plotting bode and step on the same graph

how can i plot a bode plot and a step response of a system on the same graph i used 'hold on' but it came with an error : Plots must be of the same type and size to be superimposed.

[João Felipe Gueiros Batista da Silva]

Did you manage to find a solution?

[Paul]

Can you post an example picture of what you want to accomplish? Click the Image icon on the Insert menu (next to the Paperclip) to post a picture.

Answer 1

[Sulaymon Eshkabilov]

There are a couple of issues. Step response is in time domain and Bode is in a frequency response. Therefore they are not compatibe to plot in the same figure.

T = tf(1, [1 1 3]);
step(T, 10)  % The system response on the STEP input excitation

bode(T)    % Frequency response of the system T

[Y, t]=step(T, 10);   % Collect the step response values
plot(t, Y, 'r-', 'linewidth', 2), grid on; title('Step response of the system')

% Frequency response:
f = linspace(0.1, 100, 500);
w = 1i*f;
Y = 1./(w.^2+w+3);     % Freq. Response
YR =abs(Y);            % Magnitude of the Freq. response  
subplot(211)
semilogx(f, 20*log10(YR), 'b'), grid on
subplot(212)
semilogx(f,rad2deg(phase(Y)), 'r'), grid on