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In this paper we propose a technique and an objective performance metric, that we denote "area-metric", for the analysis and overall comparison and characterization of FTIR spectral response sensitivity-improvement performances of strained-layer superlattice (SLS) 3μm-5μm MWIR single photo detectors, enhanced with microsphere lenses of different dielectric material structures and sizes....
This paper studies the H2/H∞ approach to control the Internet traffic. We are interested in using the H2 formulation to improve transient performances in addition to maintaining the robust performance offered by the formerly used H∞ formulation. In this controller, the closed-loop dynamics are monitored and controlled by the sensitivity functions along with their associated weight functions. The LMI...
Robust control aims to account for model uncertainty in design. Traditional methods for robust control typically assume knowledge of hard bounds on the system frequency response. However, this does not match system identification procedures which typically yield statistical confidence bounds on the estimated model. Recent work in this area has proposed a procedure for obtaining a better match between...
The main objective of this contribution is a new development of the continuous-time generalised predictive control (CGPC) resulting in a Youla-based CGPC design procedure for both minimumphase and nonminimum-phase uncertain SISO systems. The derived design procedure consists of two steps. In the first step nominal stability and nominal performance of the control system are established by using a fully...
In this paper the problem of fault isolation in non linear systems is considered. Faults are formulated as parameter changes and a novel definition of fault detent ability is introduced. This connects a fault with its effect on the output of the system under consideration. Based on this definition, a practical way to test the fault detectability is introduced. In this context, a general result about...
This paper deals with the design of robust digital controllers by the combined pole placement / sensitivity function shaping method. It shows that the design problem can be formulated and solved as a convex optimization problem. Specifications like dominant closed-loop poles or integration controller action may be introduced just as well as other fixed parts for the controller. The method is illustrated...
This paper describes the application of H«, design synthesis to the control of a mechanical stabilisation system with uncertain and time-varying first structural resonance frequency. The class of mechanisms under investigation is described and the design aims and classical control techniques currently employed are presented. It is shown that both an increase in performance and robustness to mechanism...
The problem considered in this paper is the robust controller design for the focus control loop of DVD-video drive. For low-speed players, is known that this problem can be solved by means of simple lead-lag regulators. For high-speed players the disturbance rejection is more difficult problem than for CD players because of higher performance requirements. The control scheme proposed here is based...
This paper shows that, in the SISO case, optimal mixed-sensitivity 2-norm controllers are also solutions to the optimal robust disturbance attenuation problem (ORDAP). That is, they deliver robust sensitivity reduction despite unstructured uncertainty at the optimal level. We explicitely identify one set of ORDAP weights for which such a controller is ORDAP optimal. Functional analysis duality theory...
Integral action is required in many controllers in order to solve real world problems. Modeling errors and disturbances are examples of issues that can be dealt with by using controllers with integral action. This paper explores the use of disturbance observers to introduce integral action into an output feedback controller. In particular, the proposed solution is generalized to include the case of...
PID controller design is considered where optimal controller parameters are found with constraint on maximum sensitivity and robustness with regard to cone bounded static nonlinearity acting on the plant.
In this paper, we study H∞ performance of interval systems. We show that, for an interval system, the maximal H∞ norm of its sensitivity function is achieved at twelve (out of sixteen) Kharitonov vertices. Furthermore, we study robustness of multivariable systems with parametric uncertainties, and establish a multivariable version of Edge Theorem. An illustrative example is presented.
The effect of the uncertainty in time-delay on the performance and robustness of a two-degree-of-freedom control system is discussed. The result shows that this delay mismatch strongly influences the reachable closed-loop performance and viceversa. Acceptable robustness and robustness sensitivity can only be reached for less demanding performance requirements.
A new monotonic companding function is proposed for non-uniform lookup table (LUT) indexation used in digital predistortion (PD) of Radio Frequency (RF) power amplifiers (PA) under wideband signals. This function, designed to be robust to the input signal statistics variations, overcomes the disadvantages of optimal indexation which depends on the input back-off (IBO) operation point of the PA. Simulations...
A framework for identification oriented robust controller design is developed. The model is identified from open-loop ilo-data and contains parametric uncertainties as well as an additive and norm-bounded error. The set of all robustly stabilising controllers, that additionally guarantee robust performance is characterised by a system of second order cones, which can be efficiently solved by interior...
This paper deals with the Boyd-Barratt paradigm for feedback controller design. This approach combines the Youla parameterization with convex optimization. In this paper, this paradigm is accepted in its entirety, but a completely different numerical approach is adopted. We propose replacing the descent methods of Boyd and Barratt by an algorithm due to Akilov and Rubinov. This alternative approach...
Iterative Feedback Tuning (IFT) is a direct tuning method using closed loop experimental data. The method is based on numerical optimization and in each iteration an unbiased gradient estimate is used. In this contribution we show how to use IFT to do robust loopshaping. One method, based on the approach suggested by Glover and McFarlane [1], uses an approximate H∞ cost function and alternates between...
In this paper the robustness of the Smith predictor is discussed. An extension of the time delay tolerance is given for systems presenting an open-loop frequency response with multiple unity gain crossover frequencies. A two-degree-of-freedom decoupling scheme is proposed to independently adjust set point and load disturbance responses. Classical design tools (PI, PID) can be used to design the feedback...
This paper presents an integrated methodology for feedback control of active vibration attenuation systems. The basic steps of the methodology are: open loop identification of the secondary path, design of a robust digital controller, identification in closed loop of a ”control oriented” model, redesign of the controller based on the closed loop identified model and controller reduction. The feasability...
The problem of eigenvalue assignment with minimum sensitivity in multivariable descriptor linear systems via state feedback is considered. Based on the perturbation theory of generalized eigenvalues of matrix pairs, the sensitivity measures of the closed-loop finite eigenvalues are established in terms of the closed-loop normalized right and left eigenvectors. By combining these measures with a recently...
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