摘要:

Earlier eigenvalue inclusion regions are replaced by new regions which are tight and thus lead to sufficient and necessary stability conditions for uncertain linear multivariate systems in the presence of unstructured perturbations. The approach provides an exact and immediate assessment of gain and phase margins. When applied to systems with sector bounded but unstructured non-linearities, the inclusion regions produce a necessary and sufficient test for the circle criterion conditions to hold in the multivariable case; as such the resulting stability criterion gives the best possible Nyquist-type extension of the circle criterion to the multivariable case for unstructured non-linearities.

ISSN:0020-7179    

DOI:10.1080/0020718508961204

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A new range of techniques is introduced for the purpose of exploiting information about the structure of the perturbation associated with uncertain linear multi-variable feedback systems. The class of perturbation considered is wide and ignores only the phase information of the individual elements of the perturbation matrix; it encompasses diagonal, block-diagonal and other forms of block-structured perturbations. The techniques developed provide a means of assessing stability margins and also lead to an extension of the Nyquist criterion.

ISSN:0020-7179    

DOI:10.1080/0020718508961205

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The parametric linear quadratic (PLQ) control problem is considered for discrete-time stochastic systems. The control problem consists of a non-linear optimization problem in the parameters of a linear regulator. Results on global convergence and on rate of convergence are given for the linear-descent mapping method for solving the optimal regulator parameter values. Furthermore a non-linear mapping method based on the solution of a generalized discrete Riccati equation is given. The PLQ control problem is a useful extension of the optimal output feedback problem with applications to the design of low-order regulators, decentralized control and adaptive control.

ISSN:0020-7179    

DOI:10.1080/0020718508961206

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The convergence properties of a general iterative (off-line) pseudo-linear regression (PLR) algorithm are examined. It is found that the basic form of the algorithm converges under quite restrictive conditions. A simple modification of the algorithm is then proposed which relaxes the convergence conditions considerably. The refined PLR algorithm converges under precisely the same conditions as the well-known recursive (on-line) PLR procedure. The problem of monitoring the algorithm to guarantee the stability of estimated models is also discussed. A modified PLR algorithm which does not require monitoring is proposed, and its convergence properties analysed. Finally, some numerical examples illustrating the main theoretical results are included.

ISSN:0020-7179    

DOI:10.1080/0020718508961207

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The decentralized control problem is considered in the context of interconnected physical systems. The system is assumed to be made up of subsystems modelled by second-order differential equations. Conditions for the non-existence of decen tralized fixed modes and the existence of a solution to the decentralized servo- mechanism problem are given. An example from a planar robotic manipulator illustrates the results.

ISSN:0020-7179    

DOI:10.1080/0020718508961208

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A decentralized control scheme is proposed for stabilization of a class of interconnected systems using local output feedback. The scheme is robust with respect to uncertainties in parameters and non-linearities in the interactions among the subsystems.

ISSN:0020-7179    

DOI:10.1080/0020718508961209

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Within the framework of structural analysis, techniques are developed for obtaining reduced-order structural models in which all structural information is preserved. The reduced models are valid for any input and output sets guaranteeing that, from the structural controllability test, the same set of feasible input-output pairings are obtained from the low-order model as would be obtained from the high-order model. New insight into the practical significance of the generic rank test for structural controllability is provided, and an algorithm for the development of low-order models for staged systems is presented.

ISSN:0020-7179    

DOI:10.1080/0020718508961210

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The aim of this article is to study the observability and state reconstruction of parabolic systems. It is shown that observability can be deduced from the coercivity of a bilinear form associated with a quadratic criterion, and that the solution depends continuously on the data. The regularization of the criterion enables the notion of ϵ-observability of parabolic systems to be introduced, and the relationships between the two notions are studied. The practical case of systems of finite dimension obtained by discretization of continuous equations is also studied, from the point of view of observability as well as ϵ-observability and the results obtained, and numerical examples are provided to indicate why it may be of interest to search apriorifor an ϵ-observation in applications.

ISSN:0020-7179    

DOI:10.1080/0020718508961211

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Implicit self-tuners based on single-stage cost-function minimization schemes require exact knowledge of the dead-time of the controlled plant. Explicit pole-placement self-tuners on the other hand, though robust against variations of the time-delay, are very sensitive to the assumptions made about the model order of the plant; wrong assumptions may result in very poor performance. An explicit method based on minimization of a multistage cost-function and a CARIMA plant model formulated in state-space is presented. The method extends the design features of the generalized minimum variance scheme to the multistage case; these can be used to tailor the closed-loop response of the system. The approach is shown to be robust against wrong a priori assumptions made about the plant dead-time or order, thus maintaining good servo and disturbance-rejection properties (see Part II).

ISSN:0020-7179    

DOI:10.1080/0020718508961212

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Implementation aspects of the LQ self-tuner proposed in Part I are discussed. The method involves solution of a Riccati equation through U-D factorization, and state estimation through transmittance matrices. Simplified vector formulations of the U-D time update and the transmittance matrix are presented. Simulation results demonstrate the superiority of this algorithm over pole-placement and the generalized minimum-variance controllers. Incorporation of the auxiliary variable ψ(t) instead ofy(t) and the incremental control law Δu(t) in the cost function ascribes the right servo properties to this algorithm with offset-free control performance. The algorithmic stability and numerical robustness, without sacrifice of implement-ational simplicity, make the proposed LQ self-tuner attractive.

ISSN:0020-7179    

DOI:10.1080/0020718508961213

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor