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In this paper, robust adaptive output feedback control is studied for a class of discrete-time nonlinear systems in output-feedback form perturbed by a class of functional nonlinear uncertainties of Lipschitz type. To construct output feedback control, the system is transformed into the form of nonlinear-auto-regressive-moving-average (NARMA), a novel future output prediction is designed based on...
The nonlinear robust stability theory of Georgiou and Smith (IEEE Trans. Auto. Control, 42(9):1200-1229, 1997) is generalized to the case of notions of stability with bias terms. An example from adaptive control illustrates non trivial robust stability certificates for systems which the previous unbiased theory could not establish a non-zero robust stability margin. This treatment also shows that...
In this paper we use bilevel programming to find the maximum difference between a reference controller and a low-complexity controller in terms of the infinity-norm difference of their control laws. A nominal MPC for linear systems with constraints, and a robust MPC for linear systems with bounded additive noise are considered as reference controllers. For possible low-complexity controllers we discuss...
We study how the maximum/minimum gain of a decentralized controller influences the maximum/minimum gain of the corresponding closed loop transfer function, and provide lower bounds on the best closed-loop performance achievable by decentralized controllers satisfying additional frequency domain restrictions. These bounds are obtained using generalizations of the structured singular value and approximated...
This paper proposes a novel synthesis approach to dynamic output feedback robust model predictive control for systems with both polytopic description and bounded disturbance. The notion of quadratic boundedness is utilized to characterize the stability properties of the augmented closed-loop system. An error signal is defined, which is a linear combination of the true state, controller state and output...
In this work, we focus on the problem of stabilization of two constrained linear systems coupled through the inputs by two different agents which communicate in order to take a decision assuming that each agent only has partial information of the model and the state of the system. We extend previous results on distributed model predictive control and provide sufficient conditions that guarantee practical...
The problem of delay-dependent robust passivity analysis and robust passification for uncertain Markovian jump linear systems (MJLs) with time-varying delay is discussed. The parameter uncertainties are time-varying but norm-bounded. Attention is focused on the design of passification controllers, which guarantee that the closed-loop MJLs is passive. By constructing a proper stochastic Lyapunov-Krasovskii...
In this paper, a new scheme inspired by the idea of decentralized control methodology is proposed to design output feedback controllers for a class of MIMO nonlinear systems with input unmodeled dynamics. With dynamic normalization and backstepping approach, the destabilizing effects of unmodeled dynamics depending on inputs are compensated and global uniform boundedness of all the signals in the...
A systematical design method for robust integer order proportional-integral-derivative (IOPID) controller with an iso-damping property was suggested in. In this paper, two auto-tuning methods of fractional order proportional integral (FOPI) and fractional order [proportional integral] (FO[PI]) controllers with iso-damping property for a class of unknown, stable and minimum phase plants are designed...
Output-based feedback control of LPV systems is an important problem, as in practice it is rarely the case that the full state variable is available for feedback. In this paper we consider this problem in the case of discrete-time LPV systems for which the parameters are not exactly known, but only available with a finite accuracy or affected by noise during their measurement. The controllers are...
The symmetric control systems have some interesting properties. This paper studies a class of symmetric system consists of a collocated second-order plant and a static output feedback controller. For the system, it is known that the internal stability and the robustness of the closed-loop system are guaranteed based only on the non-parametric structure condition. Our objective is to propose an optimal...
This paper considers robust pole assignment problem for discrete-time linear periodic systems via linear periodic output feedback. To character a measure for the sensitivity of the eigenvalues of the closed-loop system with respect to perturbations in the coefficient matrices, a robustness index for periodic systems is proposed, which can be regarded as a generalization of robustness index of normal...
This paper focuses on the designing of the robust non-fragile controller based on observer for a class of non-linear uncertain time-delay systems. The uncertainties exist in the controller. Under the assumption that the uncertainty is time-varying and norm-bounded, based on linear matrix inequality, by constructing Lyapunov functions and selecting proper observer, we bring forward an approach for...
In this paper, we show that a special class of commensurate fractional order interval plants can be stabilized by proportional compensator if some of extreme plants can be stabilized by the compensator. The special class of commensurate fractional order interval plant means that both its numerator and denominator polynomials has the orders whose values are the multiples of the irrational number between...
The robust output feedback stabilization problem for discrete-time Markov jump singular systems with parameter uncertainties is discussed. Based on the restricted system equivalent (r.s.e.) transformation and by introducing new state vectors, the singular system is transformed into a discrete-time Markov jump standard linear system, then by discussing the transformed system, the output feedback controller...
The problem of dynamic output feedback control stabilization is considered for a class of multi-time delays uncertain nonlinear systems. Based on LMI and proper Lyapunov functions, a sufficient condition for the existence of robust output feedback controller is proposed, which ensures that the closed-loop system is robust stable. The dynamic output feedback controller is designed by the feasible solution...
A robust model predictive controller is proposed for input constrained linear systems with discrete and distributed delay in the states, where uncertainty is described by an additive bounded disturbance. The method is an extension of recently developed, tube based model predictive control to time-delay systems. A robust local controller maintains the disturbed trajectory of the controlled system in...
Digital repetitive control is a technique which allows to track periodic references and/or reject periodic disturbances. Repetitive controllers are usually designed assuming a fixed frequency for the signals to be tracked/rejected, its main drawback being a dramatic performance decay when this frequency varies. A usual approach to overcome the problem consists of an adaptive change of the sampling...
Based on model reference, a global sliding mode controller (GSMC) with a new control scheme is proposed for a practical uncertain servo system. This control scheme consists of two combined controllers. The stability of the proposed controller is based on rigorous Lyapunov stability theorem and Lyapunov function methods. The presented control law can render the closed-loop controlled system asymptotically...
Verification of logic controllers can identify errors during the design stage so they can be remedied and prevent some faults from occurring once the system is running. Input order robustness is the property that multiple inputs arriving in a variety of orders, and regardless of the order, produce the same set of outputs and same final state. Verifying this property ensures determinism of the closed-loop...
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