Diff: GPA.cpp

Revision:

8:d68e177e2571

Parent:

7:87b823282bf0

Child:

10:a28f393c6716

--- a/GPA.cpp	Sat Mar 17 08:43:07 2018 +0000
+++ b/GPA.cpp	Thu Mar 22 17:32:37 2018 +0000
@@ -1,3 +1,73 @@
+/*
+    GPA: frequency point wise gain and phase analyser to measure the frequency
+         respone of dynamical system
+    
+        hint:       the measurements should only be perfomed in closed loop
+        assumption: the system is at the desired steady state of interest when
+                    the measurment starts
+    
+                             exc(2)                 C: controller
+                               |                    P: plant
+                               v                     
+     exc(1) --> o   ->| C |--->o------->| P |----------> out
+                ^                  |             |
+                |                   --> inp      |  exc: excitation signal (E)
+                |                                |  inp: input plant (U)
+                 --------------------------------   out: output plant (Y)
+  
+    instantiate option 1:
+    GPA(float fMin, float fMax, int NfexcDes, int NperMin, int NmeasMin, float Ts, float Aexc0, float Aexc1)
+    
+        fMin:     minimal desired frequency that should be measured in Hz
+        fMax:     maximal desired frequency that should be measured in Hz
+        NfexcDes: number of logarithmic equaly spaced frequency points
+        NperMin:  minimal number of periods that are used for each frequency point
+        NmeasMin: maximal number of samples that are used for each frequency point
+        Ts:       sampling time
+        Aexc0:    excitation amplitude at fMin 
+        Aexc1:    excitation amplitude at fMax
+    
+        hints:    the amplitude drops with 1/fexc, if you're using
+                  Axc1 = Aexc0/fMax the d/dt exc = const., this is recommended
+                  if your controller does not have a rolloff.
+                  if a desired frequency point is not measured try to increase Nmeas.
+    
+    pseudo code for a closed loop measurement with a proportional controller Kp:
+    
+        float inp = "measurement of inputsignal";
+        float out = "mesurement of outputsignal";
+        float exc = myGPA(inp, out);
+        float off = "desired steady state off the system";
+        
+        excitation input at (1):
+        inp = Kp*(exc + off - out);
+        
+        excitation input at (2):
+        inp = Kp*(off - out) + exc;
+        
+    usage:
+        exc = myGPA(inp, out) does update the internal states of the gpa at the
+        timestep k and returns the excitation signal for the timestep k+1. the 
+        results are plotted to a terminal (putty) over serial cennection and look
+        as follows:
+ -----------------------------------------------------------------------------------------
+   fexc[Hz]    |Gyu|     ang(Gyu)    |Gye|     ang(Gye)     |E|        |U|        |Y|
+ -----------------------------------------------------------------------------------------
+   7.01e-01   1.08e+01  -7.45e-02   1.08e+01  -7.38e-02   9.99e-01   9.99e-01   1.08e+01
+        
+    in matlab you can use:
+        dataNucleo = [... insert measurement data here ...];
+        g = frd(dataNucleo(:,2).*exp(1i*dataNucleo(:,3)), dataNucleo(:,1), Ts, 'Units', 'Hz');
+        gcl = frd(dataNucleo(:,4).*exp(1i*dataNucleo(:,5)), dataNucleo(:,1), Ts, 'Units', 'Hz');
+        
+    if you're evaluating more than one measurement which contain equal frequency points try:
+        dataNucleo = [dataNucleo1; dataNucleo2];
+        [~, ind] = unique(dataNucleo(:,1),'stable');
+        dataNucleo = dataNucleo(ind,:);
+         
+        autor: M.E. Peter
+*/ 
+
 #include "GPA.h"
 #include "mbed.h"
 #include "math.h"