Showing information on a plot

Hello,

I am analysing a control system, that has a step input and the given transfer function. I have been able to produce a graph, and obtain the information of the system (Peak, SettlingMax etc.), but I am trying to display this information as shown below on the MATLAB help centre. Unfortunately, I am unable to locate any guidance on displaying the information in this way (see below for my current graph/desired output)

For reference, my transfer function is g = tf(1,[1,8.52,5.3,26]), and as stated prior a step input is used.

This is my blank graph

An example I found in a textbook

And I am looking to display it in this way.

I

Note - I am able to find the values for each of these via the command stepinfo(g), however would like to show them as the nodes on the image above.

Any help to display my results in a similar way would be greatly appreciated!

Thank you,

Lewis

Answer 1

[Star Strider]

Retrieving and showing all that information is not straightforward, however it is definitely possible. Use stepinfo to get the information, and stepplot to do the plot since it is easier to work with than step.

This should get you started —

g = tf(1,[1,8.52,5.3,26])

g =
 
               1
  ---------------------------
  s^3 + 8.52 s^2 + 5.3 s + 26
 
Continuous-time transfer function.

si = stepinfo(g)

si = struct with fields:
         RiseTime: 0.6338
    TransientTime: 28.8675
     SettlingTime: 28.8675
      SettlingMin: 0.0149
      SettlingMax: 0.0682
        Overshoot: 77.2255
       Undershoot: 0
             Peak: 0.0682
         PeakTime: 1.9477

figure
hsp = stepplot(g);
Ampl = hsp.Responses.Data.Amplitude;
Time = hsp.Responses.Data.Time;
xl = xlim;
hold on
plot([1 1]*si.PeakTime, [0 si.Peak], '-.k')
plot([0 si.PeakTime], [1 1]*si.SettlingMax, '-.k')
sttmin = interp1(Ampl, Time, si.SettlingMin);                                   % Interpolate To Determine This Specific Time
plot([-1 1]*max(xl)*0.05+sttmin, [1 1]*si.SettlingMin, '-.k')
plot([0 si.PeakTime], [1 1]*si.SettlingMax, '-.k')
hold off
text(si.PeakTime, si.Peak, sprintf('\\leftarrow Peak = %.4f V\n    Time = %.4f s', si.Peak, si.PeakTime), 'Vert','middle')
text(max(xl)*0.05+sttmin, si.SettlingMin, sprintf('\\leftarrow Minimum = %.4f V\n    Time = %.4f s', si.SettlingMin, sttmin), 'Vert','middle')

% get(hsp)

Tweak appropriately to get the result you want.

.

[Lewis]

Thank you!!

[Star Strider]

As always, my pleasure!

Answer 2

[the cyclist]

You should be able to get everything you want, using the following commands:

title, xlabel and ylabel for the title and axes labels.

line to create the line segments.

annotation to add the text and arrows.

[Lewis]

Thank you, will I have to input the x,y coordinates of each point? Or if for example I say “Peak” will it automatically insert the “bubble” at the peak of the amplitude?

[the cyclist]

No, none of this is automatic. You will need to manually create all those additions to your plot.

I assumed that you already knew how to plot the "bubble". You can use the plot or scatter function to plot those. You might need to use the hold command to have both your line plot and the bubbles on the same figure.

[Alexander]

Not to forget:

text

.

[the cyclist]

Yes, the text command is another option. But annotation can do both arrows and textboxes.

[Lewis]

Thank you, appreciate it!