ex3_6.m

离散控制系统设计的MATLAB 代码

%%%%%%%%%%%%%%%%%% Example 3.6 %%%%%%%%%%%%%%%%%%
%   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                 %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% ---- Feedback connection using a selective output ----
%
clear
disp('Example 3.6')
Ts = 0.05                          % sampling time
% enter 1-input/2-output system
G1 = tf(0.01340,conv([1 -0.9394],[1 -0.7788]),Ts) 
disp('******>'), pause 
G2 = tf(0.2212,[1 -0.7788],Ts)
disp('******>'), pause 

G  = [G1; G2]                      % adjoin system
disp('******>'), pause 
Gc = 3
% ---- part a: controller in feedback path ------
% Gc connects from output 2 to input 1 
Gcla = feedback(G,Gc,1,2)
disp('******>'), pause 
Gcla = minreal(Gcla)               % eliminate redundent poles and zeros
disp('******>'), pause 
dtime = 0:Ts:4;                    % time vector
ya = step(Gcla,dtime);             % step response
figure
plot(dtime,ya(:,1),'o',dtime,ya(:,2),'*');grid % plot y1 & y2
xlabel('Time (s)')
ylabel('Amplitude')
title('Step response with controller in feedback path for Example 3.6')
text(0.3,0.22,'y_2')
text(1.25,0.17,'y_1')
axis([0 4 0 0.3])

% ---- part b: controller in forward path ------
% Gc connects from output 2 to input 1 
Gclb = feedback(G*Gc,1,1,2)
disp('******>'), pause 
Gclb = minreal(Gclb)               % eliminate redundent states
disp('******>'), pause 
yb = step(Gclb,dtime);             % step response

figure
plot(dtime,yb(:,1),'o',dtime,yb(:,2),'*');grid % plot y1 & y2
xlabel('Time (s)')
ylabel('Amplitude')
title('Step response with controller in forward path for Example 3.6')
text(0.3,0.7,'y_2')
text(1.25,0.5,'y_1')
%%%%%%%%%%