A solution to the diagonalization problem by constant precompensator and dynamic output feedback

A note on the problem of semiglobal practical stabilization of uncertain nonlinear systems via dynamic output feedback

In this paper, the pole placement problem by constant output feedback for linear time invariant systems is investigated. In particular, is proven that, for the class of linear time invariant systems with m inputs, p outputs, and McMillan degree n, the condition (m + p) > n is necessary for the solution of the arbitrary pole placement problem by constant output feedback.

The aim of this paper is to develop a new approach for a solution of the model following control (MFC) problem with a dynamic compensator by using linear matrix inequalities (LMIs). TheH1 model following control problem is derived following LMI formulation. First, the H1 optimal control problem is revisited by referring to Lemmas assuring all admissible controllers minimizing the H1 norm of the transfer function between the exogenous inputs and the outputs. Then, the solvability condition and a design procedure for a two degrees of freedom (2 DOF) dynamic feedback control law is introduced. The existence of a 2 DOF dynamic output feedback controller for the model following control is proven and the stability of the closed-loop system is satisfied by assuring the Hurwitz condition. The benchmark thermal process (PT-326) as the first order process with timedelay is regulated by the presented 2 DOF dynamic output feedback controller. The simulation results illustrate that the presented controller regulates a system with dead-time as a large set of generic industrial systems and the H1 norm of the closed-loop system is assured less than the H1 norm of the desired model system.

This paper presents as its main result a new and efficient method for the design of optimal dynamic compensators for linear multivariable control systems. The discussion starts with a fresh look into the design of optimal constant gain output feedback. In this context, three new ideas are introduced that prove their usefulness particularly in the dynamic compensator case: (1) deterministic measurement disturbances are included in the formulation of the underlying optimization problem, (2) the relationship between a deterministic and a stochastic optimal control problem is shown, (3) by proper modifications of the quadratic cost function, the effort involved in the numerical solution of the optimal output feedback problem is considerably reduced. Furthermore, a canonical form is introduced for the dynamic compensator and an algorithm is developed for the numerical computation of its free parameters. It is based on quasi-newtonian gradient methods and an efficient line search procedure. Some features of the new design method are demonstrated by means of a non-trivial benchmark taken from the literature.

Gradient matrices are formulated for the linear multivariable system with output feedback. The incremental motion of the poles and zeros and the coefficients of the numerator and denominator transfer function polynomials is determined as a function of the elements of an output feedback gain matrix. Also considered is the incremental movement of zeros and the coefficients of the numerator transfer function polynomials with respect to the elements of an input gain matrix. In addition, the characteristic polynomial gradient results are used to study the bounds on the number of independently assignable poles for linear multivariable systems with constant output feedback. The investigation is extended to estimate the minimum order dynamic output feedback compensator necessary to establish full polo placement for the expanded order system. Examples are included to illustrate the methods involved and to make comparisons with previous results.

Pole placement by parametric output feedback

New results on dynamic output state feedback stabilization of some class of time-varying nonlinear Caputo derivative systems

This paper presents a method for designing fixed-order dynamic compensators that approximate the Hm full state feedback, closed-loop transfer function properties from disturbance inputs to controlled outputs. This formulation uses an observer canonical form to represent the dynamic compensator which allows the design to be treated as a modified constant gain output feedback problem. The approximate recovery is accomplished through a unique selection of the quadratic performance index weighting matrices. This design procedure is demonstrated by two design examples. The first example is a simple fourth-order model used to demonstrate the procedure. The second example is a longitudinal flight controller for the F-18/HARV Supermaneuverable aircraft. This flight controller is compared to both a full- and reduced-order H^ compensator.

On Anti-Integrator-Windup and Global Asymptotic Stability

Cooperative output regulation problem for linear time-delay multi-agent systems under switching network

The paper presents the design of piecewise constant periodic output feedback control for a discrete-time singularly perturbed system resulting from the discretization of a continuous-time standard singularly perturbed system. By a suitable linear transformation of state variables, the given continuous-time singularly perturbed model is converted into a block triangular form in which the fast subsystem is decoupled. The discrete-time model corresponding to the transformed model also exhibits a two time scale property if sampling period is larger than the parameter E. Now an output injection matrix is found that stabilizes the slow subsystem. The periodic output feedback gain is then calculated only for the slow subsystem and the same for the fast subsystem is set equal to zero. Finally the periodic output feedback gain for the composite system is obtained using the periodic output feedback gains computed separately for the slow and fast subsystems. An approach has been suggested whereby the determination of periodic output feedback gain for the slow subsystem can be converted into an optimization problem. By minimization of the suggested performance index the closed loop system behavior is improved. The method has been applied to a large pressurized heavy water reactor (PHWR) for control of xenon-induced spatial oscillations. A particular grouping of state variables has been suggested for obtaining the model in standard singularly perturbed form. The periodic output feedback gain is then calculated. The efficacy of control has been demonstrated by simulation of transient behavior of the nonlinear model of the PHWR.

In this paper a numerical efficient approach to the problem of eigenvalue assignment by constant output feedback is presented. It improves the well known Kimura’s condition by 2, i. e., it is shown that if m + p ≥ n − 1 m+p\ge n-1 generically a solution to this design problem exists where n , m n,m and p denote the dimensions of the system states, inputs and outputs, respectively. The algorithm is based on a cascaded control scheme with up to three design steps. The first two steps merely require standard methods from linear algebra while the last step only in case of m + p = n − 1 m+p=n-1 demands for the numerical solution of a system of three polynomial equations each of order two. The design procedure explicitly embodies all degrees of freedom beyond eigenvalue assignment. Thus, they can be used to account for other design it is shown goals, e. g., to minimize the spectral condition number of the closed-loop system or a norm of the feedback gain as it is shown by numerical examples from literature.

This paper deals with the problems of bifurcation suppression and bifurcation suppression with stability of nonlinear systems. Necessary conditions and sufficient conditions for bifurcation suppression via dynamic output feedback are presented; Sufficient conditions for bifurcation suppression with stability via dynamic output feedback are obtained. As an application, a dynamic compensator, which guarantees that the bifurcation point of rotating stall in axial flow compressors is stably suppressed, is constructed.

This paper proposes a simple necessary condition for the stabilisation of an inherently unstable linear system with constant output feedback. This is a sign criterion obtained directly from the linear constraints on the attainable closed-loop characteristic polynomials when constant output feedback is employed. The condition is first established for single-input systems and then extended to multi-input systems, where the output-feedback matrices are restricted to have unity rank. Stabilisation with unconstrained output-feedback matrices is also discussed. Illustrative examples on stabilisation are given.

This paper describes an applications oriented approach to the generation of optimal output feedback gains for linear time-invariant systems which is dependent of the open loop stability.