Systematic design of robust controller for electro-hydraulic system with model uncertainties

2015 ◽  
Vol 230 (4) ◽  
pp. 573-582
Author(s):  
Jongguk Yim ◽  
Youngjin Choi
Keyword(s):  
Hydraulic System ◽  
Disturbance Attenuation ◽  
Model Parameters ◽  
Model Uncertainties ◽  
Robust Tracking Control ◽  
Feedback Form ◽  
Robust Controller ◽  
Recursive Procedures ◽  
Error Dynamics ◽  
Fictitious Control

A systematic method is developed to design new robust tracking control for an electro-hydraulic system. In this article, the model dynamics is represented in strict feedback form to be linearly parameterized with regard to model parameters to consider its uncertainties and the separate error dynamics are derived for the tracking of states. The proposed method is intuitively similar to a previously developed integrator backstepping approach since it designs fictitious controls as desired states for recursive procedures. However, unlike previous works that have relied exclusively on Lyapunov analysis using the sum of the squares of state errors, this work utilizes a passivity approach with an energy function for stability. The advantage of the proposed method is that the fictitious control can be designed in a decoupled form and an L2-gain analysis can be applied to guarantee the robustness to model uncertainties. For the separate error dynamics, one part of the fictitious control is designed using stability analysis with a strict passivity formulation for error convergence; this leads to a separation of the other fictitious control design for robustness from the effects of other equations of dynamics. Hence, this method makes it possible to treat the terms caused by the model uncertainties as disturbance and to design the fictitious robust control using the L2-gain analysis for the disturbance attenuation, which does not require the bound function of the disturbance to be known. The validity of the proposed method is shown through simulations.

scholarly journals Delay-Dependent Robust Stabilization for Nonlinear Large Systems via Decentralized Fuzzy Control

2011 ◽  
Vol 2011 ◽  
pp. 1-20 ◽  
Author(s):  
Chun-xia Dou ◽  
Zhi-sheng Duan ◽  
Xing-bei Jia ◽  
Xiao-gang Li ◽  
Jin-zhao Yang ◽  
...  
Keyword(s):  
Time Delay ◽  
Fuzzy Control ◽  
Upper Bound ◽  
Time Delays ◽  
Sufficient Conditions ◽  
Large System ◽  
Disturbance Attenuation ◽  
Robust Controller ◽  
Large Systems ◽  
Delay Dependent

A delay-dependent robust fuzzy control approach is developed for a class of nonlinear uncertain interconnected time delay large systems in this paper. First, an equivalent T–S fuzzy model is extended in order to accurately represent nonlinear dynamics of the large system. Then, a decentralized state feedback robust controller is proposed to guarantee system stabilization with a prescribedH∞disturbance attenuation level. Furthermore, taking into account the time delays in large system, based on a less conservative delay-dependent Lyapunov function approach combining with linear matrix inequalities (LMI) technique, some sufficient conditions for the existence ofH∞robust controller are presented in terms of LMI dependent on the upper bound of time delays. The upper bound of time-delay and minimizedH∞performance index can be obtained by using convex optimization such that the system can be stabilized and for all time delays whose sizes are not larger than the bound. Finally, the effectiveness of the proposed controller is demonstrated through simulation example.

Disturbance Attenuating Adaptive Controllers for Parametric Strict Feedback Nonlinear Systems With Output Measurements

1999 ◽  
Vol 121 (1) ◽  
pp. 48-57 ◽  
Author(s):  
I. Egemen Tezcan ◽  
Tamer Bas¸ar
Keyword(s):  
Nonlinear Systems ◽  
Output Feedback ◽  
Robust Adaptive Control ◽  
Disturbance Attenuation ◽  
Parameter Estimates ◽  
Minimum Phase ◽  
Feedback Form ◽  
Output Measurement ◽  
Adaptive Controllers ◽  
Strict Feedback

