Control Of Dynamic System Research Articles

Temperature evolution in heated premises and external boundary wall with dynamic control of heating systems

Abstract The study presents a mathematical model for building heating control. The buildings are connected to district heating or to central heating. The task of the heating control is to maintain a preset constant indoor air temperature. Control disturbance is caused by external meteorological conditions, firstly by outdoor air temperature. The control action can be the change in heat transfer capacity of the radiators, whereby the indoor air temperature can be commanded back to the present value to offset the effect of the disturbance. Just the control can be a follower or of predictive type. The expected indoor air temperature can be calculated from the energy balances. These are composed of differential equations, describing dynamic equilibrium of heat transfer through the external walls, as well as heat storage in the walls and indoor air. Type of differential equations is linear, inhomogeneous, of first or second order. Solution of the differential equation results in describing the change in indoor air temperature in time as a function of outdoor air temperature. Further on, the equation determines the function of the necessary heating capacity to keep the indoor air temperature constant. By the model several heating programs can be evaluated. The physical model is shown in Fig. 1. Intermediate variable is the average temperature of the external walls. Heat conduction and convection through the walls is calculated by the difference of the indoor air temperature and of the average wall temperature by using relevant R 1 and R 2 heat resistance factors. The model is adequate when the heat transport within the building sections is neglectable, and the thermodynamic and heat transfer characteristics of the walls are identical. Thereby the model describes the heat balance of representative premises, but the results can be transferred to similar other premises, too.

Modular SEPIC-Based Isolated dc–dc Converter with Reduced Voltage Stresses across the Semiconductors

This paper presents the theoretical analysis, experimental results and generalized structure for N modules of an isolated dc–dc SEPIC converter. The structure comes from the integration of N conventional SEPIC converters based on the input-series and output-parallel connection. The main advantages provided by the proposed structure are reduced voltage stress across the semiconductors and division of the current stress in the output diodes. The proposed converter is presented in a generalized approach, varying the voltage stress across the semiconductors according to the number of modules used. As the converter uses more than one switch, the commands can be either equal or phase-shifted by 360∘/N degrees. When operating with phase-shift modulation, a multilevel converter is obtained, which brings another advantage of the structure, since there is a reduction in the volume of the input inductors (Li1 and Li2) and the output capacitor (Co). In this paper, the steady-state analysis, a dynamic model, system control and experimental results are presented for phase-shift modulation and discontinuous conduction mode (DCM). The performance of the proposed converter was verified in a prototype with four modules and the following specifications: 500 W output power, 800 V input voltage, 120 V output voltage and 50 kHz switching frequency. The converter achieved 94.42% efficiency at rated power.

Combination of fractional-order, adaptive second order and non-singular terminal sliding mode controls for dynamical systems with uncertainty and under-actuation property

This paper introduces a new type of control strategy for dynamical systems subjected to uncertainties. The suggested controller combines the capabilities of sliding mode control with fractional-order control and a specified adaption law. The stability of the closed-loop system is examined based on Lyapunov stability theory. This control scheme can be employed in many conventional systems; however, in this paper, we try to apply it to an under-actuated system as a novel extension to the variety of its applications. The idea originates from the practical features of fractional calculus including the facts that the fractional derivative has a memory of past values and it preserves a large stability region and has more free parameters to enhance the performance of the controller. Computer simulations are included to highlight the efficiency and applicability of the proposed controller in control of an under-actuated system even in the presence of parameter uncertainties.

Three-Dimensional Dynamic Formation of Second-Order Multi-Agent System Based on Rigid Graphs

This paper studies the dynamic formation control of second-order multi-agent systems (MASs) in three-dimensional space based on the distance control approach. A rigid graph represents the communication topology between agents to improve the system’s robustness and stability and avoid collisions and deformations during formation operation. A distributed control strategy based on the relative states among neighbors is designed for each agent to achieve formation and formation maintenance under arbitrary initial conditions. The Lyapunov function, an error function of potential and kinetic energy, is constructed by rigid graph theory and a second-order integrator model. The decreasing of the Lyapunov function is proven by Barbalat’s theory, further indicating that the system is asymptotically stable. A second-order MAS composed of nine agents is constructed, and the dynamic scaling of rigid formations in 3D space is achieved through simulation to verify the effectiveness of the controller and the correctness of the theory.

Controllability and observability for fractal linear dynamical systems

In the present paper, we investigate the controllability, and observability of a non-homogeneous continuous-time fractal dynamical system (NC-TFDS). We show that the controllability is equivalent to a controllability matrix that has a full rank. We also show a relationship between controllability and fractal differential Lyapunov equation (F-DLE). We give some theorems for the observability of a NC-TFDS. Finally, we offer two examples are provided to illustrate the effectiveness of our results and compare it with the two papers Al-Zhour (2022) and (Sadek et al., 2022).

Fully Distributed Dual-Terminal Event-Triggered Bipartite Output Containment Control of Heterogeneous Systems Under Actuator Faults

This article deals with the fully distributed dual-terminal dynamic event-triggered bipartite output containment control of heterogeneous linear multiagent systems (HLMASs) subject to actuator faults. First, a class of fully distributed dynamic event-triggered observers is proposed over the directed signed communication network for each follower to estimate the leaders’ system matrices and (symmetric) combination states, which are merely available to a small fraction of followers. Then, based on the estimations of leaders’ system matrices, adaptive algorithms are employed to solve the regulator equations. Furthermore, the fully distributed observer-based dynamic event-triggered controllers are proposed by integrating the adaptive gains to compensate for actuator faults. Dual-terminal dynamic event-triggered mechanisms (ETMs) are addressed to exclude not only continuous control updates but also continuous communication among agents. Correspondingly, some mild criteria and the rigorous proofs are established to ensure the implementation of bipartite output containment through the Lyapunov stability theory. Moreover, the strictly positive lower bounds of intervals between two adjacent event-triggered time instants are derived, which indicates that Zeno behavior is ruled out in the dual-terminal dynamic ETMs. Finally, numerical simulations are performed to demonstrate the theoretical analysis.

Response Adjustability Analysis of Partial and Ordinary Differential Coupling System for Visco-Elastomer Sandwich Plate Coupled with Distributed Masses under Random Excitation via Spatial Periodicity Strategy

Vibration control of composite structures coupled with distributed masses under random excitations is a significant issue. In this paper, partial and ordinary differential coupling equations are obtained from a periodic sandwich plate coupled with supported masses under random excitation. An analytical solution to the coupling equations is proposed, and the stochastic response adjustability of the system with various periodic distributions of geometrical and physical parameters is studied. Spatial periodic layer thickness and core modulus of the sandwich plate are considered based on the active‐passive periodicity strategy. The periodically distributed masses are supported on the plate by coupling springs and dampers. Partial and ordinary differential coupling equations for the system including the periodic sandwich plate and supported masses are derived and then converted into unified ordinary differential equations for multi-mode coupling vibration. Generalized system stiffness, damping and mass are functions of the periodic parameters. Expressions of frequency response function and response spectral density of the system are obtained. Numerical results show the response adjustability via the spatially periodic geometrical and physical parameters. The results have the potential for application to dynamic control or optimization of sandwich structure systems.

Tracking error constraint-based adaptive dynamic surface control of electro-hydraulic manipulator system

Tracking error constraint-based adaptive dynamic surface control of electro-hydraulic manipulator system

Application of Super Photoacids in Controlling Dynamic Processes: Light-Triggering the Self-Propulsion of Oil Droplets.

The dynamic control of pH-responsive systems is at the heart of many natural and artificial processes. Here, we use photoacids, molecules that dissociate only in their excited state and transfer their proton to nearby proton acceptors, for the dynamic control of processes. A problem arises when there is a need to protonate highly acidic acceptors. We solve this problem using super photoacids that have an excited-state pKa of -8, thus enabling them to protonate very weak proton acceptors. The process that we target is the light-triggered self-propulsion of droplets, initiated by an excited-state proton transfer (ESPT) from a super photoacid donor to a surfactant acceptor situated on the surface of the droplet with a pKa of ∼0. We first confirm using steady-state and time-resolved spectroscopy that a super photoacid can undergo ESPT to the acidic surfactant, whereas a "regular" photoacid cannot. Next, we show self-propulsion of the droplet upon irradiating the solvated super photoacid. We further confirm the protonation of the surfactant on the surface of the droplet using transient surface tension measurements. Our system is the first example of the application of super photoacids to control dynamic processes and opens new possibilities in the field of light-triggered dynamic systems.

Stability and controllability of fuzzy singular dynamical systems

This paper is assigned to study the stability and controllability of fuzzy singular dynamical systems. Some new notions such as granular fuzzy matrix norm, the algebraic operations on the space of fuzzy matrices, fuzzy equilibrium point, and the granular fuzzy transfer function of fuzzy singular dynamical systems are introduced. Furthermore, by presenting some theorems proved in this paper, the fuzzy solutions of fully fuzzy singular dynamical systems are obtained. Moreover, some new notions regarding the analysis of the stability of fuzzy singular dynamical systems are given. The stability analysis underlies the concepts of fuzzy stable, fuzzy critical stable, and fuzzy unstable singular dynamical systems. Besides using the notions of controllability of the fuzzy slow and fast subsystems, the concept of granular controllability of the fuzzy singular dynamical system is investigated.

Trajectory controllability of nonlinear fractional Langevin systems

Abstract In this paper, we discuss the trajectory controllability of linear and nonlinear fractional Langevin dynamical systems represented by the Caputo fractional derivative by using the Mittag–Leffler function and Gronwall–Bellman inequality. For the nonlinear system, we assume Lipschitz-type conditions on the nonlinearity. Examples are given to illustrate the theoretical results.

Predictor-Based Neural Dynamic Surface Control of a Nontriangular System With Unknown Disturbances

For a class of nontriangular nonlinear systems in presence of unknown disturbances, we propose a predictor-based neural dynamic surface control (PNDSC) strategy in this paper. This nontriangular system is transformed via the mean value theorem, and a predictor is then constructed. To avoid an algebraic loop problem, partial state vectors are employed as input signals of neural networks (NNs) for approximating unknown dynamics, and compensation items are designed to compensate for approximation errors from NNs. Different from the traditional NDSC, the PNDSC in this paper utilizes prediction errors to update learning parameters for improving NNs’ learning behaviors with overlarge adaptive gains. On the basis of improved NNs’ approximation behaviors, a predictor-based NNs disturbance observer (PNNDO) is constructed for compensation for external disturbances and approximation errors from NNs. Furthermore, with predictors, a normalization method of weights is developed to reduce the number of online learning parameters. On the basis of the aforementioned result, measurement noises are taken into account in our predictor-based neural control strategy. We employ predictor states, rather than measurement information paralyzed by noises, in design of our control strategy. This reduces high-frequency oscillations in control input. A Lyapunov-based stability analysis shows that all signals are ultimately bounded in the closed-loop system. Finally, the effectiveness of the proposed control strategy is verified by a numerical example and a permanent magnet brushless DC motor system.

Reduction of Band Matrices in Large Dynamic Systems Controllability and Observability

An approach is proposed for linear stationary dynamical system with controllability and observability band matrices making it possible to simplify procedures for evaluating controllability and observability of this system. The obtained results are based on the fact that the controllability and observability criteria of a dynamic system are equivalent due to their required and sufficient properties; therefore, any transformations of one criterion not violating the conditions of necessity and sufficiency could be reduced to transformations in a sense equivalent to the initial transformations. The Popov --- Belevich --- Hautus transformations of the controllability and observability criteria were taken as a basis, and then results of such transformations were correctly extended to the band criteria. It was proved that the controllability and observability analysis of a linear stationary system with a large number of the state dimensions was reduced to studying the matrices rank of a much smaller size. The proposed approach is based on the existence condition for a numerical matrix of a certain rank of the nondegenerate matrices that satisfy certain transformations. The corresponding controllability and observability theorems for the stationary dynamical systems were provided. It was shown that for systems with one input and one output, the controllability and observability analysis was reduced to the analysis of scalars

The nonlinear dynamic characteristics analysis and vibration reduction control of the shafting system of a hydropower unit

The shafting system of a hydropower unit is accompanied by radial, axial, and torsional multi-dimensional coupled vibrations that are a serious threat to the reliability and security of the unit. However, the nonlinear dynamic characteristics and vibration reduction control of these vibrations are rarely studied. Therefore, in this study, a nonlinear model of the multi-dimensional coupled vibrations of a shafting system of conventional and pumped storage units that are excited by multi-coupled vibration sources is first established. Subsequently, the Sobol method is introduced to analyze the global sensitivity of the parameters corresponding to the mean amplitude of these vibrations. Additionally, the nonlinear dynamic behaviors of the most sensitive parameters are determined using bifurcation diagrams. Furthermore, a state feedback controller, the design principle of which is based on the Euler–Lagrange error equation and Lyapunov theory, is designed for these vibrations, and the nonlinear dynamic behaviors of the controller parameters are obtained using bifurcation diagrams. Finally, the nonlinear dynamic response characteristics of these vibrations with and without control are revealed using phase-space trajectories, Poincare cross-sections, time-domain diagrams, and frequency domain diagrams. Notably, the guide bearing stiffness coefficients have the greatest influence on these vibrations and the state feedback controller can significantly reduce the amplitude of the shafting vibrations. More importantly, the proposed dynamic models and analysis results reveal that the generator and hydro-turbine vibrations are quasi-periodic and composed of several frequency components in a three-dimensional space and the torsional vibration of the shaft is stable with a small torsional angle. These results can serve as a guideline for the safe and stable design and operation of hydropower units.

Featured Cover

The cover image is based on the Research Article Adaptive dynamic surface asymptotic tracking control of uncertain strict-feedback systems with guaranteed transient performance and accurate parameter estimation by Wenrui Shi et al., https://doi.org/10.1002/rnc.6170.

Modeling of Satellite Constellation in Modelica and a PHM System Framework Driven by Model Data Hybrid

The new generation of low-earth-orbit (LEO) satellite constellation systems has the characteristics of low delay, strong signal and global coverage, and it is an important direction for the development of next-generation communication technology. A major disadvantage is that the constellation system is huge, often composed of hundreds or thousands of satellites, which puts forward high requirements for the design and health management of the constellation system, and the existing telemetry data monitoring system cannot meet the actual needs. CPS is a multidimensional complex system that integrates computation, communication and control (3C). Through the deep integration and cooperation of 3C, the real-time monitoring and dynamic control of large-scale engineering systems are realized, which is completely suitable for the operation and maintenance requirements of the satellite constellation system. This paper firstly establishes the entire satellite constellation system model, which is integrated from the satellite multidomain system, the constellation orbit environment system and the communication link system. Then, according to the technical concept of cyber-physical systems (CPS), an implementation framework of a prognostics and health (PHM) system driven by a model–data hybrid for satellite constellation systems is proposed. The framework is based on model simulation data and telemetry data and combines virtual and real data fusion, fault diagnosis, simulation prediction and other technologies to generate enhanced data to drive the effective operation of the PHM system. Finally, a verification case is designed to prove that the satellite constellation health management system implemented under this framework has a positive effect on the reliable operation and maintenance of the satellite constellation system.

Distributed dynamic rendezvous control of the AUV-USV joint system with practical disturbance compensations using model predictive control

This paper addresses the distributed dynamic rendezvous control problem of the AUV-USV heterogeneous joint system in the presence of unknown external disturbances using nonlinear model predictive control. By utilizing the nonlinear model predictive control framework, the rendezvous problem can be solved without constructing explicit error dynamics of the heterogeneous system. The inputs and states constraints such as spatial and velocity constraints can also be considered simultaneously in an intuitive way. To facilitate distributed implementations, distributed optimization problems with incorporated moving suppression are then constructed to guarantee nominal stability. Considering unknown external disturbances, a practical disturbance compensating method is finally proposed, ensuring the satisfaction of state constraints. The nominal recursive feasibility and stability are proved in this paper. Compared with existing works, the proposed scheme improves the applicability and robustness against external disturbances for dynamic rendezvous between two heterogeneous robots. Simulations and comparisons are conducted to demonstrate the effectiveness and advantages of the proposed method.

Model-Based Dynamic Event-Triggered Control for Cyber-Physical Systems Subject to Dynamic Quantization and DoS Attacks

In this article, the problem of model-based dynamic event-triggered control (ETC) of cyber-physical systems (CPSs) with dynamic quantization effects and denial-of-service (DoS) attacks is studied. With the aid of a technique combining model-based CPSs and dynamic ETC scheme, the number of transmissions is significantly reduced to save the scarce network resources. An average dwell-time (ADT) automaton and a time-ratio monitor are firstly introduced to ETC systems to describe the frequency and duration of the DoS attacks, then a unified hybrid framework of CPSs with dynamic quantizer is established. In the presence of external disturbances, quantization effects and DoS attacks, by following the emulation approach some event-triggering conditions are designed to allow the robustness, the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$L_{2}$</tex-math></inline-formula> stability and the existence of a minimum inter-event time (MIET). Relying on a novel Lyapunov function, we derive new sufficient conditions on <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$L_{2}$</tex-math></inline-formula> -gain performance of CPSs. Moreover, the Zeno phenomenon in the quantized ETC system is excluded due to the existence of a positive MIET. Finally, a numerical example is provided to demonstrate the feasibility of the approach proposed in this paper.

Guest Editorial: Situational awareness of integrated energy systems

Guest Editorial: Situational awareness of integrated energy systems

Event-triggered output feedback dissipative control of nonlinear systems under DoS attacks and actuator saturation

This paper presents a novel event-triggered dynamic output feedback dissipative control of nonlinear systems under intermittent denial-of-service (DoS) attacks and actuator saturation. Firstly, based on attack information, a secure event-triggered mechanism (ETM) is introduced, which not only saves systems resources but also is Zeno-free and resilient to DoS attacks. Secondly, a switched T–S fuzzy closed-loop system model is built, which unifies the parameters of nonlinear plant, noises, ETM, DoS attacks, switched output feedback fuzzy controller, and actuator saturation all in one framework. Thirdly, low conservative exponential stability criteria are derived while guaranteeing strict , , -dissipativity, and hence the relationships between system performance and factors such as DoS attacks, secure ETM, noises and actuator saturation are established. Further, sufficient conditions are given for the co-design of the switched output-based fuzzy controller and the secure ETM. Finally, the effectiveness of the proposed method is confirmed by numerical examples, achieving over 92% system resources.