Multi-loop System Research Articles

Relative Stability Analysis of Multi-Loop Low Dropout Regulators Using a Sub-Loop Superposition Method

Circuit designers favor open-loop stability analysis, which finds a breaking point in phase margin (PM) simulation. However, the conventional open-loop based method may not suit a multi-loop system that has multiple potential breaking points. It is unclear which breaking point is correct, or whether a correct breaking point exists. In this work, we first define “relative stability” from the worst stable sub-system of the original closed-loop system, and use it as a “reference”. Then, we examine and discuss the limitations of the conventional open-loop based method for a multi-loop system. The conventional method only indicates the “absolute stability” if the system has no common touching point. Subsequently, we propose a Sub-loop Superposition method for such a system, analyzing the “relative stability” in an open-loop way. We use the proposed method in two multi-loop low dropout regulators. The obtained PMs match the “reference”, verifying the effectiveness of the proposed method.

Application of a Stochastic Extension of the Analytical Design of Aggregated Regulators to a Multidimensional Biomedical Object

The results of the application of the methods of the synergetic control theory to a high-dimensional immunology object with uncertainty in its descriptions are reported. The control here is the therapy treated as a problem for constructing an optimal cure program. The control object is presented in continuous and discrete forms, i.e., mathematical models given by a system of ordinary differential equations with a bounded disturbance and a system of stochastic difference equations, respectively. Two algorithms for deriving robust regulators applicable to a 10-dimensional nonlinear multi-loop system with unstable limit states, which models an immune response to the hepatitis B infection, are obtained. Analytical control design for a continuous model relies on the method of nonlinear adaptation on the target manifold. The second algorithm represents a stochastic extension of the method of analytical design of aggregated discrete regulators minimizing the variance of the target macro variable. The numerical simulation of the developed control systems indicates the performance of the designed control algorithms. The results of this study can be used as a component part of the mathematical tools of expert systems and decision support systems.

Polynomial matrix synthesis method of a subordinate control system

The main difference between controlsyn thesis approaches is the various mathematical representation of a plant or system model. The aim of the work is to represent a single channel control plant model by a multichannel one and to obtain an identical design result for a single channel multiloop synthesis method by a multichannel one. For these purposes, direct current motor model is used as an example of a single channel plant. Classical approach to design control system for that kind of plant is to describe it as a serial connected transfer functions and design a multiloop system in accordance with subordinate concept. Polynomial matrix synthesis method with Sylvester matrix is utilized to make identical subordinate regulator. By several transformations, polynomial matrix description was obtained, that describe the plant as one input and three output model and subordinate regulator as a three input and one output model. Arbitrary parameters of regulator were introduced for extended null placement.

Synthesis of Line of Sight Angle Coordinate Filter on the Basis of Interactive Multi-Model Evaluation Algorithm

On the basis of the tracking multi-loop target angle coordinate system, the article has selected and proposed a interactive multi-model adaptive filter algorithm to improve the quality of the target phase coordinate filter. In which, the 3 models selected to design the line of sight angle coordinate filter; Constant velocity (CV) model, Singer model and constant acceleration model, characterizing 3 different levels of maneuverability of the target. As a result, the evaluation quality of the target phase coordinates is improved because the evaluation process has redistribution of the probabilities of each model to suit the actual maneuvering of the target. The structure of the filters is simple, the evaluation error is small and the maneuvering detection delay is significantly reduced. The results are verified through simulation, ensuring that in all cases the target is maneuvering with different intensity and frequency, the line of sight angle coordinate filter always accurately determines the target angle coordinates.

