José Manuel Díaz

The problem of the coupling of the vertical movement control with roll movement in fast ferries

Abstract Previous researches have studied the attenuation of heaving and pitching motion in fast ferries. One observed problem that appears in these cases is the fact that actuators action (for instance, asymmetries T-foil), waves incidence with angle, and the control action itself cause a coupling with roll movement, and therefore an increasing in the rolling vertical component. Roll motion can be less relevant than the damped longitudinal movement, but it is significant and, in fact, it can result in unpleasant effects to passengers. In this work an analysis and design of a roll control have been carried out.

BENCHMARK CONTROL PROBLEMS FOR A NON-LINEAR UNDERACTUATED HOVERCRAFT: A SIMULATION LABORATORY FOR CONTROL TESTING

Abstract Hovercrafts are a type of vehicles with a structure model similar to marine vehicles. These systems are strongly non-linear so their dynamics are complex. The problems of motion control can be classified in three groups: point stabilization, trajectory tracking and path following. From a pedagogical point of view it is difficult to study the behaviour of this type of vehicles using only static graphs. In order to understand the dynamics of these vehicles it is necessary to use interactive dynamic simulations. This paper shows a simulation environment used as a laboratory to design, analyze and test controllers for the three benchmark control problems for the model of a radio control hovercraft with the possibility of implementing the designs obtained in the real system.

ROBUST CONTROL FOR THE COUPLING OF LATERAL AND LONGITUDINAL DYNAMICS IN HIGH-SPEED CRAFTS

Abstract In this work, the QFT technique was used to control a system with three degrees of freedom of coupled movement. The example is the coupling between the vertical and the horizontal dynamics of a high-speed craft. Since the angle between the heading and the seaway is different from 180 degrees, the action of the actuators for controlling each dynamic produces a coupling in the other dynamic. Firstly, controllers for the two dynamics were designed separately. Then, the actuator coupling was considered, and finally, it was shown how the controllers reduce the three coupled modes in the whole system.

ITTSAE: A Set of Interactive Software Tools for Time Series Analysis Education [Lecture Notes]

A time series is a set of observations that are generated sequentially in time. This article considers discrete-time series, where observations are made at some fixed interval h. A time series can also be considered as a possible realization of a stochastic process, which is a statistical phenomenon that evolves in time according to probabilistic laws. This article presents a set of three interactive software tools for time series analysis education (ITTSAE) written in Sysquake [17], a language similar to that used in Matlab, and that generates tools with interactive graphics that have simple interfaces. The interactive tool set ITTSAE is distributed free of charge [18] in the form of executable files for different platforms. As such, they are readily available to any user (student or instructor) who may want to use them.

Design of a stabilization control system for high-speed crafts based on robust techniques. Two different approaches

This work handles the design of a stabilization control for a high-speed craft in order to improve comfort and security in maritime transport. The goal is to damp the coupled dynamics of heave, pitch and roll by using active stabilization surfaces such as flaps, T-foil and fins. The methodology used is based on the Quantitative Feedback Theory (QFT) robust technique. Two approaches depending on the degree of coupling are presented. In the first approach, controllers for the longitudinal and transversal dynamics are designed separately and afterwards the actuator coupling is considered. The second approach provides a solution in cases where the effect of the actuator coupling is large. Hence, a combination of QFT and Eigenstructure Assignment (EA) methods is used. For both methods, time-domain simulations analyses for different conditions of sea state and angles of incidence provide satisfactory results and achieve damped responses. It is shown that robust techniques based on QFT methodology result feasible and very suitable since the problem can be applied to any angle of incidence and only one controller is required for any speed or sea state. Therefore they constitute attractive alternatives in the application of a stabilization control of an advanced marine system.

DISCRETE EVENT BASED APPROACH TO THE SIMULATION OF A CONTINUOUS NAVAL SYSTEM

Abstract In this work a simulation platform for uninhabited marine and aerial vehicles is proposed. This platform is based in the MDA (Model Driven Architecture) approach and the DEVS (Discrete Event System Specification) formalism. Platform independent models (PIM) are used to describe the vehicles and its interaction; then, theses models are traduced to platform-specific models (PSMs) in Matlab-Simulink, Java and other languages. DEVS formalism is designed to describe discrete events model, so in order to use continuous time models the second order quantified states simulation (QSS2) is proposed. This method is applied to an autonomous radio controlled hovercraft and its low level tracking controller.