摘要:

In this paper, three methods are presented to enhance the performance of an unstable missile system in the presence of multiple saturating actuators. Each method involves the design of a saturation detection system, which modifies a nominal autopilot via online optimization and maintains, to the extent possible, the multivariable properties of the nominal design. To prevent saturation due to exogenous signals, disturbances and noises, in particular, an error governor is proposed. This system processes the error signals within the feedback loop and the state of the compensator, so that appropriately co-ordinated control surface deflections may be generated. Traditionally, such a system has been applied only to stable plants. In this paper, it is shown how to design such a system for unstable plants. To prevent saturation due to reference (acceleration) commands from the guidance system, a reference governor is proposed. Such a system has traditionally required access to the entire state of the plant as well as that of the compensator. Here, it is shown how estimates of the plant state can be successfully exploited. The above systems are then combined to form a ‘performance enhancement supervisory system’ which prevents saturation for suitably (but non-conservatively) bounded exogenous signals, ensures local finite-gainℒ∞stability, and maintains, to the extent possible, the directionality properties of the original autopilot. Each method is applied to the problem of controlling an unstable bank-to-turn (BTT) missile.

ISSN:0020-7179    

DOI:10.1080/00207179608921862

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The problem of controlling the top position of a flexible-link manipulator is considered. A linear mathematical model of the flexible system is expressed in a standard singularly perturbed form. The concept of the integral manifold is utilized to design a dynamical composite control strategy to guarantee a minimum phase closed-loop system restricted to the manifold, resulting in controlling the tip position to an arbitrary degree of accuracy by just measuring the hub angle and the tip position. Numerical simulations for an approximation to the model of Canadarm (Shuttle arm) are included to demonstrate the advantages of the proposed technique. The proposed control strategy is applied to both the linear and the nonlinear models of the Canadarm with very encouraging results.

ISSN:0020-7179    

DOI:10.1080/00207179608921863

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This paper proposes a new design method of robust servo systems for step references and step disturbances. In this method, the tracking characteristics for step references and the feedback characteristics for step disturbances can be determined optimally, using independent quadratic-integral performance indices. Thus, it provides a two-degree-of-freedom design method of control systems in the context of linear-quadratic optimal control. The design procedure consists of two steps. In the first step, a servo system without integral compensation achieving the optimal responses to step references is designed. In the second step, an integral compensator is incorporated, and the feedback gain is determined so as to achieve the optimal responses to step disturbances, without changing the responses to step references. It is shown that as the ‘state weighting matrix’ becomes larger in the second step, the responses to step disturbances become quicker, and that they monotonically tend to the responses of an ‘ideally disturbance-rejected system’ (i.e. the system with the ideal disturbance compensation input).

ISSN:0020-7179    

DOI:10.1080/00207179608921864

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Although various nonlinear control theories, such as sliding mode control, have proved sound and successful, there is a serious lack of effective or tractable design methodologies due to difficulties encountered in the application of traditional analytical and numerical methods. This paper develops a reusable computing paradigm based on genetic algorithms to transform the ‘unsolvable problem’ of optimal designs into a practically solvable ‘non-deterministic polynomial problem’, which results in computer automated designs directly from nonlinear plants. The design methodology takes into account practical system constraints and extends the solution space, allowing new control terms to be included in the controller structure. In addition, the practical implementations using laboratory-scale systems demonstrate that such ‘off-the-computer’ designs offer a superior performance to manual designs in terms of transient and steady-state responses and of robustness. Various contributions to the genetic algorithm technique involving the construction of fitness functions, coding, initial population formation and reproduction are also presented.

ISSN:0020-7179    

DOI:10.1080/00207179608921865

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This paper deals withH∞control problem for systems with parametric uncertainty in all matrices of the system and output equations. The parametric uncertainty under consideration is of a linear fractional form. Both the continuous and the discrete-time cases are considered. Necessary and sufficient conditions for quadratic stability withH∞disturbance attenuation are obtained.

ISSN:0020-7179    

DOI:10.1080/00207179608921866

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In this paper, the classical row-by-row decoupling problem with stability through the use of a dynamic compensator is studied for linear periodic discrete-time systems. The necessary and sufficient conditions for the existence of a solution are found, and a design procedure of the dynamic compensator is provided by the sufficiency proof, and also for the case of a dead-beat requirement for the state free response.

ISSN:0020-7179    

DOI:10.1080/00207179608921867

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The discrete event theory of supervisory and state feedback control offers many advatages for implementing supervisory systems. Algorithmic concepts have been introduced to ensure that the supervising algorithms are correct and meet the specifications. In the current methodology, it is, in general, assumed that the supervisory specifications are invariant during the operation of the system or, at least, until a given supervisory task is completed. However, there are many practical applications where the supervising specifications need to be updated in real time. For example, when dealing with complex processes, the tasks of supervisory systems analysis and synthesis can be facilitated by partitioning the controlled Discrete-Event System (DES) into several subprocesses. This partitioning is based on operational or physical considerations and a unique supervisor is assigned to control each subprocess at a given instant of time. When a decision maker at a higher level of hierarchy decides to change the supervising algorithm, switching to a new supervisor takes place. For this adaptive implementation, the decision-maker or coordinator first decides the set of acting supervisors based on the requested supervisory tasks or current system performance requirements and then exercises control over the enabled supervisors in real time. Specifically, in a Reconfigurable Discrete Event System (RDES) architecture, a bank of supervisors is defined to accommodate each identified operational condition or different supervisory specifications. This adaptive supervisory control system can change its supervisory configuration to accept coordinator commands or to adjust for changes in the controlled process. This paper addresses reconfiguration at the supervisory level of hybrid systems along with the underlying architecture of RDES. In particular, the paper reviews the supervisory control theory in the state-based framework and extends it to the paradigm of RDES, considering process control applications. The paper addresses theoretical issues with a limited number of practical examples. This control approach is particularly suitable for hierarchical hybrid implementations with the capability of reconfiguration at both the control and supervisory levels.

ISSN:0020-7179    

DOI:10.1080/00207179608921868

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This paper concerns the problem of state-set estimation for discrete-time linear systems. The linear system is given in state-space form and the system's uncertainty is described by bounded scalar variations. We present a recursive algorithmic procedure of computing guaranteed estimated state sets. In particular, a polyhedron variation algorithm is presented. The new algorithm is based on linear-programming and sensitivity analysis techniques for improved computational efficiency and practicability.

ISSN:0020-7179    

DOI:10.1080/00207179608921869

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Structured singular value synthesis allows the design of controllers that are robust with respect to multiple block-structured uncertainty. This type of design process commonly relies on ’D-Kiteration’ and curve fitting. In particular, the optimalD-scales and the controller are iteratively optimized. Since theD-scales are optimized over frequency, they must be curve fitted with rational transfer functions before the controller is optimized. This curve fitting can be difficult and often leads to suboptimal designs. This paper presents a structured singular value process that allows theD-scales to be constrained to be constant and simultaneously optimizes theD-scales and the controllerK. The approach relies on recent results on mixed-normH2/H∞controller synthesis and also enables the direct design of reduced-order controllers.

ISSN:0020-7179    

DOI:10.1080/00207179608921870

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor