ISSN:0890-6327    

DOI:10.1002/acs.4480080401

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractA novel approach is proposed to the optimal smoothing and differentiation problem of unknown one‐dimensional signals corrupted by additive white Gaussian noise. State space techniques are used. the main feature of the method is that very littlea prioristatistical information about the signal generation process is required. Starting from the basic assumption that the actual waveform does not show relevant discontinuities, a state space representation is derived by defining a state vector composed of the signal and its derivatives. All parameters of this representation are analytically derived except two: a multiplicative scalar of the input noise covariance matrix and the variance of the measurement noise. A procedure for the optimal estimation of these parameters from noisy data is proposed. Application of a fixed‐lag Kalman smoother provides the simultaneous estimate of the signal and its derivatives. Numerical results confirm the validity of the appro

ISSN:0890-6327    

DOI:10.1002/acs.4480080402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThis paper deals with the combined use of continuous and discontinuous adaptation mechanisms in order to control uncertain linear time‐invariant systems described by I/O relationships. the complexity of the combined schemes proposed in the literature up to now relies on both the complexity of the underlying linear structure, i.e. the structure of the controller designed under the assumption of perfect knowledge of the plant parameters in order to attain the prescribed control objective, and the complexity of the additional scheme which needs to be introduced in the uncertain case so as to guarantee the stability of the relevant error equation as well as the convergence of the adjusted parameters. In the present paper it is shown how, by choosing a pole assignment control objective, it is possible to conceive a new combined variable structure‐adaptive control scheme which on the whole results in being simpler than those previously proposed in the literat

ISSN:0890-6327    

DOI:10.1002/acs.4480080403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe problem of improved performance adaptive control (IPAC) of a class of linear and non‐linear systems is considered. A method for its solution is presented, the main feature of which lies in augmenting the ‘standard’ model reference adaptive controller by a signal properly designed to compensate for the effect of plant parameter uncertainty on the output error. One of the main performance improvement characteristics of the proposed IPAC is that the zero‐state output error can be made arbitrarily small under standard model reference adaptive control (MRAC) assumptions in the case of linear systems, while a similar result holds true for a class of linearizable systems as well. the structure of the proposed controller is such that several existing MRAC results, such as exponential convergence of output and parameter errors in the presence of sufficiently rich reference inputs, remain valid. the proposed controller also achieves improved performance in the presence of a class of bounded disturbances and/or unmodelled dynamics as well as in the case of an adaptation swi

ISSN:0890-6327    

DOI:10.1002/acs.4480080404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractPredictive controllers are often only applicable for open‐loop stable systems. In this paper two such controllers are designed to operate on open‐loop critically stable systems, each of which is used to find the control inputs for the roll control autopilot of a jet fighter aircraft. It is shown how it is quite possible for good predictive control to be achieved on open‐loop critically stable sy

ISSN:0890-6327    

DOI:10.1002/acs.4480080405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractIn this paper the influence of the shape of the membership functions on the dynamic behaviour of a fuzzy controlled system is investigated. Although several works on fuzzy logic have been presented in the literature, few efforts have been made to characterize the dynamic behaviour of a fuzzy system through the shape of the membership functions. A parametrization for a class of membership functions is introduced in this work, resulting in a variety of shapes. Various system steady state dynamics are analysed as a consequence of this change in shape and chaotic dynamics is shown to arise for some membership function shapes.

ISSN:0890-6327    

DOI:10.1002/acs.4480080406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThere is an increasing concern among the scientific community and industrialists over the safe and reliable operation of control systems in industries. Although several adaptive control techniques have been introduced, they are not robust enough for many real‐world problem domains where the degree of uncertainty is high and therefore classical methods of mathematical modelling and control fail. Computer technology has reached a point wheremachine intelligencecan be incorporated in many of the systems that we use daily. Changes in environments, unmeasurable disturbances, changing reference models and performance criteria and component failures are some of the characteristics which necessitate intelligent control. the developments in the field of artificial intelligence have reached a stage which will help to reduce these control complexities by incorporatingintelligenceinto the control systems. In this paper we explain various artificial intelligence techniques that can be used to control dynamical physical system

ISSN:0890-6327    

DOI:10.1002/acs.4480080407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractGradient recurrent high‐order neural networks (GRHONNs) have found great applicability to optimization, associative memory, adaptive signal‐processing and system identification problems. In this paper we show that these neural networks are asymptotically stable dynamical systems and, moreover, that their solutions remain stable under either deterministic or stochastic disturbances. We also prove that GRHONNs are dense in the space of continuous dynamical systems, contrary to the fact that their vector fields do not satisfy the Stone‐Weierstrass theorem. the significance of these theoretical results to associative memory and optimization and to the fabrication of general‐purpose, large‐scale hardware implementations is

ISSN:0890-6327    

DOI:10.1002/acs.4480080408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThis paper introduces a fuzzy controller that can be designed without specific information on the membership functions and the fuzzy rules. We show how the membership values of crisp inputs can be determined byK‐nearest‐neighbour (KNN) distance measures applied to the centres of the input clusters. Based on this new type of membership values, we introduce a KNN defuzzification method that allows the direct estimation of the crisp output of the given input data. the proposed computational model requires a clustering (self‐organizing) process. We employ a simple clustering method that can adaptively allocate new clusters as more data become available to the controller. We prove that the resulting controller can uniformly approximate any real and continuous function to any desirable accuracy on a compact set. For hardware implementations we develop a neural network structure of the proposed fuzzy controller and compare it with other types of neural networks. It is shown that the three‐layer sigmoid neural network and the Gaussian radial basis function (GRBF) network are special cases of this structure. A learning algorithm for the new structure is provided. the performance of the proposed controller is considered through three application studies: a controller design for truck backer‐upper control, the prediction of the S&P 500 index, and the prediction of the Mackey‐Glass

ISSN:0890-6327    

DOI:10.1002/acs.4480080409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY