Dynamics Of Control System Research Articles

On the Problems of Optimal and Minmax Type Control Under Vector Criteria

The topic of this paper is to solve two types of problems in controlled system dynamics formulated in terms of vector-valued criteria whose application depends on the type of ordering for the scalar participants of each such criterion. The first problem is that of optimal control under vector criterion with ordering of the Pareto type. The problem is to indicate the dynamics of the Pareto front. The second is that of finding vector-valued controls of the minmax type. Here the internal problem of dynamic maximization is due to a vector criterion with given type of ordering while the external problem is that of vector-valued dynamic minimization under another type of ordering. A similar situation arises for controls of the maxmin type. The paper indicates a variety of solution formulas that describe vector-valued dynamic interrelations for the problems of minmax and maxmin. The solutions are reached by using the Hamiltonian formalism. The suggested vector type of control problem settings are motivated by structure of system dynamics for physical motions, economics, finance, environmental models and related issues. Examples of applications are indicated.

Design of Head-Pursuit Guidance Law Based on Backstepping Sliding Mode Control

In order to meet the needs of high-precision guidance for intercepting hypersonic targets, a novel head-pursuit guidance law considering the dynamic characteristics of a missile control system and the target mobility is presented via combining a fast power reaching law with backstepping sliding mode control in this paper. Initially, a three-dimensional head-pursuit system model of the missile and target is established. Subsequently, the system model is decomposed into a pitch plane system and lateral plane system, the control system dynamics are equivalent to second-order systems, and finite-time disturbance observers are introduced to estimate the target accelerations. On the basis of the previous work, the head-pursuit guidance laws of the vertical system and the lateral system which can stabilize the closed-loop system are designed separately and strict proofs of the methods are given. Finally, simulations are carried out to verify the effectiveness of this head-pursuit guidance law.

New results on cycle–slipping in pendulum–like systems

n this paper, we examine dynamics of multidimensional control systems obtained as feedback interconnections of stable linear blocks and periodic nonlinearities. The simplest of such systems is the model of mathematical pendulum (with viscous friction), so we call such systems pendulum-like. Other examples include, but are not limited to, coupled vibrating units, networks of oscillators, Josephson junction arrays and numerous synchronization circuits used in radio and telecommunication engineering. Typically, a pendulum-like system has infinite sequence of equilibria, and one of the central problems addressed in the theory of such systems is to find the conditions of “global stability”, or gradient-like behavior ensuring that every solution converges to one of the equilibria points. If a system is gradient-like, another problem arises, being the main concern of this paper: can we find the terminal equilibrium, given the initial condition of the system? It is well known that solutions do not converge, in general, to the nearest equilibrium; this phenomenon is known as cycle-slipping. For a pendulum, cycle-slipping corresponds to multiple rotations of the pendulum about its suspension point. In this paper, we estimate the number of slipped cycles for general pendulum-like systems by means of periodic Lyapunov functions and the Kalman-Yakubovich-Popov lemma.

Compensation‐based data‐driven ILC with input and output package dropouts

SummaryThis paper explores the problem of random data loss at both input and output sides and proposes a compensation‐based data‐driven iterative learning control (cDDILC) to refrain from deteriorating of the control performance due to the data loss. A linear data model is first established to describe the input‐output dynamics of a repetitive control system in the iteration domain. The linear data model, which only virtually exists in the computer without any physical backgrounds, is employed as a predictive model to estimate and compensate the lost output data. Meanwhile, the lost input data is replaced by the corresponding input of the same time instant in the latest previous iterations. Then, a cDDILC is proposed by introducing two Bernoulli random variables to describe the stochastic data loss at both input and output sides. The proposed cDDILC method is data driven and independent of a precise plant model. Although the design and analysis of the cDDILC start from a MIMO linear repetitive system, one can easily extend the results to a MIMO nonlinear nonaffine one. Theoretical analysis and simulations confirm the efficiency of the proposed cDDILC method.

A Full Hydrodynamic Consideration in Control System Performance Analysis for an Autonomous Underwater Vehicle

Autonomous underwater vehicles (AUVs) have important applications in several areas such as data collection, geological survey and exploration in underwater environment. The hydrodynamic forces acting on AUVs are highly nonlinear and the higher-order hydrodynamic coefficients should be taken into account to represent these nonlinear behaviors. Therefore, developing a suitable dynamic model of the AUV and also an accurate knowledge about the hydrodynamic parameters are important for proper design of the navigation and control system. The main goal of the present paper is to investigate the role of proper dynamic model for an AUV which includes different hydrodynamic stability derivatives coefficients. Design of proper actuator is also significant for the global performance of the system and the expenses of the plan. It is tried in the present paper to investigate the effect of full hydrodynamic coefficients on the design of actuators and control system performance analysis for an AUV which was ignored in the previous works. For this purpose, the effect of these parameters on the open loop characteristics of the AUV, its role in the control system design and the interaction of control system and actuator dynamics are considered in nonlinear time domain and frequency domain. It is shown that in a full hydrodynamic consideration for design of the AUV, the effect of control gains, system bandwidth and damping can be different in comparison with the cases which are not fully considered them. Finally, the design of optimum actuator and the effect of actuator natural frequency on the flight performance in the presence of full hydrodynamic coefficients are studied.

Nonlinear Controller with the Enhanced Resistance to Electromagnetic Disturbances

The controller, which provides the control system dynamics similar to PID controller, but guarantees higher resistance of the control system to electromagnetic disturbances, has been proposed. The controller is similar to Proportional Integral (PI) controller. Distinctive feature of the controller is that the impact of the proportional term on the controller output signal is proportional to the control error raised to a power. The controller investigation results and their comparison with the results obtained using popular PID and PI controllers are presented.

GEOLOGICAL-TECHNOLOGICAL COMPLEX EFFICIENCY IN THE SYSTEMOLOGY OF COMPOSITE LEVELS. PART 1. EFFICIENCY ASSESSMENT OF OIL PRODUCTION PROCESSES AT SYSTEM LEVEL

The article describes a method for determining systemic efficiency based on a comparative assessment of classical continuous and discontinuous-coordinate oil displacement technologies. This is due to the need to direct the analysis of the increase in oil recovery factor in real time. The aim of the work is to determine the system economic efficiency in the given indicators. The achievement of this goal is based on the methods of economics in oil field geology and geophysics, control theory and systemology. First, directions of feasibility are considered that ensure the obtaining of the reduced forms of the effectiveness of the geological and technological complex (GTC) in comparison with the absolute and relative estimates in the classical continuous oil displacement technologies. It has been established that for the intra-level system characteristic of the efficiency of the GTC, consideration is needed of interacting subsystems in the dynamics of oil production control systems. It is shown that to derive a generalized indicator of systemic efficiency, it is necessary to perform a comparative description and justification in the use of economic, technological, organizational, economic and investment components of efficiency in the implementation of the most complex late and final stages of development of oil and gas deposits.

A general model of hormesis in biological systems and its application to pest management.

Hormesis, a phenomenon whereby exposure to high levels of stressors is inhibitory but low (mild, sublethal and subtoxic) doses are stimulatory, challenges decision-making in the management of cancer, neurodegenerative diseases, nutrition and ecotoxicology. In the latter, increasing amounts of a pesticide may lead to upsurges rather than declines of pests, ecological paradoxes that are difficult to predict. Using a novel re-formulation of the Ricker population equation, we show how interactions between intervention strengths and dose timings, dose–response functions and intrinsic factors can model such paradoxes and hormesis. A model with three critical parameters revealed hormetic biphasic dose and dose timing responses, either in a J-shape or an inverted U-shape, yielding a homeostatic change or a catastrophic shift and hormetic effects in many parameter regions. Such effects were enhanced by repeated pulses of low-level stimulations within one generation at different dose timings, thereby reducing threshold levels, maximum responses and inhibition. The model provides insights into the complex dynamics of such systems and a methodology for improved experimental design and analysis, with wide-reaching implications for understanding hormetic effects in ecology and in medical and veterinary treatment decision-making. We hypothesized that the dynamics of a discrete generation pest control system can be determined by various three-parameter spaces, some of which reveal the conditions for occurrence of hormesis, and confirmed this by fitting our model to both hormetic data from the literature and to a non-hormetic dataset on pesticidal control of mirid bugs in cotton.

Controlling Best Response Dynamics for Network Games

Controlling networked dynamical systems is a challenging endeavor, specifically keeping in mind the fact that in many scenarios the actors engaged in the dynamism behave selfishly, only taking into account their own individual utility. This setting has been widely studied in the field of game theory. One way we can control system dynamics is through the use of control parameters that are at our disposal, but finding optimal values for these parameters is complex and time consuming. In this paper we use the relation between network structural properties and control parameters to create a mathematical model that speeds up the calculation of the aforementioned values. For this, we use learning methods to find optimal values that can control the system dynamics based on the correlation between structurally similar networks.

Online control of combine reel height in presence of farm roughness using an on-off controller

Adjusting the harvesting combine reel height in presence of the farm rough surface reduces the harvest losses, prevents possible damage to the headland and increases gravel harvest. Regarding the importance of the issue, in this study, the dynamics of the reel height control system of the John Deere1055 combine was modeled and the controllability and observability of the obtained transfer function is determined in state space. After that, with the aim of cutting the stem from a suitable point, an on-off controller is designed to keep the reel height from the ground in a permitted range. At this stage, a reduced model system is used as an approximated system to design a controller. The designed controller is simulated in MATLAB. In this simulation, the roughness of the ground was considered as the control loop noise with the normal probability distribution function. The results confirm that the reel height change is kept in the specified range against the farm roughness. The laboratory sample was also constructed using an independent excitation circuit DC motor, an optical distance sensor, and a micro controller. The experimental test shows that the height control system responses to changes in surface height at an appropriate speed without any oscillation in range.

Wave spectral analysis for design of a spar floating wind turbine in Mediterranean Sea

Floating offshore wind turbines (FOWTs) represent one promising concept for renewable energy production. However, the quantitative description of their dynamic behavior is extremely challenging, since it depends on the coupled effects of turbine aerodynamics, control system, hull hydrodynamics and mooring dynamics. In this context, hydrodynamic damping is a major source of uncertainty, particularly for relatively slender structures, such as spars. The aim of the present paper is to provide quantitative estimations of hydrodynamic damping ratios, natural frequencies and response spectra of the six rigid body motions of a spar FOWT under a wide range of wave conditions, including wind-generated sea states, swells and mixed seas. To this aim, the results of an open-sea experiment on a 1:30 model of OC3-Hywind spar in parked rotor conditions, carried out at the Natural Ocean Engineering Laboratory (NOEL) of Reggio Calabria (Italy), are analyzed and discussed. The above-mentioned dynamic properties of the model are estimated through the spectral analysis of the rigid body motion time series collected during the experiment, classified depending on the input wave conditions. As a result, quantitative estimations of the dynamic properties of the model are provided, which can be used as input values for numerical models of the full-scale structure. Hydrodynamic damping ratios are estimated, including their variability depending on sea conditions, due to nonlinearity. Also, motion response spectra obtained for wind-generated waves can be easily scaled-up to achieve a reasonable representation of the full-scale structure response under a range of relevant design conditions. Finally, additional information about nonlinear effects, coupling between degrees of freedom and close-to-resonance behavior of the model are drawn and commented.

Parametrical Non-Complex Tests to Evaluate Partial Decentralized Linear-Output Feedback Control Stabilization Conditions from Their Centralized Stabilization Counterparts

This paper formulates sufficiency-type linear-output feedback decentralized closed-loop stabilization conditions if the continuous-time linear dynamic system can be stabilized under linear output-feedback centralized stabilization. The provided tests are simple to evaluate, while they are based on the quantification of the sufficiently smallness of the parametrical error norms between the control, output, interconnection and open-loop system dynamics matrices and the corresponding control gains in the decentralized case related to the centralized counterpart. The tolerance amounts of the various parametrical matrix errors are described by the maximum allowed tolerance upper-bound of a small positive real parameter that upper-bounds the various parametrical error norms. Such a tolerance is quantified by considering the first or second powers of such a small parameter. The results are seen to be directly extendable to quantify the allowed parametrical errors that guarantee the closed-loop linear output-feedback stabilization of a current system related to its nominal counterpart. Furthermore, several simulated examples are also discussed.

Aging changes complexity of heart rate dynamics assessed by entropy and Lyapunov exponent analysis

In recent years, many research groups are trying to quantify the physiological signals of an individual, proposing new models to assess the complex dynamics of biological control systems. Indeed, life coincides with the good handling of the structures in the organism and of physiological control mechanisms, while disease and death coincide with the loss of structure and of coordinated functions. The homeodynamic systems which normally govern health are the same that cause pathological events when activated inadequately, or rather, when the balance between order and chaos of the elementary physiological processes is no longer effectively controlled in relation to any type of stress, both external and internal to the body. In a complex system, loss or alteration of communication between physiological signals means pathology. In this paper a signal analysis method based on Entropy (E), Lyapunov exponent (1), Median Absolute Deviation (MAD), Multiscale Entropy (MSE), is proposed to estimate the complexity of long-range temporal correlation heart rate (HR) time series for an elderly person and a young person both healthy. These new methods could improve overall understanding of the physiological system of the human organism, by adopting new models and experimental paradigms, such as those of fractality and entropy, who have the ability to direct from an organ medicine to a modern systemic medicine.

Zero dynamics for networks of waves

The zero dynamics of infinite-dimensional systems can be difficult to characterize. The zero dynamics of boundary control systems are particularly problematic. In this paper the zero dynamics of port-Hamiltonian systems are studied. A complete characterization of the zero dynamics for port-Hamiltonian systems with invertible feedthrough as another port-Hamiltonian system on the same state space is given. It is shown that the zero dynamics for any port-Hamiltonian system with commensurate wave speeds are a well-posed system, and are also a port-Hamiltonian system. Examples include wave equations with uniform wave speed on a network. A constructive procedure for calculation of the zero dynamics that can be used for very large system order is provided.

UKF-based Identification of Time-Varying Manual Control Behaviour

This paper describes a novel method for time-varying identification of Human Controller (HC) manual control parameters (called UKF-FPV), based on a steady-state (constant state covariance) Unscented Kalman Filter (UKF). This approach requires no a priori assumptions on the shape of HC parameter variations, which is a potential advantage over state-of-the-art methods such as the recently proposed MLE-APV approach, for which a sigmoid-shaped parameter variation is assumed. For a scenario where an HC performs a single-loop compensatory tracking task with time-varying controlled system dynamics, both identification methods are compared using Monte Carlo simulations and human-in-the-loop experiment data. Despite some lag in the HC parameter traces of UKF-FPV, the identification results and the HC model quality-of-fit obtained with both methods were found to match well for both the simulation and experiment data. For the experiment data, UKF-FPV even revealed clear "local" changes in HC parameters not captured by the MLE-APV approach, which confirms that HCs adapt unpredictably even in what are considered time-invariant conditions. Overall, the results show that an identification method that requires no a priori assumptions on HC parameter variations is of critical importance for a complete analysis of time-varying HC behaviour.

Information technology for management support of socio-economic security

The issues related to computer aids development for management information support in the field of regional security are discussed. A modern information technology for management life-cycle support of socio-economic security has been developed. The technology is based on complex system control theory, conceptual modeling, system dynamics and project management methods implementation. That provides simulation models automated synthesis to the aim of possible negative effects analysis of project implementation influencing on the state of socio-economic security, and on the basis of simulation results analytical information generation for a set of counteraction measures development corresponding to identified regional security threats.

Formal Methods for Discrete-Time Dynamical Systems [Bookshelf

Cyberphysical systems (CPSs) are the next generation of engineered systems that consist of several computing devices communicating with each other and interacting with the physical world via sensors and actuators. These complex systems are ubiquitous and can be found in automobiles, aircraft, and smart buildings. Researchers using formal methods have introduced notions of physicality into automata, called hybrid automata. The challenge with these techniques is verifying the discrete aspects of the hybrid systems, given the control system dynamics. This book is organized into three parts and one appendix. Part I, “Transition Systems, Automata, and Temporal Logics,” discusses the types of systems and specifications used throughout this book (Chapters 1 and 2). Part II, “Analysis and Control of Finite Transition Systems,” focuses on verification and control synthesis problems for finite transition systems from specifications as linear temporal logic (LTL) formulas (Chapters 3−5). Part III, “Analysis and Control of Discrete-Time Dynamical Systems,” introduces the computational frameworks for verification and control of (infinite) discrete-time dynamical systems from LTL specifications, which is the most extensive part of this book. This monograph gives a complete picture of formal methods for the two classes of discrete-time systems. It covers a wide range of advanced and fascinating topics from both computer science and control theory. This is a valuable textbook for beginners and/or experienced researchers from these two domains. Readers from computer science gain a brief introduction to control systems and further see how formal method ideas can be expanded to address these huge challenges. Meanwhile, readers with a control theory background gain a foundational introduction to specifying the system behavior in terms of temporal logic and learn how to connect their models to discrete models using bisimulation. This book is self contained and can be used in senior undergraduate-level and/or graduate-level courses. Furthermore, readers can pursue the relevant topics of interest using the bibliographical notes at the end of each chapter. Inevitably, there exist some editing typos and grammatical errors, as well as minor, insufficient descriptions. However, these errors do not hinder the book’s readability and understandability. Overall, this research monograph will serve as a fundamental and foundational introduction to this emerging and vibrant field.

Improved linearised models of wind turbine aerodynamics and control system dynamics using harmonic linearisation

Where non-linearities are not too strong, linearised frequency-domain approaches offer fast calculations, which can be valuable for preliminary design of wind turbine blades, foundations and floating platforms. But the aerodynamic and control system behaviour of a wind turbine is noticeably non-linear. Here we show for the first time that the technique of harmonic linearisation can reduce error in the approximation of aerodynamic and control system non-linearities, compared to the more common tangent linearisation. After deriving the linearised models, comparing linearised results to non-linear simulations for the NREL 5 MW turbine shows that: (1) harmonic linearisation captures aero-elastic effects and non-linearity in aerodynamic forces, giving a 2–4x reduction in error compared to the tangent linearisation; (2) harmonic linearisation can capture non-linear wake dynamics; and (3) the torque and pitch controller behaviour can be approximated with good results away from the rated wind speed but with some challenges when the two controllers interact. Further improvements in the linearised model of the control system have been identified. By improving the accuracy of linearised models, harmonic linearisation is a promising means to extend the applicability of frequency-domain approaches for initial design and optimisation of wind turbines.

Iterative Frequency-Domain Response of Floating Offshore Wind Turbines with Parametric Drag

Methods for coupled aero-hydro-servo-elastic time-domain simulations of Floating Offshore Wind Turbines (FOWTs) have been successfully developed. One of the present challenges is a realistic approximation of the viscous drag of the wetted members of the floating platform. This paper presents a method for an iterative response calculation with a reduced-order frequency-domain model. It has heave plate drag coefficients, which are parameterized functions of literature data. The reduced-order model does not represent more than the most relevant effects on the FOWT system dynamics. It includes first-order and second-order wave forces, coupled with the wind turbine structural dynamics, aerodynamics and control system dynamics. So far, the viscous drag coefficients are usually defined as constants, independent of the load cases. With the computationally efficient frequency-domain model, it is possible to iterate the drag, such that it fits to the obtained amplitudes of oscillation of the different members. The results show that the drag coefficients vary significantly across operational load conditions. The viscous drag coefficients converge quickly and the method is applicable for concept-level design studies of FOWTs with load case-dependent drag.

The design of a vibration control system for an aluminum plate with piezo-stripes based on residues analysis of model

.The design process of an active vibration control system for many mechanical structures using smart devices requires determining reduced and precise mathematical models. Such requirements cause orthogonal methods to be used and carefully analyzed. In the present paper, a plate with two simple supported edges and two free edges (SFSF) is an object of consideration. It is known that this structure represents a flexible structure wherein high natural frequencies are separated from low frequencies because they are naturally damped. Thus, in order to estimate the dynamical features of the control system, some orthogonal methods, such as the Schur and modal decomposition, were applied. A detailed analysis of the chosen methods showed us that each of them properly generates resonance frequencies while calculating different values of the anti-resonance frequencies. From the strategy control point of view, it is known that the anti-resonances play an essential role because they directly influence the dynamics of the whole control system. Thus, in order to check this behavior, different controllers are designed for various reduced models and, next, they are applied in a real mechanical structure. The dynamical behavior of the control systems with such controllers was analyzed and tested on a laboratory stand. In conclusion, we should carefully choose model reduction methods in the design process of the vibration control system. The sum of the residues of the reduced model appeared to be the best indicator during the choice process of the reduction method. It is particularly important when we design the vibration control system for a non-existent yet, but newly designed, structure.