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Disturbance Rejection (disturbance + rejection)
Selected AbstractsDISTURBANCE REJECTION USING AN ILC ALGORITHM WITH ITERATION VARYING FILTERSASIAN JOURNAL OF CONTROL, Issue 3 2004M. Norrlöf ABSTRACT An Iterative Learning Control disturbance rejection approach is considered and it is shown that iteration variant learning filters can asymptotically give the controlled variable zero error and zero variance. Convergence is achieved with the assumption that the relative model error is less than one. The transient response of the suggested ILC algorithm is also discussed using a simulation example. [source] Robust control of depth of anesthesiaINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 5 2009Guy A. Dumont Abstract This paper presents a systematic procedure to design both robust PID controllers and robust controllers based on fractional calculus (based on Commande Robuste d'Ordre Non Entier, or CRONE methodology) to regulate the hypnotic state of anesthesia with the intravenous administration of propofol. The objective of the controllers is to provide an adequate drug administration regimen for propofol to avoid under or over dosing of the patients. The controllers are designed to compensate for the patients inherent drug,response variability (uncertainty), to achieve good output disturbance rejection, and to attain good set point response. The performance of the controllers is assessed by calculating typical time domain measures and using the median PE, median absolute PE, divergence, and wobble. Copyright © 2008 John Wiley & Sons, Ltd. [source] Direct adaptive command following and disturbance rejection for minimum phase systems with unknown relative degreeINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 1 2007Jesse B. Hoagg Abstract This paper considers parameter-monotonic direct adaptive command following and disturbance rejection for single-input single-output minimum-phase linear time-invariant systems with knowledge of the sign of the high-frequency gain (first non-zero Markov parameter) and an upper bound on the magnitude of the high-frequency gain. We assume that the command and disturbance signals are generated by a linear system with known characteristic polynomial. Furthermore, we assume that the command signal is measured, but the disturbance signal is unmeasured. The first part of the paper is devoted to a fixed-gain analysis of a high-gain-stabilizing dynamic compensator for command following and disturbance rejection. The compensator utilizes a Fibonacci series construction to control systems with unknown-but-bounded relative degree. We then introduce a parameter-monotonic adaptive law and guarantee asymptotic command following and disturbance rejection. Copyright © 2006 John Wiley & Sons, Ltd. [source] Direct adaptive control for non-linear uncertain systems with exogenous disturbancesINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 2 2002Wassim M. Haddad Abstract A direct adaptive non-linear control framework for multivariable non-linear uncertain systems with exogenous bounded disturbances is developed. The adaptive non-linear controller addresses adaptive stabilization, disturbance rejection and adaptive tracking. The proposed framework is Lyapunov-based and guarantees partial asymptotic stability of the closed-loop system; that is, asymptotic stability with respect to part of the closed-loop system states associated with the plant. In the case of bounded energy L2 disturbances the proposed approach guarantees a non-expansivity constraint on the closed-loop input,output map. Finally, several illustrative numerical examples are provided to demonstrate the efficacy of the proposed approach. Copyright © 2002 John Wiley & Sons, Ltd. [source] Nonlinear predictive control of smooth nonlinear systems based on Volterra models.INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 16 2010Application to a pilot plant Abstract There is a large demand to apply nonlinear algorithms to control nonlinear systems. With algorithms considering the process nonlinearities, better control performance is expected in the whole operating range than with linear control algorithms. Three predictive control algorithms based on a Volterra model are considered. The iterative predictive control algorithm to solve the complete nonlinear problem uses the non-autoregressive Volterra model calculated from the identified autoregressive Volterra model. Two algorithms for a reduced nonlinear optimization problem are considered for the unconstrained case, where an analytic control expression can be given. The performance of the three algorithms is analyzed and compared for reference signal tracking and disturbance rejection. The algorithms are applied and compared in simulation to control a Wiener model, and are used for real-time control of a chemical pilot plant. Copyright © 2009 John Wiley & Sons, Ltd. [source] Signal reconstruction in the presence of finite-rate measurements: finite-horizon control applicationsINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 1 2010Sridevi V. Sarma Abstract In this paper, we study finite-length signal reconstruction over a finite-rate noiseless channel. We allow the class of signals to belong to a bounded ellipsoid and derive a universal lower bound on a worst-case reconstruction error. We then compute upper bounds on the error that arise from different coding schemes and under different causality assumptions. When the encoder and decoder are noncausal, we derive an upper bound that either achieves the universal lower bound or is comparable to it. When the decoder and encoder are both causal operators, we show that within a very broad class of causal coding schemes, memoryless coding prevails as optimal, imposing a hard limitation on reconstruction. Finally, we map our general reconstruction problem into two important control problems in which the plant and controller are local to each other, but are together driven by a remote reference signal that is transmitted through a finite-rate noiseless channel. The first problem is to minimize a finite-horizon weighted tracking error between the remote system output and a reference command. The second problem is to navigate the state of the remote system from a nonzero initial condition to as close to the origin as possible in finite-time. Our analysis enables us to quantify the tradeoff between time horizon and performance accuracy, which is not well studied in the area of control with limited information as most works address infinite-horizon control objectives (e.g. stability, disturbance rejection). Copyright © 2009 John Wiley & Sons, Ltd. [source] Position-dependent disturbance rejection using spatial-based adaptive feedback linearization repetitive controlINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 12 2009Cheng-Lun Chen Abstract In this paper, we propose a new design of spatial-based repetitive control for a class of rotary motion systems operating at variable speeds. The open-loop system in spatial domain is obtained by reformulating a nonlinear time-invariant system with respect to angular displacement. A two-degree-of-freedom control structure (comprising two control modules) is then proposed to robustly stabilize the open-loop system and improve the tracking performance. The first control module applies adaptive feedback linearization with projected parametric update and concentrates on robust stabilization of the closed-loop system. The second control module introduces a spatial-based repetitive controller cascaded with a loop-shaping filter, which not only further reduces the tracking error, but also improves parametric adaptation. The overall control system is robust to model uncertainties of the system and capable of rejecting position-dependent disturbances under varying process speeds. Stability proof for the overall system is given. A design example with simulation is provided to demonstrate the applicability of the proposed design. Copyright © 2008 John Wiley & Sons, Ltd. [source] Non-diagonal MIMO QFT controller design reformulationINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 9 2009Mario Garcia-Sanz Abstract This paper presents a reformulation of the full-matrix quantitative feedback theory (QFT) robust control methodology for multiple-input,multiple-output (MIMO) plants with uncertainty. The new methodology includes a generalization of previous non-diagonal MIMO QFT techniques; avoiding former hypotheses of diagonal dominance; simplifying the calculations for the off-diagonal elements, and then the method itself; reformulating the classical matrix definition of MIMO specifications by designing a new set of loop-by-loop QFT bounds on the Nichols Chart, which establish necessary and sufficient conditions; giving explicit expressions to share the load among the loops of the MIMO system to achieve the matrix specifications; and all for stability, reference tracking, disturbance rejection at plant input and output, and noise attenuation problems. The new methodology is applied to the design of a MIMO controller for a spacecraft flying in formation in a low Earth orbit. Copyright © 2008 John Wiley & Sons, Ltd. [source] A geometric approach for the design of MIMO sliding controllers.INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 1 2009Application to a wind-driven doubly fed induction generator Abstract This paper presents a systematic methodology to design controllers for a general class of nonlinear MIMO systems affine in the control in the presence of bounded uncertainties and disturbances. The design method is developed using a theoretical framework based on the combination of a geometric approach and sliding mode techniques. The resulting robust control law guarantees finite time convergence, whereas chattering reduction is achieved by utilizing the minimum discontinuous action required to ensure disturbance rejection. The proposed methodology is applied to the control of a grid-connected wind energy generation system based on a doubly fed induction generator. The control objectives considered in this paper are maximization of the wind energy conversion and reactive power regulation to minimize machine losses. Copyright © 2008 John Wiley & Sons, Ltd. [source] Rejection of persistent-bounded disturbances in linear time-delay systems by output-feedbackOPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 4 2010Magdi S. Mahmoud Abstract In this paper, the problem of persistent-bounded disturbance rejection of linear continuous-time systems with time-varying delays is investigated using the tools of invariant set analysis and Lyapunov-function methodology. We derive less conservative sufficient conditions on robust attractor for time-delay systems in terms of strict linear matrix inequalities (LMIs) to guarantee the desired ,1 -performance. A robust output-feedback controller is designed and the associated gain is determined using strict LMIs. The developed results are tested on two representative time-delay examples. Copyright © 2009 John Wiley & Sons, Ltd. [source] ,, control of discrete-time Markov jump systems with bounded transition probabilitiesOPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 5 2009E. K. Boukas Abstract This paper deals with the class of discrete-time linear systems with random abrupt changes and unknown transition probabilities but varying between known bounds for each mode. The ,, control problem of this class of systems is revisited and new sufficient conditions are developed in the linear matrix inequality (LMI) setting to design the state-feedback controller that stochastically stabilizes the system under consideration and at the same time guarantees the disturbance rejection with a desired level , . Sufficient conditions for existence of the state-feedback controller are developed. It is shown that the addressed problem can be solved if the corresponding developed LMIs are feasible. Numerical examples are employed to show the usefulness of the proposed results. Copyright © 2008 John Wiley & Sons, Ltd. [source] Singular linear systems with delay: ,, stabilizationOPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 4 2007E. K. BoukasArticle first published online: 12 MAR 200 Abstract This paper deals with the class of continuous-time singular linear systems with time-delay in the state vector. The stabilization problem of this class of systems using a state feedback controller is tackled. New delay-dependent sufficient conditions on ,, stabilization are developed. A design algorithm for a memoryless state feedback controller which guarantees that the closed-loop dynamics will be regular, impulse-free and stable with ,-disturbance rejection is proposed. It is shown that the addressed problem can be solved if the corresponding developed linear matrix inequalities (LMIs) with some constraints are feasible. A numerical example is employed to show the usefulness of the proposed results. Copyright © 2007 John Wiley & Sons, Ltd. [source] Generalized sampled-data hold functions for robust multivariable tracking and disturbance rejectionOPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 2 2001Herbert Werner Abstract A new design procedure for a multivariable sampled-data output feedback controller with generalized hold function is proposed. The controller can be designed for different operating points simultaneously. The design of the hold function is carried out in two steps: first the closed-loop discrete-time behaviour is determined by choosing a suitable output injection gain; integral action is incorporated to guarantee zero steady-state error. In a second step this discrete-time behaviour is approximately realized by output feedback with generalized hold. Minimization of a quadratic performance index simultaneously for all operating points yields hold functions with good intersample behaviour. A practical design example and experimental results illustrate the proposed method. Copyright © 2001 John Wiley & Sons, Ltd. [source] Simultaneous Automatic Control of Oxygen and Carbon Dioxide Blood Gases During Cardiopulmonary BypassARTIFICIAL ORGANS, Issue 6 2010Berno J.E. Misgeld Abstract In this work an automatic control strategy is presented for the simultaneous control of oxygen and carbon dioxide blood gas partial pressures to be used during cardiopulmonary bypass surgery with heart,lung machine support. As the exchange of blood gases in the artificial extracorporeal lung is a highly nonlinear process comprising varying time delays, uncertainties, and time-varying parameters, it is currently being controlled manually by specially trained perfusionist staff. The new control strategy includes a feedback linearization routine with augmented time-delay compensation and two external linear gain-scheduled controllers, for partial oxygen and carbon dioxide pressures. The controllers were robustly tuned and tested in simulations with a detailed artificial lung (oxygenator) model in cardiopulmonary bypass conditions. Furthermore, the controllers were implemented in an ex vivo experiment using fresh porcine blood as a substitute fluid and a special deoxygenation technique to simulate a patient undergoing cardiopulmonary bypass. Both controllers showed robust stability during the experiments and a good disturbance rejection to extracorporeal blood flow changes. This automatic control strategy is proposed to improve patient's safety by fast control reference tracking and good disturbance rejection under varying conditions. [source] Optimal grade transition control for liquid-propylene polymerization reactor,ASIAN JOURNAL OF CONTROL, Issue 3 2010Mohammad Al-haj Ali Abstract A nonlinear control system integrating an off-line optimizer and a nonlinear model-based controller is developed to perform optimal grade transition operations in a continuous pilot plant reactor. A simple black-box model is developed and used to determine optimal trajectories of inputs and outputs for a series of three polypropylene grades. The simplified model is also used to develop a nonlinear controller. This controller is similar to generic model control; however, the integral action is omitted and an on-line updating scheme is incorporated to update pre-specified model parameters using delayed process measurements. The time optimal inputs, which are calculated by the off-line optimizer, are introduced to the plant in a feedforward manner. At the same time, the deviations from the optimal output are corrected using the feedback nonlinear controller. The simulations on a complex mechanistic model of the process reveal that the nonlinear control scheme performs well for both set point tracking and disturbance rejection. This paper integrates well-known methodologies, such as the generic-model control algorithm, parameter update schemes, and off-line optimization, together to develop an applicable and robust control technique for continuous polymerization reactors. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source] Two-degree-of-freedom controller design for linear parameter-varying systemsASIAN JOURNAL OF CONTROL, Issue 1 2008Wei Xie Abstract A design strategy for linear parameter-varying (LPV) systems is considered in a two-degree-of-freedom (TDOF) control framework. First, a coprime factorization for LPV systems is introduced. Second, based on the coprime factorization, a TDOF control framework of linear timeinvariant systems is extended to that of LPV systems. Good tracking performance and good disturbance rejection are achieved by a feedforward controller and a feedback controller, respectively. Furthermore, each controller design problem can be formulated in terms of a linear matrix inequality related to the L2 gain performance. Finally, a simple design example is illustrated. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source] THE PERFORMANCE OF DISCRETE LINEAR TIME VARYING CONTROL OF LINEAR PERIODIC PLANTSASIAN JOURNAL OF CONTROL, Issue 1 2004Jingxin Zhang ABSTRACT This paper analyzes the performance of discrete linear time varying (LTV) control of discrete linear periodically time varying (LPTV) plants for l2 disturbance rejection. It extends the results of [11,13] for linear periodic controllers to general LTV control of LPTV plants. It is shown that LPTV control provides strictly better control performance than linear strictly time varying control for LPTV plants. The analysis is carried out in frequency domain. This approach provides not only new results on disturbance rejection of LTV control but also some new insight into properties of general LTV systems. [source] Output Feedback Sliding Mode Controller Design Via H, THEORYASIAN JOURNAL OF CONTROL, Issue 1 2003Jeang-Lin Chang ABSTRACT For a linear system with mismatched disturbances, a sliding mode controller using only output feedback is developed in this paper. Through application of the H, control theory, the designed switching surface can achieve robust stabilization and guarantee a level of disturbance rejection during sliding mode. Although the system exhibits disturbances, a state estimator is used which, using only measured outputs, can asymptotically estimate the system states. The control law is designed with respect to the estimated signals. Finally, a numerical example is presented to demonstrate the proposed control scheme. [source] | ||||||||||