Alessandro Antonio Zizzari

A knowledge-based decision support system for shipboard damage control

The operational complexity of modern ships requires the use of advanced applications, called damage control systems (DCSs), able to assist crew members in the effective handling of dangerous events and accidents. In this article we describe the development of a knowledge-based decision support system (KDSS) integrated within a DCS designed for a national navy. The KDSS uses a hybrid design and runtime knowledge model to assist damage control operators through a kill card function which supports damage identification, action scheduling and system reconfiguration. We report a fire fighting scenario as illustrative application and discuss a preliminary evaluation of benefits allowed by the system in terms of critical performance measures. Our work can support further research aimed to apply expert systems to improve shipboard security and suggest similar applications in other contexts where situational awareness and damage management are crucial.

Line following guidance control: Application to the Charlie unmanned surface vehicle

A line following guidance solution for underactuated marine systems is presented. The approach differs from other ones known in the literature in the definition of the error variables to be stabilized to zero. The proposed guidance technique has been applied to the Charlie USV (Unmanned Surface Vehicle), developed by CNR-ISSIA Autonomous robotic systems and control group, and experimental results are presented.

Kinematics Motion Control of an Underactuated Vehicle: a 3D Solution with Bounded Control Effort

Abstract This paper addresses the problem of motion control in three-dimensional space for underactuated autonomous underwater robots. A guidance motion control law that guarantees bounded velocity commands is derived at the kinematics level. The main difference with respect to the other approaches known in the literature is to be found in the definition of the error variables to be driven to zero. Besides the theoretical proof of error convergence to zero, simulation results are reported.

The Null-Space based Behavioral control for non-holonomic mobile robots with actuators velocity saturation

This paper presents the application of the Null-Space based Behavioral (NSB) approach to the motion control of a non-holonomic mobile robot with velocity saturated actuators. In particular, the proposed solution aims at managing actuator velocity saturations by dynamically scaling task velocity commands so that the hierarchy of task priorities is preserved in spite of actuator velocity saturations. The approach is tested on a specific case study where the NSB approach elaborates the motion directives for a mobile robot that has to reach a target while avoiding a punctual obstacle. The approach is validated by numerical simulations and by experimental results with a non-holonomic mobile robot.

A Proof of Concept for the Guidance of 3D Underactuated Vehicles Subject to Constant Unknown Disturbances

Abstract A guidance control law is designed for an underactuated 3D kinematics model of an underwater vehicle subject to constant, but unknown currents. The model captures the main features of most available Autonomous Underwater Vehicles (AUVs). The paper focuses on the description of the design criteria that allows to explicitly address the difficulties related to the underactuated structure of the model. A convergence and stability proof is sketched and numerical simulations are provided to illustrate the performances of the proposed solution.

A Path Following Controller for the Dynamic Model of a Marine Surface Vessel

Abstract A path following controller for the dynamic model of an underactuated marine vessel is presented. The solution extends previous results relative to the purely kinematics case and is able to cope with constant and known ocean currents. Based on kinematics, a reference linear and angular velocity is computed such that if the vehicle had such velocities the path following problem would be asymptotically solved. Then, applying feedback linearization to the dynamic model of the surface vessel, yaw torque and surge force commands are computed in order to drive the vessels total velocity on the desired reference values. The resulting control laws for the yaw and surge degrees of freedom result in nonlinear terms (from feedback linearization) and PI terms. Numerical simulations are provided to validate the proposed approach.

LINEAR PATH FOLLOWING GUIDANCE CONTROL FOR UNDERACTUATED OCEAN VEHICLES

Abstract A path following guidance solution for underactuated marine systems is presented. The approach differs from other ones known in the literature in the definition of the error variables to be stabilized to zero. The main idea is presented and applied to the case of linear path following in the presence of constant known currents. Simulation experiments are presented and discussed.

Path Following for the Dynamic Model of a Marine Surface Vessel without Closed-Loop Control of the Surge Speed

Abstract The paper presents a novel path-following solution for the dynamic model of an underactuated marine surface vessel. The proposed solution does not require closed loop control of the surge speed, but rather only of the yaw rate. In particular, the velocity of a virtual target on the path and a reference angular velocity for the vessel are computed such that if the vessel and the target had such velocities the path-following problem would be asymptotically solved at kinematic level. Then, applying feedback linearization to the dynamic model of the surface vessel, a yaw torque command is computed in order to steer the vessels total velocity on the desired reference value. The resulting control law for the yaw degree of freedom results in nonlinear terms (from feedback linearization) and PI terms. Numerical simulations are provided to validate the proposed approach. ©IFAC 2010.

Path Following Guidance Control with Bounded Control Effort: Application to the Charlie Unmanned Surface Vehicle

Abstract This paper addresses the problem of motion control in two-dimensional space for under-actuated unmanned surface vehicles. A guidance motion control law that guarantees bounded velocity commands is derived at the kinematics level. The main difference with respect to the other approaches known in the literature is to be found in the definition of the error variables to be driven to zero. Besides a brief explanation of the proposed approach to solve the guidance problem for under-actuated systems, numerical and experimental results carried out with the Charlie USV are reported.