Active Control of Flexible Structures Submitted to Incompressible Flows

2002 ◽  
Author(s):  
C. C. Machado ◽  
A. L. De Bortoli ◽  
S. C. P. Gomes
Keyword(s):  
Incompressible Flows ◽  
Flexible Structures ◽  
Pole Placement ◽  
Flexible Structure ◽  
Control Law ◽  
Flow Induced Vibration ◽  
Robust Controller ◽  
Numerical Tests ◽  
Noise Rejection ◽  
And Performance

This work presents a survey on the control law development to actively attenuate the vibrations of a flexible structure submitted to fluid flow. Firstly, a robust controller with LQG/LTR approach was developed. Numerical tests were carried out being robustness characteristics to flow induced vibration and to noise rejection verified, for the case of equal nominal and real plants. The same robustness was not verified, when parametric variations were introduced. Therefore, another controller, based on regulator and filter pole placement approach, was developed where the direct loop obeys stability and performance robustness criterions, allowing to obtain good numerical results, even in the presence of significant parametric variations.

New Controller and Observer Design Methods Tailored to Smart, Flexible Structure Control Applications

1999 ◽  
Author(s):  
Rama K. Yedavalli
Keyword(s):  
State Space ◽  
Flexible Structures ◽  
Systems Design ◽  
Design Methods ◽  
Observer Design ◽  
Flexible Structure ◽  
Performance Constraints ◽  
Measurement Models ◽  
Standard Design ◽  
And Performance

Abstract In this paper, we summarize the research being carried out by the author and his group of graduate students on new control and observer design methods specifically tailored towards to control of smart and flexible structure applications. The new approaches are tailored to this specific application in the sense that they take into account the various types of available measurements and provide controllers and observers in terms of the various combinations of measurement variables. This approach of tailoring the controller and observer structure around the available measurement models has significant advantages over traditional approaches. Specifically these approaches introduce two new frameworks for controller and observer design, namely “Reciprocal State Space Framework” and “Matrix Second Order Framework”. Currently State Space Framework is a popular framework for control systems design in the sense that designers always transform the dynamic model of their application into state space form and then carry out the standard design techniques of this framework. However, we argue that there are many applications in which the dynamics, measurement models and performance constraints are such that it is unnecessary and cumbersome to force this transformation and instead the design can be carried out more easily in these newly introduced frameworks that are compatible with the plant dynamics, measurement models and performance constraints. Using these frameworks, simple control and observer designs are carried out with application to the problem of control of smart, flexible structures.

Robust Observer-Based Control of Large Flexible Structures

1994 ◽  
Vol 116 (4) ◽  
pp. 713-722 ◽  
Author(s):  
Chun-Liang Lin ◽  
Bor-Sen Chen
Keyword(s):  
Output Feedback ◽  
Flexible Structures ◽  
Robust Stabilization ◽  
Output Feedback Control ◽  
Flexible Structure ◽  
Unmodeled Dynamics ◽  
Control Law ◽  
Robust Observer ◽  
Simply Supported ◽  
Observation Spillover

This paper considers robust stabilization of the spillover phenomenon of large flexible structures. New frequency domain robustness measures for a large flexible structure system controlled by an observer-based compensator is derived via a state-space framework. In the present approach, control and observation spillover are viewed as parametric perturbations, and the total spillover (combination of control and observation spillover) is treated as the unmodeled dynamics. A robust observer-based output feedback control law, obtained by solving two algebraic Riccati equations, is provided. Finally, a simply supported beam example is included to illustrate the application.

Practical Implementation Issues for Active Control of Large Flexible Structures

1989 ◽  
Vol 111 (3) ◽  
pp. 283-289 ◽  
Author(s):  
D. C. Zimmerman ◽  
H. H. Cudney
Keyword(s):  
Active Control ◽  
Control Strategies ◽  
Flexible Structures ◽  
Practical Implementation ◽  
Control Law ◽  
Actuator Dynamics ◽  
Analog To Digital ◽  
Digital Implementation ◽  
Digital To Analog Converters ◽  
And Performance

Most active control strategies, whether designed in the discrete or continuous domain, will most likely be implemented using a digital control system. Therefore, it is important to study the effects of digital implementation on the desired control law. In this work, the effect of quantization due to the finite wordlength of microprocessors, analog-to-digital, and digital-to-analog converters, on the desired control law is investigated. Additionally, the practical effect of actuator dynamics on the stability and performance of the control law is addressed. Finally, an active control experiment is reported on which takes into account and demonstrates some of these practical considerations.

