Mismatch Disturbances Research Articles

A New Sliding-Mode Observer-Based Deadbeat Predictive Current Control Method for Permanent Magnet Motor Drive

This article proposes a new deadbeat predictive current control (DPCC) method based on a sliding-mode observer (SMO), which is applied in the field of permanent magnet motor control. A novel DPCC control method based on SMO is proposed according to the inherent issues of DPCC, which can effectively suppress internal parameter mismatch disturbances and external disturbances in the current loop. The mathematical model and derivation process of the proposed method are introduced. A simulation model is built and the effectiveness of the proposed method is verified. An experimental platform is built and the superiority of the proposed method is verified based on comparative experiments. Experimental results show that the proposed algorithm has strong robustness to the motor parameter mismatch. Compared with extended state observer (ESO) and adaptive observer (AO), the proposed algorithm has faster response speed and higher steady-state accuracy.

Reinforcement learning-based fixed-time resilient control of nonlinear cyber physical systems under false data injection attacks and mismatch disturbances

This paper presents a fixed-time adaptive resilient control framework based on reinforcement learning (RL), mismatch disturbance observer and nonsingular fast terminal sliding mode scheme for nonlinear cyber-physical systems (CPS) to enhance cyber-security under False Data Injection (FDI) attacks, as well as match and mismatch disturbances. The RL algorithm contains an actor-critic neural network (NN) in which the actor NN is employed to estimate the uncertainty while the critic NN is applied to evaluate the performance cost function. Next, to compensate the detrimental effects of attacks and mismatch disturbances, a new sliding mode-based adaptive disturbance observer is designed. To achieve high precision trajectory tracking within a fixed-time interval, a nonsingular fast terminal sliding mode scheme is designed. This scheme ensures fixed-time convergence of the tracking error and facilitates disturbance attenuation and attack mitigation which are the key features of the proposed fixed-time secure control strategy. Finally, the fixed-time stability analysis of is performed through Lyapunov theory. Results reveal the effectiveness of the proposed resilient control for wind turbine system as the nonlinear CPS.

A Disturbance Observer-based Novel Fuzzy SMC Control Scheme for Path Tracking of AUV with Mismatched Disturbances

A new sliding mode control scheme is proposed for the path tracking problem of autonomous underwater vehicles (AUVs) with uncertainty and mismatch interference. Considering the complexity of parameter rectification, a fuzzy logic controller-based system rectification scheme is designed in this paper. In the control system, a disturbance observer (DOB) and a radial basis function neural network (RBFNN) are used to estimate the mismatch disturbance and uncertainty, respectively. In addition, this paper analyzes the conditions for the Liapunov stability of the designed controller and the results show the closed-loop stability of the control system. The control scheme can be applied to the path tracking of underwater robots with rapidly changing trajectories in different driving environments. Finally, a number of comparative experiments are carried out to demonstrate the good performance of the proposed controller.

Resonant Frequency Deviation Analysis and Modified Notch Filter-Based Active Damping for SiC-Based PMSM Drive With Sine Wave Filter

In the permanent-magnet synchronous machine (PMSM) drive system, the adoption of silicon carbide (SiC) devices brings up new challenges, such as overvoltage, electromagnetic interference emission, and bearing current. To surmount these barriers, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> filter designed as the sine wave filter can be introduced into the machine drive system. However, filter and stator inductance can create unwanted electrical resonance issues. For the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -equipped PMSM drive system, there are two main factors that cause the drift of resonant frequency and change of stable region: (1) synchronous coordinate transformation with variable fundamental frequency, (2) parameter variations due to the magnetic saturation effect. In this paper, the deviation of resonant frequency caused by coordinate transformation is discussed. Then, the inherent damping effects and stability range in the rotating reference frame are derived in detail. Furthermore, considering the parameter mismatch disturbances, an active damping method based on the enhanced notch filter is presented, of which notch frequency is designed lag behind the nominal resonant frequency. The accurate discretization method and theoretical stability analysis in discrete <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</i> -domain are conducted. The experimental results are presented to verify the effectiveness and robustness of the proposed analysis and method.

Composite Sliding Mode Control for TPMM Velocity Drive via a Disturbance Observer

Tubular permanent magnet motor (TPMM) can offer great thrust force density and high efficiency. To enhance its robustness against disturbances and solve the contradiction between response time and overshoot, a novel sliding mode control strategy based on disturbance observer (DOB-SMC) was proposed for a TPMM velocity drive system. The novelty of the proposed velocity control strategy lies in the incorporation of the mismatch disturbance observer in the sliding surface and the sliding mode control (SMC) law, and the introduction of internal model control (IMC) into the SMC law. The velocity control system is transformed to a first-order inertia model by IMC, thus the dynamic response performance is improved. The mismatched disturbances are estimated and the equivalent control voltage is employed, and then the effect of mismatched and matched disturbances can be restrained with little chattering. The simulated and experimental results are presented as validation for the proposed strategy.

Improved Model Predictive Current Control for SPMSM Drives With Parameter Mismatch

Model predictive current control (MPCC) can predict future motor behavior according to a motor model. In practice, however, motor parameters will vary at run time, and the parameter mismatch disturbances caused by the variation in motor parameters will deteriorate the MPCC performance. To suppress the parameter mismatch disturbances effectively, this paper proposes a modified MPCC with a current variation update mechanism. In contrast with the traditional current prediction equation that contains crude model parameters, the modified current prediction equation contains only measured information, taking advantage of the proposed current variation update mechanism, which can update the modified prediction equation within each sampling period. A simulation established by MATLAB software indicates that the proposed method can effectively suppress the parameter mismatch disturbances. Experiments are carried out to verify the correctness of the proposed method.

Synchronisation of uncertain chaotic systems via fuzzy-regulated adaptive optimal control approach

ABSTRACTThis study investigates the adaptive synchronisation of uncertain chaotic systems with unmodelled nonlinearities, dynamic mismatch, parametric perturbations, and external disturbances. A fuzzy-regulated adaptive optimal control (FRAOC) scheme is derived to realise chaotic synchronisation under both structure and parameter uncertainties. In the proposed scheme, the uncertain chaotic dynamics is firstly captured and estimated using a self-organising learning algorithm in an online fuzzy rule database. Based on the complicated and uncertain chaotic information, control strategy is adaptively regulated and configured in the form of weighting matrix for the subsequent optimal controller by the use of fuzzy logic inference. An adaptive optimal controller is then developed, so that its control behaviour and performance are adaptively adjusted for the chaotic synchronisation and compound uncertainty compensation. A supervisory compensator with recursive adaptation law is also designed to attenuate the residual compensation error and guarantee the synchronisation stability. Chaotic synchronisation convergence using the proposed approach can be mathematically ensured and speeded up with satisfactory robustness. Simulation results also demonstrate the effectiveness of the proposed control method in comparison with robust quadratic optimal control based on linear matrix inequality approach.

A Strongly Robust and Easy-Tuned Current Controller for PMSM Considering Parameters Variation

This paper proposes an improved internal-model-control (IMC)-based proportional-integral (PI) current controller for a permanent magnet synchronous motor (PMSM) drive system to solve the parameter dependence problem. The parameter sensitivity of the conventional IMC-based PI controller is analyzed, which indicates that the parameters mismatch would cause oscillation or overshoot. Therefore, this paper utilizes an uncertainty and disturbance estimator to eliminate the impact of the parameters mismatch disturbance caused by the parameters variation. The proposed controller includes an IMC-based PI controller, which is responsible for tracking, and a disturbance estimator, which deals with other control difficulties. The performance and robustness are easily achieved by separately tuning the only two parameters (the desired closed-loop bandwidth and the estimator bandwidth). The frequency-domain characteristic of the proposed current controller indicates that it can effectively suppress the parameters mismatch disturbance. Simulations and experiments have verified the effectiveness of the proposed method.

WORDS OF WISDOM, WORDS OF WAR: A STUDY OF TERMS AND CONCEPTS IN IV MACCABEES

In the words of Jan Willem van Henten (1997:296), the fourth book of Maccabees “presents itself to the reader, from the very beginning of the work, as a philosophical discourse about the dominance of devout reason over the emotions”. Despite the fact that the terminology and phraseology employed in this initial portrayal keeps recurring at various points throughout the book, several scholars have noticed a disturbing mismatch between the prologue and the main body of the work. This paper addresses the question whether or not IV Maccabees is structured according to a thematically unified plan, and attempts to find an answer by focusing on some philosophical terms and concepts and the ways in which these feature in the composition as a whole.

Disturbance rejection control based on state-reconstruction and persistence disturbance estimation

In this note, disturbance rejection control (DRC) based on unknown input observation (UIO), and disturbance-observer based control (DOBC) methods are revisited for a class of MIMO systems with mismatch disturbance conditions. In both of these methods, the estimated disturbance is considered to be in the feedback channel. The disturbance term could represent either unknown mismatched signals penetrating the states, or unknown dynamics not captured in the modeling process, or physical parameter variations not accounted for in the mathematical model of the plant. Unlike the high-gain approaches and variable structure methods, a systematic synthesis of the state/disturbance observer-based controller is carried out. For this purpose, first, using a series of singular value decompositions, the linearized plant is transformed into disturbance-free and disturbance-dependent subsystems. Then, functional state reconstruction based on generalized detectability concept is proposed for the disturbance-free part. Then, a DRC based on quadratic stability theorem is employed to guarantee the performance of the closed-loop system. An important contribution offered in this article is the independence of the estimated disturbance from the control input which seems to be missing in the literature for disturbance decoupling problems. In the second method, DOBC is reconsidered with the aim of achieving a high level of robustness against modeling uncertainties and matched/mismatched disturbances, while at the same time retaining performance. Accordingly, unlike the first method, DRC, full information state observation is developed independent of the disturbance estimation. An advantage of such a combination is that disturbance estimation does not involve output derivatives. Finally, the case of systems with matched disturbances is presented as a corollary of the main results.

Generalized Predictive Control for Spacecraft Attitude Based on Adaptive Fuzzy Estimator

AbstractA generalized predictive control with adaptive fuzzy estimator (GPC-AFE) is proposed for spacecraft. Model uncertainties and mismatch disturbances are considered in the process of controlle...

Big Data in Life Cycle Assessment

Big Data in Life Cycle Assessment

Robust synchronization for a class of fractional-order dynamical system via linear state variable

This paper reports the issue of robust synchronization for a class of fractional-order dynamical system with parameter mismatch and stochastic disturbance. Based on the fractional Lyapunov stability theorem, a linear controller is obtained to guarantee robust Mittag–Leffler synchronization of the fractional-order dynamical system. The gain matrix has been derived by solving the linear matrix inequality. As illustrative examples, the synchronization of fractional-order Newton–Leipnik chaotic system and fractional-order Chen hyperchaotic system are executed to verify the effectiveness of the proposed scheme.

Recent Trends in Leading Entrepreneurship Research: The Challenge for European Researchers

Recent researchers have noted differences in the culture of entrepreneurship research between the USA and Europe, with European researchers being more policy orientated, more methodologically open, more inclined to favour multidsciplinary approaches and less preoccupied with “grand theories”. The leading entrepreneurship journals are US based, and increasingly becoming dominated by theory-driven approaches to research. As the US journals are edited and reviewed by international academics, including many European ones, this apparent culture difference cannot be accounted by national culture alone. This paper discusses the notion that the drive for setting rigorous standards for achieving elite status for the journals mainly through championing rigorous theory development is driven by the needs for setting benchmarks for research selectivity in Universities in both sides of the Atlantic. This results in a disturbing mismatch between academic and applied research, as most of the funding comes from governments who need answers to important policies rather than academic questions. This is particularly a serious challenge for a majority of European researchers who depend largely on policy sources for funding.

Output feedback integral sliding mode controller of time‐delay systems with mismatch disturbances

AbstractFor uncertain time‐delay systems with mismatch disturbances, this paper presented an integral sliding mode control algorithm using output information only. An integral sliding surface is comprised of output signals and an auxiliary full‐order compensator. The designed output feedback sliding mode controller can locally satisfy the reaching and sliding condition and maintain the system on the sliding surface from the initial moment. Since the system is in the sliding mode and two specific algebraic Riccati inequalities are established, the proposed algorithm can guarantee the stability of the closed‐loop system and satisfy the property of disturbance attenuation. Moreover, the design parameters of the controller and compensator can be simultaneously determined by solutions to two algebraic Riccati inequalities. Finally, a numerical example illustrates the applicability of the proposed scheme.Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society

CHAOTIC SECURE COMMUNICATION WITH QUADRATIC OPTIMAL PERFORMANCE VIA LMI-BASED OBSERVER DESIGN

This paper considers an observer-based secure communication of chaotic systems with parameter mismatch, parametric perturbations and external disturbances on both transmitter and receiver systems. Based on the quadratic optimal control approach, a nonlinear observer is constructed to realize chaotic synchronization. The sufficient criterion for stability condition is formulated in two linear matrix inequality (LMI) forms. The error of the recovered message is then stated in an H∞ criterion. Using the proposed scheme, the global synchronization between the transmitter and the receiver can be obtained. Furthermore, the quadratic optimal and robust performance could be achieved in the chaos-based secure communication. Two numerical simulations of the Chua's circuit and the Rössler system verify the effectiveness of the proposed scheme.

Parallel Two-Sided Matrix Reduction to Band Bidiagonal Form on Multicore Architectures

The objective of this paper is to extend, in the context of multicore architectures, the concepts of tile algorithms [Buttari et al., 2007] for Cholesky, LU, and QR factorizations to the family of two-sided factorizations. In particular, the bidiagonal reduction of a general, dense matrix is very often used as a preprocessing step for calculating the Singular Value Decomposition. Furthermore, in the Top500 list of June 2008, 98 percent of the fastest parallel systems in the world were based on multicores. This confronts the scientific software community with both a daunting challenge and a unique opportunity. The challenge arises from the disturbing mismatch between the design of systems based on this new chip architecture-hundreds of thousands of nodes, a million or more cores, reduced bandwidth and memory available to cores-and the components of the traditional software stack, such as numerical libraries, on which scientific applications have relied for their accuracy and performance. The many-core trend has even more exacerbated the problem, and it becomes critical to efficiently integrate existing or new numerical linear algebra algorithms suitable for such hardware. By exploiting the concept of tile algorithms in the multicore environment (i.e., high level of parallelism with fine granularity and high-performance data representation combined with a dynamic data-driven execution), the band bidiagonal reduction presented here achieves 94 Gflop/s on a 12,000 × 12,000 matrix with 16 Intel Tigerton 2.4 GHz processors. The main drawback of the tile algorithms approach for the bidiagonal reduction is that the full reduction cannot be obtained in one stage. Other methods have to be considered to further reduce the band matrix to the required form.

ADAPTIVE OBSERVER BASED SYNCHRONIZATION OF A CLASS OF UNCERTAIN CHAOTIC SYSTEMS

This study addresses the adaptive synchronization of a class of uncertain chaotic systems in the drive-response framework. For a class of uncertain chaotic systems with parameter mismatch and external disturbances, a robust adaptive observer based on the response system is constructed to practically synchronize the uncertain drive chaotic system. Lyapunov stability theory ensures the practical synchronization between the drive and response systems even if Lipschitz constants on function matrices and bounds on uncertainties are unknown. Numerical simulation of two illustrative examples are given to verify the effectiveness of the proposed method.

Design and characterization of a high-precision resistor ladder test structure

A new subsite stepped multiresistor test structure is introduced. This test structure is used for studying and improving small resistance mismatch patterns in resistor ladders for high-resolution analog-to-digital converter applications. By utilizing wafer prober subsite movements and contact pad cross connections in the test structures, in combination with a Kelvin measurement method and dedicated statistical data evaluation technique, this approach enables identification of very small (<0.05%) systematic resistance mismatch patterns in realistic high- precision resistor ladder implementation. The most disturbing mismatch pattern was found to be caused by mechanical stress from the resistor ladder head layout, while others are attributed to decananometer scale reticle writing artefacts.