely used for the preliminary prediction of the performance of ship propulsors and energy-saving devices at the design stage. In this study, rudder-propeller interaction phenomena with and without a duct have been investigated numerically for the propeller of a benchmark ship. Various combinations of rudder angles have been used to figure out the open water characteristics of the propeller and the lift & drag characteristics of the rudder. Steady RANSE-based CFD simulations were performed using the SST k-omega turbulence model of a single-phase flow. The numerical results were validated and verified following the ITTC's recommended procedure.

Design for Brake Device of Rudder Pedal Based on Torsion Bar

Abstract: As airborne equipment, the rudder pedal is used by pilots to control the rudder deflection by foot, and it has two functions of apply rudder and brake. As many disadvantages existing in traditional brake device, such as complex structure, large volume, heavy weight, a brake device of integrated rudder pedal based on torsion bar is designed. The device, using a torsion bar and an angular command sensor, realizes the brake device function of integrated rudder pedal. The design methods of spare functional parts of brake device are introduced in detail. The check calculation of torsion bar, design index of brake command sensor, kinematics simulation analysis of brake device and weight comparison after lightweight design are given. The practical application shows that the principle of the brake device is correct and it has the advantages of compact structure, high utilization, lightweight and high linearity.

Data-Driven Fault Detection of AUV Rudder System: A Mixture Model Approach

Abstract: Based on data-driven and mixed models, this study proposes a fault detection method for autonomous underwater vehicle (AUV) rudder systems. The proposed method can effectively detect faults in the absence of angle feedback from the rudder. Considering the parameter uncertainty of the AUV motion model resulting from the dynamics analysis method, we present a parameter identification method based on the recurrent neural network (RNN). Prior to identification, singular value decomposition (SVD) was chosen to denoise the original sensor data as the data pretreatment step. The proposed method provides more accurate predictions than recursive least squares (RLSs) and a single RNN. In order to reduce the influence of sensor parameter errors and prediction model errors, the adaptive threshold is mentioned as a method for analyzing prediction errors. In the meantime, the results of the threshold analysis were combined with the qualitative force analysis to determine the rudder system’s fault diagnosis and location. Experiments conducted at sea demonstrate the feasibility and effectiveness of the proposed method.

Network-Based Heading Control of UMVs

Abstract: This chapter addresses network-based heading controlHeading control and rudder oscillation reduction for a UMVUnmanned Marine Vehicles (UMVs) equipped with single rudder in network environments. A novel network-based model is first established by constructing a heading controlHeading control error system and purposely dropping some control input packets, which are received by a steering machine. Then a stabilization criterion is derived to guarantee the heading angle tracking performance and to reduce the oscillation of the rudder angle.

Experimental Study on Navigation Flow Condition of Downstream Approach Channel of Navigation Facilities of Baise Water Conservancy Project

Abstract: Abstract Baise Water Conservancy Project is the second cascade in the Yujiang River planning, and its navigation facilities are one of the key projects to get through Yunnan and Guizhou. The exit of the downstream approach channel of the navigation facilities of the Baise Water Conservancy Project is located about 700 m downstream of the Dongsun Hydropower Station, so the operation of Dongsun Hydropower Station has a direct impact on the navigation flow condition of the approach channel. In addition, the topography of the river also has an obvious influence on the navigation conditions at the entrance area of the approach channel. So, based on the overall hydraulic model with a scale of 1:80 and the self-navigating ship simulation test, the navigation flow conditions at the entrance area of the approach channel and the characteristics of the ship entering and exiting the ship lock were studied. The test results show that: (1) Under the condition that the discharge of Dongsun Hydropower Station is less than1500 m 3 /s at full power, the flow pattern in the downstream channel of the hydropower station and the entrance area of the approach channel is relatively smooth. The flow pattern, velocity and wave height can meet the specification requirements. The maximum rudder angle and drift angle at the entrance area of the approach channel do not exceed the requirements, and the ship can enter and exit the downstream approach channel smoothly; (2) The maximum navigation discharge of 1700 m 3 /s can be achieved by adjusting the route of the connecting section of the downstream approach channel to the left bank and dredging the two convex points on the right bank of the entrance area of the downstream approach channel.