Generalised Entropy of Curves for the Analysis and Classification of Dynamical Systems

This paper provides a new approach for the analysis and eventually the classification of dynamical systems. The objective is pursued by extending the concept of the entropy of plane curves, first introduced within the theory of the thermodynamics of plane curves, to Rn space. Such a generalised entropy of a curve is used to evaluate curves that are obtained by connecting several points in the phase space. As the points change their coordinates according to the equations of a dynamical system, the entropy of the curve connecting them is used to infer the behaviour of the underlying dynamics. According to the proposed method all linear dynamical systems evolve at constant zero entropy, while higher asymptotic values characterise nonlinear systems. The approach proves to be particularly efficient when applied to chaotic systems, in which case it has common features with other classic approaches. Performances of the proposed method are tested over several benchmark problems

Autotuning and Monitoring

With reference to single-input single output classical control structures, we illustrate two deterministic approaches to monitoring. On fine closed loop relay tests are proposed for monitoring performance of the controlled plant and for an on-line autotuning of the controller parameters, based on the integral of the absolute value of the error (IAE). With respect to standard formulation, a modified IAE index is used, computed from the data collected during a period of the output of the process, executing the auto-tuning test, without substantial modifications of the operating point

Sulla Selezione delle Variabili in un Sistema Multivariabile: da RGA a ROmA

Un problema fondamentale nel controllo di un sistema multivariabile è la scelta preliminare dell’accoppiamento fra le variabili di controllo e di uscita. La tecnica più usata è la RGA, proposta da Bristol nel 1966; tale tecnica presenta notevoli limitazioni, per cui sono tate proposte numerose modifiche. Tuttavia nessuna tecnica tra quelle proposte presenta caratteristiche globalmente soddisfacenti. In questo lavoro viene presentato un approccio alternativo, che consente di considerare la dinamica del sistema in esame con semplici indicatori globali, mantenendo le caratteristiche di semplicità di uso tipiche della RGA. Le informazioni sulla dinamica dell’impianto necessarie per la costruzione del nuovo indice, denominato ROmA, possono essere rilevate con l’uso di procedure di autoscillazione, mediante classica inserzione di relé. Vengono infine presentati alcuni casi tipici, che mostrano i vantaggi dell’approccio proposto

Low cost robust nonlinear controllers

Most plants can be efficiently controlled by using simple low cost controllers. Many variations of the classical PID regulator have been developed in order to obtain high speed of response, steady state precision, disturbance rejection and robustness with respect to parametric variations and unmodeled dynamics. In this paper two classes of non linear plants with input saturation are considered. Class I deals with first order plus time delay processes, class II deals with plants modelled by a process with a dominant pair of complex conjugate poles. A variable structure standard regulator (VSC) for class I plants and a robust oscillating controller (ROC) is for class II plants are proposed. To improve the overall performance a ROC-PID controller is also considered. Such controllers can be easily implemented by using low cost microprocessors and their industrial use seems to be very attractive. A complete set of simulation results is reported

On Input-Output Selection for Multi-Loop Control: from RGA to ROmA

A new tool for selecting the right pairing between inputs and outputs in a multiloop system is introduced. Similar in structure to the classical RGA the new array, called a Relative Omega Array, is based on the characteristic frequencies in open and closed loop under perfect control, as eventually detected by a classical relay test. This way the dynamic properties of the system are simply taken into account. Some examples show that the new tool is effective, giving the correct pairing also when the RGA approach fails

On the Control of a Pyrolysis Process

The evaluation of the necessary operating reserve margins in an electric power system has been traditionally carried out by the System Operator (SO) on a deterministic basis, using the so called “first contingency security criterion”. According this approach, only few generating units and/or power lines are considered in order to determine the worst operation conditions. As an alternative, this paper presents a simulation method, based on a probabilistic approach using a sequential Montecarlo technique, which takes into account all the generating units and the transmission power lines of the electric system considered. Starting from the production and consumption profiles scheduled by the energy markets, the real time operation is simulated in normal, contingency and emergency conditions, taking into account the availability of generating units and power lines; the redispatching procedures activated after a contingency are carried out minimizing the expenses for the auxiliary services purchase under line power flow limits constraints. A daily case study, calibrated on an IEEE test grid, is carried out and discussed, focusing how such a technique can be suitably used to evaluate system reliability as a function of reserve margins, load shedding amounts, dispatching rules and emergency procedures

Observability And Nonlinear Observers For Mobile Robot Localization

: In this paper, the problem of localizing a nonholonomic vehicle moving in an unstructured environment is addressed by the design of a novel nonlinear observer, based on suitably processed optical information. The localization problem has been shown to be intrinsically nonlinear, indeed the linear approximation of the system has di#erent structural properties than the original model. The proposed nonlinear observer allows the localization of nonholonomic mobile robots by using an estimated expression of the extended output Jacobian, local practical stabilization of the observation error dynamics is also ensured. A singularity-avoidance exploration strategy is also included to deal with the output Jacobian singularities crossing. Keywords: Nonholonomic robot dynamics, Nonlinear observability, Nonlinear observers, Local practical stability, Singularities avoidance, Simulation results 1. INTRODUCTION The problem of mobile robot localization using optical information is intrin..