Synthesis Of Multivariable Control Systems Research Articles

Individual Channel Design for Synchronous Generators

In this paper a novel control strategy for a real synchronous generator is presented. It is based on linear, diagonal, low order, minimum-phase, fixed, and stable controllers. The controller was obtained via individual channel design (ICD), a framework that allows analysis and synthesis of multivariable control systems by means of classical techniques based on the Bode and Nyquist plots. The generator is part of a one machine – infinite bus system. A linearised model around an operating point in a rotating coordinate frame is used. The theoretical principles behind this control strategy are summarised for completeness. The results using this novel control strategy are obtained throughout simulations in MATLAB®.

H∞ Control system for tandem cold mills with roll eccentricity

In order to meet the requirement for higher thickness accuracy in cold rolling processes, it is strongly desired to have high performance in control units. To meet this requirement, we have considered an output regulating control system with a roll-eccentricity estimator for each rolling stand of tandem cold mills. Considering entry thickness variation as well as roll eccentricity as the major disturbances, a synthesis of multivariable control systems is presented based onH∞ control theory, which can reflect the knowledge of input direction and spectrum of disturbance signals on the design. Then, to reject roll eccentricity effectively, a weight function having some poles on the imaginary axis is introduced. This leads to a non-standardH∞ control problem, and the design procedures for solving this problem are analytically presented. The effectiveness of the proposed control method is evaluated through computer simulations and compared to that of the conventional LQ control and feedforward control methods for roll eccentricity.

Design of a strip thickness control system for tandem cold mills using H∞ control techniques

In order to meet the requirement for higher thickness accuracy in cold-rolling mill processes, it is strongly desired to have an increasing high performance in control units. To meet this requirement, an output regulating control system with a roll-eccentricity estimator for each rolling stand of tandem cold mills was considered. Assuming entry thickness variation as well as roll eccentricity to be the major disturbances, a synthesis of multivariable control systems is presented and based on H∞ control theory, which can reflect knowledge of the input direction and spectrum of disturbance signals on design. Then, to reject roll eccentricity effectively, a weight function having some poles on the imaginary axis is introduced. This leads to a non-standard H∞ control problem, and the design procedures for solving this problem are analytically presented. The effectiveness of the proposed control method is evaluated through computer simulations and compared with the conventional linear quadratic control and feedforward control methods for roll eccentricity.

Multivariable control system synthesis: An experimental data based numerical approach

An input-output data based numerical technique is proposed for control system synthesis. The method is applicable when the system is open-loop stable. The major merits of the method are two-fold: (1) the control system synthesis can be done before the open-loop system equation is derived, and (2) the workability of the synthesized controller may be verified during the course of the design process even though an open-loop model is absent.

Investigation of Multipurpose Control Systems Using the ASMCS Package for Analysis and Synthesis of Multivariable Control Systems

Investigation of Multipurpose Control Systems Using the ASMCS Package for Analysis and Synthesis of Multivariable Control Systems

Observer-based multivariable control of the aluminum cold tandem mill

Innovation in thickness control of the aluminum cold tandem mill has emerged from an application of modern control theory. Any good control system must deal appropriately with two fundamentals of mill operation: (1) the mutual interaction between strip thickness and interstand tension, and (2) disturbances in the mill environment. In this paper, a synthesis of multivariable control systems for aluminum cold tandem mills is presented based on the theory of output regulation established basically by Wonham and his colleagues (Wonham, 1974, Linear Multivariable Control—A Geometric Approach. Springer, New York; Wonham and Pearson, 1974, SIAM J. Control, 12, 5–18; Francis and Wonham, 1976, Automatica, 12, 457–465). The synthesis procedure is composed of the three major steps. The first one is to improve the response characteristics by state feedback. The second one is to compute the feedforward control input to counterbalance the disturbance. The third one is to implement the feedforward control by feedback control based on the estimation of the disturbance by observer. The obtained system was actually implemented and has been in full commercial operation since 1986, making splendid accomplishments.

