reinf6_7.m

离散控制系统设计的MATLAB 代码

%%%%%%%%%%% Reinforcement Problem 6.7 %%%%%%%%%%%
%   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                 %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%   ---- Response of a highpass digital filter ----
%
clear
disp('Reinforcement Problem 6.7')

Ts = 0.01;                            % sampling period
G = tf(3.077*[1 -0.5],[1 0.5385],Ts)  % highpass filter
w = logspace(-2,0,50)*pi/Ts;          % specify frequency range
figure
bode(G,w)                         % frequency response plot
title('Bode plot for Reinforcement Problem 6.7')

t = [0:Ts:10.0-Ts];               % time array from 0 to 9.99 sec
e = cos(14*pi*t)+cos(50*pi*t)+cos(86*pi*t);  % DT signal
y = lsim(G,e);                    % filter output
t9 = [901:1000]';

figure
subplot(2,1,1)                    % split graphics window
stem(t(t9),e(t9),':','filled'), grid
legend('Input signal')
axis([9.5 10.0 -4 5])		  	  % show only last 0.5 s
xlabel('Time (s)')
subplot(2,1,2)
stem(t(t9),y(t9),':o'), grid
axis([9.5 10.0 -12 12])			  % show only last 0.5 s
legend('Output signal')
xlabel('Time (s)')
title('Input and output signals for Reinforcement Problem 6.7')

N = length(y(t9));                % number of data points
Yp = fft(y(t9))/N;                % Compute Fourier Series Coeffs
ff = [0:1/Ts/N:(1.0-Ts)/Ts];      % frequency array

figure
stem(ff,abs(Yp));grid             % magnitude plot
ylabel('magnitude')
xlabel('frequency (Hz)')
title('Magnitudes of output Fourier-series coeffs for Reinforcement Problem 6.7')
%%%%%%%%%%