Diff: PID_Cntrl.cpp

Revision:

1:bf62e74fbcf3

Parent:

0:e2a7d7f91e49

Child:

2:1f8ddc46c578

--- a/PID_Cntrl.cpp	Fri Sep 28 08:34:20 2018 +0000
+++ b/PID_Cntrl.cpp	Fri Sep 28 09:01:42 2018 +0000
@@ -3,59 +3,47 @@
     see e.g.: https://www.dsprelated.com/freebooks/filters/Four_Direct_Forms.html
     everything is calculated in double
     
-                  Tn*s + 1                      
-      G(s) = Kp -------------  with s ~ (1 - z^-1)/Ts
-                    Ts*s                     
+                     Ts         z - 1             
+      G(s) = P + I ------- + D -------
+                    z - 1       z - p              
 */
 
-#include "PI_Cntrl.h"
+#include "PID_Cntrl.h"
 
 using namespace std;
 
-PI_Cntrl::PI_Cntrl(float Kp, float Tn, float Ts)
-{
-    setCoefficients(Kp, Tn, Ts);
-    uMax = 10000000000.0;
-    uMin = -uMax;
-    reset(0.0f);
-}
-
-PI_Cntrl::PI_Cntrl(float Kp, float Tn, float Ts, float uMax)
+PID_Cntrl::PID_Cntrl(float P, float I, float D, float tau_f, float Ts, float uMax, float uMin)
 {
-    setCoefficients(Kp, Tn, Ts);
-    this->uMax = (double)uMax;
-    uMin = -(double)uMax;
-    reset(0.0f);
-}
-
-PI_Cntrl::PI_Cntrl(float Kp, float Tn, float Ts, float uMax, float uMin)
-{
-    setCoefficients(Kp, Tn, Ts);
+    setCoefficients(P, I, D, tau_f, Ts);
     this->uMax = (double)uMax;
     this->uMin = (double)uMin;
     reset(0.0f);
 }
 
-PI_Cntrl::~PI_Cntrl() {}
+PID_Cntrl::~PID_Cntrl() {}
 
-void PI_Cntrl::reset(float initValue)
+void PID_Cntrl::reset(float initValue)
 {
-    s = (double)initValue;
+    Iold = (double)initValue;
+    eold = 0.0;yold = 0.0;
+    del = 0.0;
 }
 
-void PI_Cntrl::setCoefficients(float Kp, float Tn, float Ts)
+void PID_Cntrl::setCoefficients(float P, float I, float D, float tau_f, float Ts)
 {
-    b0 = (double)Kp*(1.0 + (double)Ts/(double)Tn);
-    b1 = -(double)Kp;
-    b2 = (double)Ts/(double)Tn;    
+    this->p = 1.0 - (double)Ts/(double)tau_f;
+    this->P = P;
+    this->I = I;
+    this->D = D;
+    
 }
 
-float PI_Cntrl::doStep(double e)
+float PID_Cntrl::doStep(double e)
 {
-    double u = b0*e + s;          // unconstrained output
+    double u = P*e + D*(e-eold)+p*yold  +Iold+I*Ts*(e-del);          // unconstrained output
     double uc = u;                // constrained output
     if(u > uMax) uc = uMax;
     else if(u < uMin) uc = uMin;
-    s = b1*e + u - b2*(u - uc);
+    del=(u-uc)/P;
     return (float)uc;
 }
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