Control of Marine Structures

1984 ◽  
Vol 106 (4) ◽  
pp. 399-404 ◽  
Author(s):  
E. R. Jefferys ◽  
E. Mavrommatakis
Keyword(s):  
Control Theory ◽  
Active Control ◽  
Controller Design ◽  
Equations Of Motion ◽  
Design Methods ◽  
Linear Quadratic ◽  
Marine Structures ◽  
Linear Quadratic Gaussian ◽  
Frequency Dependent

Active control of the motion of marine structures may produce structural and operational savings over conventional passive designs. It is shown how equations of motion of typical marine structures, including those with frequency-dependent coefficients, may be rendered into a form compatible with modern controller design methods. Linear quadratic Gaussian control theory is summarized and applied to a simple example. The limitations of the theory are discussed and the effects of a force-limited actuator are quantified.

Stability Robustness of LQ and LQG Active Suspensions

1994 ◽  
Vol 116 (1) ◽  
pp. 123-131 ◽  
Author(s):  
A. G. Ulsoy ◽  
D. Hrovat ◽  
T. Tseng
Keyword(s):  
Controller Design ◽  
Active Suspension ◽  
Point Of View ◽  
Linear Quadratic ◽  
Linear Quadratic Gaussian ◽  
Active Suspensions ◽  
Quarter Car Model ◽  
Stability Robustness ◽  
Trade Offs ◽  
Two Degree Of Freedom

A two-degree-of-freedom quarter-car model is used as the basis for linear quadratic (LQ) and linear quadratic Gaussian (LQG) controller design for an active suspension. The LQ controller results in the best rms performance trade-offs (as defined by the performance index) between ride, handling and packaging requirements. In practice, however, all suspension states are not directly measured, and a Kalman filter can be introduced for state estimation to yield an LQG controller. This paper (i) quantifies the rms performance losses for LQG control as compared to LQ control, and (ii) compares the LQ and LQG active suspension designs from the point of view of stability robustness. The robustness of the LQ active suspensions is not necessarily good, and depends strongly on the design of a backup passive suspension in parallel with the active one. The robustness properties of the LQG active suspension controller are also investigated for several distinct measurement sets.

scholarly journals Attitude and Altitude Controller Design for Quad-Rotor Type MAVs

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Wei Wang ◽  
Hao Ma ◽  
Min Xia ◽  
Liguo Weng ◽  
Xuefei Ye
Keyword(s):  
Attitude Control ◽  
Controller Design ◽  
Sliding Mode ◽  
Micro Air Vehicles ◽  
Triaxial Accelerometer ◽  
Linear Quadratic ◽  
Linear Quadratic Gaussian ◽  
Constant Altitude ◽  
The Military ◽  
Rotor Type

Micro air vehicles (MAVs) have a wide application such as the military reconnaissance, meteorological survey, environmental monitoring, and other aspects. In this paper, attitude and altitude control for Quad-Rotor type MAVs is discussed and analyzed. For the attitude control, a new method by using three gyroscopes and one triaxial accelerometer is proposed to estimate the attitude angle information. Then with the approximate linear model obtained by system identification, Model Reference Sliding Mode Control (MRSMC) technique is applied to enhance the robustness. In consideration of the relatively constant altitude model, a Linear Quadratic Gaussian (LQG) controller is adopted. The outdoor experimental results demonstrate the superior stability and robustness of the controllers.

Analytical Investigation on Elastodynamic Vibration Suppression of a Flexible Four-Bar Mechanism System Featuring a Smart Coupler Link and Multivariable Optimal Regulator

1997 ◽  
Author(s):  
Muhammad Sannah ◽  
Ahmad Smaili
Keyword(s):  
Active Control ◽  
Smart Materials ◽  
Vibration Suppression ◽  
Controller Design ◽  
Linear Quadratic Regulator ◽  
Piezoelectric Sensor ◽  
Analytical Investigation ◽  
Vibration Modes ◽  
Linear Quadratic ◽  
Luenberger Observer

Abstract This paper presents an analytical investigation on active control of the elastodynamic response of a four-bar (4R) mechanism system using “smart” materials featuring piezoelectric sensor/actuator (S/A) pairs and multivariable optimal control. The 4R mechanism consists of a flexible coupler link, relatively flexible follower link, and a relatively rigid crank. Two thin plate-type piezoceramic S/A pairs are bonded to the flanks of the coupler link at high strain locations corresponding to the first and second vibration modes. Based on the optimal multivariable control theory, a controller which consists of a linear quadratic regulator (LQR) and a Luenberger observer as a state estimator is designed and implemented. As the mechanism changes configuration, its modal characteristics are recalculated, and the controller is redesigned. The dynamic model used for the controller design includes the second and fourth vibration modes of the mechanism system. These modes are predominated by the first two bending modes of the mechanism’s coupler link. The results showed that while the proposed active control strategy is successful in reducing the amplitudes of vibrations about the quasistatic response, it has no effect on the quasistatic deflections due to steady state loading.

Active Control of Elastodynamic Vibrations of a Four-Bar Mechanism System With a Smart Coupler Link Using Optimal Multivariable Control: Experimental Implementation

1996 ◽  
Author(s):  
Muhammad Sannah ◽  
Ahmad Smaili
Keyword(s):  
Experimental Investigation ◽  
Active Control ◽  
Smart Materials ◽  
Controller Design ◽  
Linear Quadratic Regulator ◽  
Piezoelectric Sensor ◽  
High Mode ◽  
Multivariable Control ◽  
Linear Quadratic ◽  
Luenberger Observer

Abstract This paper presents an experimental investigation on active control of the elastodynamic response of a four-bar (4R) mechanism system using “smart” materials featuring piezoelectric sensor/actuator (S/A) pairs and muitivariable optimal control. The experimental (4R) mechanism is made such that its coupler link is flexible, its follower link is slightly less flexible and its crank is relatively rigid. Two thin plate-type piezoceramic S/A pairs are bonded to the flanks of the coupler link at the high strain locations corresponding to the first and second vibration modes. Based on the optimal multivariable control theory, a controller which consists of a linear quadratic regulator (LQR) and a Luenberger observer as a state estimator is designed and implemented. The results of the experimental investigation prove that in order to prevent high mode excitations, the controller design should be based on the modes representing vibrations of all components comprising the mechanism system rather than the modes corresponding to the link to which the S/A pairs are bonded. Response amplitude attenuation ratios up to 50 percent are achieved and high mode excitations are prevented.

Linear quadratic Gaussian controller design for plasma current, position and shape control system in ITER

1999 ◽  
Vol 45 (1) ◽  
pp. 55-64 ◽  
Author(s):  
V Belyakov ◽  
A Kavin ◽  
V Kharitonov ◽  
B Misenov ◽  
Y Mitrishkin ◽  
...  
Keyword(s):  
Control System ◽  
Shape Control ◽  
Controller Design ◽  
Plasma Current ◽  
Current Position ◽  
Linear Quadratic ◽  
Linear Quadratic Gaussian

Active Control of Elastodynamic Vibrations of a Four-Bar Mechanism System With a Smart Coupler Link Using Optimal Multivariable Control: Experimental Implementation

1998 ◽  
Vol 120 (2) ◽  
pp. 316-326 ◽  
Author(s):  
M. Sannah ◽  
A. Smaili
Keyword(s):  
Experimental Investigation ◽  
Active Control ◽  
Smart Materials ◽  
Controller Design ◽  
Linear Quadratic Regulator ◽  
Piezoelectric Sensor ◽  
High Mode ◽  
Multivariable Control ◽  
Linear Quadratic ◽  
Luenberger Observer

This paper presents an experimental investigation on active control of the elastodynamic response of a four-bar (4R) mechanism system using “smart” materials featuring piezoelectric sensor/actuator (S/A) pairs and multivariable optimal control. The experimental 4R mechanism is made such that its coupler link is flexible, its follower link is slightly less flexible and its crank is relatively rigid. Two thin plate-type piezoceramic S/A pairs are bonded to the flanks of the coupler link at the high strain locations corresponding to the first and second vibration modes. Based on the optimal multivariable control theory, a controller which consists of a linear quadratic regulator (LQR) and a Luenberger observer as a state estimator is designed and implemented. The results of the experimental investigation prove that in order to prevent high mode excitations, the controller design should be based on the modes representing vibrations of all components comprising the mechanism system rather than the modes corresponding to the link to which the S/A pairs are bonded. Response amplitude attenuation ratios up to 50 percent are achieved and high mode excitations are prevented.

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