Petr Dostálek’s research while affiliated with Tomas Bata University in Zlín and other places

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Publications (3)


Figure 4. The static characteristics of the saturation relay.
Figure 10. Comparison of SFOTDM unit step responses (vs. the original process response). Results IV, V, and VI provide an outstanding cost function value in the frequency domain, yet a worse IAE criterion compared to the remaining results. However, results V and VI give the best ITAE value. Unsatisfactory time-domain response of parameters IV can be due to an excellent characterization of the ultimate point
Figure 12. Comparison of selected HETDM unit step responses (vs. the original process response) -LM method used for transfer function numerator parameters computation.
Figure 15. Comparison of selected HETDM Nyquist plots (vs. the original process response) -NM method used for transfer function numerator parameters computation.
Figure 16. Relay experiment responses (with artificial delays).

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Root Loci Analysis of a Simple Quasi-Polynomial And Its Use For Relay-Based Parameter Identification of a Delayed Infinite-Dimensional Heat-Exchanger Process
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October 2021

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167 Reads

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The focus of this contribution is twofold. The first part aims at the rigorous and complete analysis of pole loci of a simple delayed model, the characteristic function of which is represented by a quasi-polynomial with a non-delay and a delay parameter. The derived spectrum constitutes an infinite set, making it a suitable and simple-enough representative of even high-order process dynamics. The second part intends to apply the simple infinite-dimensional model for relay-based parameter identification of a more complex model of a heating-cooling process with heat exchangers. Processes of this type and construction are widely used in industry. The identification procedure has two substantial steps. The first one adopts the simple model with a low computational effort using the saturated relay that provides a more accurate estimation than the standard on/off test. Then, this result is transformed to the estimation of the initial characteristic equation parameters of the complex infinite-dimensional heat-exchanger model using the exact dominant-pole-loci assignment. The benefit of this technique is that multiple model parameters can be estimated under a single relay test. The second step attempts to estimate the remaining model parameters by various numerical optimization techniques and also to enhance all model parameters via the Autotune Variation Plus relay experiment for comparison. Although the obtained unordinary time and frequency domain responses may yield satisfactory results for control tasks, the identified model parameters may not reflect the actual values of process physical quantities.

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Numerical Gridding Stability Charts Estimation using Quasi-polynomial Approximation for TDS

June 2021

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51 Reads

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5 Citations

The aim of this study is to present and summarize our numerical algorithm for the determination of stability charts in the delay space for linear time-invariant time systems with constant delays (TDS), both retarded and neutral ones. The core of algorithm lies in a successive (iterative) approximation of the infinite-dimensional characteristic quasi-polynomial in each grid node of the delay space. This approximation resulting in a polynomial or an exponential polynomial with commensurate delays is made in the neighborhood of the dominant characteristic value (pole) that has recently been estimated in the closest grid node. Two different approximation techniques are presented; namely, continuous-time and discrete-time ones. A complete numerical example for retarded TDS is presented, whereas the approximation issues are highlighted in another example for neutral TDS.


Improved and innovated universal DAQ microcontroller unit

April 2017

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1,885 Reads

International Journal of Electronics and Telecommunications

This paper is aimed at the description of hardware design, software equipment and the functionality of the second evolution of the intelligent multipurpose input/output microcontroller converter and control unit designed and assembled by the authors. Preceding stages of the unit development are concisely overviewed first, the deficiencies of which give rise to the primary motivation of this contribution. Then separate hardware parts of the novel unit are described in detail including electronic schematic diagrams. The device firmware and software capabilities are introduced as well. The advantages of the unit are highlighted compared to older versions. Its functionality, performance and efficiency are then verified by a laboratory control-related dynamic responses measurement example. In the contrary to previous evolutions, a more compact hardware design, increased A/D and D/A converter resolutions, added USB communication capability, better and more accurate analog circuits with more advanced operation amplifiers, the use of OLED instead of LCD display, the pulse-width modulated signal generated by the microcontroller unit itself can be considered among the most important improvements. Moreover, the direct use of the serial link may reduce noise significantly and makes the device more universal.

Citations (1)


... For example, the designer may introduce output feedback with a delay; or add a delay to the proportional, integration, or both parts of the PI controller [15,16,17,18,19,25]. An undesired consequence of implementing delays in controller design is that the infinite-dimensional spectrum reveals because of the quasi-polynomial properties of the characteristic equation [20,21]. Ensuring that stable roots of the system dominate can be a complex task for the designer. ...

Reference:

Stabilization of Second-Order Systems Using PI Controllers with Delayed Proportional and Integral Parts
Numerical Gridding Stability Charts Estimation using Quasi-polynomial Approximation for TDS