Projeto e implementação de controladores digitais: a determinação do comprimento de palavra de variáveis e coeficientes na representação em ponto fixo.

Abstract

This paper presents the design of optimal deterministic digital controllers, obtained by minimizing a quadratic performance criterion. Two of these controllers use state observers, being differentiated by their structures. The third controller is designed as a dynamic approximation of the optimal controller. A statistical technique for calculating the word length of variables is presented, whose design parameter and the maximum acceptable noise, due to the quantization of variables, in the controllers output. In addition and proposing a technique, also statistical, for the determination of the word length of coefficients from the definition of the maximum acceptable variation of the output of quantized controllers in relation to ideal controllers, not quantized. The computer-aided design of the controllers is also presented. Implementation in a system based on an eight-bit two-controller observer controller is described. The numeric representation used in the implementation is two's complement, fixed point, with rounding. The process used as a control object in the implementation is an inertially charged direct current servomotor.