I have an uncertain state-space model for which I want to tune a continuous PID controller.
The model, called my_uss_model, has order 21 and is strictly proper, with a transfer function with 1 zero and 5 poles.
The function
isProper(my_uss_model)
Unrecognized function or variable 'my_uss_model'.
confirms it by returning true.
Each uncertain root has an uncertainty percentage of 50%, and the nominal transfer function looks like the following:
7.1155e09 (s+10)
----------------------------------------------------
(s+2.907e04) (s+1917) (s+38.31) (s+10.24) (s-0.1253)
However, when I try to run the systune function with the goals and the system interconnection as defined below, I get an error:
Error using DynamicSystem/systune
Tuning of improper plants or controllers is not supported.
Error in script (line 41)
Gcl = systune(T, [Rstep Rtrack], [Rov Rmargin Rreject], tuneopts);
This is very unexpected, since all the properties of my system seem in order. Any ideas?
Here is the code I used, I'm attaching the model in a .mat with the script.
Rtrack = TuningGoal.Tracking('r', 'y', responsetime, dcerror, peakerror);
Rreject = TuningGoal.StepRejection('u', 'y', peak, tSettle);
Rstep = TuningGoal.StepTracking('r', 'y', 0.3, maxOvershoot);
Rov = TuningGoal.Overshoot('r', 'y', maxOvershoot);
Rmargin = TuningGoal.Margins('y', gain_margin, phase_margin);
C = tunablePID('C', 'PID');
C.Kp.Minimum = 0; C.Kp.Maximum = inf;
C.Ki.Minimum = 0; C.Ki.Maximum = inf;
C.Kd.Minimum = 0; C.Kd.Maximum = inf;
C.Tf.Minimum = 10 * Ts; C.Tf.Maximum = 100 * Ts;
my_uss_model.InputName = 'u';
my_uss_model.OutputName = 'y';
sumblkstring = append('e = r - ', 'y');
Sum = sumblk(sumblkstring);
T = connect(my_uss_model, C, Sum,'r', 'y', {'u', 'y'});
tuneopts = systuneOptions('RandomStart', 10, 'UseParallel', false);
Gcl = systune(T, [Rstep Rtrack], [Rov Rmargin Rreject], tuneopts);
