Switching Control Design Research Articles

Modeling and Switched Control of Modular Reconfigurable Flight Array for Faulty Redundancy

The modular reconfigurable flight array (MRFA) is composed of multiple identical flight unit modules, which has several advantages such as structural variability, strong versatility, and low cost. Due to the redundant properties of MRFA, it keeps stable by adopting a suitable control law when it suffers actuator fault or actively stops some actuators. To address the attitude stability issue of the modular flight array when actuators actively stop or encounter failures during the flight process, a modeling method based on a switched system is proposed at first, and an arbitrary switched controller design method based on the segmented Lyapunov functions and the average dwell time is also given. By introducing the actuator efficiency matrix, the dynamic switched model of the modular flight array is described. Then, a group of arbitrary switched linear feedback gains is designed to ensure the exponential stability of the flight array if the switched process satisfies the constraint of the average dwell time. Simulation and experiment results indicate that when there is an accident in the actuator states, the switched controllers can achieve precise tracking of the desired trajectory, thus confirming the effectiveness of the proposed modeling method and controller.

Composite Switched Lyapunov Function-Based Control of DC–DC Converters for Renewable Energy Applications

Renewable energy sources play a pivotal role in the pursuit of sustainable and eco-friendly power solutions. While offering environmental benefits, they present inherent challenges. Photovoltaic systems rely on surrounding conditions, wind systems contend with variable wind speeds, and fuel cells are both costly and inefficient. Furthermore, the energy injected by renewable energy sources (RES) exhibits unpredictable behavior. To tackle these problems, researchers employ diverse power electronic devices and converters like inverters, power quality filters, and DC–DC choppers. Among these, DC–DC converters stand out for effectively regulating DC voltage and enhancing the efficiency of RESs. The meticulous selection of a suitable DC–DC converter, coupled with the integration of an efficient control technique, significantly influences overall power system performance. This paper introduces a novel approach to the design of switching controllers for DC–DC converters, specifically tailored for application in renewable energy systems. The proposed controller leverages the power of composite switched Lyapunov functions (CSLF) to enhance the efficiency and performance of DC–DC converters, addressing the unique challenges posed by renewable energy sources. Through comprehensive analysis and simulation, this study demonstrates the efficacy of the controller in optimizing power transfer, improving stability, and ensuring reliable operation in diverse renewable energy environments. Moreover, the small-scale DC–DC converter experiment’s findings are presented to confirm and validate the proposed scheme’s practical applicability.

Switching Control Strategy for DC–DC Converters Based on Polynomial Lyapunov Function and Sum-of-Squares Approach

The introduction of switched system theory opens new perspectives for the control design of dc/dc converters. Regarding the classical two-level converters, two switching control design methodologies have been developed based on the common quadratic Lyapunov function (CQLF) or piecewise quadratic Lyapunov function (PQLF). However, the CQLF-based design method is not applicable for the multilevel dc/dc converter (MC). As for the PQLF-based design method, it encounters the problem that the control design is very complex, involving a nonlinear optimization problem. To further advance the application of the switching system theory in power converters, a design framework based on the polynomial Lyapunov function and the sum-of-squares approach is proposed in this article. The proposed design method generalizes the CQLF-based one. Moreover, compared with the PQLF-based design method, the mathematical design procedure can be significantly simplified. Experimental validations on an MC, i.e., the three-level flying capacitor converter and a two-level Buck-Boost converter illustrate the versatility and the effectiveness of the proposed design framework. Moreover, comparative tests show the good control performance of the designed switching control strategy. The currently presented works are preliminary but could constitute an interesting direction for developing control solutions of power converters.

Switched Controller Design for Robotic Manipulator via Neural Network-Based Sliding Mode Approach

In this brief, a novel adaptive switched controller of uncertain industry robotic manipulator (IRM) systems with switching loads is designed for trajectory tracking by utilizing switching neural network-based sliding mode control (SNNSMC) scheme. However, the error accumulation and system instability of the IRM may be caused by switching loads, while the existing single adaptive controller may not effectively deal with this issue. To do so, the IRM with switching loads is modeled as a switched system with multi-modal. Besides, the individual sub-controller with adaptive gain algorithm is devised to replace the single adaptive controller with fixed-gain for multi-modality system. Then, the radial basis function NN (RBFNN) is utilized for approaching to the plant, which avoids the limitation of the accurate model for the IRM system with switching loads. The SMC gain is designed as an adaptive adjustment value, which can be adjusted in real time to enhance the robustness of the system in spite of unknown disturbances and uncertainties. Subsequently, based on average dwell time (ADT) principle, the trajectory tracking error being close to zero is verified by the multi-Lyapunov function method. Finally, simulation results show that the provided method can both track the preset trajectory accurately, and attenuate chattering and high-speed switching of the plant effectively.

