MATLAB: Add reference line to a Bode Plot

bodebode diagramsclosed loopcontrol systemmagnitudeopen loopplot

Greetings!
I used the command
h = bodeplot(Gol,{0.1 0.5});
to plot Bode diagrams (Magnitude x Frequency and Phase Angle x Frequency) to analyze the stability of the closed-loop system. Hence, I need to draw a horizontal reference line at y = 1 on the first graph (Mag. x Freq.) so as to find out if my system stable or not.
How do I do that? Were it a simple plot, I'd use refline but it doesn't work for the bodeplot function, since it generates two plots (like subplot(2,1,1) and subplot(2,1,2)). Thank you.

Best Answer

It is not worthwhile to attempt to do anything with the plots that bode and most — if not all — of the other Control System Toolbox plots. They do not allow modifications.
Instead, get the outputs from the bode function:
[mag,phase,wout] = bode(sys);
and plot them using subplot. Remember to use the squeeze command to remove singleton dimensions from the ‘mag’ and ‘phase’ results for simple models.
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