[PDF] State Space Modeling And Optimal Control Of Ship Motions In A Seastate eBook
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(Cont.) The development from first principles of a reliable ship motion control simulation method based on SWAN and its coupling with LQ controllers used to actively regulate the angle of attack of lifting appendages, circumvents the need to perform sea trials or model experiments that are harder, time-consuming and expensive to carry out. The performance of the method is illustrated for a catamaran vessel fitted with bow and stern hydrofoils. Simulations of the vessel motions were performed with and without the effect of the controller in regular and random waves. It is concluded that the combination of the proposed state-space model with the LQ controller was very effective in reducing the undesired motions of the vessel in waves over a wide range of wave frequencies and ship speeds.
engineers into a single volume whilst concentrating on two important research control design problems: autopilots with rudder-roll stabilization and fin and combined rudder-fin stabilization. He has been guided by some of the leading marine control academics, in particular Mogens Blanke and Thor Fossen; indeed Chapters 3 and 4 on kinematics and kinetics of ship motion are jointly authored with Professor Fossen. There are some 240 cited references – an invaluable resource for interested readers. The volume is likely to appeal to a wide range of readers who will each be able to extract something different from the various parts of the monograph. Part I has some four chapters on the modelling fundamentals including kinematics, dynamics and actuators. Part II is a very useful survey of the ship roll stabilization problem and how ship roll performance is measured and assessed. This clearly motivates the human necessity for roll-reduction and roll stabilization. Parts III and IV move on to the control systems aspects of the various stabilization designs. Valuable material here includes a study of system performance limitations as caused by the presence of non-minimum phase characteristics and actuator saturation. Chapter 10 has an interesting historical review of these marine control problems stretching back some thirty-years into the 1970s.
Ship drivers have long understood that powerful interaction forces exist when ships operate in close proximity to rigid boundaries or other vessels. Controlling the effects of these forces has been traditionally handled by experienced helmsmen. The purpose of this research is to apply modern optimal control theory to these maneuvering scenarios in order to show that helmsman may some day be replaced by modern controllers. The maneuvering equations of motion are cast in a linear state space framework, permitting the design of a linear quadratic (LQ) controller. In addition, the hydrodynamic effects are modeled using potential flow theory in order to simulate the interaction forces and test the efficacy of the controller. This research demonstrates that the linear quadratic regulator effectively controls ship motions due to the presence of a boundary or other vessel over a broad range of speeds and separation distances. Furthermore, the method proposed provides stable control in the presence of additional. stochastic disturbances.
Handbook of MARINE CRAFT HYDRODYNAMICS AND MOTION CONTROL The latest tools for analysis and design of advanced GNC systems Handbook of Marine Craft Hydrodynamics and Motion Control is an extensive study of the latest research in hydrodynamics, guidance, navigation, and control systems for marine craft. The text establishes how the implementation of mathematical models and modern control theory can be used for simulation and verification of control systems, decision-support systems, and situational awareness systems. Coverage includes hydrodynamic models for marine craft, models for wind, waves and ocean currents, dynamics and stability of marine craft, advanced guidance principles, sensor fusion, and inertial navigation. This important book includes the latest tools for analysis and design of advanced GNC systems and presents new material on unmanned underwater vehicles, surface craft, and autonomous vehicles. References and examples are included to enable engineers to analyze existing projects before making their own designs, as well as MATLAB scripts for hands-on software development and testing. Highlights of this Second Edition include: Topical case studies and worked examples demonstrating how you can apply modeling and control design techniques to your own designs A Github repository with MATLAB scripts (MSS toolbox) compatible with the latest software releases from Mathworks New content on mathematical modeling, including models for ships and underwater vehicles, hydrostatics, and control forces and moments New methods for guidance and navigation, including line-of-sight (LOS) guidance laws for path following, sensory systems, model-based navigation systems, and inertial navigation systems This fully revised Second Edition includes innovative research in hydrodynamics and GNC systems for marine craft, from ships to autonomous vehicles operating on the surface and under water. Handbook of Marine Craft Hydrodynamics and Motion Control is a must-have for students and engineers working with unmanned systems, field robots, autonomous vehicles, and ships. MSS toolbox: https://github.com/cybergalactic/mss Lecture notes: https://www.fossen.biz/wiley Author’s home page: https://www.fossen.biz
Nonlinear Industrial Control Systems presents a range of mostly optimisation-based methods for severely nonlinear systems; it discusses feedforward and feedback control and tracking control systems design. The plant models and design algorithms are provided in a MATLAB® toolbox that enable both academic examples and industrial application studies to be repeated and evaluated, taking into account practical application and implementation problems. The text makes nonlinear control theory accessible to readers having only a background in linear systems, and concentrates on real applications of nonlinear control. It covers: different ways of modelling nonlinear systems including state space, polynomial-based, linear parameter varying, state-dependent and hybrid; design techniques for nonlinear optimal control including generalised-minimum-variance, model predictive control, quadratic-Gaussian, factorised and H∞ design methods; design philosophies that are suitable for aerospace, automotive, marine, process-control, energy systems, robotics, servo systems and manufacturing; steps in design procedures that are illustrated in design studies to define cost-functions and cope with problems such as disturbance rejection, uncertainties and integral wind-up; and baseline non-optimal control techniques such as nonlinear Smith predictors, feedback linearization, sliding mode control and nonlinear PID. Nonlinear Industrial Control Systems is valuable to engineers in industry dealing with actual nonlinear systems. It provides students with a comprehensive range of techniques and examples for solving real nonlinear control design problems.
Ships sailing on the ocean have many inherent dangers. One of the most compelling is when they interact with severe stochastic waves, resulting in a loss of stability and adversely affecting their operation. This can result in extreme motions, at the very least making life difficult for crew, to potentially the most catastrophic events capsize, and loss of cargo and life. This compels the need to reliably predict vessel responses to wave interactions in order to aid the decision-making process for operating the ship safely. Despite the advances in computational methods and stochastic hydrodynamic theories to this date, a general framework, capable of handling nonlinear three-dimensional effects, arbitrary wave headings and unconventional hull geometries, is still missing from the engineer's toolbox. This thesis presents a new methodology for modeling the nonlinear responses and stability of a ship in stochastic waves. Invoking the weak-scatterer hypothesis, the radiation and diffraction effects are linearized, computed via a panel method, and cast into a state-space form, aided by applying the ESPRIT algorithm. Strong free surface nonlinearities present in the Froude-Krylov exciting and hydrostatic restoring forces are modeled by Fluid Impulse Theory. In parallel, the ambient seastate is represented by a multidimensional stochastic differential equation (SDE) conforming to a prescribed spectrum. Combining the state-space and seastate models capacitates the study of the nonlinear seakeeping and stability of a ship in a broad range of stationary seastates via stochastic calculus methods. Chief among them is the use of the Fokker-Planck equation (FPE), a deterministic partial differential equation governing the joint probability density function of the states of the SDE. The formulation for a rectangular barge rolling in beam waves is presented, with the approach readily extendable to six-degree-of-freedom responses. By deriving a state-space stochastic differential equation for the states governing the vessel response motions, the joint probability density can be found either by numerical Monte-Carlo simulation of the SDE, or by numerically solving the associated FPE.