A Cross-Layer Design Approach to Strategic Cyber Defense and Robust Switching Control of Cyber-Physical Wind Energy Systems

Due to the increasing adoption of smart sensing and Internet of things (IoT) devices, wind energy system (WES) becomes more vulnerable to cyber and physical attacks. Therefore, designing a secure and resilient WES is critical. This paper first proposes a system-of-systems (SoS) framework for the cyber-physical WES. Specifically, on the one hand, we adopt a game-theoretic model to capture the interactions between the WES system defender and the adversary at the cyber layer. The outcome of this cyber defense game is reflected by control-aware Nash equilibria. On the other hand, we devise a cyber-aware robust and resilient switching controller based on a Markov jump linear system model for the physical WES. The performances of the WES cyber and physical layers are interdependent due to their natural couplings. We further investigate the SoS equilibrium of the integrated WES, which considers the system security, robustness, and resilience holistically. Finally, we use case studies to corroborate the developed cross-layer design principles for the cyber-physical WES. Note to Practitioners—Cybersecurity becomes a critical concern of wind energy system (WES) operators as an increasing amount of IoT devices are adopted for WES’s communication, monitoring, and operation support purposes. This cyber-physical integration in WES creates a much broader attack surface because adversaries can compromise the physical WES by attacking its dependent cyberspace. To mitigate the impact of attacks, the operator should not only design intelligent control strategies for WES but also strategically secure the WES’s cyber layer. These two goals are naturally coupled together. On the one hand, the WES operates under different compromised conditions depending on the attack actions at the cyber layer. Thus, the control design needs to be adversary-aware by taking the real-time cyber state into account. On the other hand, the adversary’s cyberattack strategy is influenced by the induced performance degradation of WES. Hence, the corresponding attack measures and countermeasures, in turn, should be physically control-aware. This paper establishes a holistic mathematical framework to simultaneously address these two challenging objectives. The obtained solution provides guidelines for the WES operator on the optimal security resource investment in defending against cyberattacks and the robust switching control design to mitigate the impacts of attacks further. This methodology creates a defense-in-depth paradigm for the WES operators to maintain the energy system efficiency in the adversarial environment. This cross-layer design approach is also efficient and user-friendly for online implementation with the developed iterative algorithm. The simulated-based case studies in this paper show the effectiveness of the proposed approach. However, a more thorough validation of the method in practice is necessary before its integration with the production standard.

Optimal switching control design for industrial networked control system with uncertain exogenous dynamics

Industrial networked control system performance can be compromised through introduction of intended attacks by intruders. Several ways have been reported in literature to introduce attacks like denial-of-service, packet dropout, and delays etc. in Industrial networked control system. Attacks may be designed based on the system knowledge gathered through eavesdropping process. This article deals with problem of constrained optimal switching control design with industrial networked control system (iNCS) through avoiding performance deteriorating uncertain exogenous dynamics. To characterize and detect the abnormal behaviour of iNCS a random distribution process is adopted which represent the attack sequence in the process on the plant side. The delays and packet loss are introduced through Bernoulii distribution process to express uncertainty of network and also attack introduced by intruders on either side of tightly coupled component. The iNCS performance is evaluated with uncertain exogenous dynamics i.e. packet loss 0%, 10%, 20%, 30%, delays, and malicious attack. The proposed design guarantees the transient and steady state performance of linear-time-invariant iNCS. The proposed design methodology evaluated under switching of optimal predictive control performance of networked system with simulation of numerical problem.

Safe and Efficient Switching Controller Design for Partially Observed Linear-Gaussian Systems

Switching control strategies that unite a potentially high-performance but uncertified controller and a stabilizing albeit conservative controller are shown to be able to balance safety with efficiency, but have been less studied under partial observation of state. To address this gap, we propose a switching control strategy for partially observed linear-Gaussian systems with provable performance guarantees. We show that the proposed switching strategy is both safe and Efficient, in the sense that: (1) the linear-quadratic cost of the system is always bounded even if the original uncertified controller is destabilizing; (2) in the case when the uncertified controller is stabilizing, the performance loss induced by the conservativeness of switching converges super-exponentially to zero. The effectiveness of the switching strategy is also demonstrated via numerical simulation on the Tennessee Eastman Process.

Switching control design for LTI system with uncertain equilibrium: Application to parallel interconnection of DC/DC converters

This paper addresses the problem of designing a robust control law for uncertain switched affine systems. In order to cope with model uncertainties, a dynamic controller is introduced. Local asymptotic stability of the closed-loop system as well as zero steady state error on the controlled output are proven. A constructive method based on LMI conditions is given. It delivers the control parameters and an estimation of the robust domain of attraction. The proposed strategy is applied on a parallel interconnection of m DC/DC converters. For this system, an extensive discussion is offered on specific difficulties about ill-conditioned matrix inequalities. Finally, by using a user-programmable Field-Programmable Gate Array (FPGA), experimental results are provided to illustrate the effectiveness of the control.

A state‐dependent switching controller design approach for linear systems under control constraints

In the present work, a state-dependent switching controller design approach for controlled systems under control constraints is proposed. First, the controlled system with control gain parameters is converted into a single-degree-of-freedom vibration system by using an invertible transform. Second, based on the physical significance of the single-degree-of-freedom linear vibration systems, two pairs of gain parameters are properly chosen to obtain two subsystems with sufficiently small equivalent negative-damping coefficients and sufficiently large equivalent stiffness coefficient difference. Third, by introducing an identical invertible transform, two subsystems are converted into the form of vibration systems simultaneously. As such, it is reasonable to compare the two corresponding energy functions directly. Fourth, two switching lines with maximum and minimum energy ratio between two subsystems are derived to construct a state-dependent switching law. Combining the selected control gain parameters, a state-dependent switching controller is then designed for stabilizing the original controlled system with control constraints. In the end, the effectiveness and robustness of the developed control approach are illustrated by three numerical examples.

Guaranteed performance control of switched positive systems: A switching policy design method

In this article, a state-dependent switching policy for handling the guaranteed performance control problem, by means of the partition of the nonnegative state space, for switched positive systems, is devised. The mixed performance, induced by the linear guaranteed cost and L1-gain performance for disturbance attenuation, is investigated. A corresponding optimization problem devoting to the mixed performance is considered, including an upper bound of linear guaranteed cost and an L1-gain performance. Moreover, sufficient conditions are also established by the joint design of switching rules and controllers to ensure the positivity and mixed performance of the closed-loop systems. Eventually, two examples are used to illustrate the validness and practicability of the developed results.

Switched Control Design for Nonlinear Systems Using State Feedback

Switched Control Design for Nonlinear Systems Using State Feedback

Resilient perimeter control for hyper-congested two-region networks with MFD dynamics

Understanding the resilience of transportation networks has received considerable research attention. Nevertheless in the field of network traffic flow control, few control approaches target the mitigation from hyper-congestion, and the control objective has rarely touched the system resilience requirement which focuses on system recovering from hyper-congested state. This paper sheds light on a resilience-oriented network control. We firstly define the traffic resilience as the integral of deviation against optimal state from disturbance generation moment t0 to recovery moment tf. Then, we propose a control method under hyper-congested situations by formulating the analytical problem using a two-reservoir transportation system with parabola-shaped Macroscopic Fundamental Diagrams (MFDs), using phase diagram analysis, attraction region derivation and switched controller design. Afterwards, we evaluate the system resilience performances between two classic perimeter control schemes (constant perimeter control (CPC) and state-feedback control (SFC)) and the proposed resilient control scheme. Results show that proposed controller can ensure the system to recover from hyper-congestion to the optimal state while existing studies failed to recover. This resilience is confirmed in various case study scenarios, e.g., when the level of hyper-congestion is different. More promisingly, the proposed control shows high compatibility with the form of the MFDs, e.g., the recover can be achieved under hysteresis conditions which are common for network-level traffic dynamics. These findings will help to design an intelligent transportation system with enhanced resilience.

Sliding-mode controller synthesis of robotic manipulator based on a new modified reaching law.

In this study, an adaptive modified reaching law-based switch controller design was developed for robotic manipulator systems using the disturbance observer (DO) approach. Firstly, a standard DO is employed to estimate the unknown disturbances of the plant, from which the control signal could be compensated. Then, an adaptive modified reaching law is established to dynamically adapt the switching gain of the sliding mode robust term and further guarantee the finite-time arrival of the established sliding surface. Additionally, the convergence of the error system is analyzed via the Lyapunov method. At last, the feasibility and effectiveness of the proposed control scheme are verified by using a two-joint robotic manipulator model. The simulation results show that the developed controller can achieve rapid tracking, reduce system chattering and improve the robustness of the plant. The main innovations of the work are as follows. 1) A new adaptive reaching law is proposed; it can reduce chattering effectively, and it has a fast convergence speed. 2) Regarding the nonlinear robotic manipulator model, a novel adaptive sliding-mode controller was synthesized based on the DO to estimate the unknown disturbance and ensure effective tracking of the desired trajectory.

Event‐triggered control for cyber‐physical systems with multiple transportation channels and denial‐of‐service attacks

AbstractEvent‐triggered controllers are designed for cyber‐physical systems (CPSs) with multiple transmission channels in this article, including two cases: with and without denial‐of‐service (DoS) attacks. Through the design of switching controller and the use of linear matrix inequality‐based (LMI‐based) method, the global exponential stability of the CPSs with multiple transmission channels in both cases are proved, and the relationship of parameters of DoS frequency and duration with the sampling period is established. An example of unmanned ground vehicle under DoS attacks is given to show the effectiveness of the proposed control method.

Switched control of an N-degree-of-freedom input delayed wearable robotic system

In this paper, a switched control method for a class of wearable robotic systems that prioritizes the use of human skeletal muscles in an assistive rigid powered exoskeleton is derived. A general N-degree-of-freedom (N-DOF) human–robot model is proposed to consider the challenges induced by the wearable system that include uncertainties and nonlinearities, unilateral actuation properties of the skeletal muscles, input delays, as well as a time varying actuator efficiency. Two control modes that alternatively switch and control a wearable robotic system are designed to overcome these challenges. A multiple Lyapunov functional analysis with state-dependent constraints on the switch criteria is performed to prove the stability. Simulations are performed to demonstrate the gain conditions, selected for each subsystem, that stabilize the overall system. Experiments on a human participant wearing a 4-DOF hybrid exoskeleton that combines functional electrical stimulation and a powered exoskeleton demonstrate the effectiveness of the switched control design.

<i>H</i>∞ performance analysis and switching control design for uncertain discrete switched time-delay systems

The H∞ performance analysis and switching control of uncertain discrete switched time-delay systems with linear fractional perturbations are studied in this paper. The design of a simple switching signal is developed to acquire LMI conditions which achieve H∞ performance and switching control of discrete switched time-delay system. The conservativeness of obtained results can be improved by using the delay-partitioning approach. The using LMI variables number is less than our past proposed non-negative inequality approach. Finally, we use some numerical examples to illustrate the major improvement of the developed results.

<i>H</i>∞ performance analysis and switching control design for uncertain discrete switched time-delay systems

The H∞ performance analysis and switching control of uncertain discrete switched time-delay systems with linear fractional perturbations are studied in this paper. The design of a simple switching signal is developed to acquire LMI conditions which achieve H∞ performance and switching control of discrete switched time-delay system. The conservativeness of obtained results can be improved by using the delay-partitioning approach. The using LMI variables number is less than our past proposed non-negative inequality approach. Finally, we use some numerical examples to illustrate the major improvement of the developed results.

Guaranteed cost design for controlling semilinear parabolic PDE systems with mobile collocated actuators and sensors

This paper investigates the guaranteed cost design problem for controlling a class of semilinear parabolic partial differential equation (PDE) systems using mobile collocated actuators and sensors. Initially, a mode indicator function is employed to indicate the different modes for all actuator/sensor pairs according to whether each actuator/sensor pair is static or mobile. Subsequently, a mode-dependent switching control scheme is proposed and the well-posedness of the closed-loop PDE system is also analysed. Then, based on Lyapunov direct method, an integrated design of switching controllers and mobile actuator/sensor guidance laws is developed in the form of linear matrix inequalities, such that the closed-loop PDE system is exponentially stable while providing an upper bound for the prescribed quadratic cost function. Moreover, a suboptimal guaranteed cost design problem is also addressed to make the cost bound as small as possible. Finally, numerical simulations are presented to illustrate the effectiveness of the proposed design method.

New trends in modeling and control of hybrid systems

New trends in modeling and control of hybrid systems

Robust switching control design for uncertain discrete‐time switched affine systems

SummaryThis article focuses on the design of a robust switching control law for uncertain switched affine systems in the discrete‐time domain. More precisely, a novel control law is introduced whose parameters result from an optimization problem, aiming at reducing the volume of the attractive and invariant set, where the solutions to the closed‐loop system converge to. The design is based on a quadratic Lyapunov function and guarantees global practical stabilization, that is, global stabilization in a neighborhood of a desired operating point and robustness with respect to model uncertainties. Our method and the associated relaxed control law are then compared with existing conditions from the literature and are validated through numerical examples.