摘要:

A trigonometric approximation scheme for optimal periodic control problems with state and control dependent delays is considered. The formulation of approximate problems is here adapted to a specific form of state equation with variable time delays. Sufficient conditions for the sequence of nearly optimal solutions of approximate problems to be a generalized minimizing sequence for the basic problem are given. The application of the method proposed to a periodic control of chemical reactors with recycles and controlled piping is pointed out.

ISSN:0020-7179    

DOI:10.1080/00207178908953376

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A method is presented for identifying the transfer function matrix of a continuous-time multivariate system with unknown initial conditions from sampled data of input-output measurements. Using the so-called linear integral filter, an operation of numerical integration for handling time derivatives of measurements, leads to an identification model without involving the unknown initial conditions, and thus they do not require estimation together with the system parameters. Both a theoretical analysis and simulation study show that the least squares estimates are asymptotically biased even when the system outputs are corrupted by white noise. An instrumental variable method, where instrumental variables are composed of combinations of input signals, is proposed to give consistent estimates of system parameters for open-loop operation, and it is also thoroughly evaluated by Monte Carlo simulation analysis.

ISSN:0020-7179    

DOI:10.1080/00207178908953377

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The evaluation of a new robust control design method called Robust Model Matching (RMM) is treated by applying it to the design of electrical position servos. RMM is a practical method for the control of plants with wide parameter variations, however, the effect of RMM has not yet been sufficiently examined in experiments and simulations. RMM is applied to the design of electrical position servos, and is evaluated with simulations and experiments. The results of these simulations and/or experiments show that the electrical position servos designed by RMM can eliminate the undesirable influences of: (a) load variations; (b) torque disturbances; (c) non-linear friction; (d) dead zone in a power amplifier; and (e) uncertainty of a velocity sensor's output signal; upon controlled variables. It is also shown that electrical position servos can be robustly stabilized simultaneously by RMM controllers for plants with arbitrary bounded parameter variations.

ISSN:0020-7179    

DOI:10.1080/00207178908953378

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Over the past decade, a considerable amount of attention has been devoted to the subject of robustness analysis. However, the current literature on robustness analysis concentrates largely on the qualitative issue of robust stability. To date, very few results have been developed for the quantitative issue of robust performance. An exception to this is the recent work of Hyland and Bernstein (1987) in covariance majorant analysis. This work developed bounds on cost functions which can represent the variances of selected system variables. This paper presents improvements in covariance majorant analysis. Specifically, less conservative (i.e., smaller) upper bounds are developed for the cost functions. Lower cost bounds are also developed.

ISSN:0020-7179    

DOI:10.1080/00207178908953379

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Three popular DC-to-DC switched mode power converters—Buck, Boost, and Buck-Boost—are shown to be in the same orbit of structural equivalence as a second-order controllable circuit in Brunovsky canonical form. The equivalence is achievable under non-linear feedback and explicit local difleomorphic state coordinate transformations. The implications of local exact linearizability of this class of systems in the design of Variable Structure Feedback Control laws or Pulse-Width-Modulation strategies is thoroughly discussed.

ISSN:0020-7179    

DOI:10.1080/00207178908953380

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A new state-space characterization of solutions of a class of model-matching problem (the so-called model-matching problem of the first kind by Limebeer) has recently been derived by Kimura based on the notion of conjugation (Kimura 1989 b). The results are extended to a more general case (still restricted to the problem of the first kind) and applied to the H∞control problem. It is shown that the controller has a very simple structure with its order being identical to the plant order. To obtain a controller, we only need to solve two eigenvalue problems of sizenand two Lyapunov-type equations of the same size, where n is the plant order.

ISSN:0020-7179    

DOI:10.1080/00207178908953381

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The Synchronization ofnnon-identical simple-integral plants $ with common inputsx(t)and outputs initial conditions of (ξ1,ξ2, ⃛, ξn) will be studied, with two objectives as follows: (a) making all thensteady-state outputs identical to one another; (b) having each one of thesenidentical steady-state outputs the time integral (ζdt) of the common inputsx(t). So, fulfilment of objective (a) demands that the MIMO system performs as a ‘closed-loop’ system during the transient time, to eliminate the errors between the outputs; while achievement of objective (b) warrants that the system behaves as an ‘open-loop’ one during the steady-state phase, to preserve the integrating nature of the plants. To present the techniques of achieving these two contradictory goals, first a 2-plant case will be thoroughly studied for various types of common inputsx(t); then, armed with the method and result obtained, the general case will be attacked. Through proof of a theorem, an elegant and unique way to ascertain stability of the MIMO system will be presented.

ISSN:0020-7179    

DOI:10.1080/00207178908953382

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Linear, dynamic model set estimation based on noisy, input-output data is addressed here from a confidence set standpoint. Following the usual robust control perspective a model set estimate for the ‘true’, but unknown, impulse response (truncated at the data length due to causality) is sought via a nominal model belonging to a pre-specified parametric class of approximating models (of ‘low order’) plus some quantitative information on the mismatch between the approximating model and the underlying (possibly, ‘high-order’) one. The solution proposed is based on the asymptotic, parameter estimation theory of Ljung (1978), and Ljung and Caines (1979). It hinges upon the characterization of a joint confidence set for an optimal approximation for the underlying system in a parametric class and the corresponding approximation error, which is shown to be consistent. This is done under relatively weak conditions on the system input (stationarity conditions are not imposed) and observation noise (a specific distribution form is not assumed), and without assuming that the approximating model class contains the underlying model.

ISSN:0020-7179    

DOI:10.1080/00207178908953383

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The design and practical application of series-parallel model following adaptive control techniques to a turbogenerator system is described, incorporating proportional-plus-integral and relay-plus-integral adaptation laws. An advantage of this scheme is that it does not require on-line identification, nor the solution of linear or non-linear equations in real time. The aim is to generate an adaptive command signal, such that the output of the turbogenerator will match the output of the model, even when the system is subjected to output disturbances or changes in operating conditions. The turbogenerator system consists of a synchronous generator connected to an infinite busbar through a transformer and two transmission lines in parallel. The control scheme has been thoroughly tested on a micromachine system, over a wide range of operating conditions. Typical simulation and experimental results are presented, illustrating the response to a short-circuit on the transmission network, and including comparison with a fixed-gain optimal controller. These show that the adaptive controllers are most effective, providing rapid convergence of the turbogenerator and model outputs, and an improved performance.

ISSN:0020-7179    

DOI:10.1080/00207178908953384

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A new improved computational method for a class of optimal control problems is presented. The state and the costate (adjoint) variables are approximated using a set of basis functions. A method, similar to a variational virtual work approach with weighing coefficients, is used to transform the canonical equations into a set of algebraic equations. The method allows approximating functions that need not satisfy the initial conditionsa priori. A Lagrange multiplier technique is used to enforce the terminal conditions. This enlarges the space from which the approximating functions can be chosen. Orthogonal polynomials are used to obtain a set of simultaneous equations with fewer non-zero entries. Such a sparse system results in substantial computational economy. Two examples, a time-invariant system and a time-varying system with quadratic performance index, are solved using three different sets of orthogonal polynomials and the power series to demonstrate the feasibility and efficiency of this method.

ISSN:0020-7179    

DOI:10.1080/00207178908953385

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor