Rudder Systems Research Articles

Trajectory tracking control of vectored thruster autonomous underwater vehicles based on deep reinforcement learning

ABSTRACT Vectored thruster autonomous underwater vehicles (AUVs) offer superior manoeuvrability compared to traditional fin and rudder systems, especially at low or zero velocities. However, controlling these AUVs becomes challenging in the presence of unpredictable interference forces and external water flow velocities. This paper introduces a novel three-dimensional trajectory tracking method for vectored thruster AUVs using reinforcement learning, enabling the system to learn optimal control policies through environmental interaction. A 5-degree of freedom (5-DOF) model is developed from the kinematics and dynamics equations of the underactuated AUV. An extended state observer (ESO) is used to estimate the differential expansion state based on observed variables. A reinforcement learning-based trajectory tracking strategy is then implemented. Simulation experiments demonstrate the method’s effectiveness in precisely controlling AUVs under varying environmental conditions, achieving exceptional tracking accuracy even in the presence of random interference forces and external water flow velocities.

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

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.

CNN-Based Hybrid Optimization for Anomaly Detection of Rudder System

In this study, an automatic test platform suitable for steering gears was established, which can test four sets of rudder systems separately. In addition, we propose an anomaly detection method based on deep learning technology to complete the automated multi-fault classification of the steering gear test. This paper combines the particle swarm optimization algorithm and the grey wolf optimization algorithm to optimize the convolutional neural networks (HPSOGWO-CNN). The proposed HPSOGWO-CNN model is constructed in two stages to realize the efficient and high-accuracy anomaly detection of the rudder system. In the first stage, through 10-fold cross validation, the optimal number of search agents of the HPSOGWO algorithm is obtained, and the performance is compared with GWO and PSO algorithms respectively. The results demonstrate that HPSOGWO algorithm is an excellent technique for automatic selection of hyper-parameters. In the second stage, the designed HPSOGWO algorithm is used to fine-tune the hyper-parameters of CNN, and a highly matched model for anomaly detection of rudder system test parameters was finally obtained. The experimental results show that the accuracy of this method is 99.846%, the precision is 99.748%, the recall is 99.498%, the F-score is 99.618%, and Kappa reaches 0.99565. CNN-based hybrid optimization for anomaly detection of rudder system, is advanced in comparison to KNN, SVM, BP, CNN, PSO-CNN, GWO-CNN, MGWO-CNN, WdGWO-CNN, RW-GWO-CNN models, in terms of accuracy, precision, recall, F-score, and kappa, respectively. Moreover, it is not affected by the imbalance samples, and can achieve accurate classification for small training samples.

A Genetic Algorithm Application in Planning Path Using B-Spline Model for Autonomous Underwater Vehicle (AUV)

This paper proposes a method of using the B-spline mathematical model to plan high smoothness curve trajectories with heading condition through given waypoints for autonomous underwater vehicles (AUVs) in particular and ships with rudder systems in general. In addition, this paper examines some of the physical limitations of this vehicle, which lead to some binding conditions of the trajectory. Besides, the paper applies B-spline approximation method to reduce the curvature of the trajectory, when waypoints are too close and we do not need to go through exactly these waypoints in the 2D plane. Finally, this paper also proposes the genetic algorithm application with some modifications to solve the optimization of B-spline path length with constraint in turning radius of the vehicle.

Design and Implementation of 12 Pulse AC to DC Converter in Aircraft for Aerospace Applications

Aircraft applications like landing gears, flaps, rudder systems and etc. use actuator systems which includes combination of motor, actuators and auto transformer rectifier units (ATRU). These systems work at a frequency of 400Hz. These are AC to DC converters used in aircraft's system to supply constant DC power to the motors which in turn operates actuators. These converters varies with the pulses like 12 pulse, 24 pulse etc. For the systems like this harmonics too play a major role. Less the harmonics more efficient and reliable the system will be. In this paper, a 12 pulse AC to DC converter was designed for 400Hz and 50Hz and the actual model was built for 50Hz of 1KW power. The design of 400Hz and 50Hz was done in MATLAB/Simulink and the prototype was built for 50Hz. Total harmonic distortion (THD) was obtained and compared for the two systems. All the results the simulation and the prototype are shown in this paper.

Active Fault-tolerant Control Design for a Submarine Semi-physical Simulation System

In this paper, an integrated design of fault diagnosis and active fault-tolerant control is proposed for a submarine semi-physical simulation system in the presence of unknown faults of rudder systems. The semi-physical simulation system is constructed by combining two real rudder control systems and a virtual mathematical model for the vertical movement control of a submarine. The separate modules of the semi-physical simulation system are connected by industrial communication technologies. Then, an active fault-tolerant controller is designed for unknown rudder system faults. Finally, the results of the semi-physical simulation experiments verify the effectiveness of the proposed fault-tolerant control method, and make a solid foundation for designing an active fault-tolerant control system for a real submarine.

