kstats.m

离散控制系统设计的MATLAB 代码

function [Mo,kp,kr,ks,ess] = kstats(k,y,ref)
%KSTATS [Mo,kp,kr,ks,ess] = kstats(t,y,ref)
%       Takes a discrete time vector k and a corresponding 
%       step-response vector y and returns time-domain 
%       performance measures.
%Inputs: k - discrete time vector 
%        y - step response corresponding to k
%        ref - reference level at steady-state
%Outputs: Mo - percent overshoot
%         kp - time to peak
%         kr - rise time (10% - 90%)
%         ks - settling time (2%)
%         ess - percent steady-state Error
%
%If the reference level, 'ref', is not specified, 1.0 is assumed.

%%%%%%%%%%%%%%%%%%% kstats.m %%%%%%%%%%%%%%%%%%%%
%   Discrete-Time Control Problems using        %
%       MATLAB and the Control System Toolbox   %
%   by J.H. Chow, D.K. Frederick, & N.W. Chbat  %
%         Brooks/Cole Publishing Company        %
%                September 2002                 %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

if nargin < 3
  ref = 1;
  disp('reference value set = 1.0')
end
%
[maxy,ikp] = max(y);
kp = k(ikp);
Mo = max(100*(maxy - ref)/ref,0);

%
i10 = min(find(y>=0.1*ref));
i90 = min(find(y>=0.9*ref));
if i10 > 0 & i90 < length(y)
  delk = k(2)-k(1);
  k10 = k(i10) - delk*(y(i10)-0.10*ref)...
                /(y(i10)-y(i10-1));
  k90 = k(i90) - delk*(y(i90)-0.90*ref)...
                /(y(i90)-y(i90-1));
  kr  = k90 - k10;
else
  kr = 9.9999;
end
%
is = max(find(abs(y - ref*ones(size(y)))/ref>0.02));
if is < length(y)
  ks = k(is + 1);
else
  ks = max(k);
end
%
ess = abs(100*(y(length(y)) - ref)/ref);
%%%%%%%%%%