Adaptive backstepping control for ship nonlinear active fin system based on disturbance observer and neural network

Adaptive backstepping control based on disturbance observer and neural network for ship nonlinear active fin system is proposed. One disturbance observer is given to observe the disturbances of the system, by this way, the response time is shorten and the negative impact of disturbance and uncertain elements of the system is reduced. In addition, radial basic function neural network (RBFNN) is proposed to approach the unknown elements in the ship nonlinear active fin system, therefor the system can obtain good roll reduction effectiveness and overcome the uncertainties of the model, the designed controller can maintain the ship roll angle at desired value. Finally, the simulation results are given for a supply vessel to verify the successfulness of the proposed controller

LMI - BASED H2 AND H STATE - FEEDBACK CONTROLLER DESIGN FOR FIN STABILIZER OF NONLINEAR ROLL MOTION OF A FISHING BOAT

This paper presents the analyses of nonlinear roll responses of a fishing boat in waves. In addition to roll damping nonlinearity, the nonlinear roll restoring which has seventh order equation has been taken into consideration to accurate control application. To overcome nonlinearity and the effects of uncertainties, LMI (Linear Matrix Inequality) - based H2 and H State - Feedback Control are applied for the fin roll stabilizer of a fishing boat. The fin characteristics are calculated by Star CCM+ package software. Finally, utilising the studies presented to illustrate the feasibility and efficiency of the H2 and H control methods, the results of the simulations are demonstrated the performance of fin roll stabilizer

Automatic Control and Routing of Marine Vessels

Due to the intensive development of the global economy, many problems are constantly emerging connected to the safety of ships’ motion in the context of increasing marine traffic. These problems seem to be especially significant for the further development of marine transportation services, with the need to considerably increase their efficiency and reliability. One of the most commonly used approaches to ensuring safety and efficiency is the wide implementation of various automated systems for guidance and control, including such popular systems as marine autopilots, dynamic positioning systems, speed control systems, automatic routing installations, etc. This Special Issue focuses on various problems related to the analysis, design, modelling, and operation of the aforementioned systems. It covers such actual problems as tracking control, path following control, ship weather routing, course keeping control, control of autonomous underwater vehicles, ship collision avoidance. These problems are investigated using methods such as neural networks, sliding mode control, genetic algorithms, L2-gain approach, optimal damping concept, fuzzy logic and others. This Special Issue is intended to present and discuss significant contemporary problems in the areas of automatic control and the routing of marine vessels

Missile Modeling and Simulation of Nominal and Abnormal Scenarios Resulting from External Damage

This thesis presents the development of a six-degree-of-freedom flight simulation environment for missiles and the application thereof to investigate the flight performance of missiles when exposed to external damage. The simulation environment was designed to provide a realistic representation of missile flight dynamics including aerodynamic effects, flight control systems, and self-guidance. The simulation environment was designed to be modular, expandable, and include realistic models of external damage to the missile body obtained by adversarial counteraction. The primary objective of this research was to examine missile flight performance when subjected to unspecified external damage, including changes in trajectory, stability, and controllability, and to provide a basis for the future development of fault tolerant control laws to improve target tracking and overall flight performance when experiencing abnormal conditions. To accomplish this, a variety of scenarios were developed to simulate damage to different parts of the missile, such as the fuselage, wings, and control surfaces. Three types of damage are considered: arbitrary failures which affect the major overall missile dynamic force and moment coefficients, structural failures including wings and fin breakage, and stuck fin failures where a given fin is arbitrarily fixed to a specified deflection. The missile behavior in response to these scenarios was analyzed and compared to the baseline behavior of an undamaged missile. The results of this research demonstrate how simulated missiles behave during flight, under both nominal and abnormal scenarios resulting from external damage. The simulation environment is shown to be a useful tool in examining the performance of missiles under real-world scenarios, such as during combat, in the event of an accident, or when exposed to other adversarial counteractions. This is done by producing envelopes for mission success for each tested scenario and analyzing the results. The results of this research can be used to assist in and improve the design and performance of missiles and enhance their survivability in the field. These results can also be used to determine the amount of damage necessary to prevent a given missile from reaching its target

Underwater Vehicles

For the latest twenty to thirty years, a significant number of AUVs has been created for the solving of wide spectrum of scientific and applied tasks of ocean development and research. For the short time period the AUVs have shown the efficiency at performance of complex search and inspection works and opened a number of new important applications. Initially the information about AUVs had mainly review-advertising character but now more attention is paid to practical achievements, problems and systems technologies. AUVs are losing their prototype status and have become a fully operational, reliable and effective tool and modern multi-purpose AUVs represent the new class of underwater robotic objects with inherent tasks and practical applications, particular features of technology, systems structure and functional properties

A Predictive Fuzzy-Neural Autopilot for the Guidance of Small Motorised Marine Craft

This thesis investigates the design and evaluation of a control system, that is able to adapt quickly to changes in environment and steering characteristics. This type of controller is particularly suited for applications with wide-ranging working conditions such as those experienced by small motorised craft. A small motorised craft is assumed to be highly agile and prone to disturbances, being thrown off-course very easily when travelling at high speed 'but rather heavy and sluggish at low speeds. Unlike large vessels, the steering characteristics of the craft will change tremendously with a change in forward speed. Any new design of autopilot needs to be to compensate for these changes in dynamic characteristics to maintain near optimal levels of performance. This study identities the problems that need to be overcome and the variables involved. A self-organising fuzzy logic controller is developed and tested in simulation. This type of controller learns on-line but has certain performance limitations. The major original contribution of this research investigation is the development of an improved self-adaptive and predictive control concept, the Predictive Self-organising Fuzzy Logic Controller (PSoFLC). The novel feature of the control algorithm is that is uses a neural network as a predictive simulator of the boat's future response and this network is then incorporated into the control loop to improve the course changing, as well as course keeping capabilities of the autopilot investigated. The autopilot is tested in simulation to validate the working principle of the concept and to demonstrate the self-tuning of the control parameters. Further work is required to establish the suitability of the proposed novel concept to other control

Aerial Vehicles

This book contains 35 chapters written by experts in developing techniques for making aerial vehicles more intelligent, more reliable, more flexible in use, and safer in operation.It will also serve as an inspiration for further improvement of the design and application of aeral vehicles. The advanced techniques and research described here may also be applicable to other high-tech areas such as robotics, avionics, vetronics, and space