Zoran Jovanovic

A CLASS OF ALMOST ORTHOGONAL FILTERS

In this paper we define a new class of the almost orthogonal filters. These filters are a generalization of the classical orthogonal filters commonly used in the circuit theory, control system theory, signal processing and process identification. Almost orthogonal filters generate the series of almost orthogonal Legendre functions on the interval (0, ∞). They can be successfully used for the analysis, synthesis and designing of imperfect technical systems. They can also be used for approximation of arbitrary functions on (0, ∞). A new method for obtaining the models of imperfect systems is presented as well. Simulations were performed in order to validate the theoretical results and the comparison of new filters with classical filters is given.

Modelling of dynamical systems based on almost orthogonal polynomials

A new class of the almost orthogonal filters is described in this article. These filters are a generalization of the classical orthogonal filters commonly used in the circuit theory, control system theory, signal processing, and process identification. Almost orthogonal filters generate the series of almost orthogonal Legendre functions over the interval (0, ∞). It is well known that all real systems suffer from some imperfections, so the models of these systems should reflect this fact. A new method for obtaining an imperfect system model is proposed. This method uses an almost orthogonal filter, which is based on almost orthogonal functions. Experiments with modular servo drive were performed to validate theoretical results and demonstrate that the method described in the article is suitable for modelling of imperfect systems.

Digital Sliding Mode Control of Anti-Lock Braking System

The control of anti-lock braking system is a great challenge, because of the nonlinear and complex characteristics of braking dynamics, unknown parameters of vehicle environment and sy ...

Approximation based on orthogonal and almost orthogonal functions

Abstract In this paper, we define a class of almost orthogonal rational functions of Legendre type in a new manner. Relations of these functions with classical exponentional functions orthogonal over interval (0, ∞), as well as classical polynomials orthogonal over (0, 1) are explained. Defining relations of these functions can be used for designing almost orthogonal filters. These filters are generators of orthogonal signals and can be successfully applied in finding the best signal approximation in the sense of the mean square error. The filters orthogonal property enables building of physical (in this case electrical) models of dynamical systems (the sources of signals to be approximated) either with less components for the same model accuracy or higher accuracy for the same number of components than the other known models. New filters represent further improvement of previously designed filters, by the same authors, in the sense of simplicity, higher accuracy, lesser approximation time and even a possibility to approximate signals generated by systems with built-in imperfections. Series of experiments were performed to analyze the dependence of approximation accuracy and the number of filters sections.

On a new class of quasi-orthogonal filters

In this article, a new class of quasi-orthogonal filters, based on the Legendre and Malmquist-type quasi-orthogonal polynomials, is presented. These filters are generators of quasi-orthogonal functions for which we derive and present all important properties and relations. Our article is based on the classical theory of orthogonality and orthogonal functions, and also on new results in this field of mathematics. Based on theoretical results, we design schemes for the realisation of these filters. Finally, a trail quasi-orthogonal filter is practically realised and its quasi-orthogonality is proven by performing experiments. Quasi-orthogonal filters can be successfully used for signal approximation as well as for modelling, identification, analysis, synthesis and simulation of dynamical systems.

Systems modeling based on Legendre polynomials

A new method for obtaining models of continuous systems, based on Legendre orthogonal filters, is proposed in this paper. Recent results in the field of orthogonal functions were used to improve accuracy of modeling. First, Legendre orthogonal filters were designed on the basis of orthogonal functions. Then, adjustable models were formed. Models parameters were optimized using genetic algorithm. As a case study, an experimental simple DC drive was considered and described in details. Simulations were performed out to approve theoretical results and demonstrate that the method described in the paper is very suitable for modeling continuous systems. It achieves excellent results in the sense of model accuracy and modeling algorithm speed.

Probability estimation of certain properties of the imperfect systems

This paper presents one method for probability estimation of some property of imperfect systems (stability, reliability, oscillations appearance, controllability, sensitivity, etc.). The region of certain system property is approximated in parameter space and relations for probability of defined properties are obtained. Application systems with one nonlinearity: of this approximate method in the real technical system is given for the case of determining the probability of oscillations appearance.

Monitoring the PLC based industrial control systems through the Internet using Microsoft robotics developer studio technologies

The relative cost of SCADA systems can be substantial if not used in industrial plants. In this paper we present an alternative solution to SCADA systems based on two technologies developed for the Microsoft Robotics Studio, CCR and DSS. Based on these two technologies the services for supporting remote monitoring system are developed and tested. Data acquisition services can rely on PC with direct connection to PLC through RS232, Modbus, CAN or any other protocol. The DDS service can run directly on modern PLC. Thus, the service that presents the data can be on any PC that has an internet connection with service on the PLC, and acquired data can be accessed through the web interface. Considering all of these, we have implemented the industrial monitoring system that uses already available hardware resources, while giving it reliable and secure data transfer over the internet, failure robustness, decentralization, concurrency and scalability.

Sliding Mode Based Anti-Lock Braking System Control

In this paper we consider different continuous- and discrete-time sliding mode control (SMC) techniques in the control of antilock braking system (ABS). Having in mind that ABS is characterized by nonlinear and uncertain dynamics, SMC is a right choice for its control because of its robust characteristics. The survey of continuous-time SMC algorithms based on nonlinear models of ABS is given first. Then, the discrete-time nonlinear model of ABS is derived, and the overview of existing discrete-time SMC techniques is presented. The experimental results are given to show the effectiveness of analyzed SMC methods.

Synthesis of the proportional integral controller for a minimum phase high order system by using the lambert W function

The paper presents the process of the (PI) proportional integral controller synthesis for a minimum high order phase system without a time delay. The controller projection is realized on the previously reduced order of the system by using “Skogestad half rule” method, applying the matrix Lambert W function, with a pole placement technique.