AC_PID: allow non-zero ff gain default

libraries/AC_PID/AC_HELI_PID.cpp

@@ -49,9 +49,8 @@ const AP_Param::GroupInfo AC_HELI_PID::var_info[] = {
 
 /// Constructor for PID
 AC_HELI_PID::AC_HELI_PID(float initial_p, float initial_i, float initial_d, float initial_imax, float initial_filt_hz, float dt, float initial_ff) :
-    AC_PID(initial_p, initial_i, initial_d, initial_imax, initial_filt_hz, dt)
+    AC_PID(initial_p, initial_i, initial_d, initial_imax, initial_filt_hz, dt, initial_ff)
 {
-    _ff = initial_ff;
     _last_requested_rate = 0;
 }
 

libraries/AC_PID/AC_PID.cpp

@@ -43,7 +43,7 @@ const AP_Param::GroupInfo AC_PID::var_info[] = {
 };
 
 // Constructor
-AC_PID::AC_PID(float initial_p, float initial_i, float initial_d, float initial_imax, float initial_filt_hz, float dt) :
+AC_PID::AC_PID(float initial_p, float initial_i, float initial_d, float initial_imax, float initial_filt_hz, float dt, float initial_ff) :
     _dt(dt),
     _integrator(0.0f),
     _input(0.0f),
@@ -57,6 +57,7 @@ AC_PID::AC_PID(float initial_p, float initial_i, float initial_d, float initial_
     _kd = initial_d;
     _imax = fabsf(initial_imax);
     filt_hz(initial_filt_hz);
+    _ff = initial_ff;
 
     // reset input filter to first value received
     _flags._reset_filter = true;
@@ -201,7 +202,7 @@ void AC_PID::save_gains()
 }
 
 /// Overload the function call operator to permit easy initialisation
-void AC_PID::operator() (float p, float i, float d, float imaxval, float input_filt_hz, float dt)
+void AC_PID::operator() (float p, float i, float d, float imaxval, float input_filt_hz, float dt, float ffval)
 {
     _kp = p;
     _ki = i;
@@ -209,6 +210,7 @@ void AC_PID::operator() (float p, float i, float d, float imaxval, float input_f
     _imax = fabsf(imaxval);
     _filt_hz = input_filt_hz;
     _dt = dt;
+    _ff = ffval;
 }
 
 // calc_filt_alpha - recalculate the input filter alpha

libraries/AC_PID/AC_PID.h

@@ -18,7 +18,7 @@ class AC_PID {
 public:
 
     // Constructor for PID
-    AC_PID(float initial_p, float initial_i, float initial_d, float initial_imax, float initial_filt_hz, float dt);
+    AC_PID(float initial_p, float initial_i, float initial_d, float initial_imax, float initial_filt_hz, float dt, float initial_ff = 0);
 
     // set_dt - set time step in seconds
     void        set_dt(float dt);
@@ -54,7 +54,7 @@ public:
     void        save_gains();
 
     /// operator function call for easy initialisation
-    void operator() (float p, float i, float d, float imaxval, float input_filt_hz, float dt );
+    void operator() (float p, float i, float d, float imaxval, float input_filt_hz, float dt, float ffval = 0);
 
     // get accessors
     AP_Float   &kP() { return _kp; }