Lázaro Moratelli Junior

• PhD
• Research Scientist at SINTEF Ocean AS

Maribot LoLo is an autonomous underwater vehicle (AUV) developed at the KTH Centre for Naval Architecture as part of the Swedish Maritime Robotics Centre (SMaRC). The center’s cross-disciplinary activities require an AUV research platform that can be used for data collection and to test and demonstrate novel technologies. The challenge herein is to...

An integrated geometric control for an offloading operation from a FPWSO (Floating, Production, working, Storage and Offloading) to a shuttle tanker is proposed. The floating systems are in tandem configuration connected by a hawser. Both vessels maintain their position and heading by means of their sets of thrusters and propellers. The geometric t...

The hybrid control concept is applied to the offloading operation by means of a FPWSO (Floating, Production, Working, Storage and Offloading) vessel and a shuttle tanker (ST). Both vessels are able to maintain their position and heading as a result of Dynamic Positioning System (DPS). The vessels are in tandem configuration connected by a hawser. T...

This paper addresses some preliminary discussion concerning the performance of different dynamic observer-controller-based positioning system for a shuttle tanker by considering her operational condition changes. The observer-controller models are nonlinear passivity based observer and backstepping controller, Extended Kalman Filter and Proportiona...

The application of the Observer-Lagrangian-based controller for a typical o�shore system comprised of two dynamically controlled vessels connected by a hawser in tandem con�guration is investigated. The control law is obtained by introducing some virtual constraints in the Lagrangian control model. The virtual constraints are de�ned in terms of the...

DP crane barges operate in close proximity to FPSO (Floating Production Storage and Offloading) during lifting operations. This operation is critical since small variations of the relative position may result in collision between the bodies or large motion of the lifting load. The hydrodynamic interactions between the units are an important effect...

The recent Pre-Salt oil fields discovered in Brazil are imposing some new logistical challenges concerning distribution in the internal and external markets. In order to reduce the demand in the on-shore terminals, the export oil could be directly transferred from the platforms to the export tankers. However, internal regulations define that the of...

DP crane vessel operation can be analyzed based on the uncoupled system or considering the fully coupled system. Parameters such as top-crane acceleration, thruster capability and vessel motions are evaluated for several environmental conditions. Numerical and experimental tools are used and the important result of this analysis is the maximum cond...

Vessel dynamic positioning (DP) systems are based on conventional PID-type controllers and an extended Kalman filter. However, they present a difficult tuning procedure, and the closed-loop performance varies with environmental or loading conditions since the dynamics of the vessel are eminently nonlinear. Gain scheduling is normally used to addres...

In this work, a new filtering algorithm suitable for applications in Dynamic Positioning Systems (DPS) is presented. This new filtering method relies on the Empirical Mode Decomposition (EMD) and the reasons that make the EMD Filter really attractive are as follows: it can handle both non stationary and non linear signals, it is an adaptive filteri...

This work discusses the main factors that influence the design of dynamic positioning system (DPS) of a shuttle tanker. The factors discussed are related to issues of reliability of systems and the characteristics of the thrusters typically used on DPS vessels, such as ducts and azimuth. Regarding the reliability of systems, methods of reliability...

In order to perform experimental tests with dynamic positioning system (DPS), the relationship between the propeller thrust and the shaft speed of the actuators installed in a scale model is required to calibrate control parameters. In general, DPS actuators are main propeller, duct and azimuth thrusters and their characteristic curves are quite di...

Neste trabalho é apresentada a tecnologia laboratorial desenvolvida para a realização de ensaios com sistemas de posicionamento dinâmico em tanques de provas brasileiros. São descritos, inicialmente, os componentes da topologia laboratorial que são os atuadores em escala com os seus acionadores (componentes eletromecânicos), a eletrônica embarcada,...

Two aspects of a Dynamic Positioning system (DPS), namely the filtering algorithm and the optimization of the parameters of the control law were analyzed. More specifically, the filter algorithm analyzed was the Kalman Filter, and its performance was evaluated by applying the filter to a set of signals obtained from a full scale vessel. A mathemati...

The thrust-propeller shaft speed relationship is required to calibrate control parameters in order to perform experimental tests with dynamic positioning system (DPS) installed in the scale model. In general, actuators of a DPS are main propeller, side and azimuth thrusters and their characteristic curves are quite difficult to be obtained theoreti...

The Dynamic Positioning mode operation of vessels, especially those related to the offshore oil industry, requires rigorous reliability analysis in order to eliminate the dangerous consequence of loosing position or to create a procedure when the consequence can not be eliminated. In general, the reliability analysis of the Dynamic Positioning Syst...

Este texto apresenta o contexto científico-tecnológico atual e suas implicações nos perfis dos egressos dos cursos de engenharia. O trabalho cita também as conseqüências sofridas pelas estruturas curriculares frente à necessidade da nova formação dos estudantes. É apresentada a proposta do curso de Engenharia Naval da Escola Politécnica da Universi...

In recent years, there was a continuous increase in the exploitation of oil at sea and consequently the use of dynamic positioning systems (DPS) has become important, because it keeps a vessel at a pre-defined position through propellers. Currently, the DPS are based on conventional controllers (PD + Kalman Filter). This paper proposes the applicat...

Some aspects of design of a dynamic positioning system (DPS) for ships especially those related to offloading operation are considered. The design of a DPS involves a complex integration of a large number of different components in which performance and reliability are two important issues to be taken into account. In order to achieve the desired s...

This paper describes the optimizations made in the different components of a model scale ship with a Dynamic Positioning System (DSP). Former studies have identified the necessity of improvements in the image treatment system, ship's control, perturbation treatment and in the embedded electronics. The obtained results in this paper allow more compl...

Dynamic Positioning (DP) Systems are used to keep a floating vessel on a specific position or follow pre-defined path through the action of propellers. DPS are feedback control systems, composed of position measurement systems, a set of control algorithms and propellers. Several offshore operations use DP Systems, such as drilling, pipe-laying, off...

The technique of Dynamic Positioning (DP) consists on keeping the position of a vessel by the use of active thrusters. In Brazil, the offhore oil industry follows the recent tendency of performing several operations aided by DP systems, such as prospection, drilling, offloading and others. Analysis and design of DP systems require several computati...