ISSN:0020-7179    

DOI:10.1080/00207179608921728

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A redundant dynamical sliding mode control scheme is proposed for the asymptotic stabilization of a rigid spacecraft. The input-dependent nonlinear sliding manifolds are derived from a smooth feedback control law, based on the use of nonlinear characteristic values and characteristic vectors. A scheme tolerating sudden perturbation failure is presented. Simulations studies are provided.

ISSN:0020-7179    

DOI:10.1080/00207179608921729

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In this paper, we solve guaranteed level-γℋ∞control problems in uncertain linear systems. In time-varying systems, we provide a time-varying nonlinear differential equation for these problems, which can be solved via differential equation solvers. In time invariant systems, we present linear matrix inequalities (LMIs), which allow us to overcome the limitations of the existing algebraic Riccati equation (ARE) formulations, where one can hardly find their solutions. Since LMI problems are always convex, one can solve them via convex optimization techniques, such as interior-point methods, and can easily solve them even if additional constraints are considered. As a result, we directly handle the optimal guaranteed-levelℋ∞control problem as well as a guaranteed level-γℋ∞control problem with the maximal stability margin. Finally, we present size-reduced LMIs.

ISSN:0020-7179    

DOI:10.1080/00207179608921730

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The paper addresses the problem of controlling and synchronizing chaos using the minimal control synthesis algorithm (Stoten and Benchoubane 1990b). After unifying the synchronization and control problems within the same theoretical framework, the scope of the original MCS algorithm is extended, firstly by removing the assumption that both the plant and the reference model are in phase-canonical form, and secondly by including the case of vanishing nonlinear disturbances acting on the system. Finally, the application to two common chaotic systems, the control of a Duffing oscillator and the synchronization of two Chua circuits is investigated.

ISSN:0020-7179    

DOI:10.1080/00207179608921731

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Stability robustness properties of sampled data repetitive control systems are examined. Due to the infinite loop gain at periodic frequencies originating from the included internal model (Internal Model Principle), repetitive systems are, if properly designed, not very sensitive towards possibly time-varying gains. Uncertainty in plant delay is, however, a problem. Controller action timing becomes more or less out of order and may result in severe performance degradation, depending on model type and the number of frequencies included in the design. With a Linear Time-Invariant (LTI) controller comprising the commonly used time delay internal model, the closed loop system is stable for nominal time delay plus/minus at most one sampling interval. A controller based on a reduced order model, perhaps not modelling all harmonics, is utilized lo enhance robustness properties. Simulation runs with different controllers show how different models work in the closed loop, and also that synchronization in time is of utmost importance in order to utilize the delay internal model.

ISSN:0020-7179    

DOI:10.1080/00207179608921732

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In this paper we develop a solution to the discrete-timeℋ∞output feedback control problem for linear time-varying (LTV) systems. The solution is developed along the strategy set up by Doyleet al. in 1989 and the main ingredient in its derivation is the extension of the well known bounded real lemma to a (discrete) time-varying context, developed by van der Veen and Verhaegen in 1995. This approach contributes to the conceptual simplicity, and hence to the accessibility, of the solution. Apart from that, we treat the infinite-horizon case for LTV system of non-uniform state dimension, and varying input and output dimension. Both situations can easily occur in practice, for example in multirate sampled data control systems. The algorithm that can be derived from the solution presented in then applied to theℋ∞output feedback of a dynamical system changing from one operation point in its operation envelope to another.

ISSN:0020-7179    

DOI:10.1080/00207179608921733

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The paper suggests two novel approaches to the synthesis of robust end-point optimizing feedback for nonlinear dynamic processes. Classically, end-point optimization is performed only for the nominal process model using optimal control methods, and the question of performance robustness to disturbances and model-plant mismatch remains unaddressed. The present contribution addresses the end-point optimization problem for nonlinear affine systems with fixed final time through robust optimal feedback methods. In the first approach, a nonlinear state feedback is derived that robustly optimizes the final process state. This solution is obtained through series expansion of the Hamilton-Jacobi-Bellman PDE with an active opponent disturbance. As reliable measurements or estimates of all states may not always be available, the second approach also robustly optimizes the process end-point, but uses output rather than state information. This direct use of measurement information is preferred since the choice of a state estimator for robust state feedback is non-trivial even when the observability issue is addressed. A linear time-variant output corrector is obtained by feedback parametrization and numerical optimization of a nonlinearH∞cost functional. A number of possible variations and alternatives to both approaches are also discussed. As model-plant mismatch is particularly common with chemical batch processes, the suitability of the robust optimizing feedback is demonstrated on a semi-batch reactor simulation example, where robustness to several realistic mismatches is investigated and the results are compared against those for the optimal open-loop policy and the optimal feedback designed for the nominal model.

ISSN:0020-7179    

DOI:10.1080/00207179608921734

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The paper studies the decentralized robust stabilization problem for a large-scale system which is composed of three subsystems. Each subsystem may contain nonlinear and/or time-varying uncertainties and interconnections; but one of these subsystems does not have direct control. We demonstrate a control design procedure where the interconnection characteristic is fully utilized. By showing that it is possible to use the interconnection as a bridge to convey the influence of control, decentralized controls can be designed.

ISSN:0020-7179    

DOI:10.1080/00207179608921735

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In this paper, we investigate the structural properties of balanced realizations, and their truncation, of a class of systems with symmetric interconnected and identical structure. It is established that the balanced realizations of such symmetric composite systems can be constructed via the balanced realizations of two auxiliary systems of comparatively low dimensions. The corresponding truncated realizations, which also have a certain symmetric structure, are explicitly constructed. The extension of the results to generalized symmetric composite systems is also studied.

ISSN:0020-7179    

DOI:10.1080/00207179608921736

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In this paper, the problem of robust controller design for uncertain linear continuous-and discrete-time systems with circular pole constraints is considered. The problem we address is the design of robust state feedback controllers such that all poles of the closed-loop systems are placed within a prescribed circular region. Sufficient conditions for the existence of the desired controllers are given based on the generalized inverse theory. The analytical expression of the set of desired controllers is also presented. It is emphasized that, when the uncertainties are absent, the results include the characterization of all state-feedback controllers achieving the specified circular pole constraints. An illustrative example is given to show the applicability of the proposed design procedure. Accepted in final revised form 7 February 1996. Communicated by Professor H. Kimura.

ISSN:0020-7179    

DOI:10.1080/00207179608921737

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor