Abstract: We establish necessary and sufficient conditions under which all minimal passive scattering systems that have a given transfer operator function are unitarily equivalent. These conditions can be significantly simplified in special cases important for applications, in particular, in the case where a transfer function is rational and in a more general case where this function is pseudoextendable.

Abstract: The described method and system are adapted to reduce the error between an ideally expected output signal and the actual output signal. The proposed adaptation algorithm is able to minimise, for instance in a system with a given transfer function, the error y-x between y=g(f(x)) and x, where g is an unknown and/or time-varing function and f the adaptive function for which the characteristic is changed to track g. The proposed adaptation algorithm updates not only the transfer function f at the current input value x, but also the transfer function f at other points corresponding to different input values. One of the applications for such an algorithm is digital predistortion where a transmitter's non-linear characteristic needs to be linearised, in an adaptive manner, since the characteristic exhibits slow changes with temperature, bias, ageing or the like.

Abstract: Methods and apparatus operable to create transfer or blending functions defining blending modes for image processing. The identity of a first transfer mode function T 1 and of a second transfer mode function T 2 are obtained in a graphical image process system, and a new transfer mode is dynamically defined having a new transfer mode function T defined as a mathematical combination of the first transfer mode function and the second transfer mode function. An interpolation value beta may be obtained and the new transfer mode function may be an interpolated function T=T 1 ×beta+T 2 ×( 1 −beta). A third transfer mode function T 3 may be obtained and the new transfer mode function may be a composite function T=T 3 (T 1 , T 2 ). Beta may be a position-depended value of a solidity mask.

Abstract: Describes a technique for relay based closed loop transfer function estimation. Given a closed loop system, a user selected transfer function and a defined magnitude, then a relay experiment is used to obtain the frequency corresponding to the selected transfer function magnitude. In the paper the loop transfer function and the sensitivity transfer function are considered. This information can be used to evaluate certain transfer function properties or to redesign the controller.

Abstract: This paper deals with the problem of designing a plasma current, position, and shape controller for the ITER-FEAT tokamak. Exploiting the features of the plant, we show that it is possible to design separately two control loops: a first loop which stabilizes the vertical position by means of a simple derivative action, and a second loop which drives the plasma current and the geometrical shape descriptors as close as possible to the reference values. The second loop is designed by assigning the dominant closed loop poles.

Abstract: Rational interpolants, some of the poles of which are left free, are used to approximate the transfer functions of a large class of possibly unstable infinite-dimensional control systems. The free poles are used to detect the singularities of the transfer function which are responsible for the instability of the system.

Abstract: For a class of uncertain linear systems, a necessary and sufficient condition for the existence of state feedback control laws which assign the closed loop poles in a prespecified disk is derived in terms of linear matrix inequalityies(LMIs). The problem of designing the controllers with smaller gain parameters is formulated as a convex programme with LMI constrains, which can be solved by the existing LMI software. The proposed method is applicable to both continuous and discrete time systems.

Abstract: This paper shows how to cast the classical flight control system design into the framework of modern robust control theory by using Guardian Maps. A design procedure is proposed which consists of characterizing all control gain parameters such that the resulting closed-loop poles all lie within a specific desired region. This region is obtained by projecting the boundaries of several types of handling qualities into the complex s-plane. A multivariable polynomial in the gains is then obtained such that any set of gains for which this polynomial is nonzero is guaranteed to place the closed-loop poles in the desired handling quality region. An example of longitudinal flight control system design is presented, which shows the efficiency of the proposed method.

Abstract: An example is presented of a bounded-input/bounded-output unstable plant given by convolution with a causal locally integrable impulse response whose transfer function is everywhere analytic in the finite plane.

Abstract: This work presents analytical expressions as well as related curves to determine the maximum magnitude and phase deviations caused by a zero-pole pair, an individual pole or an individual zero on a discrete-time transfer function. The main motivation is to provide a clear link between the position of zeros and poles, considering their magnitudes and phases, and the effects of discarding them from a given transfer function, since evaluating these effects is crucial to attain the order reduction of physical system models.

Abstract: We investigate the exact solution, minimizing the l/sub /spl infin// norm of the regulated output for a fixed input in SISO discrete-time feedback control systems. This is achieved by allowing non-zero steady state value and parametrizing the output to have a rational transfer function with chosen poles on the stability boundary. Alongside these l/sub /spl infin//-optimal solutions, we obtain solutions in l/sub 1/ with the same order transfer functions and arbitrarily close I/sub /spl infin// norms.

Abstract: For the linear quadratic(LQ) optimal control system, a method is proposed to choose the suitable weighting matrices which make the system have desired closed loop poles. The weighting matrices can be regulated by transformation matrices which are related to the desired system poles. So the LQ system acquires the desired dynamic quality. These designs are based on the system normal model. When perturbations occur, the stability and desired performance of the system are affected severely. So it is very important to obtain the allowable stable perturbation bounds for analysis and design of the system. In this paper, a robustness measure bound is introduced for the state feedback system, and the stable bounds of the closed loop system in the presence of perturbations are derived. The stable bounds are obtained for allowable nonlinear time varying perturbation. In particular, for linear perturbations the stable bounds are also derived. A numerical example is finally included to demonstrate the proposed procedure.

Abstract: WT5BZ]A PID controller design method that achieves high performance for a wide range of linear self regulating processes is proposed Satisfactory dynamic characteristic can be obtained for processes with various dynamics, including those with low and high order, small and large dead time, and monotonic and oscillatory responses The method is developed based on a second order plus dead time modeling technique and a closed loop pole allocation strategy through the use of root locus The model is proven to be effective for a wide class of processes, and the model is able to generate peaks in those of oscillatory processes Different closed loop poles are selected according to the damping ratio and dead time, and simple formulas are provided for the calculation Simulation show satisfactory results [WT5HZ]

Abstract: We consider a negative unity feedback control system in which a PID controller and a transfer function having only poles are in cascade. This paper present sufficient conditions for the existence of a PID controller under which the overall closed loop characteristic polynomial is stable. These sufficient conditions are based on Lehnigk's lemmas (1966).

Abstract: This paper presents a method for determining the maximum allowable perturbation, for a MIMO linear time-invariant uncertain system, such that the closed loop poles are assigned in a specified disk by static output feedback; the uncertainty being norm-2 bounded. A sufficient condition for d-stabilizability is derived. Hence, in order to solve the related optimization problem a genetic-like algorithm is performed. An illustrative example shows the effectiveness of the proposed procedure.

Abstract: We show that for linear systems represented in the controllable canonical form there are simple and systematic changes in the input/output properties of the closed-loop system from the disturbance input to the system output when controls are applied to produce a radial displacement of all the closed-loop poles. In particular this is true for the transfer function and the impulse response of the systems. This in turn leads to a better understanding of how such changes in the control gains affect the induced L/sub 2/ norm, (the H/sub 2/ norm) and the induced L/sub /spl infin// norm (the L/sub 1/ norm) of the system.

Abstract: In the last few years, many efforts have been done to design a state feedback controller which assigns all the closed loop poles in a specified region for a linear time invariant system with perturbations. This type of a pole assignment problem arises frequently when a good model of the plant is available, but uncertainties exist with respect to the parameters which may be changed during operation or are unknown or difficult to measure. Friction coefficient, inertia, mass, spring constant, reaction rate, and aerodynamic coefficient etc. are common examples of such parameters. The controller must preserve the closed loop pole locations in a specified region for known ranges of parameter excursions. Among different ways for realizing the above problem, one of the most popular is robust pole assignment in a specified region [1]-[6]. Furuta and Kim [1] proposed a design method for assigning the closed loop poles in a specified disk based on gain and phase margins which is named -stability margin. They considered that case, when the perturbations are unknown gains as a diagonal form. Figueroa and Romagnoli [2] presented a method for designing controllers which attempt to place the roots of a characteristic polynomial of an uncertain system inside some prescribed regions. The analysis is based on a transfer function of a characteristic polynomial. In [3], another pole assignment method working with a spectral radius and a pulse transfer function is proposed. The procedure is simple, but it is used only for checking the positions of closed loop poles, not for designing the controller. In this paper, we deal with the procedure to design robustly a state feedback controller which assigns all the closed loop poles in a specified disk for a linear time invariant system with perturbations of physical parameters. A distinct point of the proposed robust design procedure is that the nominal closed loop matrix is firstly established such that all its eigenvalues are positioned in a

Abstract: Based on Lyapunov stability theorem and the generalised inverse theory, we present a design procedure for synthesizing a state-feedback system possessing good characteristics due to both the placements of the closed-loop poles in a specified region and the integrity against actuator failures in this paper. Design method for state feedback controller such that all poles of the nominal closed-loop systems are placed within a prescribed circular region is addressed. The region that we consider for pole placement is a specified circular region. Then, the design of robust controller for the system subjected to plant parameter perturbation and actuator failure has been studied. Sufficient condition for the existence of the desired controller is derived. Furthermore, the result is developed for the case of sensor failure. It is shown that the proposed system design retains asymptotic stability in the presence of parameter perturbation, as well as in the case of actuator failure.

Abstract: Optimal pole placement method for singleinput singularly perturbed systems is presented in this paper. With prespecified poles, the optimal state weight can be determined by linear formulations for single-input controllable singularly perturbed systems. In order to reduce the magnitude of the state feedback control input, and to achieve better performance for the closed loop system, pre-selection of the closed loop poles can be used to attain these goals. It is shown that the singularly perturbed system can be decoupled into two subsystems by the two time scale method. These two subsystems can be transformed into two second canonical forms such that the optimal control method can be applied to find the desired state weighting matrices through prespecified closed loop poles for the slow and fast modes. It is shown that the differences between the closed loop and open loop characteristic polynomials reduce the algebraic Riccati equations (ARE) to the linear algebraic formulas. An example of control of longitudinal motion of a large commercial aircraft is given to illustrate the proposed technique.

Abstract: A special case of the model matching problem is considered: when the systems has a minimal realization in the form {A,B,T}, where T is an invertible matrix. The problem is held in the feedback group, this point of view turns out to be relevant when it is applied to solve the static feedback block decoupling problem, as it leads to sufficient conditions. In order to illustrate the procedure, the decoupling of a linear helicopter model is examined and simulation results are shown.

Abstract: This paper studies the optimal realizations of a finite-word-length (FWL) digital state-estimate feedback controller with closed-loop pole sensitivity minimization considerations. Through analysis it is shown that the pole sensitivity measure is coordinate dependent. Structures that minimize this measure are found.

Abstract: We consider the problem of controlling nonminimum phase type-1 plants in presence of model uncertainty and a saturation constraint imposed on the control input. We focus on plants that can be described by a nonminimum phase type-1 model. The control objectives include: 1) robust global asymptotic stabilization of the controlled plant; 2) output regulation in presence of external perturbations; and 3) tracking of output reference trajectories. The problem is dealt with using a saturated (indirect) adaptive regulator, based on a specific pole placement of the closed loop poles. The stability robustness is ensured with respect to a multiplicative modeling error. The obtained regulation and tracking performances are such that the slower the reference trajectory and the perturbation sequence, the better the quality of the tracking and regulation performances.

Abstract: Exact and approximate equations are derived that relate the magnitude slope of a general transfer function directly to its phase angle. The result is used to derive simple conditions on stabilizability of feedback loops with right half-plane poles and zeros or dead-time.