http://www.ifac-papersonline.net/ en Copyright 05:56 PM Tuesday 07, 2012 IFAC-PapersOnline http://www.ifacpapersonline.com 05:56 PM Tuesday 07, 2012 05:56 PM Tuesday 07, 2012 ET webmaster@ifac-papersonline.net webmaster@ifac-papersonline.net http://www.ifac-papersonline.net/Detailed/42183.html 04:00 PM Wednesday 31, 1969 The problem of path following for marine surface vessels using rudder angle is addressed in this paper. A 4 degrees of freedom nonlinear surface vessel model, together with the Serret-Frenet equations, is introduced to describe the ship dynamics and path following error dynamics. While similar models have been used and reported in literature for path following control algorithm development, the novelty of the approach presented in this work lies in the following aspects: (a) The back-stepping nonlinear controller design is based on feedback dominance, instead of feedback linearization and nonlinearity cancellation; (b) Relying on feedback dominance, the resulting controller is almost linear, with very benign nonlinearities allowing for analysis and evaluation; (c) Performance of the nonlinear controller, in terms of path following, is analyzed for robustness in the presence of rudder saturation and rate limits, delays in the control execution, as well as measurement noises. Because of its simple form, very limited on-board computational power is required to implement the control. The simulation results are presented to verify and illustrate the analytic development and the effectiveness of the resulting control. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42176.html 04:00 PM Wednesday 31, 1969 This work deals with estimators for predicting when parametric roll resonance is going to occur in surface vessels. The roll angle of the vessel is modeled as a second-order linear oscillatory system with unknown parameters. Several algorithms are used to estimate the parameters and eigenvalues of the system based on data gathered experimentally on a 1:45 scale model of a tanker. Based on the estimated eigenvalues, the system predicts whether or not parametric roll occurred. A prediction accuracy of 100% is achieved for regular waves, and up to 87.5% for irregular waves. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42199.html 04:00 PM Wednesday 31, 1969 This paper describes a localization system for Autonomous Underwater Vehicles (AUV) in structured underwater environments. It uses a Doppler Velocity Log (DVL) sensor, a pressure sensor, a compass and a mechanically scanning imaging sonar. An Extended Kalman Filter (EKF) merges the information from the DVL and the compass to estimate the robot trajectory. In order to reduce the drift inherent to this process we use acoustic images from an imaging sonar to determine the absolute robot position in the environment and update the estimated trajectory. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42196.html 04:00 PM Wednesday 31, 1969 The problem of ocean current estimation for 6DOF underwater vehicles is considered in this paper. A model-based observer for ocean current estimation is proposed and it is shown how the performance of underwater vehicles can be improved by incorporating the ocean current estimates in the controller. The results are illustrated with a simulation case study with the HUGIN AUV. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42233.html 04:00 PM Wednesday 31, 1969 This paper presents a new multi-dimension predictive model based on the diagonal recurrent neural networks (PDRNN) with a parallel learning algorithm. This method can be used to predict not only values, but also some points in the multidimension space. And also its applications in marine engine room will be discussed in the paper. Some analysis results show the significant improvement to multi parameters simultaneous prediction using the PDRNN algorithm in marine engine room. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42206.html 04:00 PM Wednesday 31, 1969 This paper proposes a physically motivated reappraisal of manoeuvring models for ships and presents a new model developed from first principles by application of low aspect-ratio aerodynamic theory and Lagrangian mechanics. The coefficients of the model are shown to be related to physical processes, and validation is presented using the results from a planar motion mechanism dataset. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42191.html 04:00 PM Wednesday 31, 1969 In this work, a combined QFT/EA approach is used to control a coupled system on a high speed-craft. Since the angle between the heading and the seaway is different from 180 degrees, the action of the actuators for controlling the longitudinal dynamic (heaving and pitching) produces a coupling in the lateral (rolling) dynamic, and vice-versa. The MIMO problem is firstly handled with EA technique in order to decouple the dynamics, which results in three SISO systems to solve with QFT design. It is shown that the combined EA/QFT technique is a robust method that accomplishes decoupling between the three dynamics and damped responses. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42174.html 04:00 PM Wednesday 31, 1969 The paper describes an adaptive neural network based nonlinear control for roll stabilization of ocean motoryachts. The advantage of the adaptive controller is to improve vessel roll stabilization performance under a variety of operational and environment conditions. The application of nonlinear control theory allows to compensate for nonlinearities in the control design. The analysis of the control stability is based on the Lyapunov theory. The proposed adaptive controller is tested by a simulation study based on a nonlinear model, describing the dynamics of a vessel in four degrees of freedom. The wave excitation forces are simulated as multisine time series. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42218.html 04:00 PM Wednesday 31, 1969 This research deals with ANN(Artificial Neural Networks) and its application to automatic ship berthing. Due to the characteristic of a ship's manoeuvre comparing with other moving objects on land, it has been known that the automatic control for ship's berthing cannot cope with various berthing situations such as various port shape and approaching directions For these reasons, the study on automatic berthing using ANN usually have been carried out based on one port shape and predetermined approaching direction. In this paper, new algorithm with ANN controller was suggested to cope with these problems. Under newly suggested algorithm, the controller can select appropriate weights on the link of neural networks according to various situations, so the ship can maintain stable berthing operation even in different situations. Numerical simulations are carried out with this control system to find its improvement. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42217.html 04:00 PM Wednesday 31, 1969 This paper presents a preliminary set of results on the design of Actuator Fault Detection Systems (AFDSs) for an underwater remotely operated vehicle (ROV) to prevent actuator faults and hence to reduce the risk of safety hazards. The approach consists of two phases. First a model-based approach is applied to the nonlinear model of the ROV. This solution permits to discover the redundancy of the system, and thus using it for fault detection purposes. Successively, by means of a Sliding Mode Control based approach, the fault is isolated and the control law is reconfigurated using the remaining working actuators. In both the phases the plant is assumed to be affected by "moderate" parametric variations. Moreover, it is supposed to undergo unknown faults, which cause the plant input components to be stuck at some uncertain but bounded time functions. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42208.html 04:00 PM Wednesday 31, 1969 A numerical algorithm for flexible linearization of substantially nonlinear ship mathematical models described by ordinary differential equations is proposed. The linearization can be performed over any pre-defined domain in the state space or subspace in the least-square sense. A discrete set of points is created inside the domain of interest by means of a quasi-random sequence generator. Then, the exact model's responses are calculated on this set and a common least-square procedure is applied. Local or differential linearization can be performed with the same algorithm choosing an appropriately small domain around any point of interest in the state space. A numerical example for a typical directionally unstable vessel is given and studied is the influence of the number of the generated quasi-random points and of the linearization domain's dimensions. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42223.html 04:00 PM Wednesday 31, 1969 Ships in moderate sea experience time-varying thrust and torque load on the shaft of their prime mover. The reason is the varying inflow velocity to the propeller during the passage of a wave. This variation has been considered a nuisance to the main engine control where the induced fluctuations in torque, shaft speed and power have been suppressed by some control schemes and ignored in others. This paper shows how the fluctuation in inflow velocity can be utilized to increase the average efficiency of propulsion in waves without reducing the vessel speed. A nonlinear controller is proposed that is shown to theoretically enhance the propulsion efficiency. Model tests determine dynamic characteristics of propellers in waves and a simulation is employed to validate the novel control scheme. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42169.html 04:00 PM Wednesday 31, 1969 Once the presence of the anomaly on the bottom of the coastal sea water is confirmed it is necessary to establish if it contains explosive charge. This could be performed by using neutron sensor installed within an underwater vessel. When positioned above the object the system inspects the object for the presence of the threat materials by using neutrons from the sealed tube d+t neutron generator with detection of associated alpha particles. The detection of alpha particles defines the neutron beam which helps the reduction of the background. Whole spectrum signature could be used for the identification of threat materials investigated. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42226.html 04:00 PM Wednesday 31, 1969 This paper considers employing missile guidance concepts to design motion control systems for marine craft. Initially, classical concepts such as line of sight (LOS), pure pursuit (PP), and constant bearing (CB) are reviewed. Subsequently, the relationship of these concepts to motion camouflage strategies in nature is pointed out, as well as their application to robot manipulators. Ultimately, the CB guidance scheme is used to design a motion control system for fully actuated marine surface craft. For this purpose, the notion of asymptotic interception becomes fundamental, as the motion control goal is not to hit a physical target in finite time, but to hit a virtual target asymptotically. A modular control design inspired by backstepping and cascade theory results in a classical inner-outer loop guidance and control structure. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42236.html 04:00 PM Wednesday 31, 1969 For the remotely operated vehicle (ROV) with an umbilical cable, it become difficult to guide it to a target as the depth increases. Especially, the vehicle for the working in the deep sea under current disturbance, the control to reach the target is the most important and difficult problem, because the tension of the umbilical cable, which connects the vehicle to the mother ship, become extremely large by current force. The author proposes the algorithm for automatic control and guidance to reach the target in the sea under the restriction of actuator's maximum force. The application was successfully coducted to ROV with umbilical cable as a basic control algorithm. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42168.html 04:00 PM Wednesday 31, 1969 Future AUV products must have a real autonomy, that is, must be able to navigate and fulfill a Mine Counter Measure (MCM) surveillance mission with high reliability without any operator control. The first step toward this product is a vehicle programmed on a defined trajectory, that records data and reports to the sonar operator when coming back to the recovery point. This step is currently under development. The second step is giving the AUV more autonomy for analysis and decision, to allow it to re-plan its trajectory in order to best fulfill its MCM mission. Besides, sonar systems, designed to detect stealthy mines, will now also hand over to the classification process many more small non-mine bottom objects (NOMBO) to be discrimined from Mine Like Contact (MILCO). This is the challenge of Automatic Target Recognition processing. In this paper, we show how data generated by Automatic Target Recognition processing can help to perform robust Concurrent Navigation and Mapping. Associated with Bottom Characterization, Mission Analysis and Re-Planning Strategy, Concurrent Navigation and Mapping constitute the Mission Control Module. We also discuss Re-Planning strategy in order to increase the efficiency of MCM mission in terms of reliability and precision. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42178.html 04:00 PM Wednesday 31, 1969 This paper is concenred with the development of control strategies for autonomous mission planning of a multiple Unhabitated Underwater Vehicles (UUVs) that cooperate in order to perform a number of tasks. Missions of this type include multi-agent reconnaissance and multi-agent mine sweeping problems. The mission planning problem is posed as a receding horizon mixed-integer constrained model based predictive control problem. This is subsequently partitioned into smaller subproblems and solved in a decentralised manner using a distributed Nash-based game approach. The paper presents further development of the method and gives a detailed example to demonstrate the main features of the control method and its implementation. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42190.html 04:00 PM Wednesday 31, 1969 This paper explores the forming-up, robustness of the ensuing formation and coordinated movement of autonomous, non-communicating submerged vehicles (AUV) planning their trajectories using a virtual potential fields method. The behavior and characteristic merits and problems of the proposed scheme, which plans the trajectory on the basis of AUV kinematics is tested in 2D simulations. A brief commentary on further avenues of research and improvement in order to make the method applicable to hardware-in-the-loop usage is given. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42198.html 04:00 PM Wednesday 31, 1969 Given the fact that AUV dynamics change depending on the payload, finding a mathematical model in a rather small period of time is quite important. Classical openloop identification methods give accurate parameter identification, but are also time consuming. In the paper we present an identification method based on induced selfoscillations, which has proved to be applicable to underwater vehicles. In addition to that, an error analysis for the proposed method is presented. Experimental results obtained on an underwater vehicle are given and compared to the results obtained using open-loop identification algorithms. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42184.html 04:00 PM Wednesday 31, 1969 The underwater environment represents one of the most difficult media for communications, especially wireless communications. In addition the difficulties with various intense noise fields, there difficulties with multi-path and multiple echoes. These problems exist for all types of wireless communications. We investigate the communication needs for collaborative control of groups of underwater vehicles, and provide communication architectures and schemes that address the sever communication environment that prevails underwater. The proposed solutions combine dynamic algorithms and innovative device and subsystems concepts such as dynamic relay nodes, collaborative communications and multi-mode communications. On the control side we demonstrate the significance of event triggered communications in such difficult and constrained environments. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42167.html 04:00 PM Wednesday 31, 1969 http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42172.html 04:00 PM Wednesday 31, 1969 This paper compares the performance of two linear observers proposed for estimating the position and velocity of marine vehicles in ocean current. The first system consists of one observer modelling the current loads as a constant bias. This observer is compared with a second second system that involves two observers; one vehicle observer which explicitly utilizes the estimated current velocity provided by the co-working current observer. The results from comparing the norm, settling time and peak amplitude of the estimation error with varying observer gains and damping coefficients indicate that the second system possesses advantageous properties related to the transient behavior of the observer. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42212.html 04:00 PM Wednesday 31, 1969 Recent experimental testing of an unmanned autonomous marine surface vehicle has demonstrated several key advances in control system performance for a wind propelled platform. The HWT X-1 is a winged catamaran based on a modified conventional sailing vessel intended for use as a surveillance and sensor platform in either littoral or unprotected waters. Using GPS and an off-the-shelf commercial Attitude and Heading Reference System (AHRS) as the primary sensors, in integrated control architecture has been implemented that has demonstrated closed loop control about a figure-8 course while under wind propulsion. A speed regulation control system maintains a minimum speed on course using a combination of electric drive motors and wind propulsion, reducing power on the drive motors as the wing-sail accelerates the vehicle. Trajectory control is accomplished with line acquisition and line tracking controllers. The line acquisition control uses a line-of-sight guidance law, and acquires the line within 100m. The line tracking controller demonstrated an ensemble mean of 1.0m and a standard deviation of 0.7m for sheltered waters, and mean of 1.6m and a standard deviation of 1.2m for open waters. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42235.html 04:00 PM Wednesday 31, 1969 The paper presents the application extent of procedures for measurement deformations on ships. The actual deformation distribution was measured on the surface of the specimen by the optical grating method (OGM) parallel to the CTOD measurements. Displacements are actually measured with two cameras, i.e. stereometric method. The stereometric method for monitoring deformation is presented with an example of application. The deformation of the surface was measured by recording the displacements of the optical marks, and captured in such a way that the 3D coordinates are connected with picture coordinates. Further calculation of the ship deformation gradient is possible by using the theory of large deformations, which allows large plastic deformations as well as rigid ship motion. Further development of research is focused on constant deformation and damage monitoring in order to take full advantage of computer technology. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/42215.html 04:00 PM Wednesday 31, 1969 The problem of fault detection and isolation is studied for critical purpose systems whose features are nonlinearities and uncertainties. Solution of the problem assumes the checking redundancy relations existing among measured system inputs and outputs. A novel method is proposed for constructing redundancy relations on the base of system model described by differential equations whose right-hand side is polynomial. The method involves nonlinear transformation of the initial system model into strict feedback form. Algebraic and geometric approaches are used for this transformation. Application of the method is demonstrated for motion model of autonomous underwater vehicle. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif