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LA COLLANA La modellistica, la simulazione, l'analisi, il controllo e le tecnologie di controllo dei sistemi dinamici rivestono, nell'attuale (e molto realisticamente nel futuro) quadro culturale, scientifico, didattico, professionale, un nuovo significato ruolo che consente sia lo studio che il controllo di realtà naturali e/o artificiali molto variegate, sia la risoluzione di numerosi problemi teorico/pratici di rilevante interesse scientifico e/o ingegneristico. Modellistica, Simulazione, Analisi, Controllo e Tecnologie dei Sistemi Dinamici è un'opera teorica, pratica, ingegneristica, è trasversale sia per livello culturale che per gli ambiti ai quali si rivolge (automatico, elettrico, elettronico, telecomunicazione, informatico, biomedico, gestionale, meccanico, aeronautico, navale, civile, chimico, economico,...), è una collana rivolta a chiunque (studente, docente, studioso, professionista) voglia trovare in quanto proposto una risposta ai suoi problemi, uno stimolo culturale o nuove idee su cui lavorare. Essa consta di quattro volumi: Modellistica e Simulazione, Fondamenti di Dinamica dei Sistemi, Elementi di Controlli Automatici e Fondamenti di Tecnologie, di cui manca solo l'ultimo testo che verrà pubblicato a breve. Questi libri sono unici nel loro genere per l'approccio didattico innovativo, per la facilità di consultazione e la varietà dei percorsi di lettura, per la completezza, l'originalità di molti contenuti, i numerosi esempi presentati in modo particolarmente incisivo grazie a schemi grafici, casi di studio realistici e supportati da programmi interattivi in Matlav/Simulink, per la presenza di un sito web come fondamentale parte integrante in quanto raccoglie e raccoglierà sempre nuovi contenuti teorici ed informatici, ulteriori esempi pratici ed una ricca libreria di esercizi e progetti svolti. Sicuramente utile è la scelta di renderli disponibili sia in formato cartaceo che ebook. Con Elementi di Controlli Automatici - Vol. III gli autori hanno redatto un testo molto sintetico, ma completo per quanto riguarda la teoria classica del controllo, che riporta anche alcuni fondamentali risultati della teoria moderna ed altri innovativi non ancora pubblicati. Alcuni elementi innovativi di tale testo riguardano: l’introduzione di nuovi parametri globali, quali la banda di inseguimento e la costante di guadagno generalizzata; l’introduzione del sistema maggiorante; nuovi legami globali analitici e grafici; la progettazione di controllori in grado di costringere un sistema a seguire, con prefissato errore massimo ed a partire da un prefissato instante di tempo, un qualsiasi riferimento con derivata (variazione se discreto) limitata, anche in presenza di un disturbo generico anch’esso con derivata (variazione) limitata; la progettazione rapida di controllori robusti PID e non solo, basata su rigorosi e innovativi teoremi, di sistemi lineari con ritardi interni ed esterni, sia a partire da un loro modello matematico che a partire da semplici prove sperimentali. Tali tecniche di progettazione sono alla portata di qualsiasi ingegnere e tecnico delle aree dell’informazione e industriale e, molto probabilmente, sono destinate a soppiantare quelle storiche basate su regole empiriche. I concetti più importati sono illustrati con numerosi esempi realistici, alcuni sviluppati con nuovi programmi Matlab di utilità generale per gli studenti, gli ingegneri e i ricercatori. Tenendo presente i numerosi esempi completamente sviluppati, le numerosissime figure illustrative, l’evidenziatura dei concetti fondamentali, si intuisce come il testo sia di rapida consultazione e di grande aiuto per apprendere in tempi brevi alcuni importanti concetti di base della teoria del controllo sia classica che moderna. Della stessa collana: Modellistica e Simulazione - Vol. I Fondamenti di Dinamica dei Sistemi - Vol. II

Recently a method to evaluate deformation imaging, 2D speckle strain echocardiography(2DSE), has been developed. We evaluated a new phase analysis technique to quantify left ventricular asynchrony from speckle strain curves. In conclusion our study shows that this new phase analysis technique is a powerful tool to quantify left ventricular asynchrony and to select responders to CRT.

The relatively high noise levels in turboprop aircraft cabins may be very unpleasant for both passengers and pilots. The noise power is radiated from the propeller blades into the cabin by the vibrations of the fuselage structure. It exhibits a mainly tonal nature, with low frequency characteristics. Unfortunately, traditional passive approaches for acoustic attenuation are limited in their low frequency effectiveness by weight and space constraints, especially for lightweight propeller aircraft. On the other hand, active control offers an attractive approach for low frequency acoustic noise attenuation inside the aircraft cabin. Several techniques are under investigation to evaluate the possibility of reducing the noise in the aircraft cabin by active noise control strategies that may provide more efficient, lightweight and relatively cheap solutions. Among others, a possible approach consists of using concentrated acoustic waves generators (loudspeakers) located inside the cabin, in order to produce a more acceptable resultant acoustic field. In this paper, an active noise-control technique has been developed for the control of the interior noise level in an aircraft cabin. Noise reduction is achieved by driving an array of speakers located over the surface of the radiating structure. A procedure of optimal allocation of such loudspeakers is also proposed in order to obtain optimal results in terms of noise reduction in predefined regions of interest.

Relay control systems are widely employed in industry because of their realization simplicity and of their high work efficiency. Nevertheless, there are numerous related theoretical and practical issues that need to be further investigated. In particular, while the stability and the limit cycle analyses can be considered sufficiently assessed, the synthesis problem of relay controllers has not been considered systematically. In this paper a method for the direct design of relay control systems is provided that makes use of graphs and tables. Such graphs and tables are obtained by an analytical/numerical technique optimised with respect to the number of parameters that characterise both the plant and the relay controller. The effectiveness of the method is illustrated by the solution of a practical engineering problem.

The possibility of guaranteeing significant fuel savings has undoubtedly contributed to the diffusion of advanced turboprop engines for the propulsion of passengers transport aircraft. An important drawback correlated to this choice is represented by the need of reducing the noise level in the aircraft cabin in order to improve the passengers comfort. Early studies have demonstrated that the main part of the interior noise in aircraft cabins originates from the airborne propeller noise which is transmitted through the fuselage structure and radiated into the cabin. Due to weight and space constraints the existing passive sound attenuation methods have shown to be effective only for alleviating the noise at relatively high frequencies. As a results, the low frequency interior sound control still represents a difficult objective to accomplish even for modern turboprop aircraft. In the last years a big effort has been spent to investigate the possibility of reducing the noise in the cabin by using alternative methodologies based on active noise control methods that may provide more efficient, lightweight and relatively cheap solutions. The active noise control techniques makes use of two different actuators typologies mainly. A first case, widely investigated in the literature, consists of concentrated acoustic waves generators (speakers) located inside the cabin, which produce a resultant acoustic field that may be reduced in some regions but may be highly increased in some other regions. A second case, more recent, consists of using piezoelectric actuators located on the bulkheads that are able to produce a more uniform acoustic field within the cabin. In this paper a procedure of optimal allocation of piezoelectric actuators is proposed that allows considerably reducing the noise in a predefined region of interest, by a suitably optimised control law.

In this paper we consider the problem of reducing the sound generated by the engine inside a car enclosure by using piezoelectric actuators located on the car's roof and microphones placed in correspondence of the passengers. A preliminary analysis shows that the frequency responses from the actuators to the microphones are characterized by a very large band and exhibit a high modal density with many resonance peaks. Based on these facts, the design of a feedback control law could originate spillover phenomena, which will manifest through the generation of high frequency sounds even more unpleasent than the original noise. Therefore we propose the design of a controller based on an open loop control philosophy; that is the control action is designed in such a way that the spectrum of the control signals is contained into the disturbance band. Since the noise we deal with is not of a classical type (pure sinusoidal or multi-tonal) but is a wide band disturbance, classical open loop control techniques, based on model inversion, cannot be implemented; to this end the concept of Generalized Frequency Response, which allows us to deal with wide band signals, is introduced in the paper. Numerical simulations show the benefits of the proposed control technique.

There are many examples of systems with delays, mainly due to transport phenomena, to the information transmission, to the calculation time of the integration digital devices, and so on. These systems, being infinite dimensional, are very difficult to analyze and to control. If they are forced by piecewise constant signals in time ranges of appropriate constant amplitude, such systems can be modeled by finite dimensional discrete-time systems. In this paper, theorems are stated that allow discretizing an LTI system with state, input and output delays, with an appropriate sampling period. A method is also proposed for the design of reduced order discrete-time controllers that allow assigning a set of arbitrary poles to the overall system. The accuracy of the discrete-time models and the effectiveness of the proposed controllers are illustrated by two interesting examples.

In this paper a new approach to the dynamic modelling of a car starting system is proposed. The system m odel isthe co mposition of three interacting parts: the battery, the starter and the internal combustion engine. Each part is modelled b y a small number of parameters and b y a relatively simple mathematical structure, in order toattain a trade-off between adequate modelling accuracy and param eter identification vi a simple dynamical experiments proposed by the au thors. The obtained model is validated b y a real starting experiment conductedo n a FIAT car.

In this paper the equivalent global dynamic model of a railway vehicle is presented. The dynamic model is based on the following fundamental submodels: inverter, asynchronous motor, train, brake, controller. These submodels, even if interacting, are developed such that they can be modified independently. Moreover, they are characterized by a minimum number of parameters and by a relatively simple mathematical structure, in order to properly describe the corresponding system, to be identified by relatively simple dynamical tests and be used by a single specialist. It is also proposed a sufficiently robust minimum energy controller. Finally several simulation results are reported that demonstrate the validity and the usefulness of the proposed dynamic model and the controller efficiency.

A sufficient condition for the robust stability of a class of interval matrices is derived using the Lyapunov approach. The matrices considered have elements which are nonlinear functions of a vector of independent and bounded parameters. The robust stability condition requires that a quadratic form be positive definite in a finite number of conspicuous points of an enlarged parameter space. >

In this paper we present a dynamic model for the analysis of the vibrations of the vibrations of a planar articulated flexible boom to be used for tokamak in-vessel maintenance operations. The peculiarity of the mechanical structure of the boom enables us to consider separately the oscillations in the horizontal and vertical planes so that two separate models can be constructed for describing these phenomena. The results of simulations based on booms like that proposed for NET in-vessel operations are presented.

Many industrial plants with high parametric uncertainties, both for constructive simplicity and/or in order to minimize the operation cost, usually are commanded with signals that may only assume a finite number of values. The paper presents the realization of a prototypal embedded system, realized through a microprocessor, which implements a new control law characterized by a fixed and quantized control set. The proposed control algorithm is robust with respect to disturbances and plant uncertain parameters and consents the plant output to practically track a given reference trajectory, with preassigned maximum values of the tracking error and its first derivative. This paper deals with the digital realization of this new multi-valued control law and the key issues associated with its microprocessor implementation. The efficiency of the design method and of the technology utilized for the realization are shown through a very interesting application: a temperature control system of a ceramic kiln.

A variety of plants with high parametric uncertainties are usually controlled with signals that may assume only a finite number of values, both to simplify actuator's construction and minimize the operation cost. The design of multi-valued control laws which provide a control signal that is discontinuous in time and quantized in magnitude is then of particular interest in many practical applications. This paper presents a new technique for robust control design in order to force a SISO linear plant, subject to disturbances and parametric uncertainties, to track a given sufficiently regular reference trajectory. The proposed approach is based on Lyapunov method and allows designing a control law which guarantees to follow the reference trajectory with prefixed values of the tracking error and of its derivatives up to the n1-th, where n is the order of the plant. Moreover, the control law is quite robust and guarantees the convergence of the error in a prefixed time. The technique is applied to design controllers characterized by control signals that may assume only a finite number of values. In this case, the control law can be seen as a generalization of the traditional relay control laws and of the sliding mode ones, with a relatively low switching frequency. Finally, a simple example shows the advantages of the control law obtained with the proposed design methodology with respect to the classical approaches.

In this paper, a new technique in controller design is presented. Its aim is to force a linear plant to track, with a prefixed error, a class of reference trajectories characterized by an assigned band. Furthermore, the designed control is robust with respect to parametric uncertainties, disturbances and it guarantees limitations of some internal signals. The design methodology is based on the introduction of an important project parameter, the time delay within which the command can be considered to have been carried out, by a controller structure with sufficient degrees of freedom and by a constrained optimization technique where the initial values of controller parameters are determined by means of the most appropriate techniques of modern control theory. The efficiency of the proposed procedure is illustrated through the design of a realistic control system for the planar laser scanner. In result consistent improvement in performance can be measured

The brake system is one of the most critical car sub-systems for what concerns safety issues. Modern automobiles are equipped with anti-lock braking systems (ABS), which have improved passengers and driver security by automatically adjusting the braking force during braking in potentially dangerous conditions. For model-based control design techniques of ABS algorithms, satisfactory improvements may be achieved if a sufficiently accurate mathematical model of the brake system is available. Nevertheless, the control synthesis may become prohibitive for such techniques if the model is too detailed. In this paper a realistic, but simple, car brake system model for longitudinal control design purposes is illustrated. The model is built starting from the modeling of the individual components characteristic dynamics. A series of experiments are conducted on a FIAT car to identify the model parameters and confirm the simulation results.

In this paper a Lyapunov technique is presented for the synthesis of controllers characterised by control signals that, for construction simplicity and/or in order to attain a better efficiency, may only assume a finite number of values. In particular, a design technique of a control law with prescribed control levels for a class of continuous-time SISO uncertain nonlinear systems is provided, which guarantees the tracking of a given reference trajectory, with a prescribed maximum error norm, a prescribed rate of convergence and a low switching frequency.

In this paper the mathematical model of a modern arc heated Plasma Wind Tunnel used to test parts of space vehicles during the re-entry phase is presented. Due to the complexity of the physical processes arising during the operating of the plant, a number of simplification is proposed to obtain a control design oriented fast and efficient simulation software. Such a software was successfully used during the design phase to become confident with the dynamic behavior of the facility and to achieve a process-control integrated design. During the operating life of the wind tunnel it will be used to support the test engineers in the design of the control laws for the tracking of the desired trajectories in temperature and pressure on the test article. A short description of the test control algorithm which is based on the above model is also provided.

We consider the tracking problem for a robotic manipulator. First, we propose an approach which allows one to place the problem of designing an optimal control law for a rigid manipulator in the context of linear matrix inequalities (LMIs) optimization; this permits one to include in the synthesis of the control law and constraints concerning the control amplitude. Then we consider flexible links manipulators, showing how the synthesis of the controller has to be modified in order to obtain good performances in presence of flexible elements.

In this paper a new technique for "instantaneous" reconstruction of the state variables of a flexible system is proposed. The reconstructor is based on the use of spline shape functions to interpolate available measurements by taking into account both constraints and boundary conditions. Unlike the usual dynamic observers, this technique does not require the use of a copy of the system neither any information about the inputs hence it is able to work well even in presence of persistent disturbances and uncertain parameters. The spline shape property of smoothest interpolation introduces a "spatial filtering" phenomenon on the high-frequency modes which increases the robustness of the control scheme against spillover.

The frozen-time approach is used to state some new sufficient conditions for the stability of linear time-varying systems. An upper bound on the norm of the time derivative of system matrix which, under different assumptions on frozen-time system eigenvalues, guarantees asymptotic stability or exponential stability of the system is established. >

It is pointed out that plasma position and shape control calls for fast algorithms for plasma boundary identification, i.e. methods capable of determining the shape in a time interval not longer than the sampling time of the controller. The authors present an online identification algorithm which realizes a trade-off between accurate plasma shape reconstruction and computational burden. The proposed identification has been tested with reference to some types of ITER (International Thermonuclear Experimental Reactor) plasmas. >

A computational tractable procedure for robust pole location analysis of uncertain linear time-invariant dynamical systems, whose characteristic polynomial coefficients depend linearly on parameter perturbations, is proposed. It is shown that, in the case of linearly dependent coefficient perturbations, the stability test with respect to any unconnected domain of the complex plane can be carried out, and the largest stability domain in parameter space can be computed by using only a quick test on a particular set of polynomials named vertex polynomials. The procedure requires only one sweeping function and simple geometrical considerations at each sweeping step. This leads to a very short execution time, as is shown in an example. A unification with Kharitonov's theory and edge theorem is also provided. >

The development of flexible manufacturing systems calls for industrial robots characterized by robustness of performance with regard to the variations of the loads and real time specification of the trajectory in the work space. In this paper, the design of a feedback controller guaranteeing such performance is considered. At first, the manipulator dynamics are embedded into a larger class of uncertain dynamical systems and a class of feedback controls is proposed that guarantees uniform ultimate boundedness of the tracking error. Successively, the methodology is specialized for the case of robotic manipulators to track trajectories described in task-oriented coordinates; the proposed control algorithm operates without requiring any explicit coordinate transformation.

In this note we prove that if in observer equation VA - FV = GC we choose matrix F in companion form, it is possible to give a very simple, explicit solution to unknown matrix V . It is furthermore shown that for almost all the matrices G , such that the pair ( F, G ) is reachable, matrix (c\over{v}) is of full rank. All this allows us to establish efficient algorthims for designing reduced observers both for the estimate of state and for that of a given linear functional, even if the spectra of F and A are not disjointed.

The problem of pole assignment in multivariable linear systems with observers of a given order v is considered. By way of a simple proof, a very general result is established which constitutes an extension of all theorems known in the literature on pole assignment via observers. On its basis, an efficient design algorithm is worked out.

The theory of pole assignment in multivariable stationary linear systems using a controller of given order is reassessed. Novel proofs, both simpler and more general than hitherto are given, enabling efficient design algorithms to be formulated. Examples of such algorithms are worked out.

We propose a new model-following control scheme for a class of nonlinear plants. The feedback control signal is a continuous function of all its arguments. It is shown that this scheme guarantees that tracking error remains bounded and tends to a neighborhood of the origin with a rate not inferior to an exponential one; furthermore, it allows the designer to arbitrarily prescribe the rate of convergence and the size of the set of ultimate boundedness.

Quality has become one of the more important factors in the purchasing decisions of the consumer. At the moment, the tools available for variability analysis in the production process, which is the main cause of quality degradation, are mostly based on statistical approaches that neglect the physical relationships that exist in a man-made system. In this paper a new general methodology is proposed, which gives evidence of how the development of a mathematical model could be more suitable if set by a relatively limited amount of data and a number of experimental tests. The implementation of the model in a dynamic simulator allows one to evaluate the effects of the variability of the most critical elements on the quality of the whole system numerically. The effectiveness of the procedure is demonstrated by the evaluation of some quality indexes of a car braking system. Copyright © 2004 John Wiley & Sons, Ltd.

A design procedure for the synthesis of an adaptive controller for a robotic manipulator is presented. The design involves the evaluation of a nominal input signal by using a model of the manipulator with nominal values of the loads, and of an adaptive component by means of the sole knowledge of the maximum possible size of the uncertain parameters of the model. The proposed control scheme also guarantees an accurate tracking of a planned path when an approximate model of the manipulator is used and/or load variations occur during operation. Moreover, the resulting control signal is smooth.