We present a systematic procedure for designing H∞-optimal adaptive controllers for a class of single-input single-output parametric strict-feedback nonlinear systems that are in the output-feedback form. The uncertain nonlinear system is minimum phase with a known relative degree and known sign of the high-frequency gain. We use soft projection on the parameter estimates to keep them bounded in the absence of persistent excitations. The objective is to obtain disturbance attenuating output-feedback controllers which will track a smooth bounded trajectory and keep all closed-loop signals bounded in the presence of exogenous disturbances. Two recent papers (Pan and Bas¸ar, 1996a; Marino and Tomei, 1995) addressed a similar problem with full state information, using two different approaches, and obtained asymptotically tracking and disturbance-attenuating adaptive controllers. Here, we extend these results to the output measurement case for a class of minimum phase nonlinear systems where the nonlinearities depend only on the measured output. It is shown that arbitrarily small disturbance attenuation levels can be obtained at the expense of increased control effort. The backstepping methodology, cost-to-come function based H∞ -filtering and singular perturbations analysis constitute the framework of our robust adaptive control design scheme.

scholarly journals Adaptive Modeling of the Global Ionosphere Vertical Total Electron Content

2020 ◽  
Vol 12 (11) ◽  
pp. 1822
Author(s):  
Eren Erdogan ◽  
Michael Schmidt ◽  
Andreas Goss ◽  
Barbara Görres ◽  
Florian Seitz
Keyword(s):  
Total Electron Content ◽  
Temporal Variations ◽  
Model Parameters ◽  
Electron Content ◽  
Vertical Total Electron Content ◽  
Model Uncertainties ◽  
Data Set ◽  
Total Electron ◽  
B Spline ◽  
Run Time

The Kalman filter (KF) is widely applied in (ultra) rapid and (near) real-time ionosphere modeling to meet the demand on ionosphere products required in many applications extending from navigation and positioning to monitoring space weather events and naturals disasters. The requirement of a prior definition of the stochastic models attached to the measurements and the dynamic models of the KF is a drawback associated with its standard implementation since model uncertainties can exhibit temporal variations or the time span of a given test data set would not be large enough. Adaptive methods can mitigate these problems by tuning the stochastic model parameters during the filter run-time. Accordingly, one of the primary objectives of our study is to apply an adaptive KF based on variance component estimation to compute the global Vertical Total Electron Content (VTEC) of the ionosphere by assimilating different ionospheric GNSS measurements. Secondly, the derived VTEC representation is based on a series expansion in terms of compactly supported B-spline functions. We highlight the morphological similarity of the spatial distributions and the magnitudes between VTEC values and the corresponding estimated B-spline coefficients. This similarity allows for deducing physical interpretations from the coefficients. In this context, an empirical adaptive model to account for the dynamic model uncertainties, representing the temporal variations of VTEC errors, is developed in this work according to the structure of B-spline coefficients. For the validation, the differential slant total electron content (dSTEC) analysis and a comparison with Jason-2/3 altimetry data are performed. Assessments show that the quality of the VTEC products derived by the presented algorithm is in good agreement, or even more accurate, with the products provided by IGS ionosphere analysis centers within the selected periods in 2015 and 2017. Furthermore, we show that the presented approach can be applied to different ionosphere conditions ranging from very high to low solar activity without concerning time-variable model uncertainties, including measurement error and process noise of the KF because the associated covariance matrices are computed in a self-adaptive manner during run-time.

Servocontrol of the GS16 Turbine Gas Metering Valve by Physics-Based Robust Controller Synthesis

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
Kamran E. Shahroudi ◽  
Peter M. Young
Keyword(s):  
Physical Meaning ◽  
State Feedback ◽  
Controller Design ◽  
Controller Synthesis ◽  
Design Approach ◽  
Balanced Truncation ◽  
Feedback Form ◽  
Robust Controller ◽  
Synthesis Procedure ◽  
Detailed Outline

We present a design approach for robust controller synthesis using a μ-synthesis procedure, which returns a controller in an observor/state-feedback form with physically meaningful states. We are also able to (approximately) retain this physical meaning when using balanced truncation to (significantly) reduce the controller order, as is often necessary in practice. The advantages of this physics-based approach are illustrated by a detailed outline of the controller design for Woodward Governor’s GS16 Turbine Gas Metering Valve.

