fuzzy21.m

FISMAT accommodates different arithmetic operators, fuzzification and defuzzification algorithm, imp

function  [sys, x0]  = fuzzy21(t,x,u,flag,ctr,ts)

% [sys,x0] = fuzzy21(t,x,u,flag,ctr,ts) 
%
% Simulink S-function-file. Fuzzy21 means Fuzzy-Controller (discrete)
% with two inputs and one output.
% ctr=string with the controller M-filename.
% ts = sample time.
% Calling this s-function with flag=0 must return a sys-vector:
% sys(1) number of continuous states       here: =0
% sys(2) number of discrete states x(n+1)        =5
% sys(3) number of outputs                       =1
% sys(4) number of inputs                        =2
% sys(5) number of discontinuous roots
% sys(6) flag for direct feedthrough (used for finding algebraic loops)
% Note that because the step time of the SIMULINK integrator is much smaller
% than the sampling interval of the discrete block, there is an implicit 
% zero-order hold on the output of the unit delay.
% u   = actual inputs at this sample point.
% x(1)= the last first-input value - one sample period ts ago.
% x(2)= the last second-input value - one sample period ts ago.
% x(3)= the last output-value - one sample period ts ago.
% x(4)= the first-input value two sample periods ago.
% x(5)= the second-input value two sample periods ago.
% In the controller file you can decide if the controller needs one sample 
% period to evalute the actual output. (This is more realistic for fuzzy-
% controller). That means in the controller file x(1),x(2) are used as the input
% value instead of u.
%
% FSTB - Fuzzy Systems Toolbox for MATLAB
% Copyright (c) 1993-1996 by Olaf Wolkenhauer
% Control Systems Centre at UMIST
% Manchester M60 1QD, UK
%
% 19-April-1994
 
% offset time (sample time is given as the parameter ts)
offset = 0;
if abs(flag) == 2  % Return discrete states in sys
  % Is it a sample hit (within a tolerance of 1e-8) ?
  if abs(round((t - offset)/ts) - (t - offset)/ts) < 1e-8
    sys(1) = u(1);
    sys(2) = u(2);
    sys(3) = feval(ctr,u,x,ts);
    sys(4) = x(1);
    sys(5) = x(2);
  else
    % otherwise, just set it equal to its last value.
    sys = x;
  end
elseif flag == 3  % Return outputs
% Is it a sample hit (within a tolerance of 1e-8) ?
  if abs(round((t - offset)/ts) - (t - offset)/ts) < 1e-8
    sys(1) = feval(ctr,u,x,ts);
  else
    % otherwise, just set it equal to its last value.
    sys = x(3);
  end
elseif flag == 4 % Return next sample hit
% ns stores the number of samples
  ns = (t - offset)/ts;
% This is the time of the next sample hit.
  sys = offset + (1 + floor(ns + 1e-13*(1+ns)))*ts;
elseif flag  == 0,  % Initial conditions and size information
  sys = [0;5;1;2;0;0]; % five states, one output, two inputs.
  x0  = zeros(5,1); 
else 
  sys = [];
end;