Design Of Multivariable Control Systems Research Articles

Quantitative design of uncertain multivariable control system with an inner-feedback loop

An additional inner-feedback loop is used to reduce the channel interaction of a multivariable control system such that the design of outer-feedback loop can be treated as a single-variable problem for ease in achieving the required main-channel performance. The relative error between the exact input–output relation tii(jω) of channel i and its approximation t̂ii(jω) = {li(jω)fii(jω)}/{1 + li(jω)} is introduced to provide an effective measure for assessing the achieved noninteraction. According to the approach proposed, the single-input/single-output quantitative-feedback-theory design method can be applied directly for the design of both inner- and outer-feedback loops.

Quantitative feedback design of uncertain multivariable control systems

An alternative QFT framework is proposed for the design of multiple-input multiple-output (MIMO) feedback systems with significant plant uncertainty. Sufficient conditions are first derived to assure the achievement of the given off-diagonal performance. Then the given performance bounds on each main channel are reallocated on a reasonable basis, such that not only is the main channel performance easily achieved, but also the trade-offs of performance bounds between the loops become transparent during the system synthesis.

S-54-2 - The integration of intrinsic properties and synaptic inputs in locus coeruleus

In this paper, a package of programs for the computer aided design of discrete multivariable linear control systems is shown. It is based on frequency-domain techniques. Also, a new stability design method for multivariable systems is described. The package performs the following tasks: calculation of the equivalent z-transfer function of a continuous system, stability design; interaction improvement; operations with transfer functions matrices and simulation of closed loop discrete multivariable systems. The solution of these tasks leads to the manipulation of transfer functions matrices. It is carried out with the aid of the Graph Theory. A design example is included to illustrate the use of the stability design method and the efectiveness of the package.

Static Output Feedback Controllers for Continuous-Time Systems with Input-Output Nonlinearities

In this paper we develop a static output feedback controller synthesis framework for continuous-time multivariable linear time-invariant systems subject to input-output time-varying nonlinearities. The proposed framework directly accounts for robust stability and robust performance over the class of input-output nonlinearities. Specifically, using absolute stability theory we develop a controller synthesis framework for constructing feedback controllers with a guaranteed domain of attraction for systems with input nonlinearities. The proposed design approach provides a systematic procedure for loop shaping and hence can account for classical design objectives within a modern multivariable control-system design framework

An algorithm for inverting rational matrices

We propose an algorithm for computing the inverses of rational matrices and in particular the inverses of polynomial matrices. The algorithm is based on minimal state space realizations of proper rational matrices and the matrix inverse lemma and is implemented as a MATLAB 1 function. Experiments show that the algorithm gives accurate results for typical rational matrices that arise in analysis and design of linear multivariable control systems. Illustrative examples are given.

Robust Multivariable Control of Nuclear Power Plant

The paper presents a design method for robust multiva-riable control design and its application to retrofit a new additional control system in an old pressurized water reactor (PWR) nuclear power plant (NPP). The mathematical model of PWR NPP, used in the design process is briefly described. The 28th dimensional state equation model accounts for the main physical processes and plant subsystems. The optimal and suboptimal linear quadratic gain (LQG) additional control, which provides improved integration of the existing automatic feedback control loops is described and dynamical behaviour of the plant is simulated. Because of the process parameters variations, the design of a robust multivariable control system is considered and a new method which leads to improvement of system robustness is proposed. The method, based on LQG control improves the response of the existing control loops and increases the closed loop system robustness. The dynamical behaviour of NPP Krsko, Slovenia, for specified design plant perturbations is presented and the use of different control systems is compared.

Applying H-infinity control methods to wind turbines using MATLAB®

SYNOPSIS In this paper, the application of robust multivariable control system design methods to wind turbines is discussed. The control problem is introduced and the background to the design method is given. The H-infinity (H ∞) controller is implemented and the Loop Shaping Design Procedure is used. MATLAB® is used for the mathematical analysis.

Output-sliding control design of multivariable systems

A theoretical development of output-sliding control for uncertain mismatched multivariable systems is presented. The control law consists of a continuous nominal control part and a discontinuous switching control part. The determination of controller gains is explicit and practical. The closed-loop eigenvalues assignment in the sliding mode is well addressed. System robustness against a larger class of parameter variations and disturbances than by conventional design methods is achieved. Simultation studies show the promise of the proposed method.

Robust control design via eigenstructure assignment, genetic algorithms and gradient-based optimisation

The paper presents a new approach for robust control design of multivariable systems via eigenstructure assignment, genetic algorithms and gradient-based optimisation. It takes the combination of the sensitivity and the complementary sensitivity functions of the closed-loop system as the robust control performance index. The gradient calculation of the performance index is described in detail for the closed-loop system with real and complex eigenvalues. The paper makes full use of the freedom provided by eigenstructure assignment to find a controller which stabilises the closed-loop system and minimises the performance index via the combination of genetic algorithms and gradient-based optimisation. The simulation results for the design of a lateral flight control system provide a tutorial demonstration of the power of the method.

Quantitative feedback theory technique and applications

Quantitative feedback theory (QFT) technique has emerged as a powerful multivariable control system design method. This design method addresses real-world problems with structured plant parameter uncertainties. The paper provides the control community with an overview and the basic mathematical concepts of the QFT technique. The solutions to some real-world flight control problems and a very powerful design tool (QFT CAD package) are presented. One of these solutions was successfully implemented and flight tested.

EXPMUL: an expert system for the design of multivariable control systems

The development of an expert system environment for the design of M1MO control systems using the frequency response approach is discussed. The aim is to provide assistance for non-experienced designers so that they can learn and gain experience of a specific area of control system theory. As a preliminary, we discuss the different configurations of expert systems used in control system design. The design heuristic is then declared, and followed by a comprehensive example. The implementation of our expert system is then illustrated, and a detailed application is also given.

Distributed multivariable control system design for coal-fired boilers

Abstract This paper describes the multivariable characteristics of industrial coal-fired boilers and associated mathematical models, such as combustion model, a water drum level model and a superheated steam model. The purpose of the paper is to design multivariable control systems using multivariable system frequency domain design theory and the Smith-predictor technique. A specific application shows how to design a model-based distributed multivariable control system for coal-fired boilers in a small-scale power station.

The role of single-loop subsystems in multivariable control by individual channel design of 2-input and 2-output systems

Individual channel design is an applications-oriented framework for the analysis and design of multivariable control systems (O'Reilly and Leithead 1991). Whilst most previous work focuses on the analysis of multivariable systems using individual channel design, this present paper concentrates on some design aspects for 2-input 2-output systems. Two basic issues are examined: first, the role of single-loop subsystems (as opposed to channels) in multivariable control by individual channel design; second, how single-loop subsystems facilitate an attractively simple sequential design procedure for channels of any bandwidth. This sequential individual channel design procedure is based on two interesting results. First, there exists a dynamic performance relationship between the individual channels and their associated single-loop subsystems in that the deviation of the single-loop subsystem sensitivity function from the associated channel sensitivity function is the same for both channels. Second, provided th...

Multivariable control system design of CO 2/amine absorber/desorber units by using a rigorous steady-state model

Computer simulations with a rigorous steady-state model were used in a multivariable control system analysis of industrial CO 2/MEA absorption/desorption units. Analysis predicts that the system is stable in a closed loop and that the variables should be paired such that the compositions of lean and rich solutions are controlled by manipulating the liquid circulation rate and the reboiler duty, respectively.

Robust digital control of a high-performance engine

The design of a robust digital multivariable feedback control system for the F-100 turbofan jet engine is considered. The control system design problem is posed, and conditions for satisfying performance specifications and stability robustness are stated. The discrete LQG/LTR methodology is used to design a compensator that meets the stated specifications. New results for multi-input LQR loop shaping are derived. To get a reasonably low-order compensator, frequency-weighted reduced-order models are exploited, with the reduction error treated as an uncertainty.

A CACE-III environment for the design of multivariable control systems

The author presents the capabilities provided by an expert-system-based design environment package developed to help non-experienced users in the design of multivariable control systems. Three external design tools have been added to handle the problems of system identification, large-scale systems and MIMO systems having feedback nonlinearities.

Reduction of Structural Complexity

Abstract The identification of weakly coupled sub-systems often provides the basis for complex multi-variable control system design. Such identification is not always easy, and conventional methods of system reduction often make such an approach impossible. An alternative approach to the reduction of system structure is suggested, based: on eigenvalue sensitivity analysis, and the procedure is applied to a high order distillation column problem. Comparative results are given

Genetic design of linear multivariable feedback control systems using eigenstructure assignment

In the design of linear multivariable feedback control systems, performance specifications can frequently be met by assigning appropriate closed-loop eigenstructure. However, although various powerful algorithms for the solution of this problem of eigenstructure assignment have been proposed over the years, no universally applicable and computationally stable methodology has yet emerged. These difficulties motivate the use of genetic algorithms in the solution of the fundamental problem of eigenstructure assignment.

An expert system for multivariable controller design

Abstract An expert system for the design of linear multivariable control systems has been implemented on a personal computer. It assists the user in formulating a comprehensive and achievable design specification, and in dealing with conflicting design constraints. The expert system also effectively extends the scope of the underlying CACSD package.

New dominance concepts for multivariable control systems design

This paper sets out a revised view of the classical diagonal dominance method for multivariable feedback systems. The various types of dominance measure are unified by using one fundamental dominance theorem (FD)l. It is shown that the fundamental dominance condition yields the smallest dominance measure when compared with all the known classical diagonal dominance measures. In addition it is shown that the dominance measures such as row/column, generalized dominance and a few new ones are special cases and can be derived from this same FD theorem. This improved dominance criterion also provides the sufficient condition for a system to be approximated by a nominal one in the sense that the stabilization of this nominal system will assure the stability of the original one. Finally, a new type of dominance measure named L-dominance is presented. It has been shown that this new approach yields an even smaller dominance measure, and that when it is applied to matrices with non-positive off-diagonal elements, ...