Propulsion Systems in Marine Navigation

Abstract This paper presents variants of propulsion systems as the main factor in the analysis and design of the power system of a sea-going or river vessel; this topic is also under research study within two doctoral theses. The analysis of the ship - main propulsion- thruster assembly is made according to the requirements imposed by the market economy. The parameters to be considered when choosing a propulsion system are: the cost of the investment, the specific cost of transport that depends both on the specific fuel consumption and on the number and level of pay of the crew members operating the propulsion system, the propulsion efficiency, the high safety in handling, and the control accessibility during operation. The Pod and Azipod propulsion systems are analyzed in terms of advantages and disadvantages compared to conventional propulsion systems. The azimuth thrusters can ensure maximum push in any direction regardless the speed of the ship, and thus can change the course of the ship according to its handling needs. The azimuth thrusters do not only operate in horizontal but also in oblique angles, providing the ship with great maneuverability, even at low speeds, where classical rudder systems have poor performance

Research on Ducted Propeller and Rudder Interactions in Extreme Conditions

This paper presents the results and analyses of a combined numerical-experimental study into the performance of three types of rudders to quantify the interactions between propeller, nozzle, and rudder at extreme rudder angles. Conventional, flapped and triple rudders are studied numerically as well as experimentally to evaluate the drag, lift, and moment generated by the rudders at moderate-to-extreme rudder angles and at forward propeller shaft speeds and inflow speeds. The experiments were carried out to evaluate the suitability of the three rudder types for a proposed cargo carrier in terms of controllability. The experiments were carried out at the selfpropulsion condition of the model equipped with twin stock ducted propellers along with each of the rudder systems. An extensive numerical study was carried out to evaluate the performance of the three rudders in terms of flow velocity, pressure, and wake fields. Drag and lift for different angles of attack are obtained for complicated propeller-nozzle-rudder arrangements. Investigations are carried out to study the effects of the interaction of the rudder with the propeller-nozzle assembly at extreme rudder angles as high as ±40°. For simplicity, the geometry of the vessel was not modeled in these simulations. The experimental results are presented along with the computational results for all three rudder cases. The lift and drag measurements are in good agreement with the corresponding predictions for each of the rudder arrangements. The mutual interactions between the rudder and the propulsion system were captured in the simulations and were comparable with the corresponding measurements. The research reveals the nature of the velocity and pressure fields due to the complex interactions between the propeller, nozzle, and rudders at extreme rudder angles. It is expected that the current investigation will assist naval architects, at the early design stage, to select the rudder type for their ships such that suitable maneuvering characteristics are obtained and stringent International Maritime Organization maneuvering criteria are met.

Innovative Fast Time Simulation Tools for Briefing / Debriefing in Advanced Ship Handling Simulator Training and Ship Operation

The innovative “Simulation-Augmented Manoeuvring Design, Monitoring & Control” system (SAMMON) based on Fast Time Simulation (FTS) technology was developed at the Institute for Innovative Ship Simulation and Maritime Systems (ISSIMS) of the Maritime Simulation Centre Warnemuende MSCW. The system consists of software modules for (a) Manoeuvring Design & Planning, (b) Monitoring & Control based on Multiple Dynamic Prediction and (c) Trial & Training. It is based on complex ship dynamic models for rudder, thruster or engine manoeuvre simulation under different environmental conditions. It is an effective tool for lecturing and demonstrating ship's motion characteristics, as well as for ship handling simulator training. It allows the trainee to immediately see the results of the actual rudder, engine or thruster commands, without having to wait for the real-time response of the vessel. The Maritime Simulation Centre of AIDA Cruises at Rostock/Germany and the CSMART Center for Simulator Maritime Training of Carnival Corporation at Almere/NL have some experience with the use of this new technology to improve simulator training in Advanced Ship Handling Training courses. Examples of its application in briefing/debriefing and introductory lectures for simulator exercises specifically for typical cruise ships with Twin-Screw and Rudder systems will be presented in the paper and at the conference.

Numerical prediction analysis of propeller bearing force for full-scale hull–propeller–rudder system

The hybrid grid was adopted and numerical prediction analysis of propeller unsteady bearing force considering free surface was performed for mode and full-scale KCS hull–propeller–rudder system by employing RANS method and VOF model. In order to obtain the propeller velocity under self-propulsion point, firstly, the numerical simulation for self-propulsion test of full-scale ship is carried out. The results show that the scale effect of velocity at self-propulsion point and wake fraction is obvious. Then, the transient two-phase flow calculations are performed for model and full-scale KCS hull–propeller–rudder systems. According to the monitoring data, it is found that the propeller unsteady bearing force is fluctuating periodically over time and full-scale propeller's time-average value is smaller than model-scale's. The frequency spectrum curves are also provided after fast Fourier transform. By analyzing the frequency spectrum data, it is easy to summarize that each component of the propeller bearing force have the same fluctuation frequency and the peak in BFP is maximum. What's more, each component of full-scale bearing force's fluctuation value is bigger than model-scale's except the bending moment coefficient about the Y-axis.

A proposal for propulsion performance prediction of a single-propeller twin-rudder ship

The influence of a rudder’s axial force on the prediction of full-scale powering performance of a ship is investigated in this paper. Axial force characteristics of different rudder types were investigated by open water experiments. Viscous scale effects on the rudder’s axial force were investigated by carrying out open water experiments with different sizes of rudder. Experiments were carried out in the towing tank for a model ship fitted with different rudder systems to investigate the influence of rudder’s axial force on full-scale propulsion performance prediction. Based on the experiment results, a new prediction method is proposed for estimating full-scale power that considers scale effect on rudder’s axial force. Good performance of the proposed prediction method is demonstrated by estimating the engine power of a ship installed with a special high lift twin-rudder system from model experiments and comparing it with the values measured on the ship during full-scale experiments.

A suggestion of gap flow control devices for the suppression of rudder cavitation

This paper presents the numerical analysis of rudder cavitation in propeller slipstream and the development of a new rudder system aimed for lift augmentation and cavitation suppression. The new rudder system is equipped with cam devices which effectively close the gap between the horn/pintle and movable wing parts. A computational fluid dynamics code that solves the Reynolds-averaged Navier–Stokes equations is used to analyze the flow field of various rudder systems in propeller slipstream. The body force momentum source terms that mimic flow field behind a rotating propeller are added in the momentum equations to represent the influence of the propeller and its slipstream. For detailed explication of the new rudder system’s lift augmentation and cavitation suppression mechanism, three-dimensional flow analysis is carried out. Simulations clearly display the mechanism of the lift augmentation and cavitation suppression. The computational results suggest that the Reynolds-averaged Navier–Stokes-based computational fluid dynamics reproduces the flow field around a rudder in propeller slipstream and that the present concept for a cavitation suppressing rudder system is highly feasible and warrant further study for inclusion of the interaction with hull and mechanical design for manufacturing and operations.

Computational hydrodynamic analysis of the propeller–rudder and the AZIPOD systems

A computational method has been developed to predict the hydrodynamic performance of the propeller–rudder systems (PRS) and azimuthing podded drive (AZIPOD) systems. The method employs a vortex-based lifting theory for the propeller and the potential surface panel method for the steering system. Three propeller models along with three steering systems (rudder and strut, flap and pod (SFP)) are implemented in the present calculations for the cases of uniform and non-uniform conditions. Computed velocity components show good agreement with the experimental measurements behind a propeller with or without the rudder. Calculated thrust, torque and lift also agree well with the experimental results. Computations are also performed for an AZIPOD system in order to obtain the pressure distributions on the SFP, and the hydrodynamic performance (thrust, torque and lift coefficients). The present method is useful for examining the performance of the PRS and AZIPOD systems in the hope of estimating the propulsion and the maneuverability characteristics of the marine vehicles more accurately.

Certification and Design Issues for Rudder Control Systems in Transport Aircraft

A recent transport aircraft accident involving inappropriate rudder inputs by the pilot flying has led to a series of National Transportation Safety Board recommendations regarding certification. In particular, certification standards are sought that will ensure safe handling qualities in the yaw axis throughout the flight envelope, including limits for rudder pedal sensitivity. This study is offered as a first step in establishing such standards. A review of current Code of Federal Regulations part 25 as regards rudder control is briefly summarized, as are pertinent sections of Federal Aviation Administration Advisory Circular 25-7A-Flight Test Guide for Certification of Transport Category Airplanes. An analytical investigation of possible piloting tasks for assessing rudder pedal force/ feel systems is presented. The tasks reflect the philosophy of advisory circular 25-7A. A comparison of the pedal force/ feel systems for three transport aircraft and four rotorcraft is presented. Three parameters for assessing the quality of pedal and rudder systems are discussed, a linearity index, maximum required pedal forces, and lateral acceleration at the pilot's station per unit of pedal force input above breakout.

High-Performance Rudders—with Particular Reference to the Schilling Rudder

The evolution of the rudder as a means of steering or maneuvering ships has not kept up with other progress in ship machinery and propulsion systems. During the past decade, however, several significant advances in ship maneuvering have been made based on the principle of diverting the propulsive thrust rather than simply steering the hull. One of these innovations is the Schilling rudder, which offers, at a relatively economical cost, greatly improved maneuverability even at very slow speeds. The Schilling rudder can be rotated 75 deg to either side without stalling, which provides stern thrust capability to the ship as the main engine thrust can be diverted at an angle of 90 deg to the hull. A twin Schilling Rudder system, with independently controllable rudders, has the additional features of allowing vectored reversal of ahead thrust, eliminating the need for a reversing gear or controllable-pitch propeller, and, when coupled with a suitable bow thrust device, can even provide a level of dynamic positioning capability to the ship. Both the single and double Schilling rudder systems have now been proven in service and their applicability extended to most types of vessels with no limit on size.