摘要:

A three-step method for obtaining asymptotically maximum likelihood ARMA spectral estimates using only linear transformations of the data is presented. The computational efficiency of the algorithm is comparable to that of Yule-Walker algorithms, but the three-step method gives asymptotically statistically efficient estimates. The implementation of the algorithm is discussed in detail, and numerical examples are presented to illustrate its performance.

ISSN:0020-7179    

DOI:10.1080/00207179408923081

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0020-7179    

DOI:10.1080/00207179408923082

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

An eigenstructure assignment-based method for reconfigurable control systems designs is developed. When the dynamics of the process being controlled are changed due to operating condition variations, or system component failures, the proposed method is capable of reconfiguring the control system so that the eigenvalues and eigenvectors of the original closed-loop system are recovered to a maximum extent. If full state feedback is permissible, the method guarantees the stability of the reconfigured system. If only system output is accessible, the method will recover the subsequent dominant eigenvalues and eigenvectors of the original system, and the stability of the reconfigured system will be maintained if a sufficient condition derived herein is satisfied. This condition unveils some intrinsic relationships between the degree of process variations, stability margins of the original system and the stability of the reconfigured system with output feedbacks. The steady-state performance of the original system under step inputs is also recovered via an optimal selection of a closed-loop system input weighting matrix. To illustrate the effectiveness of the proposed reconfigurable control system design technique, an aircraft longitudinal control system is used to demonstrate the reconfiguration procedure.

ISSN:0020-7179    

DOI:10.1080/00207179408923083

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A design procedure is proposed for synthesizing a linear-quadratic-Gaussian (LQG) optimal controller to obtain excess robustness optimization against noise spectral uncertainties, non-linear time-varying (NLTV) unmodelled dynamics in the discrete saturating systems. A robust stability criterion is derived for multivariable stochastic discrete-time systems with NLTV unmodelled dynamics and constrained actuators. An algorithm based on the robust stabilization criterion is presented for synthesizing a robust controller not only to minimize the least favourable cost functional J but also to maximize the excess robustness with respect to H∞-norm criterion by selecting two adequate weighting matrices Q(z) and R(z). We shall adopt the transfer function approach and two weighting matrices in the cost functional are shaped via the inverse LQG method to achieve excess robustness optimization.

ISSN:0020-7179    

DOI:10.1080/00207179408923084

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A state feedback H∞optimal disturbance attenuation for the model reference control of rigid robotic systems is studied. The disturbances affecting the system dynamics come from the residue of the applied torques due to perturbations of the system parameters and external noise. The design objective is that the disturbance attentuation level must be less than or equal to a desired positive value γ. By combining the nonlinear minimax control technique with the work of Johansson (1990) we are able to present an explicit global solution to this nonlinear time-varying H∞-control problem. In particular, it turns out that if y, the desired attenuation level, is greater than the magnitude of the weighting matrix on control inputs, then a state feedback law achieving the desired performance can be explicitly constructed. Hence, it is advantageous to consider our approach for H∞tracking control of other physical systems, Finally, extensive simulations are made for tracking control of a two-link robotic manipulator with the proposed H∞designs.

ISSN:0020-7179    

DOI:10.1080/00207179408923085

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The discrete-time algebraic Riccati equation

ISSN:0020-7179    

DOI:10.1080/00207179408923086

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Although considerable work has been done in the area of translating time-domain uncertainty into frequency-domain uncertainty, little has been done on translating frequency-domain uncertainty into time-domain uncertainty. It has been shown here that when there are known bounds on the system frequency response, it is possible to calculate the analytically exact corresponding boundaries of the system time response for a periodic input. This is then extended to give less conservative results for step responses than those obtained using periodic inputs.

ISSN:0020-7179    

DOI:10.1080/00207179408923087

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The simultaneous robust stabilization of two single-input single-output plants each having additive unstructured uncertainty is considered. First a para-metrization of all stabilizing controllers, which simultaneously stabilize the two nominal plants, is developed. A closed-loop stability criterion consisting of an easily checkable necessary condition is then proposed for the defined uncertainty set. Based on this criterion a computationally tractable robust stabilizing compensator design procedure is developed which is applicable to both minimum phase and non-minimum phase nominal plants. Several examples are presented to illustrate the design procedure.

ISSN:0020-7179    

DOI:10.1080/00207179408923088

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The set theoretic approach to parameter estimation is introduced for the robust identification of the local subsystem parameters of an interconnected system. The main contribution of this paper is the introduction of a concept and method to estimate subsystem parameters in the presence of subsystem interactions and external disturbances. The subsystem parameter set estimation problem, from the input-output point of view, can be formulated as several parameter set estimation problems, each with ARMAX model structure. A two-step strategy is proposed to extend the optimal volume ellipsoid algorithm for parameter set estimation to ARMAX models. Simulation results are given to substantiate the theoretical development for subsystem parameter set estimation.

ISSN:0020-7179    

DOI:10.1080/00207179408923089

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A viable design methodology to construct observers for a class of nonlinear systems is developed. The proposed technique is based on the off-line solution of a Riccati equation, and can be solved using commercially available software packages. For globally valid results, the class of systems considered is characterized by globally Lipschitz nonlinearities. Local results relax this assumption to only a local requirement. For a more general description of nonlinear systems, the methodology yields approximate observers, locally. The proposed theory is used to design an observer for a single-link flexible joint robot. This observer estimates the robot link variables based on the joint measurements.

ISSN:0020-7179    

DOI:10.1080/00207179408923090

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor