Francisco J. Velasco

Improving the comfort of a fast ferry

A study was conducted to determine the effectiveness of using controlled flaps and a T-foil to smoothen a ships vertical motion while navigating in head seas. The study comprised two steps: to develop a tool for control design in the form of a computer-based simulation and to use this tool to develop satisfactory controllers. The simulation was based on mathematical models of the ship, the actuators, the waves and the seasickness effect. Since the actuators have limited action, there is a limited margin for improvement based on more sophisticated control strategies. Possible improvements of motion sickness incidence (MSI) are linked to a control strategy that exploits better synchronization with incident waves.

Remote laboratory for marine vehicles experimentation

This article describes a remote experimentation environment for marine vehicles (Hardware and Software) and its application in engineering education. The laboratory has an in‐scale model of a turbo‐ferry tf‐120 which keeps all the hydrodynamic characteristics of the full‐scale vessel. The physical model was developed to be autonomous and is controlled remotely from a PC using Wi‐Fi communications. It has the instruments commonly used in vessels such as: GPS, UMI, accelerometers and gyrocompass. A simulation of a manoeuvring model has been developed based on geometrical definitions and compared to a heading identified model. The possibilities of the remote laboratory for engineering education are discussed.

Identification for a Heading Autopilot of an Autonomous In-Scale Fast Ferry

The aim of this paper is to obtain a heading model for the purpose of control of an in-scale fast-ferry TF-120 physical model, including the dynamics and kinematics, using a remote experimentation platform for marine vehicles. The physical model is developed to be autonomous and is controlled remotely from a PC using WiFi communications. The identification and validation of the model dynamics is obtained with turning circle maneuverings. The tests with the autonomous in-scale physical model of the high-speed ship were carried out on the coastline of the Bay of Santander. The parametric model identified is used to design different classical control structures for a heading autopilot, and a simulation of this system is performed in Simulink.

MARINE VEHICLES WEB-WIFI PLATFORM FOR REMOTE EXPERIMENTATION PROGRAMMED IN LABVIEW

Abstract This paper describes the development of a platform for performng tests on marine vehicles for cooperative actions, valid both for industrial application and for training in identification and control, using a physical in-scale model of an autonomous high-speed vessel. The model has an Industrial PC which acts as a web server and communicates through a wireless connection with a portable PC located on land. A software support in LabVIEW has been implemented in the Industrial PC which is capable of capturing and storing data. It is posible from a distance, via the web, to view data and modify the parameters of all of the instruments of the platform using the wireless network with wifi technology. This software is suitable for performing the Guidance, Navigation and Control (GNC) of the physical model since it permits the modification of commands.

OVERVIEW OF A RESEARCH ON ACTUATORS CONTROL FOR BETTER SEAKEEPING IN FAST SHIPS

Abstract The paper is an overview of a research initiated seven years ago by three groups of three universities, under the auspices of a Spanish shipbuilder. The research aims to improve the seakeeping performances of fast ferries, by using moving appendages such transom flaps and T-foil. There is a problem of control design to move the actuators in adequate way, to counteract the effect of encountered waves. The research focuses on alleviation of seasickness. Several aspects have been covered along the research, motivating a long series of papers. The overview gives an ordered account of the main results, with the corresponding references. Main results concerning seasickness and navigation, prediction of seasickness during ship design, experimental modelling, control design and experimental verification, are presented.

Pitch movement QFT control to reduce the MSI of a turbo ferry

Abstract This article describes the tuning of a QFT controller (Quantitative Feedback Theory) designed in order to reduce the pitch movement generated in a high-speed Turbo Ferry and so reduce the MSI (Motion Sickness Incidence). The objective pursued in the design was to improve the performance of the craft for speeds of 20, 30 and 40 knots and for ssn 4 (sea state number 4), and also the minimization of the control effort. For the QFT controller tuning a linearized model of the ship was used. System specifications are robust stability, sensitivity reduction to the waves effect and minimization of the control effort. In order to control the heave movement we have used a first order controller tuned by means of genetic algorithms applied to the non-linear model of the ship. A Simulink non-linear model has been used to simulate and validate the response of the ship with the designed controllers. It is found that these controllers provide a significant reduction of the vertical acceleration and MSI for the studied cases.

A Research on Motion Smoothing of Fast Ferries

Abstract This paper is about a research on the use of active appendages to smooth the motions of fast ferries. According to BAZAN specifications, the research focused on a fast ferry with a T-foil and transom flaps. A collaboration of three research groups, with the experimental support of CEHIP AR was established to accomplish the objectives. The research was scheduled as two main steps. A first step of control-oriented modelling has successfully been achieved. The second step is dedicated to control design and experimental evaluation, seeking for the best solution. First experimental results confirm good expectations with the use of the active controlled appendages. This paper describes the main aspects of the research: the problem to be solved, the methodology and fulfilment of the research project, and the most relevant results obtained.

Robust predictive PI controller

A robust discrete-time PI controller can be designed for stable systems based on a simple model. The controller has three tuning parameters, one of them being the sampling period, which can be chosen from the step response of the plant. The relationships between the parameters assuring the stability of the system are derived. The structure of the controller is a particular case of Internal Model Control (IMC) (Morari and Zafiriou, 1989), and can also be used to control processes with large dead times. The paper establishes the model and derives the discrete controller. The conditions for asymptotic stability of the closed-loop system for an unknown stable plant are derived. The paper applies the proposed scheme to plant with large dead times and its relationship with the predictive PI controller of (Hagglund, 1992) is shown.<<ETX>>

Thruster Control Based On The Shunt Dc Motors For A Precise Positioning Of The Marine Vehicles

Abstract The aim of the paper is the control of the number of revolutions developed by the shaft of a shunt direct current motor coupled to the stern propeller of an underwater vehicle with the purpose of controlling its horizontal orientation. Its dynamic can be expressed by two non linear decoupled equations. The procedure is based on the decomposition of the model with uncertainties by a suitable transformation onto a controlled subsystem and a stable non-controlled part, followed by the control design technique based in a sliding mode control algorithm using the backstepping theory, to achieve a controller capable to perform the fixed and tracking control purposes. The results show that the proposed procedure performs the control task satisfactory under uncertainties on the nonlinear model parameters. In the same way, once guaranteed the stability in order to satisfy the control requirements of efficiency and robustness, an error criteria have been applied. Validation of the control system is carried ...

Nonlinear Iterative Control of Manoeuvring Models for Transport over Water

This chapter addresses the problem of control design and implementation of a nonlinear marine vessel manoeuvring model. The chapter includes a thorough literature review of the current state of the art in the nonlinear control of marine vessels field. Then, the model will be presented; the authors will consider a highly nonlinear vessel 4 DOF model as the basis of the work. The control algorithm will be introduced providing the adequate mathematical description. The control algorithm here proposed consists of a combination of two methodologies: (i) An iteration technique that approximates the original nonlinear model by a sequence of linear time varying equations whose solution converge to the solution of the original nonlinear problem and, (ii) A lead compensation design in which for each of the iterated linear time varying systems generated, the controller is optimized at each time on the interval for better tracking performance. The control designed for the last iteration is then applied to the original nonlinear problem. Simulations and results will be presented and will show an accurate performance of the approximation methodology to the non linear manoeuvring model and also an accurate tracking for certain manoeuvring cases under the control of the designed lead controller. The main characteristics of the nonlinear systems response are the reduction of the settling time and the elimination of the steady state error and overshoot.