Volume 70, Issue 4
December 2020

Guest Editor-in-Chief
Cor. member Prof. Petko Petkov, D.Sc.
Preface for Issue 4

DOI: 10.47978/TUS.2020.70.04

Table of Contents

CONTROL SYSTEMS WITH TRANSPORT DELAY Ahmed Kula, Georgi Ruzhekov	PDF
CASCADE CONTROL OF A MULTI INPUT AND MULTI OUTPUT (MIMO) THERMAL CONTROL SYSTEM Anna Georgieva, Georgi Ruzhekov	PDF
ADVANTAGES OF USING DECOUPLING MATRIX FOR MIMO CONTROL Bozhidar Rakov, Georgi Ruzhekov	PDF
A MODIFIED METHOD FOR CONTROL OF MIMO PLANT USING PID AND DECOUPLING MATRIX Bozhidar Rakov, Georgi Ruzhekov	PDF
RISK-BASED TESTING APPROACH FOR MEDICAL DEVICES SOFTWARE Ivan E. Ivanov, V. Gueorguiev, D. Georgieva, M. Nenova, B. Ivanov	PDF
OBJECTS DETECTION FROM AN IMAGE USING MATLAB Sherif Sherif, Jordan Kralev, Tsonyo Slavov	PDF
CYBERSECURITY IN SMART CARS Maria Nenova, Vesselin Gueorguiev, Stoyan Madzhirov, Desislava Georgieva, Ivan Evg. Ivanov	PDF
LABORATORY SETUP FOR INVESTIGATION OF CONTROL SYSTEM FOR ELECTROHYDRAULIC STEERING UNITS Alexander Mitov, Tsonyo Slavov, Jordan Kralev, Ilcho Angelov	PDF

CONTROL SYSTEMS WITH TRANSPORT DELAY
Ahmed Kula, Georgi Ruzhekov

Abstract
A hybrid system is being developed. The plant is realized in MATLAB, works in real-time. The control system uses an industrial controller and a SCADA system. Estimation of time-delay, modeling of reference object and autotune is performed. The developed hybrid system gives opportunities for research different types of regulators for plants with a big time-delay.

Keywords:
Control plant with time-delay, Hybrid system, PLC, SCADA, MATLAB.

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DOI: 10.47978/TUS.2020.70.04.021

References:

[1] Ружеков Г., Обработка на данни и сигнали, Технически университет - София, 2011.
[2] Драготинов И., И. Ганчев, Автоматизация на технологични процеси, УХТ-Пловдив, 2003.
[3] Danium M., M. Awtoniuk, R. Salat, Implementation of PID autotuning procedure in PLC controller, ITM Web Conferences 15, 2017. https://doi.org/10.1051/itmconf/20171505009
[4] Sophocles J. O., Introduction to Signal Processing, Rutgers University, 2010.
[5] Hanta V., A. Prochazka, Rational Approximation of Time Delay, Institute of Chemical Technology in Prague, 2009.
[6] Åström K-J., T. Hägglund, Revisiting The Ziegler-Nichols step response method for PID control, Journal of Process Control, 2004. https://doi.org/10.1016/j.jprocont.2004.01.002

CASCADE CONTROL OF A MULTI INPUT AND MULTI OUTPUT (MIMO) THERMAL CONTROL SYSTEM
Anna Georgieva, Georgi Ruzhekov

Abstract
Cascade control of a “Multi Input and Multi Output (MIMO) Thermal Control System” is developed for better speed, better reduction of noise, lower overshoot. The thermal object consists of 4 thermally connected modules (three with a heater and one with a cooler), which is a MIMO object – 4 inputs and 4 outputs. The control system is realized with CPU and contains developing of PID control, Autotune system, history data.

Keywords:
Cascade control, “Multi Input and Multi Output (MIMO) Thermal Control System”, PLC control, controllers, Autotune.

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DOI: 10.47978/TUS.2020.70.04.022

References:

[1] Б. Раков, Г. Ружеков, Научен отчет етап 1: Разработване на система за управление на мно-госвързан обект № 172ПД0015-08, НИС, ТУ-София, 11.2017
[2] Б. Раков, Г. Ружеков, Научен отчет етап 2: Разработване на система за управление на мно-госвързан обект № 172ПД0015-08, НИС, ТУ-София, 06.2018
[3] Б. Раков, Г. Ружеков, Експериментална система за управление на лабораторен модел-Многосвързан обект, Годишник на Технически Университет-София, том 68, книга 2, 2018, стр. 315-324.
[4] Емил М. Гарипов, Цифрови системи за управление - Проектиране на ПИД регулатори, ТУ-София, 2007.
[5] М. Хаджийски, К. Велев, Г. Сотиров, И. Калайков , Методи и алгоритми за управлени", Техника, София1992.
[6] Х. Хинов, К. Наплатаров, Автоматизация на технологични процеси, Техника, София, 1991.
[7] Application Description 02/2015 - Single and Multi Loop Controller Structures (Cascade Control) with PID_Temp, Siemens, 02.2015.
[8] Application Description 08/2019 - Single and Multi Loop Controller Structures (Cascade Control) with PID_Temp, Siemens, 08.2019.

ADVANTAGES OF USING DECOUPLING MATRIX FOR MIMO CONTROL
Bozhidar Rakov, Georgi Ruzhekov

Abstract
A research for the effectiveness of using decoupling matrix for MIMO PID control is conducted. Approximations of different orders are used for the calculation of the decoupling matrix. The estimation of the effectiveness is measured by а modified criterion.

Keywords:
Multi-dimensional PID, decoupling matrix.

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DOI: 10.47978/TUS.2020.70.04.023

References:

[1] Vladimir Kučera, Diagonal decoupling of linear systems by static state feedback, IEEE Transactions on Automatic Control, 2017. https://doi.org/10.1109/TAC.2017.2710098
[2] Carl A. Smith, Armando B. Corripio, Principles and practice of automatic control 2nd edition, John Wiley & Sons 1997.
[3] Juan Garrido, Francisco Vazquez, Fernando Morilla, An extended approach of inverted decoupling, Journal of process control 21, 2011. https://doi.org/10.1016/j.jprocont.2010.10.004
[4] Емил М. Гарипов, Идентификация на системи, ч.2, Технически университет-София, 2007.

A MODIFIED METHOD FOR CONTROL OF MIMO PLANT USING PID AND DECOUPLING MATRIX
Bozhidar Rakov, Georgi Ruzhekov

Abstract
A modified scheme is proposed for control of MIMO plant using a PID and decoupling matrix. The goal better performance of the closed loop systems and in-creased stability margin. By using a relay experiment an oscillating ultimate frequency is found, when the system is on the verge of instability. Using this estimation one applies a correction, which increases the stability margin of the closed loop system.

Keywords:
Multi-dimensional PID, decoupling matrix, structured singular value.

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DOI: 10.47978/TUS.2020.70.04.024

References:

[1] Carl A. Smith, Armando B. Corripio, Principles and practice of automatic control 2nd edition -, John Wiley & Sons 1997.
[2] Б. Раков, Независим синтез на ПИД регулатор за тримерен обект, Годишник на Технически Университет 2018.
[3] Sigurd Skogestad, Ian Postlethwaite, Multivariable Feedback Control: Analysis and Design 2nd Edition, Wiley & Sons 2001.
[4] Juan Garrido, Francisco Vazquez, Fernando Morilla, An extended approach of inverted decoupling, Journal of process control 21, 2011. https://doi.org/10.1016/j.jprocont.2010.10.004

RISK-BASED TESTING APPROACH FOR MEDICAL DEVICES SOFTWARE
Ivan E. Ivanov, V. Gueorguiev, D. Georgieva, M. Nenova, B. Ivanov

Abstract
A successful "medical device" development requires the collaboration between designers, developers, and quality engineers to be able to assess needs, functional requirements, specifications, and problems at every stage of development. The quality control of the developing process is achieved through a predefined set of policies, quality assessment, and the management of activities to eliminate defects and weaknesses wherever the development process.
The paper presents a successful approach to the development of a new medical device that will successfully pass all stages of certification to obtain a CE-mark.

Keywords:
risk analysis, testing, CE mark, medical device.

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DOI: 10.47978/TUS.2020.70.04.025

References:

[1] U.S. Food & Drag Administration, Classify Your Medical Device, 2020, https://www.fda.gov/medical-devices/overview-device-regulation/classify-your-medical-device
[2] Registrar Corp, FDA Issues Guidance on Medical Device Accessories, Jan. 2018, https://www.registrarcorp.com/fda-issues-guidance-on-medical-device-accessories/
[3] Johner Institute, Classification of Medical Devices, https://www.johner-institute.com/articles/regulatory-affairs/classification/
[4] Emergo by UL, Medical Device Classification in Europe, https://www.emergobyul.com/services/europe/european-medical-device-classification
[5] M. El Azzouzi, Complete Guide: Medical Device Classification EU MDR, April 2020, https://easymedicaldevice.com/new-eu-medical-device-classification/
[6] News-Medical.Net, Test Methods for Medical Devices, 2018, https://www.news-medi-cal.net/whitepaper/20171018/Test-Methods-for-Medical-Devices.aspx
[7] A. F. Benet, A Risk Driven Approach to testing Medical Device Software, Advances in Systems Safety, Springer, Nov. 2010, pp 157-168, ISBN 978-0-85729-132-5 https://doi.org/10.1007/978-0-85729-133-2_10
[8] J. Speer, T. Rish , ISO 14971 RISK MANAGEMENT FOR MEDICAL DEVICES: THE DEFINITIVE GUIDE, Greenlight Guru, https://www.greenlight.guru/blog/iso-14971-risk-management
[9] EU Directorate B Unit B2, MEDICAL DEVICES: Guidance document (Classification of medical devices), June 2010.
[10] N. Pontius, The Ultimate Guide to Medical Device Design and Development: From Discovery and Concept to Design Controls, Navigating Medical Device Regulations, Risk Management, Quality Assurance, and More, 2020, https://www.pannam.com/blog/guide-medical-device-design-and-development/
[11] M. Strålin, Classification Of Medical Devices And Their Routes To CE Marking, March 2020, https://support.ce-check.eu/hc/en-us/articles/360008712879-Classification-Of-Medical-De-vices-And-Their-Routes-To-CE-Marking
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OBJECTS DETECTION FROM AN IMAGE USING MATLAB
Sherif Sherif, Jordan Kralev, Tsonyo Slavov

Abstract
Objects detection from a cluttered scene is one of the main tasks in computer vision. A lot of research has focused on the optimization of this process by using ma-chine learning, where creating algorithms with specific instructions for solving a prob-lem is not applicable. Most of embedded systems for detection object are based on al-gorithms using monochrome (intensity) images. Therefore, in the article are created models for color space conversion from images and the main stages of the object de-tection algorithm are discussed, as well as the functions through which this is done in MATLAB.

Keywords:
models for color space conversion, intensity images, object detection.

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DOI: 10.47978/TUS.2020.70.04.026

References:

[1] Bay, H., A. Ess, T. Tuytelaarss, L. Van Gool, SURF: Speeded Up Robust Features, Computer Vision and Image Understanding (CVIU), Vol. 110, No. 3, pp. 346-359, 2008. https://doi.org/10.1016/j.cviu.2007.09.014
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[5] Grimson, W., L. Eric, J. Mundy, Computer vision applications, Communications of the ACM 37.3 (1994), pp. 45-51. https://doi.org/10.1145/175247.175251
[6] Kagami, S. High-speed vision systems and projectors for real-time perception of the world, IEEE Computer Society Conference on Computer Vision and Pattern Recognition-Workshops, 2010. https://doi.org/10.1109/CVPRW.2010.5543776

CYBERSECURITY IN SMART CARS
Maria Nenova, Vesselin Gueorguiev, Stoyan Madzhirov, Desislava Georgieva, Ivan Evg. Ivanov

Abstract
This paper covers the main concepts of smart cars – threats, security, privacy, and a base overview of the technology.

Keywords:
autonomous; cars; IoT; security; smart.

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DOI: 10.47978/TUS.2020.70.04.027

References:

[1] Srdjan Capkun, Jun Luo, The Security and Privacy of Smart Vehicles, IEEE Security and Privacy Magazine, May 2014.
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LABORATORY SETUP FOR INVESTIGATION OF CONTROL SYSTEM FOR ELECTROHYDRAULIC STEERING UNITS
Alexander Mitov, Tsonyo Slavov, Jordan Kralev, Ilcho Angelov

Abstract
In this paper, the developed experimental setup for investigation of electrohydraulic steering units (EHSU) is presented. The workability of designed by the authors system for control of electrohydraulic steering with controller is investigated. In comparison with other similar control systems, the presented one uses additional feedback-signal from sensor for position of proportional spool valve (LVDT) integrated into EHSU. This feedback allows achieving better performance of control systems. The design of the controller is done by solving a mixed sensitivity optimization problem. The plant model used in controller synthesis is multivariable model with three outputs and one input. This model is obtained by identification procedure. The presented experimental results show workability of the developed system.

Keywords:
embedded control system, H∞ controller, electrohydraulic steering system.

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DOI: 10.47978/TUS.2020.70.04.028

References:

[1] Más, F., Zhang, Q. etc. Mechatronics and Intelligent Systems for Off-road Vehicles. Springer-Verlag London Limited, 2010
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[5] Mitov, Al., Kralev, J., Slavov, Ts., Angelov, Il. SIMO System Identification of Transfer Function Model for Electrohydraulic Power Steering. 16th International Conference on Electrical Machines, Drives and Power Systems (ELMA), June, 2019, Bulgaria, pp. 130-135. https://doi.org/10.1109/ELMA.2019.8771571
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