Output Regulation Performance Research Articles

Event-Triggered Multisource Bumpless Transfer Control for Networked Switched Systems With Almost Output Regulation Against Switching Deception Attacks

This article investigates the event-triggered multisource bumpless transfer (MSBT) control problem of networked switched systems (NSSs) with the almost output regulation (AOR) performance subject to switching deception attacks (SDAs). First, an improved dwell-time approach is developed to derive a proper switching law and ensure the feasibility of the AOR for NSSs allowing the AOR of each subsystem unsolvable and some switching instants destabilizing (i.e., with Lyapunov function increments), where destabilizing and stabilizing switching instants are subsystem independent. Second, a novel description of deception attacks called SDAs is established that contains multiple attack functions switching based on the currently activated subsystem, which considers the characteristics of NSSs and can cause the most severe damage to system control performance. Due to the networks and the event-triggered scheme, the switching of SDAs does not coincide with the switching of subsystems and controllers, which pose a challenge to system analysis. Third, MSBT controllers are designed to suppress the control bumps induced by multiple sources, including asynchronous controller switching, event-triggering mechanism, and SDAs. Finally, an application to a switched resistance–inductor–capacitance circuit is given to verify the effectiveness of the proposed method.

Fully distributed event-triggered cooperative output regulation for switched multi-agent systems with combined switching mechanism

The cooperative output regulation for switched heterogeneous multi-agent systems under aperiodic triggering and combined switching tactics is studied in this article. Since the global information of Laplacian matrix is not available in design, the fully distributed event-triggered protocol including integral-type term is implemented under directed topology that contain a spanning tree. Based on the relative estimator state between neighbors at triggering instants, the time-varying coupled weight of each agent is used to compensate the global information via designing the adaptive laws. Meanwhile, the integral-type term in event-triggering condition can further enlarge the inter-event times and avoid Zeno behavior. To reduce the switching frequency, the combined switching rules constituted by the dwell time and agent-dependent switching strategies are then established based on time-varying multiple Lyapunov functions. Further, the cooperative output regulation performance for switched multi-agent systems is achieved through the joint action of the combined switching laws and controller. Finally, two examples are used to clearly verify the effectiveness of results.

A Transformer Design for High-Voltage Application Using LLC Resonant Converter

The inductor–inductor–capacitor (LLC) resonant converter is a suitable topology for wide output voltage and load range applications with limited circuit parameters. One of the most significant design boundaries of an LLC resonant converter in high-voltage applications is the parasitic capacitance effect of the main circuit components, particularly the transformer and junction capacitances of the secondary rectifier network. Parasitic capacitance effects are much higher in high-voltage applications than in low-voltage applications. Therefore, the use of an LLC resonant converter is limited to high-voltage applications. This study proposes to reduce the capacitive effects of high-voltage transformers and rectification networks with a multi-winding transformer with an integrated rectifier design and to use it in high-voltage applications with the advantages of the LLC resonant converter. For the proposed prototype, comparative experimental measurements were conducted using a conventional scheme. The measurements validate the reliability of the LLC converter for high-voltage applications, improving the output regulation performance while significantly reducing parasitic capacitances.

Tracking and Regulation Performance Limitations of Networked Control Systems Over Erasure Channel With Input Quantization

Limitations in communication networks, such as delays, packet dropouts, and insufficient bandwidth, create great challenges in the output tracking control and regulation performance of networked control systems. In this article, we propose some novel performance indexes for achieving the optimal tracking and regulation performance. By considering the influences of noise, packet dropouts, and logarithmic quantization on the channel input, the performance limitations of the networked systems are investigated by applying a two-degree-of-freedom (TDOF) control technique. The results obtained prove that the tracking and regulation performance is dependent not only on the position of the plant’s nonminimum phase zeros and unstable poles, but also on the directions. Furthermore, it is demonstrated that noise and quantization error have a negative influence on the control performance, and the design of the TDOF controller can eliminate the effect of packet dropouts on control performance. To validate the innovation results, several simulations are conducted.

Regulated Series Hybrid Converter With DC Transformer (DCX) for Step-Up Power Conversion

The partial power converter, which is composed of isolated topology and dc–dc topology is getting more and more attention due to its efficient power delivery. This article proposes a partial power regulated series hybrid converter (RSHC), which is suitable for power conversion in step-up isolated applications. The proposed RSHC architecture consists of a dc–dc converter aiming to regulate the output voltage and a secondary-side series resonant converter (SSRC) operating as a high-efficiency dc transformer (DCX). The resonant tank of SSRC is derived from the reverse structure of a conventional LLC resonant converter. Different from the two-stage structure, the bulk power from the input to output is directly transmitted by SSRC with DCX function (SSRC-DCX), and part of the total power is delivered by dc–dc converter. Moreover, the voltage stress across the power devices of the dc–dc converter in the proposed RSHC is reduced in comparison with the two-stage structure. Therefore, the proposed RSHC can improve efficiency as well as save costs. The steady-state operation principle of RSHC is analyzed. Finally, a 250 W prototype is built to verify the output regulation mechanism and performance of the proposed RSHC.

Output Regulation State Bumpless Transfer Control for Switched Descriptor Systems

This brief is concerned with the state bumpless transfer control problem for switched descriptor systems with output regulation performance. Firstly, in order to alleviate state jumps at the switching instants while ensuring the solvability of the output regulation problem, a definition of the output regulation state bumpless transfer performance of switched descriptor systems is proposed for the first time. Then, sufficient conditions are put forward to ensure the output regulation performance and state bumpless transfer performance for the closed-loop switched descriptor systems based on the co-design scheme of switching rule and controller. Meanwhile, the co-design scheme gets rid of the requirement that each subsystem satisfies output regulation performance. In the end, a simulation example certifies that the given control technique is effective.

Almost Output Regulation of Switched Affine Systems and Its Application to a Circuit Model

This brief is concerned with the almost output regulation issue of switched affine systems. For switched affine systems, affine terms make the absence of the common equilibrium point, which also brings the distinct and difficulty on the analysis of output regulation performance. Moreover, in contract to the classical output regulation problem, a more extensive situation where the controlled plant and exosystem suffer from the unknown external interferences is concerned. Accordingly, the concept of the almost output regulation problem of switched affine systems is presented. Then, the co-design method of the switching law and regulators is established to guarantee the almost output regulation property. The given co-design method gets ride of the requirement for the almost output regulation performance of each subsystem. At last, the employed electronic circuit model substantiates the applicability and validity of the developed results.

Output regulation for networked switched systems with alternate event-triggered control under transmission delays and packet losses

This paper is concerned with the event-triggered output regulation problem for a class of linear networked switched systems (NSSs). A mode-dependent alternate event-triggered mechanism (AETM) is integrated into the NSSs with transmission delays and packet losses for the first time based on continuous detection and periodic sampling, and a joint-designed switching signal with the triggering information is presented. Under transmission delays and packet losses, a series of resultant error feedback controllers are synthesized in four cases based on the relationships between switching instants and event-triggered instants. Then, a criterion ensuring asynchronous output regulation performance is formed with transmission delays by the input delay method. With the presence of packet losses, a set of sufficient conditions is also dedicated to the proposed control issue by adding the restraint in the number of successive packet losses associated with a modified AETM. Eventually, a comparison and an F-18 aircraft model reveal the effectiveness of the obtained results in the simulation.

Output Regulation for Switched Systems With Multiple Disturbances

This article aims at proposing a regulation anti-disturbance control scheme for switched systems encountered by multiple disturbances, including the measurable disturbance and unmeasurable disturbance, through a multiple Lyapunov functions method. A switched estimator is developed for estimating the unmeasurable disturbance, under which a switched regulator and a switching law are co-designed to regulate the system output, while resisting the influence of the disturbances on the switched systems. Sufficient conditions are provided to ensure the output regulation performance and the disturbance restrain performance for the switched systems, even if all subsystems may not have the performances. These conditions are also appropriate for non-switched systems. By applying the established regulation anti-disturbance control method to the regulation of the speed for an engine model, the validity of the control scheme is displayed.

The Adaptive Distributed Event-Triggered Observer Approach to Cooperative Output Regulation of Discrete-Time Linear Multi-Agent Systems Under Directed Switching Networks

In the paper, we solve the cooperative output regulation problem of discrete-time linear multi-agent systems under directed switching networks. Firstly, a new adaptive distributed event-triggered observer is proposed, which does not require each follower to know the leader matrix information. In addition, we propose relative threshold and novel switching threshold event-triggered strategy, which can be used in different situations according to their respective characteristics. Then, we solve the cooperative output regulation problem for discrete-time linear multi-agent systems under directed switching networks by both distributed state feedback and distributed dynamic output feedback control laws utilizing the adaptive distributed event-triggered observer. Finally, a corresponding numerical simulation on the discrete-time linear multi-agent systems is conducted, and the cooperative output regulation performance is verified.

Output Regulation for a Class of MIMO Uncertain Stochastic Nonlinear Systems by Active Disturbance Rejection Control Approach

In this paper, the active disturbance rejection control (ADRC) approach is applied to a class of multi-input multioutput (MIMO) uncertain stochastic nonlinear systems. An extended state observer (ESO) is first designed for estimation of both unmeasured states and stochastic total disturbance of each subsystem which represents the total effects of internal unmodeled stochastic dynamics and external stochastic disturbance with unknown statistical property. The ADRC controller based on the states of ESO is further designed to achieve the closed-loop system’s output regulation performance including practical mean square reference signals tracking, disturbance attenuation, and practical mean square stability when the reference signals are zero avoiding solving any partial differential equations in the conventional output regulation theory. Some numerical simulations are presented to demonstrate the effectiveness of the proposed ADRC approach.

Cooperative output regulation of heterogeneous multi‐agent systems with a leader of bounded inputs

In this study, the cooperative output regulation problem for heterogeneous multi-agent systems is addressed by considering a leader dynamics subject to bounded (possibly non-zero, persistent, and time varying) inputs. Compared to many existing works with a leader of zero input, using such a leader dynamics will facilitate realisation of more diverse and sophisticated tracking trajectories for cooperative output regulation control. However, it also poses a challenge to pursue exact output regulation performance. To this end, a new two-layer hierarchical design framework is proposed. This framework consists of an upper-layer cooperative estimator for estimating the leader's state information in finite time, and a lower-layer distributed output regulator to achieve exact output regulation performance. Both finite-time estimation and asymptotic output regulation performance are analysed using the Lyapunov function method, and the associated solvability conditions are established as a set of linear matrix inequalities plus linear matrix equations. Simulation studies are also included to demonstrate the effectiveness of the proposed approach.

Performance analysis of networked control systems over AWGN fading channels

Abstract In this paper, the optimal performance of multi-input and multi-output (MIMO) linear time-invariant (LTI) discrete-time networked control systems (NCSs) are investigated based on state-space representation. In communication channels, channel fading, additive white Gaussian noise (AWGN) and scaling parameter matrix are considered. An average performance index is constructed. Moreover, the control energy and the output energy of the system are considered simultaneously in the output regulation performance. The scaling parameter matrix is introduced, which may be considered as an encoder or modification on the channel. The optimal regulation performances of the system are obtained, and the relationship is given between the optimal regulation performances and the steady-state solution of the corresponding algebraic Riccati equation (ARE). Results indicate that the optimal performance is influenced by the non-minimum phase zeros, unstable poles, the scaling parameter matrix, and the characteristics of the communication noise and fading. In addition, the channel power constraint is considered in Theorem 2 . We introduce a novel power weighting factor, which can weigh the relative importance of system output and channel input energy. The obtained results will give some guidance for the design of NCSs. Finally, a simulation example is given to demonstrate effectiveness of the theoretical results.

Almost output regulation of LFT systems via gain-scheduling control

ABSTRACTOutput regulation of general uncertain systems is a meaningful yet challenging problem. In spite of the rich literature in the field, the problem has not yet been addressed adequately due to the lack of an effective design mechanism. In this paper, we propose a new design framework for almost output regulation of uncertain systems described in the general form of linear fractional transformation (LFT) with time-varying parametric uncertainties and unknown external perturbations. A novel semi-LFT gain-scheduling output regulator structure is proposed, such that the associated control synthesis conditions guaranteeing both output regulation and disturbance attenuation performance are formulated as a set of linear matrix inequalities (LMIs) plus parameter-dependent linear matrix equations, which can be solved separately. A numerical example has been used to demonstrate the effectiveness of the proposed approach.

LQ control based actuator failure compensation

Summary In this paper, LQ control based actuator failure compensation schemes are developed for possibly nonminimum phase overactuated systems with actuator failures. The actuator failure is considered as an unmatched input disturbance signal, and a new disturbance rejection problem is formulated as an LQ control problem using a new cost function to enhance output regulation performance in the presence of actuator failures disturbances. Then the failure compensation design is developed to ensure the maximum reduction of the failure disturbance effect on the system output. New controller structures and design conditions are derived through dynamic programming for compensation of actuator failures, including a finite-time horizon control design and an infinite-time horizon control design, and their observer-based counterparts. Closed-loop stability and output regulation performance are analyzed in details. Simulation results are presented to verify the desired control system performance in the presence of actuator failures, as compared with a traditional design. Moreover, the new LQ based failure compensation schemes are derived in a parametrized framework suitable for adaptive LQ designs to deal with system parameter and failure uncertainties. Copyright © 2015 John Wiley & Sons, Ltd.

Optimal Output Regulation for Discrete-Time Switched and Markovian Jump Linear Systems

First, three different but related output regulation performance criteria for the linear time-varying system are defined in the discrete-time domain, namely, the peak impulse response, peak output variance, and average output variance per unit time. Then they are extended for switched linear systems and Markovian jump linear systems, and characterized by an increasing union of finite-dimensional linear matrix inequality conditions. Finally, the infinite-horizon suboptimal LQG control problem, which aims to maintain the average output variance below a given level subject to the uniform exponential stability of the closed-loop system, is solved for both switched linear systems and Markovian jump linear systems; the solution is given by a dynamic linear output feedback controller that not only perfectly observes the present mode but also recalls a finite number of past modes.

Stator flux and torque decoupling control for induction motors with resistances adaptation

An adaptive state feedback control has been designed for direct torque and stator flux regulation with a fifth-order model of an induction motor. The control design is based on exact input-output decoupling linearisation via non-linear state feedback. To achieve decoupling control, it is shown that the tracking dynamics with respect to the outputs (stator flux amplitude and electrical torque) is asymptotically stable at an admissible operating equilibrium. In the adaptive control, the uncertainty in the resistances of the stator and the rotor is considered, and the adaptation law is design to guarantee the boundedness of parameter estimation and output regulation performance. Finally, simulation results are presented to demonstrate the availability of the proposed controller.