Romeo Urbieta Parrazales

A fuzzy logic controller applied to a d.c. motor

This paper describes a Fuzzy Control System applied to the shaft position of a direct current motor of 1/15 H.P. (with a tension of 0 to 24 V at 0.75 A), running from 100 to 6500 R.P.M. The work includes three important aspects: Design, Simulation, and Implementation. In this design the Variable Structure System was used to stabilize using 11 If-Then rules, and for tuning using the Genetics Algorithms Method, which use 10 fuzzy membership functions. The simulation used a structured programming language based on Turbo C++ to present the variable of interest against the time. The implementation used a personal computer, a converted board A/D and D/A (-5 to volt), a current driver (3 A), a digital encoder of 240 slots, and a real time structured program based also on Turbo C++.

Equivalent Neural Network Optimal Coefficients Using Forgetting Factor with Sliding Modes

The Artificial Neural Network ANN concept is familiar in methods whose task is, for example, the identification or approximation of the outputs of complex systems difficult to model. In general, the objective is to determine online the adequate parameters to reach a better point-to-point convergence rate, so that this paper presents the parameter estimation for an equivalent ANN EANN, obtaining a recursive identification for a stochastic system, firstly, with constant parameters and, secondly, with nonstationary output system conditions. Therefore, in the last estimation, the parameters also have stochastic properties, making the traditional approximation methods not adequate due to their losing of convergence rate. In order to give a solution to this problematic, we propose a nonconstant exponential forgetting factor NCEFF with sliding modes, obtaining in almost all points an exponential convergence rate decreasing. Theoretical results of both identification stages are performed using MATLAB® and compared, observing improvement when the new proposal for nonstationary output conditions is applied.

High precision programmable adaptive digital frequency multiplier

This paper presents and justifies the use of an architecture which increases the precision in the output pulse of an adaptive frequency multiplier. This is done without using a correction circuit, a component which was necessary in previous work in the area.