Periodic Piecewise Linear Systems Research Articles

Asynchronous control of networked periodic piecewise linear systems under time-varying transmission delay

This paper studies the stability of networked periodic piecewise linear systems (NPPLSs) of which communication channels are subject to a time-varying transmission delay. Under data-sampling, the NPPLS is modeled as an asynchronous controlled periodic piecewise linear system with time-varying input delay, where the interval of asynchronous control in each subsystem is uncertain but bounded. Aimed at obtaining less conservative stability and synthesis results when tackling the uncertain switching, the dwell time of each subsystem is divided into three subintervals according to the asynchronous control interval and the maximum delay assumption. In this way, it allows the construction of piecewise Lyapunov functionals for one subsystem, the piecewise Lyapunov functionals capture different dynamic characteristics in each subinterval. Using this approach, general stability conditions of NPPLSs are derived. Then, by constructing Lyapunov functionals as a set of delay-dependent time-varying functionals, tractable exponential stability conditions of NPPLSs under transmission delay are developed using a scaling technique. Due to the coupling of the decision variables in the conditions, an iterative algorithm is proposed to solve the periodic controller gains. A numerical example is provided to illustrate the merits of the obtained controllers.

Stability and Stabilization of Almost Periodic Piecewise Linear Systems With Dwell Time Uncertainty

This article is dedicated to the stability and stabilization of almost periodic piecewise linear systems (APPLSs) with the uncertain dwell time of subsystems. Taking into account the uncertainty in dwell time for the first time, a novel mixed-mode time-varying Lyapunov function is constructed. A sufficient condition is proposed to guarantee the exponential stability of the system, where the switching instants over each period are unknown and inaccessible except their bounds. Moreover, a periodic time-scheduled state-feedback control approach is developed to stabilize the APPLS affected by dwell time uncertainty and possibly unstabilizable subsystem dynamics. A stabilizing controller design algorithm is provided to compute the time-varying gains. The effectiveness of the proposed approach is illustrated via a numerical example involving comparative case studies.

Stabilization of networked periodic piecewise linear systems under asynchronous switching with packet dropouts

In this paper, the networked stabilization of discrete-time periodic piecewise linear systems under transmission package dropouts is investigated. The transmission package dropouts result in the loss of control input and the asynchronous switching between the subsystems and the associated controllers. Before studying the networked control, the sufficient conditions of exponential stability and stabilization of discrete-time periodic piecewise linear systems are proposed via the constructed dwell-time dependent Lyapunov function with time-varying Lyapunov matrix at first. Then to tackle the bounded time-varying packet dropouts issue of switching signal in the networked control, a continuous unified time-varying Lyapunov function is employed for both the synchronous and asynchronous subintervals of subsystems, the corresponding stabilization conditions are developed. The state-feedback stabilizing controller can be directly designed by solving linear matrix inequalities (LMIs) instead of iterative optimization used in continuous-time periodic piecewise linear systems. The effectiveness of the obtained theoretical results is illustrated by numerical examples.

Bumpless [formula omitted] control for periodic piecewise linear systems

This paper investigates the bumpless H∞ control problem based on exponential stability and L2-gain analyses for a class of periodic piecewise linear systems. A novel characterization of bumpless transfer among a variety of subsystem controllers satisfying some interpolation constraints is introduced. By utilizing adjustable interpolation functions and multiple Lyapunov functions, more flexibility is provided so as to guarantee a desirable closed-loop performance and trajectory smoothness. Since the problem formulated boils down to a feasibility problem involving nonlinear matrix inequalities, an iterative algorithm which solves a series of convex optimization problems is developed. Numerical examples are presented to show the validity of the proposed methods.

Design of resilient reliable control for uncertain periodic piecewise systems with time-varying delay and disturbances

In this paper, the stabilization problem for a class of periodic piecewise linear systems with uncertainties, time-varying delay, actuator faults and disturbances is discussed. Precisely, the resilient reliable control scheme is designed to stabilize the addressed system with satisfactory disturbance attenuation index. Moreover, the concerned system is a kind of periodic system which consists of many subsystems with constant state dynamics. Based on fixed dwell time approach, the addressed system is divided into many piecewise subsystems and activated periodically. Depending on the division of subintervals, the sufficient conditions are derived by constructing a proper Lyapunov–Krasovskii functional with piecewise time-varying positive definite matrices. Further, the periodic time-varying control gain matrices for individual subsystems are obtained via solving the developed constraints. Specifically, the potential and impact of the developed control scheme is examined by presenting two numerical examples including the periodic piecewise vibration systems.

Fault detection observer design for periodic piecewise linear systems

This article deals with the problem of fault detection observer design for continuous-time periodic piecewise linear systems. Mixed performance index is introduced, which results in a trade-off between robustness to unknown input and sensitivity to a fault. Based on a class of Lyapunov functions with time-varying Lyapunov matrices, sufficient conditions are developed to investigate the existence of periodic piecewise fault detection observer with weighted performance. A tractable iterative algorithm is proposed to establish the desired periodic piecewise fault detection observer. Finally, a numerical example is provided to illustrate the effectiveness of the proposed approach.

New Conditions of Analysis and Synthesis for Periodic Piecewise Linear Systems With Matrix Polynomial Approach

In this paper, new conditions of the stability, stabilization and L 2 -gain performance of periodic piecewise systems are proposed. Both the continuous and discontinuous Lyapunov functions with dwell-time related time-varying Lyapunov matrix polynomial are adopted, and methods guaranteeing the positive and negative definiteness of a matrix polynomial are introduced. Exponential stability conditions are derived based on continuous and discontinuous Lyapunov functions, respectively. A stabilizing controller with time-varying controller gain is designed with continuous Lyapunov function and the weighted L 2 -gain performance based on the discontinuous Lyapunov matrix polynomial is studied as well. Numerical examples are used to verify the effectiveness of the proposed methods.

Non‐fragile control of periodic piecewise linear time‐varying systems with time delay

In this study, the stability and stabilisation issues of a class of periodic piecewise linear time-varying systems with time delay are studied. Based on a lemma with respects to the negative definite matrix polynomial, a sufficient delay-dependent exponential stability condition is obtained via constructing a Lyapunov–Krasovskii functional with periodic matrix functions. Then, for two types of norm-bounded uncertainties of time-varying controller gains, the non-fragile stabilising controllers under the multiplicative and additive gain perturbations are designed to stabilise the closed-loop system. The obtained controller gains could be solved with linear matrix inequalities directly instead of using the iterative algorithm. That is valued in engineering applications. Numerical examples are presented to demonstrate the effectiveness of the proposed methods.

Peak-to-peak filtering for periodic piecewise linear polytopic systems

In this paper, the robust peak-to-peak filtering problem for periodic piecewise systems with polytopic uncertainties is investigated. Attention is focused on designing of robust peak-to-peak filters that guarantee the robust asymptotic stability of periodic piecewise filtering error system and satisfy a prescribed peak-to-peak disturbance attenuation level for all admissible uncertainties. A sufficient condition is proposed for robust stability and peak-to-peak performance by employing the constructed time-varying Lyapunov function. Two design approaches based on the Lyapunov function with parameter-dependent matrices and parameter-independent matrices are utilised to solve this problem. An algorithm is proposed to compute the periodic filter parameters governed by non-convex feasibility conditions. Two numerical examples are presented to demonstrate the effectiveness of the proposed techniques.

Robust time-weighted guaranteed cost control of uncertain periodic piecewise linear systems

This paper studies the design problem of periodic piecewise guaranteed cost controllers for a class of continuous-time uncertain periodic piecewise linear systems using a time-weighted quadratic cost function. By developing Lyapunov functions with quadratic cost matrices to a time-varying form, sufficient conditions are proposed to ensure the exponential stability of the closed-loop system and a guaranteed upper bound of the cost function. To minimize the upper bound in the controller design process, an iterative algorithm is developed to solve the problem via convex optimization. The effectiveness of our proposed algorithm is demonstrated via a numerical example, and the impact of time-weighted cost is illustrated by simulation results.

Guaranteed cost control of periodic piecewise linear time-delay systems

This paper is concerned with the guaranteed cost control problem for continuous-time periodic piecewise linear systems with time delay. Sufficient delay-dependent conditions of closed-loop asymptotic stability are presented based on an improved formulation, which uses a novel Lyapunov–Krasovskii functional with relaxed requirement in positive definiteness of the involved symmetric matrices. The corresponding optimization problems aiming at the mixed performance involving an upper bound of H2 guaranteed cost and an H∞ performance index for disturbance attenuation are established. By designing an iterative algorithm subject to the proposed conditions, the periodic guaranteed cost controller gains over each sub-interval are tractable for the resulting closed-loop time-delay system. The effectiveness and reduced conservatism of our proposed criteria are validated and illustrated via numerical simulations.

Stability and stabilization of periodic piecewise linear systems: A matrix polynomial approach

In this paper, new conditions of stability and stabilization are proposed for periodic piecewise linear systems. A continuous Lyapunov function is constructed with a time-dependent homogeneous Lyapunov matrix polynomial. The exponential stability problem is studied first using square matricial representation and sum of squares form of homogeneous matrix polynomial. Constraints on the exponential order of each subsystem used in previous work are relaxed. State-feedback controllers with time-varying polynomial controller gain are designed to stabilize an unstable periodic piecewise system. The proposed stabilizing controller can be solved directly and effectively, which is applicable to more general situations than those previously covered. Numerical examples are given to illustrate the effectiveness of the proposed method.

求解周期性分段线性系统动态响应的高效数值方法

An efficient method based on the parametric variational principle (PVP) was proposed for computing the dynamic responses of periodic piecewise linear systems with multiple gap-activated springs. Through description of gap-activated springs with the PVP, the complex nonlinear dynamic problem was transformed to a standard linear complementary problem. This method can avoid iterations and updating the stiffness matrix in the computing process and can accurately determine the states of the gap-activated springs. Based on the periodicity of the system and the precise integration method (PIM), an efficient numerical time-integration method was developed to obtain the dynamic responses of the system. This method indicates that there are a large number of identical elements and zero elements in the matrix exponents of a periodic structure, and saves computation load and computer storage by avoiding repeated calculation and storage of these elements. Numerical results validate the proposed method. The dynamic behaviors of a 5-DOF piecewise linear system under harmonic excitations were analyzed, including the stable periodic motion, the quasi-periodic motion and the chaotic motion. In comparison with the Runge-Kutta method, the proposed method has satisfactory correctness and efficiency.

Finite-time H∞ control of periodic piecewise linear systems

ABSTRACTIn this paper, the finite-time stability, stabilisation, L2-gain and H∞ control problems for a class of continuous-time periodic piecewise linear systems are addressed. By employing a time-varying control scheme in which the time interval of each subsystem constitutes a number of basic time segments, the finite-time controllers can be developed with periodically time-varying control gains. Based on a piecewise time-varying Lyapunov-like function, a sufficient condition of finite-time stability and the relevant time-varying controller are proposed. Considering the finite-time boundedness of the closed-loop periodic system, the L2-gain criterion with continuous time-varying Lyapunov-like matrix function is studied. A finite-time H∞ controller is proposed based on the L2-gain analysis. Finally, numerical simulations are presented to illustrate the effectiveness of the proposed criteria.

Stability, stabilization and [formula omitted]-gain analysis of periodic piecewise linear systems

In this paper, the stability, stabilization and L2-gain problems are investigated for periodic piecewise linear systems, in which not all subsystems are Hurwitz. First, some sufficient and necessary conditions for the exponential stability are established. By employing a discontinuous Lyapunov function with time-varying Lyapunov matrix, stabilization and L2-gain conditions of periodic piecewise linear systems are proposed by allowing the corresponding Lyapunov function to be possibly non-monotonically decreasing over a period. A state-feedback periodic piecewise controller is developed to stabilize the system, and the corresponding algorithm is proposed to compute the controller gain. The L2-gain criteria with continuous time-varying Lyapunov matrix and piecewise constant Lyapunov matrices are studied as well. Numerical examples are given to show the validity of the proposed techniques.