scholarly journals Robust Switching Control and Subspace Identification for Flutter of Flexible Wing

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Yizhe Wang ◽  
Zhiwei Xu ◽  
Wei Li
Keyword(s):  
Wind Tunnel ◽  
Lyapunov Function ◽  
Closed Loop ◽  
Pole Placement ◽  
Subspace Identification ◽  
Aeroelastic System ◽  
Common Lyapunov Function ◽  
Flexible Wing ◽  
Arbitrary Switching ◽  
Wide Range

Active flutter suppression and subspace identification for a flexible wing model using micro fiber composite actuator were experimentally studied in a low speed wind tunnel. NACA0006 thin airfoil model was used for the experimental object to verify the performance of identification algorithm and designed controller. The equation of the fluid, vibration, and piezoelectric coupled motion was theoretically analyzed and experimentally identified under the open-loop and closed-loop condition by subspace method for controller design. A robust pole placement algorithm in terms of linear matrix inequality that accommodates the model uncertainty caused by identification deviation and flow speed variation was utilized to stabilize the divergent aeroelastic system. For further enlarging the flutter envelope, additional controllers were designed subject to the models beyond the flutter speed. Wind speed was measured online as the decision parameter of switching between the controllers. To ensure the stability of arbitrary switching, Common Lyapunov function method was applied to design the robust pole placement controllers for different models to ensure that the closed-loop system shared a common Lyapunov function. Wind tunnel result showed that the designed controllers could stabilize the time varying aeroelastic system over a wide range under arbitrary switching.

scholarly journals Discrete Fundamental AC Voltage Controller for Three-Phase Standalone Converters

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 650
Author(s):  
Alejandro García-Fernández ◽  
Jesús Doval-Gandoy ◽  
Diego Pérez-Estévez
Keyword(s):  
State Space ◽  
Closed Loop ◽  
Design Procedure ◽  
Pole Placement ◽  
Discrete State ◽  
Voltage Controller ◽  
Three Phase ◽  
Wide Range ◽  
Lc Filter ◽  
Output Filter

Voltage control of standalone converters with LC filter is usually based on proportional-resonant or proportional-integral controllers, which often require further active damping methods to achieve stability. These solutions place design constraints in the selection of the closed-loop pole locations which limit the achievable bandwidth and increase the design complexity. In contrast, in state-space based controllers, the closed-loop poles can be placed freely through state feedback, which makes them particularly suitable for high order plants and/or low sampling frequencies. Among the modern control methods, direct pole placement is a simple technique that enables the establishment of a straightforward relationship between outcome and design, as opposed to more advanced approaches. This paper presents a discrete state-space voltage controller for standalone converters with LC output filter. The proposed method combines the direct pole placement technique with a virtual disturbance observer in order to compensate the effects produced by the load and model mismatches. The design process takes into account both the filter parameters and the sampling frequency, rendering the performance of the obtained controller independent of both. The result is a streamlined design procedure that leads to consistent outcomes for a wide range of plant parameter variations, requiring only one input: the desired closed-loop bandwidth.

scholarly journals Common Lyapunov Function Based on Kullback–Leibler Divergence for a Switched Nonlinear System

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
Omar M. Abou Al-Ola ◽  
Ken'ichi Fujimoto ◽  
Tetsuya Yoshinaga
Keyword(s):  
Lyapunov Function ◽  
Switched Systems ◽  
Switched System ◽  
Algebraic Equations ◽  
Common Lyapunov Function ◽  
Arbitrary Switching ◽  
Switched Nonlinear System ◽  
Linear Algebraic Equations ◽  
Leibler Divergence ◽  
The Stability

Many problems with control theory have led to investigations into switched systems. One of the most urgent problems related to the analysis of the dynamics of switched systems is the stability problem. The stability of a switched system can be ensured by a common Lyapunov function for all switching modes under an arbitrary switching law. Finding a common Lyapunov function is still an interesting and challenging problem. The purpose of the present paper is to prove the stability of equilibrium in a certain class of nonlinear switched systems by introducing a common Lyapunov function; the Lyapunov function is based on generalized Kullback–Leibler divergence or Csiszár'sI-divergence between the state and equilibrium. The switched system is useful for finding positive solutions to linear algebraic equations, which minimize theI-divergence measure under arbitrary switching. One application of the stability of a given switched system is in developing a new approach to reconstructing tomographic images, but nonetheless, the presented results can be used in numerous other areas.

