Abstract
In this paper, a SIL simulation of a developed model-free method for time-varying dynamic measurements in the control system is presented. As an example, the dynamic mass measurement process is examined. The method is based on the online estimation of time-varying parameters of the linear regressive model by recursive least square method with a constant trace of a covariance matrix. The model order selection is performed by Akaike’s information criteria. The performance of the method with respect to the variance of measurement noise is empirically tested by simulation experiments. For the aim of comparison, the Kalman filter for estimation of unknown measurement is designed. The simulation results show the advantage of the model-free method.
Keywords
Dynamic measurements, Model-free method for dynamic measurements, Kalman filter, SIL simulation.
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DOI: 10.47978/TUS.2021.71.02.007
Abstract
Comparison of two embedded multivariable control algorithms based on advanced control techniques - LQG and H∞ is done. The controllers are designed to control a load-sensing electro-hydraulic system for driving the power steering of modern generation mobile machinery. The authors have developed the two controllers separately in previous works, where their theoretical and experimental research was performed. The purpose of the present article is to compare the two controllers in terms of physical experiment and numerical simulation, and on the basis of their comparison to being analyzed their workability and control performance. The comparison is made on the basis of several indices defined the control system performance in both the time domain and the frequency domain. Simulation and real-time experiments show the advantages of the H-infinity controller.
Keywords
Electro-hydraulic, H∞, load-sensing, LQG, servo.
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DOI: 10.47978/TUS.2021.71.02.008
MOBILE SPY COMMUNICATIONS
J. Ostrev, V. Galabov, V. Karlova – Sergieva, T. Pavlov, A. Marinchev
Abstract
Security in communications is always critical. It includes two or more sources of transmission-reception and transmission medium and affects a set of protocols and devices and data transfer systems. Usually, encryption and decryption do not solve all security issues. Interference in the communication process is possible and can often destroy security. There are complex hardware and software systems that can often successfully replace one or more parts of the communication process, the identification of which is almost impossible during the process, especially by users and cases of lack of control. Typically, government organizations (but not only) own and use such systems. At the same time, such systems can be used illegally - at any time, for anyone, and for any purpose of espionage. This makes the topic of spying on mobile communications extremely important and relevant.
Keywords
security in communications, communication process, spying on mobile communications, home location register (HLR).
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DOI: 10.47978/TUS.2021.71.02.009
MODELING AND SIMULATION OF TECHNICAL SUPPORT SERVICES USING ARENA
Andrey Yonchev, Lyubomir Mirchev
Abstract
The publication investigates the modeling of queuing processes simulated with the software Arena. In the beginning, we consider Poisson queues and their performance characteristics. An application of the considered package Arena in representing the work of a real technical-economical queuing system will be investigated. The paper aims to create a simulation model for the simulation of entities coming into a technical organization and their optimal distribution to a proper team, which has to serve them. We will apply Arena software to build a model of tasks spreading to various working equips attempting to increase the service performance. First, we will formulate the problem set up and then we will proceed with the solution approach. Finally, we will present experiments and the obtained results.
Keywords
Queues, modeling, simulation.
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DOI: 10.47978/TUS.2021.71.02.010
LYOPHILIZATION PLANT CONTROL SYSTEM
Georgi Ruzhekov
Abstract
Lyophilization or Freeze-drying is a low-temperature dehydration process [1], [2] that involves freezing the product, very low pressure by which the ice is removed by sublimation. The plant is designed for the production of vaccines and immunostimulants. The control system is realized with a Siemens controller, operator panel, and SCADA system.
Keywords
Freeze-drying system, Programmable Logic Controller (PLC), SCADA.
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DOI: 10.47978/TUS.2021.71.02.011
DESIGN AND IMPLEMENTATION OF A REGIONAL PACS
Ivan E. Ivanov, Vesselin E. Gueorguiev, Borislav Ivanov, Desislava Georgieva
Abstract
For a period of 10-15 years (2005 - 2020), the number of PACS (Picture Archiving and Communication System) systems offered on the market has increased more than 10 times. Despite this growth, some of the main disadvantages of this class of systems persist: the systems are complex and expensive to acquire, replace, maintain, or repair and to connect them in a regional map. This paper aims to show an approach that allows us to build a regional PACS connecting several hospitals and maintaining medical information exchange.
Keywords
regional PACS; DICOM standard; interoperability; medical requirements.
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DOI: 10.47978/TUS.2021.71.02.012
PROGRAM GENERATION APPROACH FOR HIL SIMULATORS DESIGN
Vesselin E. Gueorguiev, Ivan E. Ivanov, Emanuil K. Markov, Desislava Georgieva
Abstract
The problem of design, implementation, and tuning of HIL simulators is rising together with systems complexity. Many elements of the real system cannot be simulated easily and precisely. In the case of hybrid objects the complexity arises. Very hard is an implementation of mixed simulators – having both computer elements and hardware elements for extended object simulation. Here is presented an approach of using program generation technique for the creation of object simulators. Using one and the same approach for implementation of the simulator and the control system is also discussed. Objects and control systems having different structures are presented in this paper.
Keywords
program generation; HIL simulation; object- control system co-design.
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DOI: 10.47978/TUS.2021.71.02.013
ROBUST CONTROL OF A SERVO SYSTEM USING MU SYNTHESYS AND REGIONAL POLE PLACEMENT CONSTRAINTS
Asparuh G. Markovski
Abstract
Two approaches for synthesizing a robust regulator for a laboratory model of the servo system manufactured by Inteco are compared: mu synthesis using dksyn routine and H∞ design with regional pole placement constraints using h2hinfsyn, both from Robust Control Toolbox for MATLAB. Some of the inaccurate parameters are introduced as sources of structured uncertainty. Additionally, unstructured uncertainty has been introduced due to the presence of nonlinearity in the "gap" type object. Simulation experiments were performed with the model. The operability of the created regulator was tested on the experimental set-up.
Keywords
Robust Control, μ synthesis, H∞ design, pole placement.
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DOI: 10.47978/TUS.2021.71.02.014
HARDWARE VERSUS ANALYTICAL REDUNDANCY FOR FAULT DETECTION. APPLICATION FOR A SERVO SYSTEM
Alexandar Ichtev
Abstract
In this paper, two approaches for fault diagnosis are considered. The first investigated approach uses parity relations for fault detection and isolation. The second one is based only on the models. It relies only on analytical redundancy. The problem is stated in its general formulation as well as for implementation – application to a servo system. From the system’s model, structured residuals for fault detection and fault isolation are obtained. The main emphasis is placed on the sensor fault. However, actuator fault can be considered as well. The results are compared to the second approach based on models. The advantages and disadvantages of the two approaches are discussed. Experiments with laboratory setup – servo system are carried out. The obtained results are discussed as well.
Keywords
Fault diagnosis, Analytical redundancy, Hardware redundancy, Servo system.
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DOI: 10.47978/TUS.2021.71.02.015