Abstract: A problem of practical and theoretical interest in control is the synthesis of a compensator such that the closed-loop system step response does not overshoot. In this paper we present an approach for synthesizing such compensators for SISO, minimum phase plants. The essential idea of the technique is to appropriately locate the closed loop poles with respect to fixed and added zeros. Admissible pole-zero locations are characterized by two sufficiency theorems.

Abstract: The paper is concerned with the design of robust state feedback controllers for a class of uncertain systems with norm bounded uncertainty, where uncertainty enters in both the state and input matrices. The controller is designed to place the closed loop poles of the uncertain system in a specified disk and guarantees an upper bound on a quadratic cost function. A procedure is given for the construction of a controller which minimises a bound on an integral quadratic performance index.

Abstract: Alternative voltage control strategies for current-regulated PWM inverters are analyzed, including previously established feedforward and feedforward/feedback controllers and a newly proposed decoupling feedback control strategy. The steady-state and dynamic characteristics of each of these control methods are illustrated and compared for a selected inverter design. It is shown that the feedforward controller exhibits steady-state error and an undesirable overshoot of the output voltages during startup. The addition of a feedback loop eliminates the steady-state error and reduces the overshoot; however, the natural response is underdamped regardless of the choice of feedback gains. A decoupling feedback control strategy that eliminates the disadvantages of the feedforward and feedforward/feedback controllers is described. Using the decoupling feedback controller, it is possible to eliminate the steady-state error and place the closed-loop poles wherever desired. Moreover, if the closed-loop poles are selected appropriately, it is possible to eliminate the overshoot of the output voltages during startup transients.

Abstract: A new graphical tool called the phase-root locus is introduced. It is the dual of the conventional root locus, and indicates the motion of closed-loop poles in the s-plane as phase is added to the open-loop transfer function. The root locus/phase-root locus plots are shown to facilitate destabilization diagnosis, which may help determine what part of an unstable physical system requires modification. For example, destabilization may be caused by one closed-loop pole due to a phase-shift at one value of system gain, and by a different pole due to gain variations at another value of system gain. The phase-root locus also allows relative stability information, including phase margin, to be accessed from the s-plane. Thus the s-plane can now be used for robustness analysis/design as well as transient analysis/design. The phase-root locus shows promise as a tool in compensator design as well as in the teaching of classical control theory.

Abstract: This paper considers the problem of robust H/sub /spl infin// control with regional stability constraints via error feedback for uncertain track-following systems of optical disk drives. A robust H/sub /spl infin// control problem and the generalized Lyapunov theory are introduced for dealing with the problem. The error feedback H/sub /spl infin// controller presented in this paper makes the tracking error settle within a tolerable limit and the control input not to be saturated. The regional stability constraints problem for uncertain systems can be reduced to the problem for the nominal systems by finding sufficient bounds of variations of the closed-loop poles due to modeling uncertainties. A controller design procedure is established using the Lagrange multiplier method. To evaluate the proposed controller design method, it is applied to the track-following system or a digital video disk recorder (DVDR).

Abstract: A generalized predictive controller (GPC) is derived based on a general state-space model. The link between the predictive control problem and the perturbation problem is highlighted. In the case of small perturbation, the closed-loop poles are calculated with high accuracy. For the case of a general perturbation, an upper bound on the permissible perturbation norm is derived assuming an open-loop stable system. Both the plant-model match and plant-model mismatch cases are analyzed. The controller is so robust that an adaptive implementation is motivated. For open-loop stable systems,the convergence and stability of the control scheme are insured by proper tuning of the control weight and prediction horizon. The results are applicable to a wide range of predictive controllers.

Abstract: This paper provides a computational procedure for a type of robust regional pole assignment problem. It allows the closed-loop poles to be settled at certain perturbation insensitive locations within some prespecified regions in the complex plane. The novelty of our approach lies in the versatility of the proposed algorithm which provides a rich set of constrained regions for the assignment of individual or subsets of closed-loop poles, in contrast to other conventional regional pole assignment methods. The algorithm is based on a gradient flow formulation on a potential function which provides a minimizing solution for the Frobenius condition number of the closed-loop state matrix.

Abstract: One of the most significant benefits in the application of feedback in the design of electronic amplifiers is an increase in the midband frequency bandwidth. Because of the complexity of the mathematics involved in modeling feedback amplifier performance characteristics, several simplifying techniques are typically introduced. Among these in the frequency domain are single-pole approximations and the concept of dominant poles. While these techniques can reasonably approximate many amplifiers, they fail to adequately address some of the significant phenomena invoked when feedback is applied. In addition, it is often difficult for the typical student of electronics to understand the fundamental reasoning behind each approximation and its realm of validity. A unique approach to understanding feedback amplifier frequency response through the use of simple graphical heuristics is introduced. Primary among these is a display of pole migration using a plot of the pole polynomial as a function of the amount of feedback. General pole migration and the formation of pole pairs can easily be seen using this technique. The graphical nature of the approach brings particular significance to understanding pole dominance throughout the possible range of feedback. It can also be seen that the two-pole approximation to multipole feedback amplifiers has a significant region of validity while the validity of single-pole approximations is questionable.

Abstract: In this paper, the problems of pole assignment of singular systems are investigated by algebraic geometric method The sufficient conditions for assignment of finite poles and other kinds of poles are developed In addition, equivalence of the existence of a Complex state feedback to the real state feedback is proved

Abstract: The goal of the present paper is to provide an useful computational relation between the transfer function angles and the gain of transfer function. First of all we use the Hermite-Gauss formula to obtain some quadrature formula for transfer function angle. Finally the Kantorovich method gives us a differential relation between the transfer function angle and the gain.

Abstract: A technique is discussed for the selection of the closed loop poles in the output (or state) feedback problem. Each closed loop pole is placed on a circular arc whose radius corresponds to that pole's open loop natural frequency. It is shown that the damping value is the only parameter which can be changed so that the eigenvalues remain on the defined circle. The required gain matrix for pole placement can then be formulated as an unconstrained optimization problem. The Powell method and a heuristic search technique, called a genetic algorithm, are used in the optimization. A 6-DOF continuous time structural model with low damping and two closely spaced modes is used to obtain the required pole placement gain matrix. It is shown that the genetic algorithm gave overall better results than Powell's method in terms of minimizing the norm of the state and output pole placement gain. In addition, an eigenparameter sensitivity calculation was successful only in further reducing the norm in the state feedback case. Furthermore, it is shown that only velocity feedback terms need be considered. This has the advantage of a 50-percent reduction in the design space. (Author)