摘要:

A new approach—individual channel design (ICD)—to an enduring problem— multivariable feedback control—is presented. The approach is applications-oriented: it starts from the engineering premise that feedback control design is interactive; it involves an interplay between customer specification, uncertain plant characteristics, and the multivariable feedback design process itself. It is shown that individual signal transmission channels arise naturally from customer specification on selected plant outputs with no loss of structural (loop interaction) information. By invoking customer performance specification on different channels, highly successful single-input single-output classical (Nyquist-Bode) design is made possible. ICD is not a design method per seper se; rather it is a global structural framework wherein the possibilities and limitations for local-loop-shaping design (e.g. Bode or Nichols) of a particular plant are made apparent from the outset. Also, the conditions are established whereby channel gain and phase margins are robust measures of stability. In this way, a transparent, flexible and supportive design methodology is developed which directly aims to meet the users’ control requirements and is well-suited to the engineering context. An automotive gas turbine control case study illustrates the salient features of the processs of ICD.

ISSN:0020-7179    

DOI:10.1080/00207179108934150

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A new applications-oriented approach—individual channel design (ICD)—to multivariable feedback control—was presented in an earlier paper (O'Reilly and Leithead 1991). This paper is the first part of a three-part investigation into the performance issues raised by ICD for 2-input 2-output multivariable systems. The three-part series of papers also develops an analytic framework for investigating and understanding the potential and limitations of the feedback design of any linear time-invariant controller. The main results of this first paper are threefold. First, the ICD framework advanced by O'Reilly and Leithead (1991) is justified for all multivariable system structures. In particular, it is shown that ICD on the original 2-input 2-output cross-coupled multivariable system is valid irrespective of the degree of cross-coupling. Second, the influence of (individual transfer function, channel, transmission) right half-plane zeros on controller design and closed-loop channel performance is elucidated. Third, a generalization of a result concerning the existence of fixed stabilizing controllers for uncertain systems, equivalent to one due to Kwakernaak (1982), is presented.

ISSN:0020-7179    

DOI:10.1080/00207179108934151

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Single loop dithered (at frequency ω0) feedback systems containing a severely non-linear element, can be designed to behave quasilinearly to control signals with bandwidth small relative to ω0. They can also have zero sensitivity to gain factor uncertainty. However, the constraints due to quasilinearity may lead to severely large ω0. This paper presents an externally excited adaptive loop structure with ‘externally excited’ signal A0sin ω0t and an added ‘adaptive loop’, which permits a large reduction in g. An additional phase-adaptive loop can be added to the above structures, which reduces the plant phase uncertainty and consequently the loop bandwidth requirements. Quantitative design procedures, with examples, are presented for the above structures, which reveal the advantages of the more complex designs.

ISSN:0020-7179    

DOI:10.1080/00207179108934152

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A non-linear dynamical compensator design, based on Fliess’ generalized controller canonical form for non-linear dynamical systems, is proposed for the asymptotic stabilization of output load voltage, or current, in pulse-width-modulation controlled d.c.-to-d.c. power supplies. The technique rests on the recently introduced differential algebraic approach to the study of controlled dynamical systems.

ISSN:0020-7179    

DOI:10.1080/00207179108934153

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

NASA experiments have indicated the need for non-linear damping models to describe the motion of large flexible space structures. In this work, energy type non-linear damping models in an infinite dimensional setting are studied. According to the geometry of the structures considered, energy type non-linear damping models are divided into two types. Their frequency response is found and compared with that given by linear models and non-linear stiffness models. It is concluded that non-linear damping models do not produce peculiar behaviours such as internal resonance, jump phenomenon or chaotic behaviour.

ISSN:0020-7179    

DOI:10.1080/00207179108934154

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Time series model validity tests based on general correlations are presented in this paper. It is shown that the tests Φxixi(τ), Φxixi2(τ) and Φxixixi(τ1, t2) can only detect a subset of any possible unmodelled terms in the residuals, whereas Φxi2xi2(τ) detects all possible terms. These basic results are then extended to include functions of process or residual terms as entries in the correlation. Simulation studies are included to demonstrate the effectiveness of the tests when applied to estimated models of both simulated and real data sequences.

ISSN:0020-7179    

DOI:10.1080/00207179108934155

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The development of a computationally-effective recursive lagrangian formulation, applied to robot manipulators with revolute and prismatic joints, is presented. These equations result in an efficient and explicit set of closed second-order non-linear differential equations with vector cross-product terms in symbolic form. The method is simple and straightforward to follow, and readily identifies the interaction and coupling reaction forces/torques between neighbouring joints of a manipulator. The model is accurate, without having to resort to simplifying assumptions. The computational load is such that it can easily be implemented on microcomputers and still give real-time performance.

ISSN:0020-7179    

DOI:10.1080/00207179108934156

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A method For the numerical synthesis of compensators for non-linear control systems is proposed. The non-linear systems investigated are the type in which the system can be represented by two separate parts: a linear element and a non-linear element, as shown in Fig, 1. The approach adopted is called the method of inequalities, in which the problem is formulated as a set of inequalities, which represent the specified closed loop performance of the system as well as constraints of an engineering and financial kind. The non-linear part of the system is linearized using an exponential input describing function. An inequality is then formulated concerning the non-linear element to ensure that every point in the admissible space represents a closed loop system which does not exhibit autonomous limit cycle oscillation. This inequality is defined by using an enhanced sinusoidal describing function which takes account of the effects of higher harmonic signal components as well as of a fundamental sinusoid in the search for regions of possible limit cycle operation.

ISSN:0020-7179    

DOI:10.1080/00207179108934157

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A normalizing signal that does not require the knowledge of the stability margin of the unmodelled dynamics is used in robust model reference adaptive control (MRAC) for plants with an enlarged class of unmodelled dynamics. The modified robust MRAC scheme guarantees that all signals in the closed-loop plant are uniformly bounded and the tracking error is of the order of the modelling error in the mean.

ISSN:0020-7179    

DOI:10.1080/00207179108934158

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor