Plot Specific Points on Nichols Chart
5 views (last 30 days)
Show older comments
I am currently trying to plot specfic points onto a Nichols chart so that I can find the limit cycle for the original system.
The gain and phase co-ords have been included below:
I am trying to add these to this Nichols plot:
Any help would be appreciated.
2 Comments
Accepted Answer
Paul
on 2 Apr 2024
Hi Amaan,
The input to nichols has to be an a dynamic system model. So either you have to convert AbsN and AngN to such a model and then call nichols, or just plot the dat on the Nichols chart. The code below does both just to illustratre. I assumed that AbsN is already in dB. I assigned an arbiitrary frequency vector to create the frd object for purposes of the Nichols plot, but it would be better to use the actualy frequency vector, if you have it, in case you want to use the frd object for other purposes.
AbsN = [-4.609, -13.9794, -17.5012, -18.8897, -19.5545, -19.8245, -15.4170, -7.6042, -1.5836]; % Absolute Value -1/N
AngN = [-123, -150, -166, -173, -177, -179, -179, -180, -180]; % Angle of -1/N in degrees
K = 0.528;
T = 1.5;
Gc = 1;
PwrAmp = 10;
Mtr = 5;
Grs = 0.2;
Flp = tf(K, [T 1 0]);
OpenLoop = (Gc*PwrAmp*Mtr*Grs*Flp);
hold on
nichols(OpenLoop)
%nichols(AbsN,AngN)
nichols(frd(10.^(AbsN/20).*exp(1j*AngN*pi/180),0:8))
plot(AngN,AbsN,'o')
hold off
0 Comments
More Answers (0)
See Also
Categories
Find more on Triangulation Representation in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!