CLOWT: A Multifunctional Test Facility for the Investigation of Organic Vapor Flows

2018 ◽  
Author(s):  
Felix Reinker ◽  
Eugeny Y. Kenig ◽  
Stefan aus der Wiesche
Keyword(s):  
Wind Tunnel ◽  
Scaling Laws ◽  
Closed Loop ◽  
Modular Design ◽  
Test Facility ◽  
Settling Chamber ◽  
Process Conditions ◽  
Vapor Flow ◽  
Organic Vapor ◽  
Wide Range

Organic vapor flows are met in a wide range of technical applications (e.g., energy conversion, chemical processes, and refrigeration). Typically, organic fluids contain complex molecules, and their thermodynamic behavior deviates significantly from the ideal or perfect gas laws. The applicability of scaling laws to organic vapor flows is very limited, and there is a need for detailed experimental investigations under relevant process conditions. Furthermore, such investigations can provide a validation basis for the simulations performed with Computational Fluid Dynamics (CFD) tools. On the other hand, there exists a serious lack in experimental organic vapor flow test facilities. In this contribution, a novel Closed Loop Organic vapor Wind Tunnel (CLOWT) is presented. The concept of CLOWT is based on a closed-loop continuously running wind tunnel cycle. Its main components are a blower, a diffuser, a settling chamber, a contraction zone, a test section module, and a return, including a throttle valve and a mass flow meter. The test facility CLOWT applies the modular design approach which enables analysis of various flow configurations and components like blowers, small axial test turbines, nozzle flows or transonic flows past test objects. Thanks to an auxiliary heating system, organic vapor flows can be investigated at elevated pressure and temperature levels. The operation of CLOWT is based on closed gas turbine cycle control methods (e.g., inventory control). In addition to the general test facility concept, the paper gives a detailed discussion of the CLOWT special design features.

A closed-loop wide-range tunable mechanical resonator for energy harvesting systems

2009 ◽  
Vol 19 (9) ◽  
pp. 094004 ◽  
Author(s):  
Christian Peters ◽  
Dominic Maurath ◽  
Wolfram Schock ◽  
Florian Mezger ◽  
Yiannos Manoli
Keyword(s):  
Energy Harvesting ◽  
Closed Loop ◽  
Mechanical Resonator ◽  
Wide Range ◽  
Harvesting Systems

Robust stability and memory state feedback control for a class of switched nonlinear systems with multiple time-varying delays

2021 ◽  
pp. 107754632098598
Author(s):  
Marwen Kermani ◽  
Anis Sakly
Keyword(s):  
Nonlinear Systems ◽  
Lyapunov Function ◽  
Feedback Stabilization ◽  
State Feedback Control ◽  
Multiple Time ◽  
Time Varying ◽  
Switched Nonlinear Systems ◽  
Common Lyapunov Function ◽  
Suggested Approach ◽  
Aggregation Techniques

This study is concerned with the stability analysis and the feedback stabilization problems for a class of uncertain switched nonlinear systems with multiple time-varying delays. Unusually, more general time delays, which depend on the subsystem number, are considered. In this regard, by constructing a novel common Lyapunov function, using the aggregation techniques and the Borne and Gentina criterion, new algebraic stability and feedback stabilization conditions under arbitrary switching are derived. The proposed results are explicit and obtained without searching a common Lyapunov function through the linear matrix inequalities approach, considered a difficult matter in this case. At last, two numerical simulation examples are shown to prove the practical utility of the suggested approach.

scholarly journals Pinning Synchronization of Switched Complex Dynamical Networks

2015 ◽  
Vol 2015 ◽  
pp. 1-8
Author(s):  
Liming Du ◽  
Feng Qiao ◽  
Fengying Wang
Keyword(s):  
Lyapunov Function ◽  
Complex Networks ◽  
Function Method ◽  
Complex Dynamical Networks ◽  
Switching Topology ◽  
Dynamical Networks ◽  
Switching Law ◽  
Arbitrary Switching ◽  
Lyapunov Function Method ◽  
Networks With Switching Topology

Network topology and node dynamics play a key role in forming synchronization of complex networks. Unfortunately there is no effective synchronization criterion for pinning synchronization of complex dynamical networks with switching topology. In this paper, pinning synchronization of complex dynamical networks with switching topology is studied. Two basic problems are considered: one is pinning synchronization of switched complex networks under arbitrary switching; the other is pinning synchronization of switched complex networks by design of switching when synchronization cannot achieved by using any individual connection topology alone. For the two problems, common Lyapunov function method and single Lyapunov function method are used respectively, some global synchronization criteria are proposed and the designed switching law is given. Finally, simulation results verify the validity of the results.

A Note on Pole Placement of Mechanical Systems

1991 ◽  
Vol 113 (3) ◽  
pp. 420-421 ◽  
Author(s):  
C. Minas ◽  
D. J. Inman
Keyword(s):  
Least Squares ◽  
Canonical Form ◽  
Output Feedback ◽  
Closed Loop ◽  
Weighted Least Squares ◽  
Mechanical Systems ◽  
Pole Placement ◽  
Feedback Gain ◽  
Closed Loop System ◽  
Feedback Method

An output feedback method is developed, that systematically places a desired number of poles of a closed-loop system at or near desired locations. The system is transformed to its equivalent controllable canonical form, where the output feedback gain matrix is calculated in a weighted least squares scheme, that minimizes the change of the remaining modes of the system. The advantage of this method over other pole placement routines is the fact that the influence on the remaining unplaced modes of the system is minimum, which is particularly important in preserving closed-loop stability.

Exploratory Wind Tunnel Gust Alleviation Tests of a Multiple-Flap Flexible Wing

2022 ◽  
Author(s):  
John Berg ◽  
Kuang-Ying Ting ◽  
Tyler J. Mundt ◽  
Marat Mor ◽  
Eli Livne ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Flexible Wing ◽  
Gust Alleviation
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