In this paper, we consider the problem of robust pole placement using fixed-order compensation. It is assumed that the coefficients of the numerator and denominator polynomials of the uncertain plant depend muitilinea...
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In this paper, we consider the problem of robust pole placement using fixed-order compensation. It is assumed that the coefficients of the numerator and denominator polynomials of the uncertain plant depend muitilinearly on the "parameters" and that the design specifications are given in the form of a two-pole dominant model. We present a design methodology for choosing a fixed-order compensator which ensures that all the roots of the closed loop polynomial lie in the regions prescribed by the two-pole dominant model.
For a given plant transfer function P ( s ) and cone size k, solutions to versions of the absolute stability problem boil down to finding a SPR multiplier Z ( s ) such that [ k ¯ - 1 + P ( s ) ] Z ( s ) is SPR. I...
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For a given plant transfer function P ( s ) and cone size k, solutions to versions of the absolute stability problem boil down to finding a SPR multiplier Z ( s ) such that [ k ¯ - 1 + P ( s ) ] Z ( s ) is SPR. In this paper, we consider an interval plant P ( s , q , r ) and prove that first order multiplierslead to vertex results when establishing the positive realnells of [ k ¯ - 1 + P ( s , q , r ) ] Z ( s ) . Additionally, we give an example of a second order multiplier and interval plant which fails to have this vertex property. These new results are then applied to the problem of robust stability of time-varying interval systems.
This paper presents several results concerned with finding the zero distribution of a polynomial with respect to the unit circle using variants of the Schur-Cohn procedure. First, new and simple proofs of the Schur-Co...
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This paper presents several results concerned with finding the zero distribution of a polynomial with respect to the unit circle using variants of the Schur-Cohn procedure. First, new and simple proofs of the Schur-Cohn procedure in the regular and singular cases are presented. A new method for handling one type of singular case is also developed, Next, we consider several aspects of the 'inverse problem', in which one wishes to alter a given polynomial to have a prescribed zero distribution. Three methods for forcing all zeros of a polynomial to lie inside the unit circle are derived. Also, two algorithms for solving singular inverse problems are presented;specifically, one corrects a symmetric polynomial to ensure that all its zeros lie on the unit circle, and the other corrects a symmetric polynomial to ensure that none of its zeros lie on the unit circle. The inverse problems have applications in spectral estimation, signal processing and system identification.
The accurate modelling of robot dynamics is essential for the design of model-based robot controllers. However, dynamic models have very complicated features which can be attributed to several reasons. For example, th...
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The accurate modelling of robot dynamics is essential for the design of model-based robot controllers. However, dynamic models have very complicated features which can be attributed to several reasons. For example, the continuously-varying arm configuration, uncertain effects of load handling on the dynamic stability of the arm, and the high degree of non-linearity and coupling exhibited between the different links. Hence, the accurate modelling of these effects will play an important role in the design of robust controllers. Towards this end, an efficient and fast method for the on-line tuning of robot dynamic parameters must be devised. This work proposes to solve this problem as follows. First, a simplified dynamic model of the robot is developed. The model allows for direct and straightforward extraction and regrouping of dynamic parameters. The resulting dynamic parameters are formulated as a regression equation which is linear in the dynamic parameters. Finally, the algorithm is executed using a Transputer development system to speed up the computation and meet real-time constraints. The efficiency of the approach is demonstrated by a case study.
A new approach for identifying continuous time models from discrete time sampled-data records is presented. The proposed method involves estimating and validating a discrete time model, linear or non-linear, based on ...
A new approach for identifying continuous time models from discrete time sampled-data records is presented. The proposed method involves estimating and validating a discrete time model, linear or non-linear, based on sampled data records, evaluating the discrete time linear and non-linear frequency response functions and then curve fitting to the frequency response data to yield a continuous time model. No numerical differentiation and integration is involved and hence higher derivatives of input and output data records are avoided. Errors which would be introduced by the numerical approximation of differentiation and integration are therefore eliminated. The orthogonal estimator which is introduced to curve fit to the complex frequency response functions provides information on the model structure and the unknown parameter values for linear and non-linear continuous time models. The advantage of this approach is that non-linear differential equation models which can be related to the physical behaviour of the system can be readily computed from discrete time data.
The paper presents a synthesis of a nonlinear ship steering control system through application of the simultaneous stabilization and parametric optimization methods. The ship steering control system is closed through ...
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The paper presents a synthesis of a nonlinear ship steering control system through application of the simultaneous stabilization and parametric optimization methods. The ship steering control system is closed through the gyrocompass and autopilot. The loop consists of an autopilot, the steering gear subsystem, and a ship. For linearization of the nonlinear steering gear subsystem the procedure of quasi - linearization is used. The steering gear linearized model structure and initial parameters are determined by means of frequency characteristics of the steering gear subsystem, while the time response is utilized for the fine adjustment of parameters. The dynamics of the ship, treated as a linear part of the system, varies depending on conditions (trim, depth etc.) to which the ship is subjected, and can be described by a set of transfer functions. The linearized steering gear model together with a set of the ship linear models produce the nonlinear ship steering control system model with variable parameters. The obtained model consists of a set of transfer functions describing the complete system dynamics in open loop. After obtaining such a model of the system, an autopilot design is taking place by applying the simultaneous stabilization procedure. The obtained regulator stabilizes the system under given operating conditions, respectively, it stabilizes the set of transfer functions. The procedure of parametric optimization of the nonlinear system with variable parameters is used to improve the system dynamics, whereas through the simultaneous stabilization procedure only the system stability conditions are checked. The procedure is verified, and the obtained results confirm the advantage of the autopilot obtained in such a manner.
This paper deals wich the analysis of stochastic Petri net (SPN) models with generally distributed transition firing times. A so - called hybrid state analysis (HSA) method is developed. The bask idea is to make the e...
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In this paper, we consider the problem of steady-state tracking with disturbance rejection for nonlinear systems, using nonlinear static state feedback only. It is shown that, under certain conditions, a nonlinear sta...
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Adaptive techniques such as gain scheduling, automatic tuning and continuous adaptation have been used in industrial single-loop controllers for about ten years. This paper gives a survey of the different adaptive tec...
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Adaptive techniques such as gain scheduling, automatic tuning and continuous adaptation have been used in industrial single-loop controllers for about ten years. This paper gives a survey of the different adaptive techniques, the underlying process models and control designs. The paper ends with an overview of industrial adaptive single-loop controllers.
This paper proposes an algorithm combining variable structure control and observation for robot control using only joint position measurements. This algorithm investigates the interactions between the observer and the...
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