ISSN:0020-7179    

DOI:10.1080/00207179508921597

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Many fixed-order suboptimal control problems with stability, performance and robustness specifications can be reduced to a search for a matrixX > 0 satisfying a linear matrix inequality (LMI) whileX−1satisfies another LMI. This paper defines a certain class of these problems we shall call the ‘dual LMI problem’, and a computational algorithm to solve our dual LMI problem is given. Properties and limitations of the algorithm are discussed in comparison with the existing algorithm (the min/max algorithm). An extension to optimal control problems is provided. Numerical examples for the fixed-order stabilization problem and the static output feedback linear quadratic optimal control problem demonstrate the applicability of the proposed algorithm.

ISSN:0020-7179    

DOI:10.1080/00207179508921598

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The originalq-Markov COVariance Equivalent Realization (q-Markov Cover) method for identification required white noise test signals, which cannot be generated exactly. This paper replaces the unrealizable white-noise signal with a realizable signal (the pseudo-random binary signal, PRBS), and proves that when the period of the PRBS approaches infinity theq-Markov Cover algorithm, operating with PRBS, matches the first q Markov and covariance parameters (as in the original theory with white-noise test signals). The existingq-Markov Cover algorithm will fail to match covariance and Markov parameters exactly due to non-white test signals. The new algorithm will fail to match covariance and Markov parameters exactly due to the finite period of PRBSs. We demonstrate however that the results with PRBSs are far superior to results with ‘white’ noise signals. Apparently, the ‘non-whiteness’ of the test signal degrades the identification performance worse than the ‘non-infinite’ period of the PRBS.

ISSN:0020-7179    

DOI:10.1080/00207179508921599

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In this paper, we consider an inverse problem for a linear time invariant dynamic system with noise. It is shown that after adjusting the system by shifting the eigenvalues of the system matrix, the disturbance of the system noise can be reduced and the input signal of certain types of the system can be recovered from the discrete observations of the system output.

ISSN:0020-7179    

DOI:10.1080/00207179508921600

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This paper presents a procedure for the design of open loop controllers for flexible structures using multiple step inputs delayed in time. The controller attenuates the residual vibration by cancelling the complex poles of the system. Robustness is achieved by locating additional zeros at the cancelled poles of the system. The paper begins by addressing the control of a single mode and examines the effect of user selected time-delays on robustness and the reference input. Next, a procedure for the design of robust time-delay controllers for multiple modes with user selected time-delays is considered. This is followed by a design of a minimum time-delay controller, such that the step input magnitudes are constrained to values between 0 and 1. Two examples, a spring-mass system and a single-link flexible-arm robot are used to illustrate the effectiveness of the proposed controller.

ISSN:0020-7179    

DOI:10.1080/00207179508921601

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

We give an alternative, more convenient expression of the well known Cayley-Hamilton theorem when polynomial matrices of arbitrary degree are involved. Based on the results of a recently developed algorithm (Fraguliset al. 1991) for the computation of the inverse of a polynomial matrix, certain relationships among the coefficient matrices of the given polynomial matrix are obtained. We also propose two ways of finding the powers of a polynomial matrix: one in terms of its coefficient matrices and the other making use of the generalized Cayley-Hamilton theorem. These methods are of closed form and are easily implementable in a digital computer.

ISSN:0020-7179    

DOI:10.1080/00207179508921602

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The purpose of this paper is to show how one can achieve regional controllability for distributed systems. First, we give a definition and some properties of this new concept, then we concentrate on the determination of a control achieving regional controllability with minimum energy. A direct method is developed and is illustrated by a hyperbolic system with point control and a parabolic system with zone control. We also give an important remark that converts the problem into a constrained optimization one.

ISSN:0020-7179    

DOI:10.1080/00207179508921603

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In this paper we introduce a novel measure of asymptotic disturbance rejection for a feedback system. This notion of asymptotic performance is particularly well suited to the robust control of systems that exhibit both parametric and dynamic modelling uncertainty. We then derive a switching-type controller that provides optimal asymptotic disturbance rejection properties. The particular notion of disturbance rejection we consider is rejection of persistent bounded disturbances (i.e.l1-optimal control). While asymptotic performance is guaranteed, we also provide bounds that quantify the transient response behaviour of this particular control scheme.

ISSN:0020-7179    

DOI:10.1080/00207179508921604

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In this paper we discuss the role of criterion minimization as a means for parameter estimation. Most traditional methods, such as maximum likelihood and prediction error identification are based on these principles. However, somewhat surprisingly, it turns out that it is not always ‘optimal’ to try to find the absolute minimum point of the criterion. The reason is that ‘stopped minimization’ (where the iterations have been terminated before the absolute minimum has been reached) has more or less identical properties as using regularization (adding a parametric penalty term). Regularization is known to have beneficial effects on the variance of the parameter estimates and it reduces the ‘variance contribution’ of the misfit. This also explains the concept of ‘overtraining’ in neural nets. How does one know when to terminate the iterations then? A useful criterion would be to stop iterations when the criterion function applied to a validation data set no longer decreases. However, in this paper, we show that applying this technique extensively may lead to the fact that the resulting estimate is an unregularized estimate for the total data set: estimation + validation data.

ISSN:0020-7179    

DOI:10.1080/00207179508921605

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This paper is concerned with a class of time-optimal control problems for the swing and the ski. We first consider the motion of a man standing on a swing. For simplicity, we neglect friction and air resistance and assume that the mass of the swinger is concentrated in his baricentre B. For the ski, we use the model considered by Aldo Bressan (1991), with a special approximation of the skier. Our main concern is the existence and the structure of time-optimal controls. As a first step, we introduce an auxiliary control system with control entering linearly and show the relationships between this and the original system. We then perform a detailed study of the auxiliary system, using geometric techniques. In turn, this provides accurate information on the time-optimal controls for the original system.

ISSN:0020-7179    

DOI:10.1080/00207179508921606

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor