Oscar Calvo

Coordinated path following for multiple underactuated AUVs

This paper addresses the problem of coordinated path following whereby multiple underactuated marine crafts are required to follow a prescribed paths while keeping a desired inter-vehicle formation pattern. We show how Lyapunov- based techniques and graph theory can be brought together to yield a decentralized control structure where the dynamics of the cooperating vehicles and the constraints imposed by the topology of the inter-vehicle communications network are explicitly taken into account. Path following for each vehicle consists of converging the geometric error at the origin. Vehicle coordination is achieved by adjusting the speed of each vehicle along its path according to information on the positions and speeds of a subset of the other vehicles of the group. We illustrate our design procedure for three underwater marine craft. Simulations results are presented and discussed.

Experimental Study of Imperfect Phase Synchronization in the Forced Lorenz System

In this work we demonstrate for an experimental system, that exhibits the Lorenz butterfly attractor behavior, that perfect chaotic phase synchronization cannot be achieved in systems with an unbounded distribution of intrinsic time scales. Instead, imperfect phase synchronization is characterized by the occurrence of phase slips, associated to epochs of time during which the chaotic oscillator exhibits a slower time scale. Interestingly, during phase slips the chaotic oscillator keeps in sync with the drive, but with a different locking ratio.

Experimental results on smooth path tracking with application to pipe surveying on inexpensive AUV

This paper details the development aspects of a low cost AUV autonomous, designed for autonomous pipline inspections, describing: hardware, software and control aspects. The article details three of the mains stages of the project, that have been already achieved: (a) the simulation results of Lyapunov based path planning of torpedo shaped AUV on pipe searching; (b) the construction details of dual torpedo AUV for pipeline inspection and (c) the experimental results when using the prototype in path following using the line of sight (LOS) algorithm.

Smooth path planning for autonomous pipeline inspections

This paper details a control method, used to guide an autonomous underwater vehicle (AUV) in the task of locating and tracking underwater pipeline and cables. The article details the simulation and experimental results of the navigation when searching for simulated pipes on the seabed in shallow waters.

Formation control of multiple marine vehicles with velocity reference estimation-based passivity-control design

This paper addresses the problem of coordination path following control of multiple autonomous vehicles. Stated briefly, the problem consists of steering a group of vehicles along a specified path, while holding a desired inter-ship formation pattern. Path following for each vehicle amounts to reducing an appropriately defined geometric error to zero. We first show a passivity property for the path following system and, next, combine this with a passivity-based synchronisation algorithm to coordinate the vehicles along their paths. Vehicle coordination is achieved by adjusting the speed of each vehicle along its path according to information exchanged on the positions of a subset of the other vehicles, as determined by the communication topology adopted. We further assume the unavailability of the reference velocity to each vehicle; we consider the situation where this information is only available to a leader of this formation. Distributed observers are designed for the follower vehicles, under the assumption that the velocity of the leader cannot be measured in real time. Simulations results are presented and discussed.

Formation control of multiple marine vehicles based passivity-control design

This paper addresses the problem of coordination path following control of multiple autonomous vehicles. Stated briefly, the problem consists in steering a group of vehicles along a specified paths, while holding a desired inter-ship formation pattern. Path-following for each vehicle amounts to reducing an appropriately defined geometric error to zero. We first show a passivity property for the path following system and, next, combine this with a passivity-based synchronization algorithm developed in [2] to coordinate the vehicles along their paths. Vehicle coordination is achieved by adjusting the speed of each vehicle along its path according to information exchanged on the positions of a subset of the other vehicles, as determined by the communication topology adopted. Global stability and convergence of the closed-loop system are guaranteed.

Control of Power System Using Adaptive Fuzzy Controller

Abstract This paper presents a control system for an asynchronous AC drive based on an adaptive fuzzy identifier and a neuro-fuzzy controller. The system is able to adapt itself to changes in load or power line by changing the rules of the neurofuzzy controller. A model-reference approach is used to impose transient closed loop performance. The architecture chosen for the controller is based on an ANFIS structure (Jang 1993) that utilizes a hybrid mechanism of adjust combining LSE with back propagation and descend methods. The system is used to control an asynchronous triphase AC motor.