Talar Sadalla

Stability analysis and tracking performance of fractional-order PI controller for a second-order oscillatory system with time-delay

The main aim of this paper is to present the analysis of stability regions and tracking performance for the closed-loop system with second-order plant with time-delay and continuous fractional-order PI controller. It is a trial to extend the results and methodology presented in [11] to non-integer order systems. The tracking performance is based on two quality indices IAE and ISE. The tuning method of fractional PI controller is with respect to Hermite-Biehler and Pontryagin Theorems.

Stability analysis of simple anti-windup compensation in approximate pole-placement control of a second order oscillatory system with time delay

The main aim of this paper is to present analysis of anti-windup compensation impact on tracking performance for a second-order plant with time delay and continuous-time PID controller tuned by pole-placement. The paper uses a first-order non-Pade approximation of the delay in order to streamline the solution of the Diophantine equation. In the case of using Pade approximation, the solution could only be obtained approximately, because of greater number of variables than equations. The paper also studies influence of time delay approximation with first-order model to make approximate pole-placement possible. The performance of the system is compared on the basis of computing differences between integral of absolute and squared tracking errors for the system with and without compensation, as well as observing the excess of windup phenomenon taking place. The control system quality is described on the basis of two quality indices in the case of stable oscillatory second-order plant and square-wave reference signal.

Mathematical models database (MMD ver. 1.0) non-commercial proposal for researchers

Mathematical Models Database (MMD) is an online repository of mathematical models that can be easily used for research purposes, in teaching or in performing comparative tests. In a single free-of-charge, freely accessible Internet service all the data from the database is available with an expected (in its final form) several ready-to-use models, either purely mathematical or physics-based. Apart from the models themselves there are also documents describing the background of their derivation included, references to bibliography for further reading where they have been used and numerous attachments, e.g. parts of the code, time plots, results of simulations, ready handouts, etc. Using a simple browser it is possible to constraint the search to selected classes of models. It is planned in the future to make MMD a platform where every interested researcher will be able to include their models. This should streamline the possibility of creating a single Internet site where models from a vast number of disciplines can be found, such as from the field of control engineering and robotics, electrotechnics, mechatronics, computer science, and other fields, even those not directly connected to the latter.

Initial Comparison of Experimental Vs. Simulation Results of Velocity Fractional-Order PI Controller of a Servo Drive

In the paper, an initial comparison of experimental vs. simulation results from a tracking system is presented, in the case of a Fractional-Order PI controller for a time-delay system. The controller is implemented as to work in real-time regime, for the Modular Servo System (Inteco). Based on theoretical results, stability regions are computed using Hermite-Biehler and Pontryagin theorems. Next, based on identification carried out in previous work, simulation results of a tracking performance (velocity control) are presented, and compared with experimental results from the laboratory stand, to verify if any conclusions can be drawn using computer models, concerning real-world control system with fractional-order controller. To compare control performance, IAE and ISE indices are used.

Robust CDM and pole placement PID based thrust controllers for multirotor motor-rotor simplified model: The comparison in a context of using anti-windup compensation

Positioning and orientation precision of a multirotor aerial robot can be increased by using additional control loops for each of the driving units. As a result, one can eliminate lack of balance between true thrust forces. A control performance comparison of two proposed thrust controllers, namely robust controller designed with coefficient diagram method (CDM) and proportional, integral and derivative (PID) controller tuned with pole-placement law, is presented in the paper. The research has been conducted with respect to model/plant matching uncertainty and with the use of anti-windup compensators for a simple motor-rotor model approximated by first-order inertia plus delay. From the obtained simulation results one concludes that appropriate choice of AWC compensator improves tracking performance and increases robustness against parametric uncertainty.

Kaldi Toolkit in Polish Whispery Speech Recognition

In this paper, the automatic speech recognition task has been presented. Used toolkits, libraries and prepared speech corpus have been described. The obtained results suggest, that using different acoustic models for normal speech and whispered speech can reduce word error rate. The optimal training steps has been also selected. Thanks to the additional simulations it has been found that used corpus (over 9 hours of normal speech and the same of the whispery speech) is definitely too small and must be enlarged in the future. Streszczenie. W artykule przedstawiono automatyczne rozpoznawanie mowy. Wykorzystane narzędzia, biblioteki i korpus opisano w artykule. Uzyskane wyniki wskazują, że wykorzystując różne modele akustyczne dla mowy zwykłej i szeptanej uzyskuje się polepszenie skuteczności rozpoznawania mowy. W wyniku wykonanych badań wskazano również optymalną kolejność kroków treningu. Dzięki dodatkowym obliczeniom stwierdzono, że użyty korpus (ponad 9 godzin zwykłej mowy i drugie tyle szeptu) jest zdecydowanie za mały do dobrego wytrenowania systemu rozpoznawania mowy i w przyszłości musi zostać powiększony. (Narzędzia Kaldi w rozpoznawaniu polskiej mowy szeptanej).

Particle filter in multidimensional systems

The article presents studies on the estimation quality of a particle filter applied to small multidimensional objects. For the purposes of the article, a new type of network has been proposed, in which each node is associated with one state variable. Based on performed simulations it has been found that particle filter implemented for small systems (1- or 2-dimensional) is a good choice. However, for larger objects Kalman filter may return better results (it depends on the chosen particles number). This is due to the exponential dependence of needed particles number to the object dimension. It has been also observed that the particle filter, in comparison to the Extended Kalman filter, better estimates the state variables which are well metered, and simultaneously worse estimates the state variables which are worse metered. Possible approaches for objects with a greater number of state variables also have been adduced, including the dispersed particle filter.

Fractional-Order PI Controller with Anti-windup Compensation for First Order Delay System

The main aim of this paper is to present the analysis of stability regions for the closed-loop system with first-order linear model of the Inteco Servo Drive with additional time delay and continuous fractional-order PI controller and anti-windup compensators. It is a extension to Authors previous works concerning non-integer order controllers, in which stability issues are considered by means of BIBO simulation-based tests, with several anti-windup compensation schemes considered. The tuning method of fractional-order PI controller is with respect to Hermite-Biehler and Pontryagin theorems.

Particle Filtering in Servo Drive Velocity Control with Fractional-Order PI Controller

The main aim of this paper is to compare the closed-loop system based on combination of Fractional-order PI and Particle Filter with combination of Fractional-order PI and Kalman Filter, based on quality IAE index. Authors verified the results of a real-world experimental setup which was the Modular Servo System. The article is a combination of previous work and implementation of fractional-order PI controller with Particle Filter or Kalman Filter to a real-world system.

The impact of vocabulary size and language model order on the polish whispery speech recognition

The article presents studies on the automatic whispery speech recognition. In the performed research a new corpus with whispery speech has been used. The aim of studies presented in this paper was to check, how the vocabulary size and the language model order influence on the speech recognition quality. It has been concluded that even using recordings with 5,000 different words only it is possible to prepare large vocabulary continuous speech recognition (LVCSR) model. It has been also found that the third order of language model is the best choice. The difference between normal and whispery speech is negligible and is manifested only in higher word error rate index (about 1.5 times higher for whispery speech).