Manuel J. López

LQG/LTR control of ship steering autopilots

A linear-quadratic-Gaussian/loop-transfer-recovery (LQG/LTR) controller is used for automatic steering of ships. Identification of the discrete-time system is based on Nomotos model and on the innovation model. The system is non-minimum-phase, which is the sampled version of the continuous system. The benefits of this controller are demonstrated by simulation results.<<ETX>>

Genetic algorithm for LQG/LTR design parameters. a flight control system application

Abstract In this paper we propose a method for tuning Linear Quadratic Gaussian/Loop-Transfer Recovery (LQG/LTR) controller based on genetic algorithms. Suitable time responses as well as satisfactory robustness properties are obtained using two optimisation loops, where genetic algorithms are employed to satisfy design specifications for a flight control system.

Adaptive Optimal Control of Ship Steering Autopilots

Abstract This paper describes the application of an adaptive LQG/LTR controller to automatic steering of ships. The controller is based on Nomotos model and on the innovation model to identify the discrete time system. The benefits of this controller are demonstrated by simulation.

Robust Roll Motion Regulator Based on IMC Structure

Abstract In this work a design methodology for roll damping is developed, which is based on internal model control structure, and on an H∞ optimization procedure. The final controller is suboptimal due to the fact that the optimal regulator is modified by a filter to get a proper controller and adequate robustness properties, in spite of which it achieves the design specifications. The proposed controller properties are analysed and proved by computer simulation with the non-linear mathematical model of a ship.

Multivariable Robust LTR-i Controller for a Ship

Abstract This paper describes the application of a multivariable robust controller based on LTR-i methodology for roll damping and course steering of a ship by rudder and fins. The controller uses a non observer based control structure, and a partial recovery procedure over the band of interest frequencies. Robustness characteristics of the controller in the face of uncertainties are analyzed and the benefits are proved by simulation with a non linear model.

Variable Structure H∞ Controller for Aircraft

This paper proposes a new synthesis method and tuning procedure for a variable structure H∞ multivariable controller for fixed wing aircrafts attitude control, which consists in switching from one-degree of freedom controller (1-DOF) to two degrees of freedom controller (2-DOF), and vice versa, with a method for bump-less transfer in switching transitions. The proposed method is tested using robustness analysis based on frequency domain and time analysis computer simulations based on a nonlinear mathematical model of the F-16 aircraft published by the NASA, from which satisfactory results are obtained.

Method for nonlinear L 2 control of ships: course-changing and path tracking

Abstract In this work a design procedure for course-changing control and path tracking control is presented, which is based on nonlinear L 2 control theory. The proposed method uses a nonlinear model of the ship and obtains a non-linear suboptimal H ∞ controller (state feedback version or state estimated approach with a non-linear observer). A symbolic computation environment is necessary to carry out the steps of the control system methodology; which has been implemented using Maple and Matlab programs. Software environment and simulation results are presented for course-changing and path tracking control.

Course-Keeping and Course-Changing H∞ Controller for a Ferry

Abstract In this work we present a study carried out for a ship of Ferry type. An H ∞ regulator is developed to keep a fixed course of the ship, and another H ∞ controller is designed for course changing operation. Both designs have into account the physical limitations of the rudder servosystem. and uncertainties in ship dynamics. The objective of the control system is to achieve robust performance

Comparison Between Multivariable H∞ and LTR Controllers for a Ship

Abstract This paper describes and compares the application of a multivariable robust controllers based on LTR and H ∞ methodologies for a steering-satabilisation system. Performance and robustness characteristics of the controllers with respect to high frequency modelling errors are analyzed. In order to evaluate every designed controller we proposed a set of performance and robustness indicators.