PT2.cpp

00001 #include "PT2.h"
00002 
00003 PT2::PT2() {
00004     u = y = u_p1 = y_p1 = u_p2 = y_p2 = 0;
00005     setParameters(1, 1, 0.5, 0.1);
00006 }
00007 
00008 PT2::PT2(double K_, double T_1_, double T_2_, double T_d_) {
00009     u = y = u_p1 = y_p1 = u_p2 = y_p2 = 0;
00010     setParameters(K_, T_1_, T_2_, T_d_);
00011 }
00012 
00013 void PT2::setParameters(double K_, double T_1_, double T_2_, double T_d_) {
00014     if (T_d_ > 0)
00015         T_d = T_d_;
00016     else
00017         T_d = 0.1;
00018     K = K_;
00019     T_1 = T_1_;
00020     T_2 = T_2_;
00021     a = 1 / T_1;
00022     b = 1 / T_2;
00023     c = exp(-a * T_d);
00024     d = exp(-b * T_d);
00025     b_1 = -K * ( (a - b)*(c + d) + b*(1 + d) - a*(1 + c) ) / (a - b);
00026     b_2 = K * ( (a - b)*c*d + b*d - a*c ) / (a - b);
00027     a_1 = -(c + d);
00028     a_2 = c*d;
00029 }
00030 
00031 double PT2::out() {
00032     y = -a_1 * y_p1 - a_2 * y_p2 + b_1 * u_p1 + b_2 * u_p2;
00033     y_p2 = y_p1;
00034     y_p1 = y;   
00035     u_p2 = u_p1; 
00036     u_p1 = u;
00037     return y;
00038 }
00039 
00040 void PT2::in(double u_) {
00041     u = u_;
00042 }