Describing function

About: Describing function is a research topic. Over the lifetime, 1742 publications have been published within this topic receiving 26702 citations.

Recursive estimation of the Preisach density function for a smart actuator

Abstract: The Preisach operator and its variants have been successfully used in the modeling of a physical system with hysteresis. In an application, one has to determine the density function describing the Preisach operator from measurements. In our earlier work, we described a regularization method to obtain an approximation to the density function with limited measurements. In this paper, we describe methods for recursively computing the approximate density function. These methods can be implemented in real-time controllers for smart actuators.

A describing function technique for sampling period selection and controller discretisation

Abstract: Most industrial processes that are to be controlled are continuous in nature. A very> extensive range of well tried methods for control systems analysis and design, together with the associated algorithms for implementation, are in continuous time form. Digital control algorithms can be produced by translation of the analogue designs or they can be developed using digital design techniques. Discretisation of analogue controllers can be done in many well known ways. In general the stability of the resulting system cannot be guaranteed, both because of inherent approximation and lack of guidance on choice of sampling period. The criticalfactor is the sampling period, too high a value and the system is unstable, too low and the controller is overdesigned.A discretisation method for translation from analogue to digital is given here where, subject to certain constraints, the sampling period can be chosen so as to guarantee stability. Following on this, the Z transfer function of the controller is taken as the...

Analysis and Design of an Adaptive Multi-Loop Controlled Two Winding Buck/Boost Regulator

Abstract: Small signal low frequency linear average model is derived for a multi-loop controlled two-winding buck/boost converter employing average techniques and the describing function method. The model reveals that a well-designed multi-loop control can provide a second-order zero adaptive to output filter parameter changes due to component tolerances, temperature changes, aging, and the effect of duty cycle modulation. It also can provide stabilization effect by shifting the positive zero to the left-half S-plane. Design quidelines are formulated to optimize regulator-loop dependent characteristics.

Robust stability analysis of a fuzzy vehicle lateral control system using describing function method

Abstract: In this paper, the robust stability analysis of a fuzzy vehicle lateral system with perturbed parameters is presented. Firstly, the fuzzy controller can be linearized by utilizing the describing function method with experiments. After the describing function is obtained, the stability analysis of the vehicle lateral control system with the variations of velocity and friction is then carried out by the use of parameter plane method. Afterward some limit cycle loci caused by the fuzzy controller can be easily pointed out in the parameter plane. Computer simulation shows the efficiency of this approach.

Frequency Response Methods for Nonlinear Multivariable Systems

Abstract: : A new graphical procedure for the analysis of nonlinear multivariable systems is presented. The method uses the eigenvalue loci of the linear part of the system and the describing function loci of the nonlinear parts, and is an extension of the eigenvalue methods first introduced by Bohn for the analysis of linear multivariable systems. For some special classes of systems, it is shown that very realistic stability estimates can be obtained in a simple manner. Examples are given to illustrate the use of the method and the stability bounds obtained are compared with those resulting from the use of other stability criteria. (Author)