Analysis of loading effect of systems in a bond graph approach with application to a synchronous machine

Author(s):  
G Gonzalez

A new type of bond designed as an adapted bond is proposed. This bond can be considered in the transition from an active bond to a bond. This approach makes it possible to know the loading effect of the controller–plant and the feedback connections. In order to determine the loading effect of the closed-loop system, the transfer function using causal paths and causal loops of the system in the physical domain is presented. However, this proposed adapted bond should be used in fault cases. Finally, some examples of bond graph models in open- and closed-loop systems are given.

Symmetry ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 854
Author(s):  
Raquel S. Rodríguez ◽  
Gilberto Gonzalez Avalos ◽  
Noe Barrera Gallegos ◽  
Gerardo Ayala-Jaimes ◽  
Aaron Padilla Garcia

An alternative method to analyze a class of nonlinear systems in a bond graph approach is proposed. It is well known that the analysis and synthesis of nonlinear systems is not a simple task. Hence, a first step can be to linearize this nonlinear system on an operation point. A methodology to obtain linearization for consecutive points along a trajectory in the physical domain is proposed. This type of linearization determines a group of linearized systems, which is an approximation close enough to original nonlinear dynamic and in this paper is called dynamic linearization. Dynamic linearization through a lemma and a procedure is established. Therefore, linearized bond graph models can be considered symmetric with respect to nonlinear system models. The proposed methodology is applied to a DC motor as a case study. In order to show the effectiveness of the dynamic linearization, simulation results are shown.


2017 ◽  
Vol 55 (3) ◽  
pp. 357
Author(s):  
Nguyen Doan Phuoc ◽  
Nguyen Hoai Nam

In this paper, the settling time of closed loop systems controlled with PID, which is established by using magnitude and symmetric optimum methods, are analyzed. These methods have some limitations such as limited frequency bands, existence of overshoot and larger settling time. Thus, our aim is to improve these performances of the closed loop system for a certain class of transfer functions. The proposed method will be tested on a DC motor by simulation. It can be concluded that the method provides a larger range of frequency, smaller settling time and no overshoot.


Author(s):  
С.Л. Подвальный ◽  
Д.В. Логунов ◽  
Е.М. Васильев

Рассматривается задача воспроизведения в искусственных объектах способности естественных систем к самовосстановлению вследствие существования в них замкнутого круговорота вещества и энергии. Показано, что создание замкнутого жизненного цикла в системе предполагает реализацию в ней процессов восстановления ресурсов и их накопления в виде внутренних резервов, расходуемых системой в неблагоприятных условиях существования. Получена функциональная схема системы с замкнутым циклом и предложена математическая модель её функционирования в виде дискретного однородного марковского процесса без последействия. Обнаружено, что введение в систему внутреннего резервирования требует рассмотрения двух альтернативных вариантов модели системы: варианта для случая, в котором объём резервов ограничен возможностями каналов восстановления в системе, и варианта, в котором указанное ограничение отсутствует. Составлены графы состояний системы для указанных режимов функционирования и получены выражения для финальных вероятностей этих состояний. На основе полученных финальных вероятностей составлены аналитические расчётные соотношения для характеристик эффективности системы с замкнутым циклом. В качестве основной характеристики эффективности такого рода систем предлагается использовать вероятность полного функционирования системы, т.е. вероятность её работы с использованием всего объёма активных ресурсов. Представлен числовой пример, подтверждающий работоспособность предложенной модели, и проведён сопоставительный анализ вариантов управления эффективностью замкнутой системы путём изменения объёма резервов, количества процессов восстановления и интенсивности этих процессов. Выявлено доминирующее значение внутренних резервов при обеспечении заданных показателей эффективности системы с замкнутым циклом Here we consider the problem of reproduction of the ability of natural systems to self-repair in artificial objects due to the existence of a closed loop of matter and energy in them. We show that the creation of a closed life cycle in the system presupposes the implementation of the process of restoring resources and their accumulation in the form of internal reserves consumed by the system in unfavorable conditions of existence. We obtained a functional diagram of a closed-loop system and proposed a mathematical model of its functioning in the form of a discrete homogeneous Markov process without aftereffect. We found that the introduction of internal redundancy into the system requires consideration of two alternative options for the system model: the option for the case in which the volume of reserves is limited by the capabilities of the recovery channels in the system, and the option in which the specified limitation is absent. We compiled the graphs of the states of the system for the specified modes of operation and obtained expressions for the final probabilities of these states. On the basis of the obtained final probabilities, we got analytical design ratios for the characteristics of the efficiency of a system with a closed loop. As the main characteristic of the efficiency of such systems, we propose to use the probability of the complete functioning of the system, i.e. the probability of its work using the entire volume of active resources. We present a numerical example that confirms the performance of the proposed model, and carried out a comparative analysis of options for managing the efficiency of a closed-loop system by changing the volume of reserves, the number of recovery processes and the intensity of these processes. We revealed the dominant value of internal reserves while ensuring the specified performance indicators of a closed-loop system


Volume 3 ◽  
2004 ◽  
Author(s):  
Robert A. Leishear ◽  
Jeffrey H. Morehouse

The effects of fluid transients, or water hammer, in closed loop systems are somewhat different than those observed in open ended systems. The open loop system has received much attention in the literature, not so for the closed system. The generally accepted method of characteristics (MOC) technique was applied herein to investigate closed loop systems. The magnitudes of the pressures during fluid transients were investigated for examples of rapid valve closures, and the operations of parallel pumps. The effects of trapped air in the system were also considered for these examples. To reduce the pressures caused by the transients, the installation of slow closing valves were evaluated for different conditions.


2012 ◽  
Vol 490-495 ◽  
pp. 3065-3069
Author(s):  
Wei Yan ◽  
Jie Zhang ◽  
Ying Sheng Zhou

Many control systems are subject to extraneous disturbance signals that cause the system to provide an inaccurate output. The extraneous disturbance signals in steel rolling process are analysis in this paper. If the frequency spectrums of the noise and input signals are of a different character, the output signal-noise ratio can be maximized, often by simply designing a closed-loop system transfer function that has a low-pass frequency response.


SIMULATION ◽  
1967 ◽  
Vol 8 (5) ◽  
pp. 255-257 ◽  
Author(s):  
Willard A. Gilly

Several methods have been devised for generating Bode diagrams on an analog computer. All of them, or at least all of them that we are familiar with, are either imprecise or they are excessively laborious. And the method most commonly used by analog pro grammers -graphical comparison of variables on a strip chart recording-combines both disadvantages. These can be largely avoided by a method we have found quite convenient, using analog logic and memory equipment. Our method yields phase and gain information directly and requires no manual adjustments by the computer operator other than to change the frequency of the input signal and to adjust the abscissa of the X-Y plotter. The method can be used for both open-loop and closed-loop systems and is especially useful for obtaining the open-loop response of a closed-loop system, as in figure 1. Here is how it works:


Author(s):  
Keisuke Yagi ◽  
Hiroaki Muto ◽  
Yoshikazu Mori

Abstract The paper proposes the digital redesign technique called plant-input-mapping (PIM) method for a feedback system described in the state-space form. The PIM method, which was originally presented in the transfer function form, focuses on the plant input signal via the plant input transfer function and discretizes it so as to satisfy the control zero principle in the resulting discrete-time closed-loop system, which leads to guaranteeing the closed-loop stability for any non-pathological sampling interval. In accordance with this approach, the proposed PIM method focuses on the control zeros included in the plant input signal. The paper proves that the matched-pole-zero discrete-time model of the plant input state-equation satisfies the control zero principle with the step-invariant model of the plant. Then, when the matched-pole-zero model is set as the target of model matching, the parameters of the state-space PIM controller employing the observer-based dynamic state-feedback can systematically be determined from the underlying continuous-time closed-loop system with guaranteed stability. This discretization process can immediately be applied to a state-feedback system and a class of multi-input multi-output systems without any modification, which cannot be discretized by the conventional PIM methods. The discretization performance of the proposed PIM method is evaluated through illustrative examples with comparable digital redesign methods, which reveal that the proposed method performs a good reproduction of the characteristics of the underlying closed-loop system.


2019 ◽  
Vol 13 (4) ◽  
pp. 674-681 ◽  
Author(s):  
Meng Wang ◽  
Lakshmi G. Singh ◽  
Elias K. Spanakis

Improvements in glycemic control using continuous glucose monitoring (CGM) systems have been demonstrated in the outpatient setting. Among hospitalized patients the use of CGM is largely investigational, particularly in the non-ICU setting. Although there is no commercially available closed-loop system, it has recently been evaluated in the non–critical care setting. Both CGMs and closed-loop systems may lead to improved glycemic control, decreased length of stay, reduced risk of adverse events related to severe hypoglycemia or hyperglycemia. Limitations of inpatient use of CGM and closed-loop systems include lack of FDA approvals, inexperience with this technology, and costs related to supplies. Significant investment may be necessary for hospital staff training and for development of infrastructure to support inpatient use. Additional limitations for CGM systems includes potential inaccuracy of interstitial glucose measurements due to medication interferences, sensor lag, or sensor drift. Limitations for closed-loop systems also includes need for routine monitoring to detect infusion site issues as well as monitoring to ensure adequate insulin supply in reservoir to avoid abrupt cessation of insulin infusion leading to severe hyperglycemia. Hospital staff must be familiar with trouble-shooting and conversion to alternative mode of insulin delivery in the event of insulin pump malfunction. Given these complexities, implementation of closed-loop systems may require involvement of an endocrinology team, limiting widespread adoption. This article reviews current state of CGM and closed-loop system use in the non-ICU setting, available literature, advantages and limitations, as well as suggestions for future CGM design, specifically for the inpatient setting.


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