Show Step Response Information on Step Response Plot

Normally, if I want to display the information of the Step Response (peak, rise time, etc). I click on the plot and select "Characteristics > Peak Response",etc. I intend to design a Gui (very basic one) that the Step Response will automatically show these information at run-time.

step(handles.axes_step,sys, stepinfo(sys)) %I have trouble with the show stepinfo on the plot. If I cannot find a way, I just let it be but I guess there should be a way.

Answer 1

[Jonathan LeSage]

You're on the right track trying to use stepinfo. The stepinfo function returns a structure containing all the common step response metrics. You can directly plot the these results. Here is some example code to get you started:

% Defining an arbitrary system
s = tf('s');
G = 1/(s^2 + 5*s + 2);

% Computing the system step response
[y,t] = step(G);
stepResults = stepinfo(y,t);

% Extract the settling time from the stepinfo structure
tSettle= stepResults.SettlingTime;

% Other step response results of interest can be found by looking in
% the stepResults structure

% Find the first index where time exceeds the settling time
% To further improve this, you could interpolate between the points.
indexSettle = find(t >= tSettle,1,'first');
xSettle = t(indexSettle);
ySettle = y(indexSettle);

% Plot step response
plot(t,y); 
grid on;
hold on;

% Plot settling time point
plot(xSettle,ySettle,'ro');

% Plot chart lines to settling point
plot([0 xSettle],[ySettle ySettle],'g-.');
plot([xSettle xSettle],[0 ySettle],'g-.');
hold off;

You could easily repeat this same process for each step response metric of interest. Hope this helps!

[MatlabNewbie01232015]

Very nice - I understand the approach - well I still need to learn but the example is very clear and easy to follow.

Answer 2

[Jeffry]

sys = tf(1,[1 .5]);
h = stepplot(sys);
grid on
% characteristics are those found under h.CharacteristicManager.CharacteristicID
h.showCharacteristic('PeakResponse')
h.showCharacteristic('RiseTime')

[James Richard]

Go to

[Your Installation Directory]\toolbox\shared\controllib\graphics\@wrfc\@plot\

for more information on this topic

because showCharacteristic.m file is also available there

Answer 3

[Tekno]

dear Jonathan LeSage i have data in figure , how can i get the step info from it? im using matlab 2015 version, please your support.

Answer 4

[SimTec]

what if we don't have the math model in my case, I saved data to "to Workspace" but got erros