FUZZY CHAOS SYNCHRONIZATION VIA SAMPLED DRIVING SIGNALS

2004 ◽  
Vol 14 (08) ◽  
pp. 2721-2733 ◽  
Author(s):  
JUAN GONZALO BARAJAS-RAMÍREZ ◽  
GUANRONG CHEN ◽  
LEANG S. SHIEH
Keyword(s):  
Continuous Time ◽  
System Approach ◽  
Chaos Synchronization ◽  
Chaotic Systems ◽  
Disturbance Attenuation ◽  
Fuzzy Observer ◽  
Master System ◽  
Error Dynamics ◽  
Takagi Sugeno ◽  
Driving Signal

In this paper, a methodology to design a system that robustly synchronizes a master chaotic system from a sampled driving signal is developed. The method is based on the fuzzy Takagi–Sugeno representation of chaotic systems, from which a continuous-time fuzzy observer is designed as the solution of an LMI minimization problem such that the error dynamics have H∞disturbance attenuation performance. Then, from the dual-system approach, the fuzzy observer is digitally redesigned such that the performance is maintained for the sampled master system. The effectiveness of the proposed synchronization methodology is finally illustrated via numerical simulations of the chaotic Chen's system.

Robust Output Regulation Via Sliding Mode Control and Disturbance Observer: Application in a Forced Van Der Pol Chaotic Oscillator

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
F. Shiravani ◽  
M. H. Shafiei
Keyword(s):  
Disturbance Observer ◽  
Sliding Mode ◽  
Tracking Error ◽  
Output Regulation ◽  
Chaotic Oscillator ◽  
Model Uncertainties ◽  
Feedback Form ◽  
Van Der Pol ◽  
Effective Performance ◽  
Robust Output Regulation

This paper considers the problem of robust output regulation of nonlinear systems in semi strict-feedback form in the presence of model uncertainties and nonvanishing disturbances. In the proposed procedure, two exosystems are considered to generate the disturbance and reference signals. In order to reduce both the conservatism of the control law and the chattering phenomena, a disturbance observer is designed for disturbance estimation instead of assuming the known upper bound for the disturbance. Moreover, a novel sliding surface is designed based on the tracking error to guarantee that the output of the system tracks the output of the exosystem. In this regard, some theorems are given and according to the Lyapunov approach, it is proved that the robust output regulation is guaranteed in the presence of model uncertainties and external disturbances. Finally, in order to show the applicability of the proposed controller, it is applied to the Van der Pol chaotic oscillator. Computer simulations verify the theoretical results and also show the effective performance of the proposed controller.

Robust Tracking Control of a Direct Drive Robot

1999 ◽  
Vol 121 (2) ◽  
pp. 261-269 ◽  
Author(s):  
Bong Soo Kang ◽  
Soo Hyun Kim ◽  
Yoon Keun Kwak ◽  
Craig C. Smith
Keyword(s):  
Tracking Control ◽  
Torque Control ◽  
Joint Control ◽  
Robust Tracking ◽  
Direct Drive ◽  
Robust Tracking Control ◽  
Tracking Errors ◽  
Robust Controller ◽  
Residual Errors ◽  
Computed Torque

This paper presents a robust controller for tracking control of a direct-drive robot. The proposed controller consists of two portions: a computed torque method which precompensates for dynamics of the modeled plant and an H∞ controller which postcompensates for residual errors which are not completely removed by the computed torque method. Experimental methods for identifying appropriate model structure and parameters are presented, and three specific controller types are compared. Using the robot designed in our laboratory, the combined controller reduced tracking errors by one half compared to computed torque control alone, and by one sixth compared to conventional independent joint control.

scholarly journals Temperature Control of Continuous Chemical Reactors Under Noisy Measurements and Model Uncertainties

2012 ◽  
Vol 10 (3) ◽  
Author(s):  
Ricardo Aguilar López ◽  
Rafael Martínez Guerra ◽  
Juan L. Mata Machuca
Keyword(s):  
Sliding Mode ◽  
System Stability ◽  
Chemical System ◽  
Control Law ◽  
Model Uncertainties ◽  
Uncertainty Estimator ◽  
The Face ◽  
Oscillatory Chemical ◽  
Error Dynamics ◽  
Noisy Measurements

The aim of this paper is to present the synthesis of a robust control law for the control of a class of nonlinear systems named Liouvillian. The control design is based on a sliding-mode uncertainty estimator developed under the framework of algebraic-differential concepts. The estimation convergence is done by the Lyapunov-type analysis and the closed-loop system stability is shown by means of the regulation error dynamics. Robustness of the proposed control scheme is tested in the face of noise output measurements and model uncertainties. The performance of the proposed control law is illustrated with numerical simulations in which a class of oscillatory chemical system is used as application example.

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