www.pudn.com > chap1.rar > chap1_3s.m

%S-function for continuous state equation 
function [sys,x0,str,ts]=s_function(t,x,u,flag) 
 
switch flag, 
%Initialization 
  case 0, 
    [sys,x0,str,ts]=mdlInitializeSizes; 
%Outputs 
  case 3, 
    sys=mdlOutputs(t,x,u); 
%Unhandled flags 
  case {2, 4, 9 } 
    sys = []; 
%Unexpected flags 
  otherwise 
    error(['Unhandled flag = ',num2str(flag)]); 
end 
 
%mdlInitializeSizes 
function [sys,x0,str,ts]=mdlInitializeSizes 
sizes = simsizes; 
sizes.NumContStates  = 0; 
sizes.NumDiscStates  = 0; 
sizes.NumOutputs     = 1; 
sizes.NumInputs      = 3; 
sizes.DirFeedthrough = 1; 
sizes.NumSampleTimes = 0; 
 
sys=simsizes(sizes); 
x0=[]; 
str=[]; 
ts=[]; 
 
function sys=mdlOutputs(t,x,u) 
error=u(1); 
derror=u(2); 
errori=u(3); 
 
kp=60; 
ki=1; 
kd=3; 
ut=kp*error+kd*derror+ki*errori; 
 
sys(1)=ut;