Active Control of Flexible Riser Vibration by Boundary Control Based on LQR Controller

2019 ◽  
Author(s):  
Jinxin Yu ◽  
Weimin Chen
Keyword(s):  
Boundary Control ◽  
Vibration Suppression ◽  
Lateral Displacement ◽  
Open Loop ◽  
Loop System ◽  
Ocean Current ◽  
Control Law ◽  
Flexible Riser ◽  
Linear Quadratic ◽  
Rotational Angle

Abstract The lateral displacement and the rotational angle of marine riser are likely to get larger as it is in stronger ocean current and, particularly, undergoes the consequences such as vortex-induced vibration or collisions between individual risers. The riser vibration with large amplitude value will lead to fatigue or coating damage of the structural body. In this study, the active vibration control, in terms of its angle and the displacement reductions, of a flexible riser under time-varying distributed load are considered using boundary control. The governing equations of the structural dynamics involving the control system of a flexible riser are built. The riser is modeled as an Euler-Bernoulli beam under the actions of ocean loads and the feedback controller. A torque actuator is introduced at the upper riser boundary, and the control law is employed to generate the required signal for riser angle control and displacement reduction. The feed-back control law is designed in state space, and the optimization of the control law is implemented based on the LQR approach. The linear quadratic regulator is used to determine the gain matrix, which can calculate the boundary control law by solving the Recatti equation. Based on the numerical simulations, the responses of the open-loop system and closed-loop system are presented and compared. The effectiveness of the vibration suppression of the flexible riser is examined.

Enhanced Active Constrained Layer Damping Treatment for Broadband Vibration Suppression

2002 ◽  
Vol 8 (6) ◽  
pp. 777-803 ◽  
Author(s):  
Y. Liu ◽  
K. W. Wang
Keyword(s):  
Closed Loop ◽  
Noise Suppression ◽  
Vibration Suppression ◽  
Wide Frequency Range ◽  
Open Loop ◽  
Loop System ◽  
Constrained Layer Damping ◽  
Edge Elements ◽  
Modal Damping ◽  
Active Constrained Layer

In this paper, the Enhanced Active Constrained Layer (EACL) treatment is investigated for broadband damping augmentations on beam structures. The EACL concept was originally proposed to improve the damping performance of the Active Constrained Layer (ACL) by introducing edge elements at the treatment boundaries. It has been recognized that the edge elements can increase ACL performance by enhancing the direct active authority of the piezoelectric constraining layer. It has also been demonstrated that the edge element stiffness and the host structure strain field have significant influence on the overall closed-loop system damping and its various components: the active damping, the closed-loop passive damping, and the open-loop passive (fail-safe property - without any active action) damping. Through utilizing this finding, the present study explores how the EACL performance can be synthesized for multiple mode broadband applications using symmetric configurations. Although the edge elements will tend to reduce the maximum possible open-loop damping of one (or a few) vibration mode, open-loop damping of the other higher order modes could actually be increased. Moreover, the modal damping reduction in the open-loop system can generally be compensated by the significant increase of the closed-loop damping. In other words, the closed-loop EACL system damping over a wide frequency range can be significant, which makes it attractive for broadband vibration and noise suppression.

Output feedback boundary control of a flexible marine riser system

2017 ◽  
Vol 24 (16) ◽  
pp. 3617-3630 ◽  
Author(s):  
Yu Liu ◽  
Fang Guo
Keyword(s):  
Boundary Control ◽  
Closed Loop ◽  
Vibration Suppression ◽  
High Gain ◽  
Loop System ◽  
System State ◽  
Marine Riser ◽  
Closed Loop System ◽  
Observer Error ◽  
System States

This paper is concerned with the design of boundary control for globally stabilizing a flexible marine riser system. The dynamics of the riser system are represented in the form of hybrid partial–ordinary differential equations. Firstly, when the system state available for feedback is unmeasurable, an observer backstepping method is employed to reconstruct the system state and then design the boundary control for vibration suppression of the riser system. Subsequently, for the case that the system states in the designed control law cannot be accurately obtained, the high-gain observers are utilized to estimate those unmeasurable system states. With the proposed control, the uniformly ultimately bounded stability of the closed-loop system is demonstrated by the use of Lyapunov’s synthetic method and the state observer error is converged exponentially to zero as time approaches to infinity. In addition, the disturbance observer is introduced to track external environmental disturbance. Finally, the control performance of the closed-loop system is validated by carrying out numerical simulation.

Design and performance comparison of interconnection and damping assignment passivity-based control for vibration suppression in active suspension systems

2020 ◽  
pp. 107754632093374
Author(s):  
Pramod Sistla ◽  
Sheron Figarado ◽  
Krishnan Chemmangat ◽  
Narayan Suresh Manjarekar ◽  
Gangadharan Kallu Valappil
Keyword(s):  
Vibration Suppression ◽  
Sliding Mode ◽  
Active Suspension ◽  
Control Law ◽  
Linear Quadratic ◽  
Scaled Model ◽  
Suspension Systems ◽  
Active Suspension Systems ◽  
Special Cases ◽  
Passivity Based Control

This study presents the design of interconnection and damping assignment passivity-based control for active suspension systems. It is well known that interconnection and damping assignment passivity-based control’s design methodology is based on the physical properties of the system where the kinetic and potential energy profiles are shaped, and asymptotic stability is achieved by damping injection. Based on the choice of control variables, special cases of the control law are derived, and tuning of the control law with the physical meaning of the variables is demonstrated along with their simulation results. The proposed control law is experimentally validated on a scaled model of a quarter-car active suspension system with different road profiles, varying load conditions, and noise and delay in the sensor measurements and actuator respectively. The results are compared with that of an uncontrolled system with linear quadratic regulator and sliding mode control.

Active multimodal vibration suppression of a flexible structure with piezoceramic sensor and actuator by using loop shaping

2011 ◽  
Vol 17 (13) ◽  
pp. 1994-2006 ◽  
Author(s):  
V Sethi ◽  
MA Franchek ◽  
G Song
Keyword(s):  
Vibration Suppression ◽  
Parametric Identification ◽  
Open Loop ◽  
Pole Placement ◽  
Flexible Beam ◽  
Loop Model ◽  
Linear Quadratic ◽  
Beam Structure ◽  
Control Effort ◽  
Loop Shaping

This paper represents active multimodal vibration control of a flexible beam structure with piezoceramic (PZT) actuators and sensors using the loop shaping method. With surface-bonded PZT patch actuators and sensors, the flexible beam has both sensing and actuating capacities. Due to its flat auto spectrum in the specified frequency range, the Schroeder wave is used as an excitation signal for the non-parametric identification of the flexible beam structure. The identified open loop model is then used for the closed loop design by using the loop shaping method based on the extended sensitivity charts. A loop shaping compensator is designed to achieve multimodal vibration suppression. Numerical results showed a reduction of 8 decibels for the first mode and 12–14 decibels for the second and third modes. Experimental results closely match the simulation results. Furthermore, the results of loop shaping method are compared with those of the methods of linear quadratic regulator and pole-placement control, which are designed based on state space models via the parametric identification of the flexible beam. Comparisons show that the loop shaping method is easier to design since a parametric identification is not required and requires less control effort while maintaining the effectiveness in vibration suppression.

scholarly journals Temperature Control of Stirred Tank Heater using Optimal Control Technique

2020 ◽  
Author(s):  
Mustefa Jibril ◽  
Messay Tadese ◽  
Eliyas Alemayehu
Keyword(s):  
Optimal Control ◽  
Temperature Control ◽  
Open Loop ◽  
Loop System ◽  
Stirred Tank ◽  
Control Technique ◽  
Closed Loop System ◽  
Linear Quadratic ◽  
Linear Quadratic Gaussian ◽  
Quadratic Integral

This paper presents the application of optimal control problem in modeling of stirred tank heater temperature control. The analysis of the open loop system shows that the system is not efficient without a controller. Linear Quadratic Gaussian (LQG) and Linear Quadratic Integral (LQI) controllers are used to increase the performance of the system. Comparison of the closed loop system with the proposed controllers have been done with Matlab/Simulink Toolbox and a promising results have been analyzed.

Analysis and Feedback Control of Planar SOFC Systems for Fast Load Following in APU Applications

2006 ◽  
Author(s):  
Handa Xi ◽  
Jing Sun
Keyword(s):  
Feedback Control ◽  
Closed Loop ◽  
High Efficiency ◽  
Open Loop ◽  
Loop System ◽  
System Response ◽  
Closed Loop System ◽  
Linear Quadratic ◽  
Load Following ◽  
Model Linearization

Solid Oxide Fuel Cell (SOFC) based Auxiliary Power Unit (APU) systems have many practical advantages given their high efficiency, low emissions and flexible fueling strategies. This paper focuses on model-based analysis and feedback control design for planar SOFC systems to achieve fast load following capability. A dynamic model is first developed for the integrated co-flow planar SOFC and CPOX (Catalytic Partial Oxidation) system aiming at APU applications. Simulation results illustrate that an open-loop system with optimal steady-state operating setpoints exhibits a slow transient power response when load increases. Feedback control is then explored to speed up the system response by controlling the flow rates of fuel and air supplies to the system. Model linearization, balanced truncation and Linear Quadratic Gaussian (LQG) approaches are used to derive the low-order observer-based controller. With the feedback controller developed, we show, through simulations, that the closed-loop system can have faster load following capability. Different feedback strategies are also considered and their impacts on closed-loop system performance are analyzed.

scholarly journals Temperature Control of Stirred Tank Heater using Optimal Control Technique

2020 ◽  
Author(s):  
Mustefa Jibril ◽  
Messay Tadese ◽  
Eliyas Alemayehu
Keyword(s):  
Optimal Control ◽  
Temperature Control ◽  
Open Loop ◽  
Loop System ◽  
Stirred Tank ◽  
Control Technique ◽  
Closed Loop System ◽  
Linear Quadratic ◽  
Linear Quadratic Gaussian ◽  
Quadratic Integral

This paper presents the application of optimal control problem in modeling of stirred tank heater temperature control. The analysis of the open loop system shows that the system is not efficient without a controller. Linear Quadratic Gaussian (LQG) and Linear Quadratic Integral (LQI) controllers are used to increase the performance of the system. Comparison of the closed loop system with the proposed controllers have been done with Matlab/Simulink Toolbox and a promising results have been analyzed.

scholarly journals Design and Simulation of a Steam Turbine Generator using Observer Based and LQR Controllers

2020 ◽  
Author(s):  
mustefa jibril ◽  
Messay Tadese ◽  
Eliyas Alemayehu
Keyword(s):  
Steam Turbine ◽  
Performance Improvement ◽  
Linear Quadratic Regulator ◽  
Electrical Energy ◽  
Open Loop ◽  
Loop System ◽  
Linear Quadratic ◽  
Turbine Generator ◽  
Open Loop System ◽  
Lqr Controller

A steam turbine generator is an electromechanical system which converts heat energy to electrical energy. In this paper, the modelling, design and analysis of a simple steam turbine generator have done using Matlab/Simulink Toolbox. The open loop system have been analyzed to have an efficiency of 76.92 %. Observer based & linear quadratic regulator (LQR) controllers have been designed to improve the generating voltage. A comparison of this two proposed controllers have been done for increasing the performance improvement to generate a 220 DC volt. The simulation result shows that the steam turbine generator with observer based controller has a small percentage overshoot with minimum settling time than the steam turbine generator with LQR controller and the open loop system. Finally, the steam turbine generator with observer based controller shows better improvement in performance than the steam turbine generator with LQR controller.

Effect of the Actuators’ Location on Vibration Suppression Using Minimum Modal Energy Eigenstructure Assignment

2007 ◽  
Author(s):  
Mohammad Rastgaar Aagaah ◽  
Steve C. Southward ◽  
Mehdi Ahmadian
Keyword(s):  
Closed Loop ◽  
Vibration Suppression ◽  
Null Space ◽  
Flexible Structures ◽  
Output Feedback Control ◽  
Open Loop ◽  
Loop System ◽  
Eigenstructure Assignment ◽  
Gain Matrix ◽  
Coefficient Vector

A new Eigenstructure Assignment (ESA) method for vibration confinement of flexible structures has been developed. This method is based on finding an output feedback control gain matrix in such a way that the closed-loop eigenvectors are orthogonal to the open-loop ones. Singular Value Decomposition (SVD) is used for finding the matrix that spans the null space of the closed-loop eigenvectors. It is shown that this matrix has a unique property that can be used to regenerate the open-loop system. This method finds a coefficient vector which leads to a zero gain matrix while several coefficient vectors can be found simultaneously which are orthogonal to the open-loop coefficient vector. As a result, the closed-loop eigenvectors are orthogonal to the open-loop ones. It is shown that the modal energy of the closed loop system is reduced. Moreover, the proposed method needs neither to specify the closed-loop eigenvalues nor to define a desired set of eigenvectors. Also it is shown that if the maximum force of the actuators and the consumed energy of the actuators need to be low, actuators have to be relatively close to input. If the amplitude of vibration in isolated area has to be minimized as much as possible, the actuators need to be relatively closer to isolated area. Also the algorithm of the minimum eigenstructure assignment method has been modified to eliminate the effect of the actuators that are located on the nodes of different vibrational modes.

A novel method of angular positioning error analysis of rotary stages based on the Abbe principle

2017 ◽  
Vol 232 (11) ◽  
pp. 1885-1892 ◽  
Author(s):  
Yi-Tsung Li ◽  
Kuang-Chao Fan
Keyword(s):  
Lateral Displacement ◽  
Linear Displacement ◽  
Open Loop ◽  
Positioning Error ◽  
Motion Error ◽  
Rotational Angle ◽  
Rotary Stage ◽  
Measured Angle ◽  
Abbe Error ◽  
Circular Grating

Abbe error is the inherent systematic error in linear displacement measurement due to the measuring axis being out of line with the moving axis. The resulting gap is called the Abbe offset, which will multiply the angular pitch error of the moving stage to become the positioning error of the linear stage along the moving axis. Analogous to the Abbe principle, in the rotary stage, the rotary encoder is used to detect the worktable’s rotational angle. The encoder is normally mounted at a distance from the bearing. This distance can be also regarded as Abbe offset. Due to the inherent tilt and radial motions of the axis of rotation, the encoder’s rotating component, that is, the circular grating, would result in a lateral displacement relative to its sensing head that is fixed inside the stage housing. The actual measured angle is, therefore, different from the commanded angle, causing the angular positioning error of the rotary stage in machine tools and open-loop controlled system. In this article, the angular positioning error of the rotary stage caused by the tilt motion error and radial motion error of the spindle, the offset and the size of encoder is analyzed and experimentally verified.

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