Justifying the Stabilization of a Marginally Stable Ship

2017 ◽  
Author(s):  
David Shekhtman ◽  
Dirk M. Luchtenburg
Keyword(s):  
Energy Dissipation ◽  
Closed Loop ◽  
Equations Of Motion ◽  
Marginal Stability ◽  
Stability Conditions ◽  
Stability Criteria ◽  
Benchmark Problem ◽  
Zero Energy ◽  
External Disturbances ◽  
Lyapunov Stability Criteria

As a precursor to capsize, marginal stability, resulting from incorrect loading conditions and crew negligence, poses a serious danger to ships. Therefore, as a benchmark problem for preventing capsize, the use of an actively controlled pendulum for the stabilization of a marginally stable ship was analyzed. Lyapunov stability criteria and closed loop eigenvalues were used to evaluate the extent to which a proposed pendulum controller could cope with different ship stability conditions. Equations of motion were solved to observe the controller’s performance under different damping conditions. The behavior of the controller yielded the following results: a marginally stable ship can be stabilized, as long as there is no right hand plane zero; energy dissipation is key to the stabilization of a marginally stable ship; the controller must have knowledge of the ship’s stability to prevent controller-induced excitation; and a stabilized tilted ship is more robust to external disturbances than a stabilized upright ship.

scholarly journals Generalized ESO and Predictive Control Based Robust Autopilot Design

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Bhavnesh Panchal ◽  
S. E. Talole
Keyword(s):  
Predictive Control ◽  
Closed Loop ◽  
Specific Information ◽  
Disturbance Compensation ◽  
External Disturbances ◽  
Output Tracking ◽  
Control Gain ◽  
Predictive Controller ◽  
Mismatched Uncertainty ◽  
Acceleration Tracking

A novel continuous time predictive control and generalized extended state observer (GESO) based acceleration tracking pitch autopilot design is proposed for a tail controlled, skid-to-turn tactical missile. As the dynamics of missile are significantly uncertain with mismatched uncertainty, GESO is employed to estimate the state and uncertainty in an integrated manner. The estimates are used to meet the requirement of state and to robustify the output tracking predictive controller designed for nominal system. Closed loop stability for the controller-observer structure is established. An important feature of the proposed design is that it does not require any specific information about the uncertainty. Also the predictive control design yields the feedback control gain and disturbance compensation gain simultaneously. Effectiveness of GESO in estimation of the states and uncertainties and in robustifying the predictive controller in the presence of parametric uncertainties, external disturbances, unmodeled dynamics, and measurement noise is illustrated by simulation.

scholarly journals Asymptotic Behavior of a Viscoelastic Fluid in a Closed Loop Thermosyphon: Physical Derivation, Asymptotic Analysis, and Numerical Experiments

2013 ◽  
Vol 2013 ◽  
pp. 1-20 ◽  
Author(s):  
Justine Yasappan ◽  
Ángela Jiménez-Casas ◽  
Mario Castro
Keyword(s):  
Asymptotic Behavior ◽  
Viscoelastic Fluid ◽  
Closed Loop ◽  
Theoretical Study ◽  
Equations Of Motion ◽  
Asymptotic Properties ◽  
Inertial Manifold ◽  
Thermal Gradients ◽  
External Temperature ◽  
First Time

Fluids subject to thermal gradients produce complex behaviors that arise from the competition with gravitational effects. Although such sort of systems have been widely studied in the literature for simple (Newtonian) fluids, the behavior of viscoelastic fluids has not been explored thus far. We present a theoretical study of the dynamics of a Maxwell viscoelastic fluid in a closed-loop thermosyphon. This sort of fluid presents elastic-like behavior and memory effects. We study the asymptotic properties of the fluid inside the thermosyphon and the exact equations of motion in the inertial manifold that characterizes the asymptotic behavior. We derive, for the first time, the mathematical derivations of the motion of a viscoelastic fluid in the interior of a closed-loop thermosyphon under the effects of natural convection and a given external temperature gradient.

Nonlinear Analysis of a Rigid Rotor on Magnetic Bearings

1995 ◽  
Author(s):  
C. Nataraj
Keyword(s):  
Nonlinear Analysis ◽  
Equations Of Motion ◽  
Forced Response ◽  
Magnetic Bearings ◽  
Rigid Rotor ◽  
Stability Criteria ◽  
Safe Operation ◽  
Qualitative And Quantitative ◽  
Quantitative Results ◽  
Nonlinear Equations Of Motion

A simple model of a rigid rotor supported on magnetic bearings is considered. A proportional control architecture is assumed, the nonlinear equations of motion are derived and some essential nondimensional parameters are identified. The free and forced response of the system is analyzed using techniques of nonlinear analysis. Both qualitative and quantitative results are obtained and stability criteria are derived for safe operation of the system.

scholarly journals Methodology for studying impulse disturbance from rail joints to the railway vehicle and assessment of the efficiency of the new spring suspension

2018 ◽  
Vol 239 ◽  
pp. 01032
Author(s):  
Viktor Nekhaev ◽  
Viktor Nikolaev ◽  
Evgenii Cheltygmashev
Keyword(s):  
Energy Dissipation ◽  
Comparative Assessment ◽  
Railway Track ◽  
Railway Vehicle ◽  
Vertical Acceleration ◽  
External Disturbances ◽  
Spring Suspension ◽  
Dynamic Forces ◽  
Typical Scheme ◽  
Freight Car

The methodology for studying the impulse disturbance of the railway track joints on the indicators of the dynamic qualities of the railway vehicle has been developed. The dependence of the impulse repetition factor on the energy dissipation level in the system and the speed of the vehicle is obtained. A comparative assessment of the dynamic qualities of a freight car with a typical scheme of spring suspension and a car with suspension based on the principle of compensation of external disturbances is performed. It has been established that the spring suspension of a freight car based on the principle of compensation of external disturbances delivers to it significantly better indicators of dynamic qualities in comparison with car equipped with a new three-piece truck with a typical scheme of springs. Vertical acceleration of the car’s body with a new scheme of vibration protection and dynamic forces in spring suspension is several times less than for a car with a typical three-piece truck structure.

A Modified Active Anti-Disturbance Control for a Nonlinear CSTR Model

2018 ◽  
Author(s):  
Sudeshna Dasgupta ◽  
Smita Sadhu ◽  
T. K. Ghoshal
Keyword(s):  
Closed Loop ◽  
Continuous Stirred Tank Reactor ◽  
External Disturbances ◽  
Parameter Perturbations ◽  
Internal Model Controller ◽  
Continuous Stirred Tank ◽  
Nonlinear Plants ◽  
Cstr System ◽  
Plant Parameter ◽  
Nonlinear Plant

Active Anti-Disturbance Control, which so far had reportedly been applied to linear plant models, has been extended in this work to cover control of nonlinear plant models. To accommodate nonlinear plants, an Internal Model Controller (IMC) and a Disturbance Observer (DOB) for nonlinear systems have been used innovatively in the design architecture. It is conjectured that the IMC approach would mitigate plant parameter perturbations whereas the DOB would take care of external disturbances together to conjugatively produce a more robust closed loop plant. To illustrate the proposed algorithm, viz., Modified Active Anti-Disturbance Control (MAADC), the proposed technique has been employed to control a nonlinear Continuous Stirred Tank Reactor (CSTR) system. It is shown that strong external disturbances and model uncertainties have been actively mitigated by using the proposed MAADC, indicating superior robustness compared to ordinary nonlinear IMC based control. Different set-point and disturbance conditions have been considered to characterize the algorithm.

A comparative study for collocated and non-collocated sensor/actuator placement in vibration control of a maneuvering flexible satellite

2014 ◽  
Vol 229 (8) ◽  
pp. 1415-1424 ◽  
Author(s):  
Morteza Shahravi ◽  
Milad Azimi
Keyword(s):  
Vibration Control ◽  
Closed Loop ◽  
Equations Of Motion ◽  
Lyapunov Analysis ◽  
Closed Loop System ◽  
Sensors And Actuators ◽  
Sensor Actuator ◽  
Attitude Maneuver ◽  
System Equations ◽  
Actuator Placement

This paper presents a study concerning the vibration control of smart flexible sub-structures of satellite during attitude maneuver. A comparison between the collocated and non-collocated piezoceramic patches acting as sensors and actuators is performed in order to investigate their effectiveness to suppress vibrations in flexible substructures. A rigid hub with two elastic appendages containing surface bounded piezoelectric patches is being considered as satellite model. Finite element method and Lagrangian formulation are used for derivation of system equations of motion. Stability proof of the overall closed-loop system is given via Lyapunov analysis. The numerical simulations verify the results of the study.

Paper 5. Directional Stability and Control of a Vessel in Restricted Waters

1972 ◽  
Vol 14 (7) ◽  
pp. 29-33 ◽  
Author(s):  
M. Fujino
Keyword(s):  
Hydrodynamic Force ◽  
Equations Of Motion ◽  
Narrow Channel ◽  
Order Theory ◽  
Stability Criteria ◽  
First Order ◽  
Stability And Control ◽  
First Order Theory ◽  
And Control ◽  
Improve Stability

By way of introduction the paper discusses conflicting observations of stability behaviour of ships in restricted waters. The equations of motion of a ship in a narrow channel are given, leading to stability criteria; differences from the deep water case are highlighted. More qualitatively, the theory also illustrates the asymmetric hydrodynamic force. Criteria are outlined for an automatic control system to improve stability. However, the first-order theory is shown to provide an inadequate description of all experimental results.

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