Identification of Nonlinear Ship Model Parameters Based on the Turning Circle Test

2007 ◽  
Vol 51 (02) ◽  
pp. 174-181
Author(s):  
Manuel Haro Casado ◽  
Ramón Ferreira ◽  
F. J. Velasco
Keyword(s):  
Model Parameters ◽  
Steering Control ◽  
Adaptive Procedure ◽  
Ship Model ◽  
Ship Steering ◽  
Trial Test ◽  
Turning Radius ◽  
Additional Coefficient ◽  
Turning Test ◽  
True Values

This work presents a contribution to solving the problem of identification of ship model parameters using the experimental results from a particular trial test. The innovation of this paper lies in the fact that for this identification purpose it is necessary to know only the turning radius that describes the ship during the performance of the turning test trial. A relatively complex nonlinear model of Norrbin has been chosen as a basis because it represents the ship's dynamics appropriately, as proven through experimental measurements obtained during the course change test. The proposed algorithm of identification of the four ship model parameters is based on an adaptive procedure and the backstepping theory. Another additional coefficient can be determined by an alternative procedure. The knowledge of the true values that characterize the dynamic of a ship is fundamental in the ship steering control that is carried out by autopilots. The simulation results show the suitability of the proposed procedure.

Comparison of Analytical and Empirical Models to Capture Variations in Off-Road Vehicle Dynamics

2005 ◽  
Author(s):  
Paul J. Pearson ◽  
David M. Bevly
Keyword(s):  
Empirical Data ◽  
Vehicle Dynamics ◽  
Experimental Validation ◽  
Inertial Sensors ◽  
Analytical Models ◽  
Control Algorithms ◽  
Model Parameters ◽  
Steering Control ◽  
Steering Angle ◽  
Yaw Rate

This paper develops two analytical models that describe the yaw dynamics of a farm tractor and can be used to design or improve steering control algorithms for the tractor. These models are verified against empirical data. The particular dynamics described are the motions from steering angle to yaw rate. A John Deere 8420 tractor, outfitted with inertial sensors and controlled through a PC-104 form factor computer, was used for experimental validation. Conditions including different implements at varying depths, as would normally be found on a farm, were tested. This paper presents the development of the analytical models, validates them against empirical data, and gives trends on how the model parameters change for different configurations.

Output Adaptive Observers Design for Linear Non-Stationary Systems with Polynomial Parameters

2021 ◽  
Vol 22 (8) ◽  
pp. 404-410
Author(s):  
K. B. Dang ◽  
A. A. Pyrkin ◽  
A. A. Bobtsov ◽  
A. A. Vedyakov ◽  
S. I. Nizovtsev
Keyword(s):  
Linear Time ◽  
State Observer ◽  
Observer Design ◽  
Model Parameters ◽  
Time Varying ◽  
State Variables ◽  
Unknown Constant ◽  
Established Method ◽  
Time Varying Parameters ◽  
True Values

The article deals with the problem of state observer design for a linear time-varying plant. To solve this problem, a number of realistic assumptions are considered, assuming that the model parameters are polynomial functions of time with unknown coefficients. The problem of observer design is solved in the class of identification approaches, which provide transformation of the original mathematical model of the plant to a static linear regression equation, in which, instead of unknown constant parameters, there are state variables of generators that model non-stationary parameters. To recover the unknown functions of the regression model, we use the recently well-established method of dynamic regressor extension and mixing (DREM), which allows to obtain monotone estimates, as well as to accelerate the convergence of estimates to the true values. Despite the fact that the article deals with the problem of state observer design, it is worth noting the possibility of using the proposed approach to solve an independent and actual estimation problem of unknown time-varying parameters.

Inversion of helicopter electromagnetic data to a magnetic conductive layered earth

Geophysics ◽  
2003 ◽  
Vol 68 (4) ◽  
pp. 1211-1223 ◽  
Author(s):  
Haoping Huang ◽  
Douglas C. Fraser
Keyword(s):  
Magnetic Permeability ◽  
Field Data ◽  
Model Parameters ◽  
Relative Importance ◽  
Magnetic Polarization ◽  
Inversion Algorithm ◽  
Layered Earth ◽  
Electromagnetic Data ◽  
Airborne Electromagnetic ◽  
True Values