Energy Budget of Plasma Motions, Heating, and Electron Acceleration in a Three-loop Solar Flare

Abstract Nonpotential magnetic energy promptly released in solar flares is converted to other forms of energy. This may include nonthermal energy of flare-accelerated particles, thermal energy of heated flaring plasma, and kinetic energy of eruptions, jets, upflows/downflows, and stochastic (turbulent) plasma motions. The processes or parameters governing partitioning of the released energy between these components are an open question. How these components are distributed between distinct flaring loops and what controls these spatial distributions are also unclear. Here, based on multiwavelength data and 3D modeling, we quantify the energy partitioning and spatial distribution in the well-observed SOL2014-02-16T064620 solar flare of class C1.5. Nonthermal emission of this flare displayed a simple impulsive single-spike light curve lasting about 20 s. In contrast, the thermal emission demonstrated at least three distinct heating episodes, only one of which was associated with the nonthermal component. The flare was accompanied by upflows and downflows and substantial turbulent velocities. The results of our analysis suggest that (i) the flare occurs in a multiloop system that included at least three distinct flux tubes; (ii) the released magnetic energy is divided unevenly between the thermal and nonthermal components in these loops; (iii) only one of these three flaring loops contains an energetically important amount of nonthermal electrons, while two other loops remain thermal; (iv) the amounts of direct plasma heating and that due to nonthermal electron loss are comparable; and (v) the kinetic energy in the flare footpoints constitutes only a minor fraction compared with the thermal and nonthermal energies.

Investigation of the influence of the physicochemical characteristics of waste on the quality of liquid fuel products from them, obtained by multi-loop recirculation pyrolysis

Purpose: To study the properties of MSW generated in Ukraine in order to ensure their most efficient processing using the multi-loop recirculation pyrolysis technology in order produce a liquid fuel product. Design/methodology/approach: The problem' study of MSW accumulation in the world countries was carried out on the basis scientific databases PubMed, ScienceDirect, Mendeley, ResearchGate, Google Scholar for the corresponding keywords. The MSW properties generated in Ukraine were determined in accordance with the current standards to determine the specific properties of materials. For the experimental study, 3 types of solid organic waste mixtures were compiled, the composition of which characterizes the variable data on the accumulation of household and industrial waste of Ukraine. The quantity and quality of the liquid product obtained was determined using certified equipment. Findings: The tests revealed that the composition of the solid organic waste mixture when disposing of them by the multi-loop recirculation pyrolysis method has little effect the composition and properties of the obtained liquid hydrocarbon product; the total time of complete degradation for different mixtures of composite materials (mixtures of polymeric substances) is 180-250 min; the correct selection of the temperature of the circulation system makes it possible to produce a gaseous or liquid product which can then be used as an alternative fuel. Research limitations/implications: Current study of solid organic waste degradation was carried out by the multi-loop recirculation pyrolysis method. The experimental waste mixtures did not contain very wet waste of small fractions. Practical implications: The technology of circulating pyrolysis makes it possible to change the qualitative and quantitative composition of the obtained liquid hydrocarbon product, which is a potential fuel, irrespective of the composition of the solid organic waste mixture.Originality/value: It has been experimentally established that the quality of the liquid hydrocarbon product obtained by the multi-loop recirculation pyrolysis process does not depend on the composition of the solid organic waste mixture, but depends on the process' duration and the third circuit' temperature of the multi-loop recirculation system.

Twin Null-Point-Associated Major Eruptive Three-Ribbon Flares with Unusual Microwave Spectra

On 23 July 2016 after 05:00\,UTC, the first 48-antenna stage of the Siberian Radioheliograph detected two flares of M7.6 and M5.5 GOES importance that occurred within half an hour in the same active region. Their multi-instrument analysis reveals the following. The microwave spectra were flattened at low frequencies and the spectrum of the stronger burst had a lower turnover frequency. Each flare was eruptive, emitted hard X-rays and gamma-rays exceeding 800\,keV, and had a rare three-ribbon configuration. An extended hard X-ray source associated with a longest middle ribbon was observed in the second flare. The unusual properties of the microwave spectra are accounted for by a distributed multi-loop system in an asymmetric magnetic configuration that our modeling confirms. Microwave images did not to resolve compact configurations in these flares that may also be revealed incompletely in hard X-ray images because of their limited dynamic range. Being apparently simple and compact, non-thermal sources corresponded to the structures observed in the extreme ultraviolet. In the scenario proposed for two successive three-ribbon eruptive flares in a configuration with a coronal-null region, the first eruption causes a flare and facilitates the second eruption that also results in a flare.

Моделювання системи керування з регулятором на підставі внутрішньої моделі

Засобами імітаційного моделювання проаналізовано функціонування замкнутих систем керування в умовах зміни властивостей інерційного об'єкта керування. Порівняли роботу таких систем: одноконтурної з ПІД регулятором, багатоконтурних з ПІ-ПД керуванням та систем із зовнішнім регулятором на підставі внутрішньої моделі. Серед систем керування із внутрішньою моделлю одна побудована на підставі моделі об'єкта керування. Ми запропонували іншу система, в якій структура зовнішнього регулятора реалізована на базі внутрішньої моделі замкнутого внутрішнього контуру з ПД регулятором. Для спрощення процедури налаштування зовнішнього регулятора вибрано наближену модель об'єкта керування у вигляді послідовно з'єднаних аперіодичної ланки першого порядку та ланки запізнення. Знайдено наближену внутрішню модель зустрічного паралельного з'єднання об'єкта керування та ПД регулятора та отримано наближену обернену модель. Встановлено, що в умовах зміни властивостей об'єкта керування запропонована система зберігає достатній запас стійкості і порівняно з іншими досліджуваними системами має переваги. Так, зі збільшенням коефіцієнта передачі об'єкта керування у 2 рази та збільшенням інерційності на 30 % перехідні процеси каналом заданого значення мають найменший час регулювання. Окрім цього, каналом збурення така система забезпечує найменше динамічне відхилення для всіх варіантів дослідження.

Online implementation of time augmentation of over current relay coordination using water cycle algorithm

In the present paper, a technique is presented for new investigations for the constrained type optimal coordination of over current relay problem using the water cycle algorithm (WCA). It is shown that the operating time of relay mainly depends upon the time dial setting (TDS) and plug settings. The paper introduces a novel metaheuristic optimizer algorithm, WCA, encouraged by the water sequence process and movements of rivers and flows on the way to the sea. Results are presented for the application of the methodology on a distribution system of single-end one loop system, Single-end multi-loop system and single-end multi-parallel feeder distribution system. Subsequently, the results find the minimal operating time of relay with optimized TDS for over current relay. The result reveals the effectiveness and superiority of the proposed WCA over the other techniques presented in the literature in terms of accuracy, input parameter and iterations.

Topological Classification-Based Splitting–Combining Methodology for Analysis of Complex Multi-Loop Systems and Its Application in LDOs

Multiple loops have been used extensively to enhance the system performance in various applications. However, the increasing complexity of multi-loop systems also makes them much more difficult to analyze and implement. In this paper, a new methodology to analyze multi-loop system is proposed. In the proposed framework, multi-loop systems are regarded to be built upon of sub-modules of cascade, parallel adding, and feedback units, and then, they are simplified following a certain procedure based on the correlation of the Bode characteristics of the segmented sub-modules. Applying this methodology, the Bode plot and the transfer function of the system can be easily obtained with the system properties of gains, zeros, and poles. Two examples are provided as demonstrators, including a multi-loop low-dropout regulator (LDO) from literature, and a newly designed multi-loop LDO aiming at enhancing the stability over a wide load range, which show that the Bode plot and the transfer function can be obtained more intuitively and rapidly. Excellent agreements among theory, simulations, and measurements are confirmed, which verify the proposed method. It can help designers to gain more intuitions and insights on multi-loop systems from both circuit and device perspectives, which is also an effective tool for both stability analysis and circuit design.

Wave modes excited by photosphericp-modes and mode conversion in a multi-loop system

Context. Waves are ubiquitous in the solar corona and there are indications that they are excited by photosphericp-modes. However, it is unclear howp-modes in coronal loops are converted to sausage modes and transverse (kink) modes, which are observed in the corona.Aims. We aim to investigate how those wave modes are excited in the lower corona by photospheric acoustic waves.Methods. We built 3D magnetohydrostatic loop systems with multiple inclinations spanning from the photosphere to the lower corona. We then simulated these atmospheres with the MANCHA code, in which we perturb the equilibrium with ap-mode driver at the bottom of the domain. By splitting the velocity perturbation into components longitudinal, normal, and azimuthal to the magnetic flux surfaces we can study wave behavior.Results. In vertical flux tubes, we find that deformed fast sausage surface waves and slow sausage body waves are excited. In inclined flux tubes fast kink surface waves, slow sausage body waves, and either a fast sausage surface wave or a plane wave are excited. In addition, we calculate a wave conversion factor (0 ≤ C ≤ 1) from acoustic to magnetic wave behavior by taking the ratio of the mean magnetic energy flux to the sum of the mean magnetic and acoustic energy flux and compare it to a commonly used theoretical conversion factor. We find that between magnetic field inclinations of 10° to 30° those two methods lie within 40%. For smaller inclinations the absolute deviation is smaller than 0.1.

A Design Method for Linear Motion Servocontrol System

This paper proposes some practical methodology and design aids for the linear motion servocontrol systems such as the electromagnetic launchers. Mason’s gain formula was first used in the state space to solve for the transfer function of the complex and multiloop system rapidly and conveniently. The classical feedback control referring to the separation principle, involving a tracking controller and an observer-based compensator, may work well but has limited bandwidth under the constraint of the nominal inertia, and this fact is demonstrated rigorously in this paper and improved by a novel compensation scheme. According to the time-domain performance and Nyquist view, a delicate parameter design of control parameters is made for the tracking controller and the robust observer. The algorithm is verified by use of a rapid control prototype real-time simulation platform. The comparison of the experimental results shows that the proposed control scheme has good properties of trajectory tracking, antidisturbance, and noise suppression.

Sigma-Point Kalman Filter Algorithm in the Problem of GNSS Signal Parameters Estimation in Non-Coherent Tracking Mode in Spacecraft Autonomous Navigation Equipment

The paper presents a multiloop system for noncoherent tracking of the radionavigation parameters of global navigation satellite system (GNSS) signals in autonomous satellite navigation system. Comparative analysis of accuracies of traditional tracking system with discriminators and filter in the tracking loop and the proposed system without discriminators is conducted. RMS errors of estimates, pull-in range and the probability of signal acquisition are studied under various SNR values. Experimental tests of derived noncoherent tracking loop are performed.

Deployment accuracy analysis of cable-strut deployable mechanism with joint clearances and forces constrained

The effects on deployment accuracy of joint clearances and forces acting on the deployable mechanism are investigated. “A virtual massless link” is used to describe the joint clearance of the mechanism in the free state. Aiming at the following problems of multi-loop linkages mechanical system such as loop constraints coupling and complicated topology structure, the geometric relationships and the deploying error equations of deployable mechanism are provided based on Denavit-Hartenberg matrix by splitting multi-loop linkage into 3 single-loop linkages. In addition, with consideration of forces, “a virtual massless rope” is used instead of “virtual massless link” to describe the joint clearance for avoiding the extra singularities. And the criterion of mechanism in stable configuration is obtained by weighting coefficient method on the basis of minimum potential principle. The solving procedure of deploying error equations in the state of forces constrained is presented by combining Monte-Carlo method with genetic algorithm, it is an effective solution for the nonlinear objective function with multiple constraints and strong coupling. The results indicate that the appropriate forces acting on mechanism produce a significant effect on improving repeat accuracy, and the absolute accuracy can be improved with the future error compensation.

RADIO-PHOTON MULTILOOP DELAY LINE FOR MONITORING AND VERIFICATION OF TECHNICAL PARAMETERS OF DOPPLER RADAR SYSTEM

One of them actual problems of development doppler radar is technical parameters quality control. Especially it concerns the development of reference standards for sounding and imitation of Doppler shifts of the carrier frequencies of the radar, which is difficult and economically unprofitable task. The article considers the possibility of measuring and controlling the technical parameters of meteorological Doppler radars using the time delay multi-loop radio-photon system for imitation distance and Doppler shift. A method for controlling the range, spatial resolution, blind zone, sensitivity of the receiver, as well as the accuracy of determining the wind speed along the beam is proposed on the basis of data obtained as a result of the calibration bench for metrological control of laser meteorological locators prototype development. Methods for checking the trace standards and Doppler shifts in a radio-photon imitation multi-loop time delay line are proposed.

Synthesis of High-Precision Hydraulic Control Systems of an Excavator

Practical implementation of the program controlling the movement of the excavator’s working tool (including the use of satellite navigation system) imposes stringent requirements on the dynamic and static accuracy of automatic control systems for the hydraulic excavator’s operating mechanisms, in conditions of non-stationary parameters of these mechanisms as control objects. The authors describe the effective solution of this problem by implementing structural synthesis of each servo hydraulic drive as a multi-loop system with one measured coordinate (MLSOMC). The EO-4121 excavator with four hydraulic drives (rotary platform, boom, arm and ladle) was used as an example to demonstrate that the implementation of three circuits in the multi-loop system with one measured coordinate in each of these drives with typical PID-controllers allows to ensure the robustness of the ACS for known uncertainties, as well as the required rates of control quality in static and dynamic modes.

Measuring and modeling driver steering behavior: From compensatory tracking to curve driving

Drivers rely on a variety of cues from different modalities while steering, but which exact cues are most important and how these different cues are used is still mostly unclear. The goal of our research project is to increase understanding of driver steering behavior; through a measuring and modeling approach we aim to extend the validity of McRuer et al.’s crossover model for compensatory tracking to curve driving tasks. As part of this larger research project, this paper first analyzes the four main differences between compensatory tracking and curve driving: (1) pursuit and preview, (2) viewing perspective, (3) multiple feedback cues, and (4) boundary-avoidance strategies due to available lane width. Second, this paper introduces multiloop system identification as a method for explicitly disentangling the driver’s simultaneous responses to various cues, which is subsequently applied to two sets of human-in-the-loop experimental data from a preview tracking and a curve driving experiment. The results suggest that recent human modeling advances for preview tracking can be extended to curve driving, by including the human’s adaptation to viewing perspective, multiple feedback cues, and lane width. Such a model’s physically interpretable parameters promise to provide unmatched insights into between-driver steering variations, and facilitate the systematic design of novel individualized driver support systems.

Quasioptimal estimation of GNSS signal parameters in coherent reception mode using sigma-point Kalman filter

The paper presents a multiloop system for tracking the radionavigation parameters of navigation satellite signals in the user equipment. Comparative analysis of accuracies of traditional tracking system with discriminators and filter in the tracking loop and the proposed system without discriminators is conducted. RMS errors of estimates and the probability of signal acquisition are studied under various SNR values. The proposed scheme is shown to outperform the traditional tracking system with discriminators.

A Study on Type of Smart Water Grid Pipeline System (multi waterloop system) and Application Method

In these days, water-loop system using multi water resources is lively discussed. This system distributes water effectively by using multi water resources instead of new water resources development. Multi water resources consist of surface water, rainwater, reclaimed water, seawater etc. This system would be distributing sanitary water stably, and able to economical maintain the related facilities. Also, this system has an emergency reaction ability when system is faced with accident. Especially, if multi water loop system is constructed by using the city’s securable water, nation’s water resources will be utilized effectively and water resources will be developed or reused on a small scale. The neces elements of water-loop system design are suggested in this research. The elements are the followings; Model of connected water-loop pipe networks, platform model of multi water resources loop system, range of technology, difference with existing systems and direction of construction.

Design and Stability Analysis of a Frequency Controlled Sliding-Mode Buck Converter

Power management of mobile digital systems-on-chip necessitates large voltage regulation performances. DC/DC converters used to supply digital cores are facing stringent constraints with respect to load transients, reference tracking and accuracy. The fast transient response offered by sliding-mode control is well suited to DC/DC converters with fast varying load. Fixed switching-frequency is also mandatory for EMI and noise related issues. Fixed-switching frequency sliding-mode control has been experimented as a multi-loop system. There is a necessity to investigate the stability when multi-loops interact and the parameter set for each loop is quite large. The paper details a methodology for the stability analysis of a frequency-controlled sliding-mode DC/DC converter. The proposed stability analysis takes the possible cross-interactions into account and can be used to optimise the DC/DC controller without the limitations of a non-interaction criterion. As a verification a DC/DC converter is implemented in CMOS 130 nm. Experimental results agree with the analysis main recommendations.