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Vibrations in dynamical structures, as those encountered for instance in mechanical, aerospace or civil engineering, are often caused by internal or external excitations. One way to attenuate vibrations that can be undesirable for safety or other reasons is by the use of active control systems. This means to use feedback controllers driving actuators at appropriate locations between the structure...
The first purpose of this paper is to present shortly an idea of soft variables and evaluating functions as a tool for the unification and generalisation of decision making problems in control systems with a static plant. The random variables, uncertain variables and fuzzy descriptions are considered here as special cases of the descriptions based on the soft variables. The second purpose of the paper...
Solving unstructured linear differential-algebraic equations in the presence of numeric uncertainty in the equation coefficients is an ill-posed problem — arbitrarily small changes in the coefficients of the leading matrix may change the solution completely. To obtain well-posedness, assumptions must be made, even for DAE of index 0. In this work, we propose assumptions about the system poles to obtain...
The aim of this paper is to find a fixed structure transfer matrix, whose dynamics (i.e. whose poles) are not a priori fixed, and whose frequency response is the closest as possible to a target one. This non convex optimization problem is recast into a generalized μ problem. A generalized n lower bound is proposed, which provides an a priori suboptimal solution (i.e. a local minimum), namely a transfer...
There are significant incentives in controlling the end-use properties in batch reactors to reduce the variability in the final product quality specifications. Here we define an approach for controlling the properties within a desired target region, instead of a set point, with an economic objective and with consideration of the model uncertainty. The approach to handling process-model mismatch is...
This paper addresses the problem of stabilization of linear systems subject to both model uncertainties, additive disturbance and input limits. A design technique, based both on the solution of a r-parameterized family of Riccati equations and the use of the S-procedure, is proposed to compute a piecewise linear state feedback control law. The links and tradeoffs between tolerance to the additive...
This paper considers the problem of applying eigenstracture assignment to parameter dependant systems. The concept of modal sensitivity is introduced, and a recently presented method for the assignment of reduced sensitivity eigenstracture is presented in this context. A new proof for this method is presented, allowing greater insight into the sensitivity problem, and leading to a more flexible design...
For both continuous and discrete-time cases, this paper presents a simple solution to the robust H∞ unbiased functional reduced order filtering problem via LMI methods in the presence of norm-bounded time-varying uncertainties. Necessary and sufficient conditions for the existence and the stability of the unbiased filter are given in the nominal case; the filter differs from that of 11] (only nominal...
In many applications of motion control, problems associated with imprecisely measured or changing load (mass or moment of inertia) constitute a serious obstacle in the design of satisfactory controlling systems, more and more often compelling the introduction of various forms of uncertainties to engineering solutions. This paper deals with the time-optimal control for mechanical systems with uncertain...
Undesirable time-variable motions of dynamical structures (e.g. scales, balances, vibratory platforms, bridges and buildings) are mainly caused by unknown or uncertain excitations. In a variety of applications it is desirable or even necessary to attenuate these disturbances in an effective way and with moderate effort. Hence, several passive as well as active methods and techniques have been developed...
In this paper, a nonlinear robust controller is proposed for the goal of power stabilization in power systems. The here-proposed approach is based on both the use of a properly-chosen sliding surface and the derivation of a disturbance attenuation condition (nonlinear L2-gain). The controller design is then applied to a single-machine-infinite-bus (SMIB) system and some simulation results demonstrate...
This report presents a study on the problem of residual evaluation and threshold computation for detection of faults in continuous time nonlinear systems. A generalized framework for designing norm-based residual evaluation scheme is proposed. The problem of threshold computation is formulated as an optimization problem and its solution is developed using the well known LMI technique. Three commonly...
This paper deals with the controller design for the lateral motion of automatic steering of vehicles. The nonlinear models without and with uncertainties are considered. Sliding mode controllers with first order sliding surfaces are proposed for the control of lateral velocity and yaw rate. These controllers are designed directly based on the second order differential equation model which simplifies...
This paper proposes a method of controlling the vibration of a flexible structure using H-infinity control theory. For this purpose, two reduced order lumped mass models, expressed by 5-DOF systems each, are derived. These models are derived by considering the five vibration modes along the x and y direction respectively and neglecting all the other higher frequency modes. Neglected vibration modes...
A parametric H2 optimal control problem for linear continuous time-invariant systems is discussed. The control setup allows that any matrix coefficient of a system state space description be subjected to parameter uncertainties. Controllers with any order and any structure can be synthesized by recasting it as a Static Output Feedback problem. A modified H2 cost functional that allows to start the...
In this paper, the author proposes an algorithm of dual predictive control for a system expressed by a linear ARX (auto-regressive and exogenous) model with uncertain plant model parameters. Previously, the author proposed a dual predictive control algorithm which first considered the uncertainties in future control input values and in future output values included in an ARX model. The future input...
In this paper, robust fault detection using a parity equation passive robust approach based on generating an adaptive threshold considering that the system to be monitored can be described by an interval linear parameter varying (LPV) model with variable transport delay is proposed. This approach allows to consider parameters and associated uncertainty intervals dependence on the operating point....
Considering the rotating engine speed control problem, speed sensors of measurement output are replaced by an event-detection scheme or simply an imprecise and low-resolution encoder. This results in considerable measurement simplification and cost reductions. Modeling the integrated plant-detector system will result in a nonlinear discrete-time model with a sample time dependent on state vector....
This paper develops a necessary and sufficient condition for the following relationship to exist between two given uncertain systems defined in terms of IQCs: Every input-output behaviour of the first uncertain system is an input-output behaviour of the second uncertain system.
This study proposes a sliding mode control (SMC) framework for the reconstruction and rejection of mismatched and matched unknown disturbances. First, a robust proportional-integral (PI) type controller is designed for dealing with an uncertain scalar system subject to matched disturbance. Then, a 2nd order uncertain system subjected to both matched and mismatched disturbances is discussed. By incorporating...
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