Inversion of airborne electromagnetic (EM) data for a layered earth has been commonly performed under the assumption that the magnetic permeability of the layers is the same as that of free space. The resistivity inverted from helicopter EM data in this way is not reliable in highly magnetic areas because magnetic polarization currents occur in addition to conduction currents, causing the inverted resistivity to be erroneously high. A new algorithm for inverting for the resistivity, magnetic permeability, and thickness of a layered model has been developed for a magnetic conductive layered earth. It is based on traditional inversion methodologies for solving nonlinear inverse problems and minimizes an objective function subject to fitting the data in a least‐squares sense. Studies using synthetic helicopter EM data indicate that the inversion technique is reasonably dependable and provides fast convergence. When six synthetic in‐phase and quadrature data from three frequencies are used, the model parameters for two‐ and three‐layer models are estimated to within a few percent of their true values after several iterations. The analysis of partial derivatives with respect to the model parameters contributes to a better understanding of the relative importance of the model parameters and the reliability of their determination. The inversion algorithm is tested on field data obtained with a Dighem helicopter EM system at Mt. Milligan, British Columbia, Canada. The output magnetic susceptibility‐depth section compares favorably with that of Zhang and Oldenburg who inverted for the susceptibility on the assumption that the resistivity distribution was known.

scholarly journals On the ship course-keeping control system design by using robust feedback linearization

2013 ◽  
Vol 20 (1) ◽  
pp. 70-76 ◽  
Author(s):  
Zenon Zwierzewicz
Keyword(s):  
Feedback Linearization ◽  
High Performance ◽  
Linearization Method ◽  
Model Parameters ◽  
Control System Design ◽  
Control Approach ◽  
Ship Model ◽  
Control Techniques ◽  
System Nonlinearity ◽  
Ship Autopilot

Abstract In the paper the problem of ship autopilot design based on feedback linearization method combined with the robust control approach, is considered. At first the nonlinear ship model (of Norrbin type) is linearized with the use of the simple system nonlinearity cancellation. Next, bearing in mind that exact values of the model parameters are not known, the ensuing inaccuracies are taken as disturbances acting on the system. Thereby is obtained a linear system with an extra term representing the uncertainty which can be treated by using robust, H∞ optimal control techniques. The performed simulations of ship course-changing process confirmed a high performance of the proposed controller despite the assumed significant errors of its parameters.

scholarly journals Analysis of Impact of Ship Model Parameters on Changes of Control Quality Index in Ship Dynamic Positioning System

2019 ◽  
Vol 26 (1) ◽  
pp. 6-14 ◽  
Author(s):  
Tacjana Niksa Rynkiewicz ◽  
Anna Witkowska
Keyword(s):  
Quality Index ◽  
Adaptive Controller ◽  
Model Parameters ◽  
Dynamic Positioning ◽  
Positioning System ◽  
Integral Control ◽  
Dynamic Positioning System ◽  
Ship Model ◽  
Control Quality ◽  
The Impact

Abstract In this work there is presented an analysis of impact of ship model parameters on changes of control quality index in a ship dynamic positioning system designed with the use of a backstepping adaptive controller. Assessment of the impact of ship model parameters was performed on the basis of Pareto-Lorentz curves and ABC method in order to determine sets of the parameters which have either crucial, moderate or low impact on objective function. Simulation investigations were carried out with taking into account integral control quality indices.

Anomalous Behavior of Merchant Ship Steering Systems

1970 ◽  
Vol 7 (02) ◽  
pp. 205-215 ◽  
Author(s):  
Robert Taggart
Keyword(s):  
High Speed ◽  
Mechanical Characteristics ◽  
Anomalous Behavior ◽  
Similar Response ◽  
Steering Control ◽  
Unstable Condition ◽  
Ship Steering ◽  
Merchant Ship ◽  
Automatic Steering ◽  
And Control

An unusual combination of circumstances occurring during an Atlantic crossing of a highspeed containership created a situation where the rudder, acting in response to automatic steering control demands, caused excessive ship rolling. Further investigation revealed the existence of an unstable condition due to a combination of asymmetrical hydrodynamic and mechanical characteristics and the interrelationship of ship motion and control actuation. Similar response has been noted on other high-speed vessels and is a cause for major concern in future containership operations. The elements involved in creating these conditions have been examined in detail and a plausible explanation has been evolved as to how they can combine to produce the observed results. With an understanding of the causes of this anomalous behavior it is possible to devise means for preventing its occurrence in future designs.

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