Merged in alessiomorale/librepilot/amorale/LP-276_measurement_based_d_term (pull request #218)

[LP-276] Support D Term calculation on measurement only

flight/libraries/math/pid.c

@@ -76,7 +76,7 @@ float pid_apply(struct pid *pid, const float err, float dT)
  * This version of apply uses setpoint weighting for the derivative component so the gain
  * on the gyro derivative can be different than the gain on the setpoint derivative
  */
-float pid_apply_setpoint(struct pid *pid, const pid_scaler *scaler, const float setpoint, const float measured, float dT)
+float pid_apply_setpoint(struct pid *pid, const pid_scaler *scaler, const float setpoint, const float measured, float dT, bool meas_based_d_term)
 {
     float err = setpoint - measured;
 
@@ -85,9 +85,18 @@ float pid_apply_setpoint(struct pid *pid, const pid_scaler *scaler, const float
     pid->iAccumulator  = boundf(pid->iAccumulator, pid->iLim * -1000.0f, pid->iLim * 1000.0f);
 
     // Calculate DT1 term,
+    float diff;
+    float derr = (-measured);
+
+    if (!meas_based_d_term) {
+        derr += deriv_gamma * setpoint;
+    }
+
+    diff = derr - pid->lastErr;
+    pid->lastErr = derr;
+
     float dterm = 0;
-    float diff  = ((deriv_gamma * setpoint - measured) - pid->lastErr);
+
-    pid->lastErr = (deriv_gamma * setpoint - measured);
     if (pid->d > 0.0f && dT > 0.0f) {
         // low pass filter derivative term. below formula is the same as
         // dterm = (1-alpha)*pid->lastDer + alpha * (...)/dT
@@ -95,7 +104,6 @@ float pid_apply_setpoint(struct pid *pid, const pid_scaler *scaler, const float
         dterm = pid->lastDer + dT / (dT + deriv_tau) * ((scaler->d * diff * pid->d / dT) - pid->lastDer);
         pid->lastDer = dterm;
     }
-
     return (err * scaler->p * pid->p) + pid->iAccumulator / 1000.0f + dterm;
 }
 

flight/libraries/math/pid.h

@@ -70,7 +70,7 @@ typedef struct pid_scaler_s {
 
 // ! Methods to use the pid structures
 float pid_apply(struct pid *pid, const float err, float dT);
-float pid_apply_setpoint(struct pid *pid, const pid_scaler *scaler, const float setpoint, const float measured, float dT);
+float pid_apply_setpoint(struct pid *pid, const pid_scaler *scaler, const float setpoint, const float measured, float dT, bool meas_based_d_term);
 void pid_zero(struct pid *pid);
 void pid_configure(struct pid *pid, float p, float i, float d, float iLim);
 void pid_configure_derivative(float cutoff, float gamma);

flight/modules/Stabilization/innerloop.c

@@ -68,7 +68,7 @@ static uint8_t previous_mode[AXES] = { 255, 255, 255, 255 };
 static PiOSDeltatimeConfig timeval;
 static float speedScaleFactor = 1.0f;
 static bool frame_is_multirotor;
-
+static bool measuredDterm_enabled;
 // Private functions
 static void stabilizationInnerloopTask();
 static void GyroStateUpdatedCb(__attribute__((unused)) UAVObjEvent *ev);
@@ -99,6 +99,7 @@ void stabilizationInnerloopInit()
     PIOS_CALLBACKSCHEDULER_Schedule(callbackHandle, FAILSAFE_TIMEOUT_MS, CALLBACK_UPDATEMODE_LATER);
 
     frame_is_multirotor   = (GetCurrentFrameType() == FRAME_TYPE_MULTIROTOR);
+    measuredDterm_enabled = (stabSettings.settings.MeasureBasedDTerm == STABILIZATIONSETTINGS_MEASUREBASEDDTERM_TRUE);
 }
 
 static float get_pid_scale_source_value()
@@ -250,6 +251,7 @@ static void stabilizationInnerloopTask()
     StabilizationStatusOuterLoopGet(&outerLoop);
     bool allowPiroComp = true;
 
+
     for (t = 0; t < AXES; t++) {
         bool reinit = (StabilizationStatusInnerLoopToArray(enabled)[t] != previous_mode[t]);
         previous_mode[t] = StabilizationStatusInnerLoopToArray(enabled)[t];
@@ -290,7 +292,7 @@ static void stabilizationInnerloopTask()
                                  StabilizationBankMaximumRateToArray(stabSettings.stabBank.MaximumRate)[t]
                                  );
                 pid_scaler scaler = create_pid_scaler(t);
-                actuatorDesiredAxis[t] = pid_apply_setpoint(&stabSettings.innerPids[t], &scaler, rate[t], gyro_filtered[t], dT);
+                actuatorDesiredAxis[t] = pid_apply_setpoint(&stabSettings.innerPids[t], &scaler, rate[t], gyro_filtered[t], dT, measuredDterm_enabled);
                 break;
             case STABILIZATIONSTATUS_INNERLOOP_ACRO:
             {
@@ -305,7 +307,7 @@ static void stabilizationInnerloopTask()
 
                 pid_scaler ascaler = create_pid_scaler(t);
                 ascaler.i *= boundf(1.0f - (1.5f * fabsf(stickinput[t])), 0.0f, 1.0f); // this prevents Integral from getting too high while controlled manually
-                float arate  = pid_apply_setpoint(&stabSettings.innerPids[t], &ascaler, rate[t], gyro_filtered[t], dT);
+                float arate  = pid_apply_setpoint(&stabSettings.innerPids[t], &ascaler, rate[t], gyro_filtered[t], dT, measuredDterm_enabled);
                 float factor = fabsf(stickinput[t]) * stabSettings.acroInsanityFactors[t];
                 actuatorDesiredAxis[t] = factor * stickinput[t] + (1.0f - factor) * arate;
             }

shared/uavobjectdefinition/stabilizationsettings.xml

@@ -48,6 +48,8 @@
 	<field name="ScaleToAirspeedLimits" units="" type="float" elementnames="Min,Max" defaultvalue="0.05,3"/>
 	<field name="FlightModeAssistMap" units="" type="enum" options="None,GPSAssist" elements="6" defaultvalue="None,None,None,None,None,None" />
 
+	<field name="MeasureBasedDTerm" units="" type="enum" elements="1" options="False,True" defaultvalue="True"/>
+
 	<access gcs="readwrite" flight="readwrite"/>
 	<telemetrygcs acked="true" updatemode="onchange" period="0"/>
 	<telemetryflight acked="true" updatemode="onchange" period="0"/>