Closed-loop Analysis Research Articles

Control of Homogeneous Linear Multiagent Networks in the Presence of a Misbehaving Node*

This paper focuses on a multiagent network with homogeneous linear time-invariant node dynamics, where nodes exchange their local state information with each other. Specifically, we consider the case when there exists a misbehaving node in this multiagent network that is subject to a disturbance. To suppress the undesired effects of this misbehaving node in the overall multiagent network, we propose a control architecture to be executed by the driver node. A detailed closed-loop system analysis is presented that reveals how the driver node needs to be selected to allow the states of nodes belonging to a portion of the multiagent network (or all nodes) approach a desired synchronization state generated by an exosystem. The efficacy of the proposed control architecture is also demonstrated through illustrative numerical examples.

Modeling and analysis of articulated steering mechanism

The current article deals with the dynamic analysis of closed-loop controlled orbitrol steering unit. Mathematical model of the steering system is developed in MATLAB environment and results are well validated with the experimental results. The experimental setup is equipped with the conventional PID controller. Comparison analysis has been performed for different steering position command profiles. It is observed from the comparative analysis that the developed system performs well and offers satisfactory response for a diverse range of positioning requirements.

Optimal Virtual Inertia Design for VSG-based Motor Starting Systems to Improve Motor Loading Capacity

Virtual synchronous generator (VSG)-based control approaches for AC machine drivers have attracted much attention in recent years. The contradiction between the strong motor loading capacity and the small DC voltage fluctuation is disregarded in previous studies. A larger virtual inertia is required to raise the torque gain and drive the motor with heavier loads, thus resulting in larger DC voltage variations. A systematic method is proposed for the optimal design of the virtual inertia for VSG-based motor starting systems to achieve the maximal motor loading capacity and the low DC voltage fluctuation in this paper. Firstly, the relationship between the virtual inertia and the loading capacity is revealed on the basis of the closed-loop analysis. Considering the DC voltage variation, the constraint on the maximal value of the virtual inertia is proposed from the energy-balance perspective despite the unknown contribution of the DC capacitors to the virtual inertia. To fully exploit the energy storage capacity of the DC capacitors and raise the upper limit of the virtual inertia under the same permitted DC voltage variation, a modified DC voltage reference is introduced. Extensive simulation and experimental results are presented to validate the effectiveness of the proposed methods.

State Prediction of Human-in-the-Loop Multi-rotor System with Stochastic Human Behavior Model

Reachability analysis is a widely used method to analyze the safety of a Human-in-the-Loop Cyber Physical System (HiLCPS). It allows the HiLCPS to respond against an imminent threat in advance by predicting reachable states of the system. However, it could lead to an unnecessarily conservative reachable set if the prediction only relies on the system dynamics without explicitly considering human behavior, and thus the risk might be overestimated. To avoid the conservativeness, we present a state probability distribution function (pdf) prediction method which takes into account a stochastic human behavior model represented as a Gaussian Mixture Model (GMM). In this paper, we focus on the multi-rotor controlled by a human operator in a near-collision situation. The stochastic human behavior model is trained using experimental data to represent the human operators’ evasive maneuver. Then, we can retrieve a human control input pdf from the trained stochastic human behavior model using the Gaussian Mixture Regression (GMR). The proposed algorithm predicts the multi-rotor's future state pdf by propagating the pdf of the retrieved human control input according to the given dynamics, which yields closed-loop analysis of the HiLCPS. Human subject experiment results are provided to demonstrate the effectiveness of the proposed algorithm.

Data-Driven Stabilizer Design and Closed-Loop Analysis of General Nonlinear Systems Via Taylor's Expansion

Data-Driven Stabilizer Design and Closed-Loop Analysis of General Nonlinear Systems Via Taylor's Expansion

The Development of a Flight Test Platform to Study the Body Freedom Flutter of BWB Flying Wings

A flight test platform is designed to conduct an experimental study on the body freedom flutter of a BWB flying wing, and a flight test is performed by using the proposed platform. A finite element model of structural dynamics is built, and unsteady aerodynamics and aeroelastic characteristics of the flying wing are analyzed by the doublet lattice method and g-method, respectively. Based on the foregoing analyses, a low-cost and low-risk flying-wing test platform is designed and manufactured. Then, the ground vibration test is implemented, and according to its results, the structural dynamics model is updated. The flight test campaign shows that the body freedom flutter occurs at low flight speed, which is consistent with the updated analytical result. Finally, an active flutter suppression controller is designed using a genetic algorithm for the developed flying wing for future tests, considering the gains and sensor location as design parameters. The open- and closed-loop analyses in time- and frequency-domain analyses demonstrate that the designed controller can improve the instability boundary of the closed-loop system effectively.

Positive-Sequence Voltage Control, Full Negative-Sequence Cancellation, and Current Limitation for Static Compensators

This article presents a control scheme in the stationary reference frame for static synchronous compensators (STATCOMs) that provide three features: 1) regulation of the positive-sequence voltage to the nominal value; 2) full cancellation of the negative-sequence voltage; and 3) peak limitation of the injected currents. These features can help to improve the performance of these devices under perturbed grid conditions, including low, high, and unbalanced voltages. Also, the peak current limiter guarantees both the safe operation of the converter and a priority-based achievement of the voltage regulation targets, which is of interest during severe perturbations like voltage dips. Experimental results, implementation details, and closed-loop analysis are presented to validate the regulation capabilities and demonstrate the feasibility of the power quality improvement.

Optimal tuning of PI controller using system identification for two-phase boost converter for low-voltage applications

<span lang="EN-US">This paper presents modeling and hardware implementations of a two-phase DC-DC boost converter by using the system identification approach. The main objective of this research was to study new methods to obtain the values of the constants for the proportional-integral (PI) controller. Existing methods are time-consuming, since the values of the constants for the PI controller need to be calculated. The system identification approach for the closed-loop boost converter saves more time. This method has the fastest technique to find constants </span><em><span lang="EN-US">K<sub>p</sub></span></em><span lang="EN-US"> and </span><em><span lang="EN-US">K<sub>i</sub></span></em><span lang="EN-US"> for the closed-loop two-phase boost converter. To model a two-phase boost converter using the system identification approach, input duty cycle and output voltage are collected in the time domain data. In this study, the transfer function (TF) model, the autoregressive moving average with exogenous (ARMAX) model and the output-error (OE) model were used to generate a mathematical model. To perform the closed-loop analysis, constants </span><em><span lang="EN-US">K<sub>p</sub></span></em><span lang="EN-US"> and </span><em><span lang="EN-US">K<sub>i</sub></span></em><span lang="EN-US"> were obtained based on the generated mathematical model from the system identification approach. The result from the experiment shows that the percentages of overshoot for the TF, ARMAX and OE models were 19%, 25.36% and 24.6%, respectively. The output voltage ripples obtained for all three models were less than 5% of output voltage.</span>

Numerical prediction of operating characteristics of micro-gas turbine combustor with on-board reformed EGR system using co-simulation model and 1D reduced model

In this study, an on-board reforming gas turbine system was proposed to expend the combustion stability and operating points of as gas turbine combustor aiming for fuel lean condition. On-board reforming does not store the syngas unlike the existing conventional reforming device, but formed syngas as the operating load changes and participates in combustion. In previous research conducted for this study, a concept single nozzle combustor was designed that satisfies the thermal output of 150 kW and the turbine inlet temperature of 1200 K. In addition, by designing a non-catalytic partial oxidation-based concept reformer, syngas formation was confirmed in various operation points. In previous research, closed-loop analysis was performed to analyze the independent effects of combustor and reformer. However, in this study, open-loop analysis that simulates the combustor and reformer simultaneously was performed to analyze the effect of the combined system at various operating points. As a result, improved combustion was confirmed by the generation of OH radicals when the oxidizing agent was diluted with increasing hydrogen content. This is similar to the lean OH radical distribution in a low-oxidizing environment, which is the basic characteristics of moderate or intense low-oxygen dilution combustion. The reformer analyzed the reaction by changing the reformate fuel inlet velocity. Through this, it was confirmed that the mixedness inside the reformer improved as the reformate fuel inlet velocity. Finally, to calculate the efficiency of the hydrogen addition operating points under various conditions, suitable operating points were derived by comparison with conventional partial oxidation reforming. The operating range of moderate or intense low oxygen dilution combustion in an on-board reforming gas turbine system was numerically predicted. This is expected to greatly contribute to the study to improve the stability of moderate or intensive low oxygen dilution combustion in the future.

Observer-Based Proportional-Type Controller for Two-Wheeled Mobile Robots via Simple Coordinate Transformation Technique

This article briefs on an advanced observer-based proportional-type control scheme that stabilizes the attitude and regulates the position of two-wheeled mobile balancing robots. The robot parameter and load uncertainties are under consideration. There are three main differences from previous results: (a) the development of coordinate transformation for securing the applicability of the proposed nonlinear controller design technique, (b) the pole-zero cancellation parameter-independent observers for estimating the wheel and yaw angular velocities, and (c) the guarantees of performance recovery and offset-free properties through the replacement of integrators via observer-based disturbance observers. The practical merits of the closed-loop analysis are confirmed by performing experiments with a LEGO Mindstorms EV3 operated by MATLAB/Simulink.

Design of a Neural Super-Twisting Controller to Emulate a Flywheel Energy Storage System

In this work, a neural super-twisting algorithm is applied to the design of a controller for a flywheel energy storage system (FESS) emulator. Emulation of the FESS is achieved through driving a Permanent Magnet Synchronous Machine (PMSM) coupled to a shaft to shaft DC-motor. The emulation of the FESS is carried out by controlling the velocity of the PMSM in the energy storage stag and then by controlling the DC-motor velocity in the energy feedback stage, where the plant’s states of both electrical machines are identified via a neural network. For the neural identification, a Recurrent Wavelet First-Order Neural Network (RWFONN) is proposed. For the design of the velocity controller, a super-twisting algorithm is applied by using a sliding surface as the argument; the latter is designed based on the states of the RWFONN, in combination with the block control linearization technique to the control of the angular velocity from both machines in their respective operation stage. The RWFONN is trained online using the filtered error algorithm. Closed-loop stability analysis is included when assuming boundedness of the synaptic weights. The results obtained from Matlab/Simulink validate the performance of the proposal in the control of an FESS.

Spatiotemporally asynchronous sampled-data control of a linear parabolic PDE on a hypercube

This paper employs the observer-based output feedback control technique to deal with the problem of spatiotemporally asynchronous sampled-data control for a linear parabolic PDE on a hypercube. By the spatiotemporally asynchronous sampled-data observation outputs, an observer-based output feedback control law is constructed, where the sampling interval in time is bounded. By constructing an appropriate Lyapunov–Krasovskii functional candidate and applying a weighted Poincaré–Wirtinger inequality on a hypercube, it is shown under a sufficient condition presented in terms of standard linear matrix inequalities that the suggested spatiotemporally asynchronous sampled-data control law asymptotically stabilises the PDE in the spatial norm but its convergence speed can be regulated by a known constant. Moreover, both open-loop and closed-loop well-posedness analysis are done within the framework of semi-group. Finally, numerical simulation results are presented to support the proposed design method.

Closed loop analysis of Dual Bridge Converter with 4- levels

Abstract: A dual bridge (DB) LLC resonant converter for dc-dc conversion with closed loop is proposed in the system. The model is capable of delivering very low voltage, with a variable input dc fluctuations in the source side. The new PWM technique used helps the bridge output robust. The proposed model works only in 4 modes of operation. DB LLC converter uses different phase shift for each individual switches with different duty ratios. The model is simulated with 160V/200V DC input and 24V output with 20A i.e. 480W is provided to verify the operation. Keywords: Dual Bridge, LLC resonant converter, Closed loop operation, Boost converter.

Closed-Loop Identification of Baroreflex Properties in the Frequency Domain.

The arterial baroreflex system plays a key role in maintaining the homeostasis of arterial pressure (AP). Changes in AP affect autonomic nervous activities through the baroreflex neural arc, whereas changes in the autonomic nervous activities, in turn, alter AP through the baroreflex peripheral arc. This closed-loop negative feedback operation makes it difficult to identify open-loop dynamic characteristics of the neural and peripheral arcs. Regarding sympathetic AP controls, we examined the applicability of a nonparametric frequency-domain closed-loop identification method to the carotid sinus baroreflex system in anesthetized rabbits. This article compares the results of an open-loop analysis applied to open-loop data, an open-loop analysis erroneously applied to closed-loop data, and a closed-loop analysis applied to closed-loop data. To facilitate the understanding of the analytical method, sample data files and sample analytical codes were provided. In the closed-loop identification, properties of the unknown central noise that modulated the sympathetic nerve activity and the unknown peripheral noise that fluctuated AP affected the accuracy of the estimation results. A priori knowledge about the open-loop dynamic characteristics of the arterial baroreflex system may be used to advance the assessment of baroreflex function under closed-loop conditions in the future.

RISE-Based Composite Adaptive Control of Electro-Hydrostatic Actuator with Asymptotic Stability

The electro-hydrostatic actuator (EHA), the actuator of electric drive and hydraulic transmission, is competitive since it is small in size, light in weight and high in power density. However, the existence of the velocity loop error of servo motors, unmodeled dynamics and highly nonlinear uncertainties restrict the improvement of the tracking accuracy of the EHA system. In order to achieve high-precision motion control of EHAs, a RISE-based composite adaptive control scheme is proposed in this paper. In the proposed composite adaptive control design, a novel parameter adaptive law is synthesized to compensate for the parametric uncertainties and a robust integral of the sign of error (RISE) feedback is utilized to suppress the adverse effects caused by the lumped disturbances, including the velocity loop error of a servo motor and other unmodeled dynamics. The synthesized parameter adaptive law possesses the advantage of fast convergence, which is beneficial to achieve transient tracking performance improvement. In addition, the proposed controller is more suitable for practical applications since it is chattering free. The closed-loop system stability analysis shows that the proposed control scheme guarantees an excellent asymptotic tracking performance. Finally, comparative simulations are conducted to verify the high-performance nature of the proposed controller.

RETRACTED ARTICLE: Constant water circulating ecological influence and remote English education system development based on sequence matching

This article discusses the development status of sequence matching and closed-loop detection, and focuses on the inherent problems in closed-loop analysis methods. By analyzing the basic theory of sequence matching, the closed-loop detection implementation method of each sequence matching is summarized, and detailed closed-loop components corresponding to sequence matching are summarized, and the existing methods for achieving different modules are summarized and their disadvantages are reviewed. In line with this, this paper focuses on the focus on the central Z Basin area of the H River domain. Combined with systematic analysis of surface water and groundwater conversion characteristics, the Z Basin annual water balance model is proposed, and the relationship between surface water and groundwater is further explained. The annual water balance model contains a nonlinear model of water circulating ecology, which fully considers the runoff of rivers under river water abundance changes and irrigation on water cycle ecology. Finally, this paper proposes a remote English education system based on JavaBean components and software architectures. After comprehensive, extensive testing and research, it reduces software development costs under this field, not only improves system reliability, but also shortens the development cycle, simplifies system maintenance measures, and ultimately makes the maximum extension and stability. With regard to system testing, a complete test will be performed through web test methods and cookie laws, performance, feasibility, compatibility, and security. This article uses a variety of test methods, a variety of test content, through comprehensive testing, which fully meets the expected requirements, promoting the system to fully meet the ability of daily learning and work requirements.

Nonlinear Analysis of the C-Peptide Variable Related to Type 1-Diabetes Mellitus

Type-1 diabetes mellitus is a chronic disease that is constantly monitored worldwide by researchers who are strongly determined to establish mathematical and experimental strategies that lead to a breakthrough toward an immunological treatment or a mathematical model that would update the UVA/Padova algorithm. In this work, we aim at a nonlinear mathematical analysis related to a fifth-order ordinary differential equations model that describes the asymmetric relation between C-peptides, pancreatic cells, and the immunological response. The latter is based on both the Localization of Compact Invariant Set (LCIS) appliance and Lyapunov’s stability theory to discuss the viability of implementing a possible treatment that stabilizes a specific set of cell populations. Our main result is to establish conditions for the existence of a localizing compact invariant domain that contains all the dynamics of diabetes mellitus. These conditions become essential for the localizing domain and stabilize the cell populations within desired levels, i.e., a state where a patient with diabetes could consider a healthy stage. Moreover, these domains demonstrate the cell populations’ asymmetric behavior since both the dynamics and the localizing domain of each cell population are defined into the positive orthant. Furthermore, closed-loop analysis is discussed by proposing two regulatory inputs opening the possibility of nonlinear control. Additionally, numerical simulations show that all trajectories converge inside the positive domain once given an initial condition. Finally, there is a discussion about the biological implications derived from the analytical results.

Tuning of PID Controller with Differential Evolution Algorithm for LCC Resonant Converter

This paper deals with the optimization of LCC Resonant Converter based on Differential Evolution Algorithm. Closed Loop Analysis of LCC Resonant Converter have been Simulated by tuning PID Controller for different values of Kp, Ki and Kd values. Optimum Values of Kp, Ki and Kd were obtained using Differential Evolution Algorithm and these values were fitted to Obtain Maximum Output Voltage with LCC Resonant Converter. Initially three Variables namely Series Inductance, Series Capacitance and Parallel Capacitance were considered, out of which the Value of Series Capacitance was tuned with Differential Evolution.

Integrated modeling of microvibrations induced by Solar Array Drive Mechanism for worst-case end-to-end analysis and robust disturbance estimation

Modern and future observation Space missions face increasingly more demanding pointing performance requirements. This is accompanied with the development of larger lightweight flexible structures. This paper outlines a methodology for modeling a generic multi-body flexible spacecraft in an end-to-end fashion within the Two-Inputs Two-Outputs Port framework: from disturbance all the way to pointing performance by taking into account all the uncertainties of each sub-system. A particular focus is dedicated to a novel generic model for Solar Array Drive Mechanism and its harmonic disturbances produced by the micro-stepping driver and the gearbox imperfections. The proposed model is validated with the on-board telemetries of a European spacecraft. Moreover this paper shows how the proposed model-based approach can be easily used for control design and closed-loop robust performance analysis. Worst-case scenarios of mechanical parameters combination are investigated to provide robust performance certificate of the reference study case. A Linear Parameter-Varying observer, scheduled by the solar array rotor angle, is finally proposed in order to estimate the disturbance torques induced by the gearbox imperfections just using the measurements coming from a classical attitude control system: a star tracker and a gyrometer.

Approximation-Based Quantized State Feedback Tracking of Uncertain Input-Saturated MIMO Nonlinear Systems with Application to 2-DOF Helicopter

This paper addresses an approximation-based quantized state feedback tracking problem of multiple-input multiple-output (MIMO) nonlinear systems with quantized input saturation. A uniform quantizer is adopted to quantize state variables and control inputs of MIMO nonlinear systems. The primary features in the current development are that (i) an adaptive neural network tracker using quantized states is developed for MIMO nonlinear systems and (ii) a compensation mechanism of quantized input saturation is designed by constructing an auxiliary system. An adaptive neural tracker design with the compensation of quantized input saturation is developed by deriving an augmented error surface using quantized states. It is shown that closed-loop stability analysis and tracking error convergence are conducted based on Lyapunov theory. Finally, we give simulation and experimental results of the 2-degrees-of-freedom (2-DOF) helicopter system for verifying to the validity of the proposed methodology where the tracking performance of pitch and yaw angles is measured with the mean squared errors of 0.1044 and 0.0435 for simulation results, and those of 0.0656 and 0.0523 for experimental results.