This paper investigates the design of robust observer-based controllers for a class of uncertain linear time-lag systems. The uncertainties are assumed to be norm-bounded. We extend the previous results on quadratic-c...
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This paper investigates the design of robust observer-based controllers for a class of uncertain linear time-lag systems. The uncertainties are assumed to be norm-bounded. We extend the previous results on quadratic-cost control to the case of observer-based control for uncertain systems with unknown state and input time-lags. By introducing an appropriate definition of quadratic stability for uncertain time-lag systems, it is shown that observer-based controllers can be constructed via solutions of linear-matrix inequalities. A simulation example is given to illustrate the theoretical developments, (C) 2002 Elsevier Science Ltd. All rights reserved.
Control design using a model matching method with an observer-based structure is developed in this study. A designed compensator consists of a pre-filter and an observer-based feedback controller of internal structure...
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A methodology is proposed to control the transient sway and residual oscillation of a payload carried by an overhead crane. The design approach is based on a linearised model of the crane and consists of dampening the...
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A methodology is proposed to control the transient sway and residual oscillation of a payload carried by an overhead crane. The design approach is based on a linearised model of the crane and consists of dampening the linearised system by an observer-based controller and applying a dynamic inversion procedure in order to assure a predetermined oscillation free polynomial motion law for the payload. Polynomial functions are adopted in order to guarantee that the input function has a continuous derivative of an arbitrary order. Moreover, the motion time can be minimised, taking into account constraints on the actuators, by means of a simple bisection algorithm. Parameter uncertainties are taken into account during the whole design procedure. Simulation results, based on a nonlinear crane model, show how the method is also effective when the payload is hoisted or lowered during the motion, and when friction effects are considered.
This paper discusses two different ways, one said “direct” and the other “indirect”, leading to an observer-based H ∞ compensator. Although easily applicable to most full-order dynamic controllers (not restricted...
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This paper discusses two different ways, one said “direct” and the other “indirect”, leading to an observer-based H ∞ compensator. Although easily applicable to most full-order dynamic controllers (not restricted to H ∞ ones), the indirect method requires some restrictive conditions. On the other hand, the direct method is more general at the price of a more complex optimization problem. Recent progress to solve some BMI optimization problems makes the indirect method tractable and efficient with regard to the observer-based H ∞ control design problem.
This paper presents an approach based on standard TITO (Two Inputs Two Outputs) form and H2 synthesis for the lateral flight control design of a flexible aircraft. This approach proceeds in two steps: the first deals ...
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This paper presents an approach based on standard TITO (Two Inputs Two Outputs) form and H2 synthesis for the lateral flight control design of a flexible aircraft. This approach proceeds in two steps: the first deals with the synthesis of a dynamic output feedback satisfying modal specifications on the rigid modes, the stability requirements on the structure and the robustness specifications of these performances to the various cases of loading. The originality in the block diagram set-up (standard TITO form) we propose lies in the fact that the high level adjustments are independent of the used measurements. That enables to study the influence of these measurements and their positioning along the fuselage on the closed-loop system performances and robustness. The second step uses a recent theoretical result to transform the previous compensator into a two degrees of freedom LQG compensator involving a judiciously selected on-board model.
This paper presents simple and explicit formulae of an 'observer-based H-infinity controller' for linear time-delay systems. based on the LMI approach, we design a dynamical controller which guarantees the asy...
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This paper presents simple and explicit formulae of an 'observer-based H-infinity controller' for linear time-delay systems. based on the LMI approach, we design a dynamical controller which guarantees the asymptotic stability of the closed-loop system and reduces the effect of the perturbation to a prescribed level. The main contribution of the paper is to provide closed-loop stability analysis when the system time delay is unknown. We give delay-dependent and delay-independent stability results. The proposed method is illustrated by examples. The paper completes the work of the same authors. Copyright (C) 2000 John Wiley & Sons, Ltd.
This paper addresses the problem of output feedback stabilization of linear continuous time systems with time-delay in the control input. Attention is focused on the design of delay-dependent output feedback controlle...
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This paper addresses the problem of output feedback stabilization of linear continuous time systems with time-delay in the control input. Attention is focused on the design of delay-dependent output feedback controllers that ensure global asymptotic stability of the closed-loop system. Two controller design methods have been developed. The first one is concerned with the design of a control law which comprises a static feedback of the system output with the addition of a term involving the integral of past values of the input signal on a window of the size of the time-delay. On the other hand, the second method provides an observer-based controller.
In this paper, some new techniques for determining the observer-based or LQG form of any full-order compensator, that is, a compensator whose order is the same as the plaint's order, are discussed. The practical a...
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In this paper, some new techniques for determining the observer-based or LQG form of any full-order compensator, that is, a compensator whose order is the same as the plaint's order, are discussed. The practical appeal of such techniques is that they allow for a simplified implementation and reduced memory storage of general controllers and offer additional flexibility for handling gain-scheduling and input saturation constraints. The derived observer-based controllers are input-output equivalent to the original controller but with an explicit separated estimation/control structure and an extra Youla parameter. Necessary conditions to apply this general controller equivalence principle are derived. The interest and practicality of such techniques are then investigated with regards to the LQG implementation of H ∞ and μ controllers, classes of controllers that does not generally enjoy ease of implementation. In particular, these aspects have revealed to be of crucial importance for the applicability of the H ∞ technique to attitude control of launchers.
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