Observer-Based Multivariable Control of the Aluminium Cold Tandem Mill

Abstract Innovation in thickness control of the aluminum cold tandem mill has emerged from an application of modern control theory. Any good control system must deal appropriately with two fundamentals of mill operation: 1) The mutual interaction between strip thickness and interstand tension, and 2) disturbances in the mill environment. In this paper, a synthesis of multivariable control system for the aluminum cold tandem mill is presented based on the theory of output regulation established basically by Wonham and his colleagues (Francis and Wonham, 1976; Wonham, 1974; Wonham and Pearson, 1974). The synthesis procedure is composed of the three major steps. The first one is to improve the response characteristics by state feedback. The second one is to compute the feedforward control input to counterbalance the disturbance. The third one is to implement the feedforward control by feedback control based on the estimation of the disturbance by observer. The obtained system was actually implemented and has been in full commercial operation since 1986, making splendid accomplishments.

The UMIST Control System Design and Synthesis Suites

Two suites of Fortran programs, which allow the design and synthesis of multivariable control systems are discussed. Both suites operate in an interactive conversational mode, and make appropriate use of graphic output. Powerful data input-output facilities and data transformation routines are provided. These are augmented by flexible analysis and automatic system simulation programs.

Interactive package for analysis and synthesis of multivariable control systems

This paper describes an interactive package for designing multivariabl e control systems. It is assumed that a model of the system, either in the form of a matrix of transfer functions or in state-space form is known. The design procedure is by successive analysis. In each iteration the designer checks the stability and transient response of the system. The package is implemented on a PDP-9 computer with precision display, disk, line printer and teletype.

Sensitivity Reduction of Multivariable Systems with a Prespecified Structure of Transfer Matrix

In the synthesis of multivariable control systems by state feedback, the choice of the closed loop transfer matrix fixes all free parameters in a lot of cases. However, the use of a dynamic compensator together with state feedback is shown to provide additional degrees of dreedom in the form of inner feedback loop. A design procedure is outlined to use this additional state feedback to reduce the sensitivity of the system against internal and external disturbances.

Decoupling in the design and synthesis of multivariable control systems

Necessary and sufficient conditions for the "decoupling" of an <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</tex> -input, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</tex> -output time-invariant linear system using state variable feedback are determined. Given a system which satisfies these conditions, i.e., which can be decoupled by state variable feedback, the class φ of all feedback matrices which decouple the system is characterized. The characterization of φ is used to determine the number of closed-loop poles which can be specified for the decoupled system and to develop a synthesis technique for the realization of desired closed-loop pole configurations. Transfer matrix consequences of decoupling are examined and practice implications discussed through numerical examples.

Multivariable control system synthesis utilizing the generalized inverse of a matrix

By utilizing the concept of the generalized inverse of a matrix, it is possible to obtain more complete multivariable control system design equations than have previously been published. Also, condition equations can define the limitations which must be imposed upon the desired system H' in order to realize a mathematical solution.

Synthesis of Optimum Multivariable Control Systems by the Method of Steepest Descent

The optimum synthesis of multivariable control systems with generalized quadratic error criterion is solved by using time method of steepest descent in the Hilbert space. Apart from the conventional minimization techniques, this approach works directly on the functional of the error criterion itself so that the optimal solution can be determined through sucessive approximations. Since this solution can be obtained at high speed and with high accuracy by using a digital computer, this method is particularly useful in solving the actuation problem of adaptive control systems.

Synthesis of multi-variable control systems by means of sampled-data compensations

Synthesis of multi-variable control systems by means of sampled-data compensations

The linear least squares synthesis of multivariable control systems

A MULTIVARIABLE system is characterized by a multiplicity of inputs and outputs. In the following, it will be assumed that such systems can be described by linear, time-in variant, input-output relations over the whole range of operation or over the restricted range of interest. Thus, let then, the system input-output relation may be expressed compactly as where R, C, and A are input, output, and transfer-function matrices respectively; see Fig. 1. It is seen that a multivariable system derives each output by a simultaneous operation on all its inputs. Furthermore, it is apparent that the class of multivariable systems includes the common single-variable system as a special case.

Multivariable control system synthesis

An important problem in the field of multivariable control systems is the design of suitable feedback and series compensation elements which, when added to a given system, result in an over-all system with improved characteristics. This improvement may apply to the behavior of the controlled variables, to the disturbance response of the system, or to both simultaneously.