scholarly journals Doubly fed induction generators to enhance inter-area damping based on a Robust controller: $${{\varvec{H}}}_{2}/{{\varvec{H}}}_{\infty }$$ Control

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Ali Goodarzi ◽  
Ali Mohammad Ranjbar ◽  
Moslem Dehghani ◽  
Mina GhasemiGarpachi ◽  
Mohammad Ghiasi
Keyword(s):  
Working Conditions ◽  
Reactive Power ◽  
Wind Farms ◽  
System Stability ◽  
Pole Placement ◽  
Linear Matrix ◽  
Robust Controller ◽  
Induction Generators ◽  
Doubly Fed ◽  
Oscillation Damping

AbstractIn this study, an auxiliary damping controller based on a robust controller considering the active and reactive power control loops for a doubly-fed induction generator for wind farms is proposed. The presented controller is able to improve the inter-area oscillation damping. In addition, the proposed controller applies only one accessible local signal as the input; however, it can improve the inter-area oscillation damping and, consequently the system stability for the various working conditions and uncertainties. The oscillatory modes of the system are appointed using the linear analysis. Then, the controller’s parameters are determined using the robust control approaches ($${H}_{\infty }/{H}_{2})$$ H ∞ / H 2 ) with the pole placement and linear matrix inequality method. The results of the modal analysis and time-domain simulations confirm that the controller develops the inter-area oscillation damping under the various working conditions and uncertainties.

scholarly journals Anℋ∞Optimal Robust Pole Placement with Fixed Transparent Controller Structure on the Basis of Nonnegativity of Even Spectral Polynomials

2012 ◽  
Vol 2012 ◽  
pp. 1-25 ◽  
Author(s):  
Andrej Sarjaš ◽  
Rajko Svečko ◽  
Amor Chowdhury
Keyword(s):  
Controller Design ◽  
Polynomial Equation ◽  
Pole Placement ◽  
Robust Controller ◽  
Reference Tracking ◽  
Common Criteria ◽  
Sensitivity Problem ◽  
The Common ◽  
Partial Fraction Decomposition ◽  
Iterative Evolution

This paper presents the synthesis of an optimal robust controller with the use of pole placement technique. The presented method includes solving a polynomial equation on the basis of the chosen fixed characteristic polynomial and introduced parametric solutions with a known parametric structure of the controller. Robustness criteria in an unstructured uncertainty description with metrics of normℋ∞are for a more reliable and effective formulation of objective functions for optimization presented in the form of a spectral polynomial with positivity conditions. The method enables robust low-order controller design by using plant simplification with partial-fraction decomposition, where the simplification remainder is added to the performance weight. The controller structure is assembled of well-known parts such as disturbance rejection, and reference tracking. The approach also allows the possibility of multiobjective optimization of robust criteria, application of mixed sensitivity problem, and other closed-loop limitation criteria, where the common criteria function can be composed from different unrelated criteria. Optimization and controller design are performed with iterative evolution algorithm.

Tensegrity Structures in the Design of Flexible Structures for Offshore Aquaculture

2007 ◽  
Author(s):  
O̸sten Jensen ◽  
Anders Sunde Wroldsen ◽  
Pa˚l Furset Lader ◽  
Arne Fredheim ◽  
Mats Heide ◽  
...  
Keyword(s):  
Flexible Structures ◽  
Weather Conditions ◽  
High Energy ◽  
Open Ocean ◽  
Element Analysis ◽  
Tensegrity Structures ◽  
Stiffness Properties ◽  
Offshore Aquaculture ◽  
And Performance ◽  
Open Ocean Aquaculture

Aquaculture is the fastest growing food producing sector in the world. Considerable interest exists in developing open ocean aquaculture in response to a shortage of suitable, sheltered inshore locations. The harsh weather conditions experienced offshore lead to a focus on new structure concepts, remote monitoring and a higher degree of automation in order to keep the cost of structures and operations within an economically viable range. This paper proposes tensegrity structures in the design of flexible structures for offshore aquaculture. The finite element analysis program ABAQUS™ has been used to investigate stiffness properties and performance of tensegrity structures when subjected to various forced deformations and hydrodynamic load conditions. The suggested concept, the tensegrity beam, shows promising stiffness properties in tension, compression and bending, which are relevant for development of open ocean aquaculture construction for high energy environments. When designing a tensegrity beam, both pre-stress and spring stiffness should be considered to ensure the desired structural properties. A large strength to mass ratio and promising properties with respect to control of geometry, stiffness and vibration could make tensegrity an enabling technology for future developments.

Robust vibration control of flexible panel: modeling and simulation

2017 ◽  
Vol 14 (5) ◽  
pp. 433-442
Author(s):  
Aalya Banu ◽  
Asan G.A. Muthalif
Keyword(s):  
Robust Control ◽  
Vibration Control ◽  
Controller Design ◽  
Control Strategies ◽  
Active Vibration Control ◽  
Flexible Structures ◽  
Parametric Uncertainty ◽  
Design Algorithm ◽  
Content Type ◽  
And Performance

Purpose This paper aims to develop a robust controller to control vibration of a thin plate attached with two piezoelectric patches in the presence of uncertainties in the mass of the plate. The main goal of this study is to tackle dynamic perturbation that could lead to modelling error in flexible structures. The controller is designed to suppress first and second modal vibrations. Design/methodology/approach Out of various robust control strategies, μ-synthesis controller design algorithm has been used for active vibration control of a simply supported thin place excited and actuated using two piezoelectric patches. Parametric uncertainty in the system is taken into account so that the robust system will be achieved by maximizing the complex stability radius of the closed-loop system. Effectiveness of the designed controller is validated through robust stability and performance analysis. Findings Results obtained from numerical simulation indicate that implementation of the designed controller can effectively suppress the vibration of the system at the first and second modal frequencies by 98.5 and 88.4 per cent, respectively, despite the presence of structural uncertainties. The designed controller has also shown satisfactory results in terms of robustness and performance. Originality/value Although vibration control in designing any structural system has been an active topic for decades, Ordinary fixed controllers designed based on nominal parameters do not take into account the uncertainties present in and around the system and hence lose their effectiveness when subjected to uncertainties. This paper fulfills an identified need to design a robust control system that accommodates uncertainties.

Nonlinear Torsional Vibration Absorber for Flexible Structures

2018 ◽  
Vol 86 (2) ◽  
Author(s):  
Xiao-Ye Mao ◽  
Hu Ding ◽  
Li-Qun Chen
Keyword(s):  
High Efficiency ◽  
Rotation Angle ◽  
Flexible Structures ◽  
Nonlinear Energy Sink ◽  
Flexible Structure ◽  
Vibration Absorber ◽  
Special Perturbation ◽  
Energy Sink ◽  
Simulation Parameters ◽  
Nonlinear Energy

A new kind of nonlinear energy sink (NES) is proposed to control the vibration of a flexible structure with simply supported boundaries in the present work. The new kind of absorber is assembled at the end of structures and absorbs energy through the rotation angle at the end of the structure. It is easy to design and attached to the support of flexible structures. The structure and the absorber are coupled just with a nonlinear restoring moment and the damper in the absorber acts on the structure indirectly. In this way, all the linear characters of the flexible structure will not be changed. The system is investigated by a special perturbation method and verified by simulation. Parameters of the absorber are fully discussed to optimize the efficiency of it. For the resonance, the maximum motion is restrained up to 90% by the optimized absorber. For the impulse, the vibration of the structure could attenuate rapidly. In addition to the high efficiency, energy transmits to the absorber uniaxially. For the high efficiency, convenience of installation and the immutability of linear characters, the new kind of rotating absorber provides a very good strategy for the vibration control.

Adaptive Pole Placement Control Law Using the Delta Operator

1991 ◽  
Vol 24 (1) ◽  
pp. 127-132
Author(s):  
M.A. Garnero ◽  
G. Thomas ◽  
B. Caron ◽  
J.F. Bourgeois
Keyword(s):  
Pole Placement ◽  
Control Law ◽  
Delta Operator ◽  
Pole Placement Control

H∞ loop Shaping Robust Postprandial Glucose Control for Type 1 Diabetes

2021 ◽  
Vol 39 (2A) ◽  
pp. 268-279
Author(s):  
Safa F. Fadhel ◽  
Safanah M. Raafat
Keyword(s):  
Blood Glucose Concentration ◽  
Artificial Pancreas ◽  
Postprandial Glucose ◽  
Robust Controller ◽  
Control Effort ◽  
Loop Shaping ◽  
Design Requirements ◽  
And Performance

The Bergman model is one of the most commonly used models applied to the representation of the artificial pancreas (AP). It is important to study the effects of the insulin infusion on blood glucose concentration. This work includes a case study for the design of a robust controller for an AP. Robustness is a structured control that improves a system's ability to keep its stability and performance under various conditions. The proposed H∞ loop shaping HLS method will fulfill the design requirements of robust control and performance. The results of the simulation prove the superiority of the intended approach in terms of simple structure, robust performance, and stability with the least control effort

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