The System Identification Analysis of the Rolling Motion Model for the Unmanned Boat

2014 ◽  
Vol 1037 ◽  
pp. 288-293
Author(s):  
Wang Lin Yang ◽  
Song Lin Yang ◽  
Sheng Zhang ◽  
Tian Yu Ma
Keyword(s):  
System Identification ◽  
Tilt Angle ◽  
Nonlinear Damping ◽  
Roll Motion ◽  
Motion Model ◽  
Cross Combination ◽  
Decay Test ◽  
Object Of Study ◽  
Identification Analysis ◽  
Visual Basic 6.0

In this paper, the author took an unmanned planting boat as the object of study and conducted a series of roll decay test on condition that the ship model was in different drafts and tilt angle. The author established eight kinds of mathematical model of roll decay motion model system identification by making a cross combination of linear or nonlinear righting moment and linear or nonlinear damping. Based on the principle of system identification, the author established the optimization calculation of the objective function. Then the author adapted the genetic algorithm of system identification program based on Visual Basic 6.0 and got eight kinds of identification programs. By identifying respectively the test data of the roll motion of the unmanned planting boat, the author confirmed the feasibility of the adapted program. Comparing large drafts and tilt angle identification results, the author found a reasonable hydrostatic roll motion equation of the unmanned planing boat in the case of large drafts and tilt angle, and made a preliminary analysis.

System Identification of Unmanned Planning Boat Rolling Motion Mode

2013 ◽  
Vol 823 ◽  
pp. 285-290
Author(s):  
Wang Lin Yang ◽  
Hai Tong Xu ◽  
Song Lin Yang ◽  
Sheng Zhang
Keyword(s):  
System Identification ◽  
Visual Basic ◽  
Roll Angle ◽  
Motion Model ◽  
Ship Model Test ◽  
Optimization Calculation ◽  
Object Of Study ◽  
Visual Basic 6.0 ◽  
Righting Moment ◽  
Motion Mode

In this paper, the author took an unmanned planning boat as the object of study and carried out a series of rolling decay ship model test by changing the draft. The author established nine kinds of mathematical model of rolling decay motion model system identification by using different damping and righting moment and established the optimization calculation of the objective function based on the principle of system identification. Then the author adapted the genetic algorithm of system identification program which is based on the Visual Basic 6.0 and got 15 kinds of identification programs. By doing research on the first three cycles of the series of rolling angular velocity curve and identifying respectively the resulting 15 kinds of identification programs, the author confirmed the feasibility of the adapted program. Comparing different drafts and the initial roll angle identification results, the author found a reasonable hydrostatic roll motion equation of the unmanned planning boat in the case of different drafts and the initial roll angle, and made a preliminary analysis.

A Study of the Roll Motion by Means of a Free Decay Test

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Hamid Zeraatgar ◽  
Mohsen Asghari ◽  
Firooz Bakhtiari-Nejad
Keyword(s):  
Damping Ratio ◽  
Nonlinear Damping ◽  
Damping Coefficient ◽  
Roll Motion ◽  
Damping Force ◽  
Restoring Force ◽  
Cubic Form ◽  
Damping Coefficients ◽  
Decay Test ◽  
Nonlinear Form

In this study, a method for the extraction of damping by tracing free roll decay is presented. For this purpose, in calm waters, a bulk carrier model is given a large initial roll angle and then released. Consequently, the roll motion is recorded. Restoring coefficients and virtual moments of inertia for the model are determined by means of an inclining test and recording the damped period, respectively. The linear damping coefficient is evaluated by using the damping ratio. Four different forms of combinations of restoring moment and damping coefficient are assumed in order to determine the nonlinear form of the roll motion. These equations are numerically solved for various damping coefficients and results are compared with the experimental data. By virtue of this comparison, the damping coefficients are determined for each case. It may be concluded that the use of the nonlinear restoring moment, which is an odd polynomial of the fifth order, and the cubic form for the nonlinear damping moment best fits the roll behavior for the ship model. The amount of energy dissipated by the damping moments is also calculated in the time domain. The energy method also confirms that the nonlinear form of restoring force in conjunction with the cubic form of the damping force is the best solution of the roll motion for small to large angles.

BACKSTEPPING CONTROL OF NONLINEAR ROLL MOTION FOR A TRAWLER WITH FIN STABILIZER

2021 ◽  
Vol 159 (A2) ◽  
Author(s):  
H Demirel ◽  
A Doğrul ◽  
S Sezen ◽  
F Alarçin
Keyword(s):  
Lift Coefficient ◽  
Design Procedure ◽  
Nonlinear Damping ◽  
Backstepping Control ◽  
Roll Motion ◽  
Scaled Model ◽  
3 Dimensional ◽  
Roll Control ◽  
Fin Stabilizer ◽  
Volume Method

A backstepping control design procedure for nonlinear fin roll control of a trawler is presented in this paper. A roll equation consisting of linear and nonlinear damping and restoring moment on the roll response is expressed. Flow analyses are carried out for a scaled model of trawler type fishing vessel including fin stabilizers on both sides of the hull. The fin stabilizer geometry is chosen as NACA 0015 foil section which is widely used in the literature. The flow analyses are performed by using a commercial computational fluid dynamics (CFD) software based on finite volume method. The flow problem is modeled in a 3-dimensional manner while the flow is considered as steady, incompressible and fully turbulent. The numerical model consists of the ship wetted surface and the fin stabilizer in order to investigate the hull-fin interaction. Non-dimensional lift coefficients of the fin stabilizer for different angles of attack are gained. Both controlled and uncontrolled roll motions are examined and simulated in time domain for the maximum lift coefficient. Backstepping controller for roll motion has given a rapid and precise result.

A system identification analysis of optogenetically evoked electrocorticography and cerebral blood flow responses

2020 ◽  
Vol 17 (5) ◽  
pp. 056049
Author(s):  
Rex Chin-Hao Chen ◽  
Farid Atry ◽  
Thomas Richner ◽  
Sarah Brodnick ◽  
Jane Pisaniello ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
System Identification ◽  
Identification Analysis

Nonlinear System Identification of Frictional Connections in a Bolted Beam Assembly

2012 ◽  
Author(s):  
Melih Eriten ◽  
Mehmet Kurt ◽  
Guanyang Luo ◽  
Donald M. McFarland ◽  
Lawrence A. Bergman ◽  
...  
Keyword(s):  
System Identification ◽  
Nonlinear System ◽  
Energy Levels ◽  
Nonlinear System Identification ◽  
Flow Analysis ◽  
Nonlinear Damping ◽  
Experimental Measurements ◽  
Slow Flow ◽  
Reduced Order Models ◽  
Reduced Order

In modern structures, mechanical joints are ubiquitous, significantly influencing a structure’s dynamics. Frictional connections contained in a joint provide coupling of forces and moments between assembled components as well as localized nonlinear energy dissipation. Certain aspects of the mechanics of these friction connections are yet to be fully understood and characterized in a dynamical systems framework. This work applies a nonlinear system identification (NSI) technique to characterize the influence of frictional connections on the dynamics of a bolted beam assembly. The methodology utilized in this work combines experimental measurements with slow-flow dynamic analysis and empirical mode decomposition, and reconstructs the dynamics through reduced-order models. These are in the form of single-degree-of-freedom linear oscillators (termed intrinsic modal oscillators — IMOs) with forcing terms derived directly from the experimental measurements through slow-flow analysis. The derived reduced order models are capable of reproducing the measured dynamics, whereas the forcing terms provide important information about nonlinear damping effects. The NSI methodology is applied to model nonlinear friction effects in a bolted beam assembly. A ‘monolithic’ beam with identical geometric and material properties is also tested for comparison. Three different forcing (energy) levels are considered in the tests in order to study the energy-dependencies of the damping nonlinearities induced in the beam from the bolted joint. In all cases, the NSI technique employed is successful in identifying the damping nonlinearities, their spatial distributions and their effects on the vibration modes of the structural component.

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