Add option to fully disable PID controller on zero throttle

src/main/config/config.c

@@ -220,6 +220,7 @@ void resetPidProfile(pidProfile_t *pidProfile)
     pidProfile->dterm_lpf_hz = 100;    // filtering ON by default
     pidProfile->deltaMethod = DELTA_FROM_MEASUREMENT;
     pidProfile->vbatPidCompensation = 0;
+    pidProfile->zeroThrottleStabilisation = PID_STABILISATION_OFF;
 
     // Betaflight PID controller parameters
     pidProfile->toleranceBand = 15;

src/main/flight/mixer.c

@@ -70,8 +70,6 @@ static bool syncPwmWithPidLoop = false;
 static mixerMode_e currentMixerMode;
 static motorMixer_t currentMixer[MAX_SUPPORTED_MOTORS];
 
-float errorLimiter = 1.0f;
-
 #ifdef USE_SERVOS
 static uint8_t servoRuleCount = 0;
 static servoMixer_t currentServoMixer[MAX_SERVO_RULES];

src/main/flight/pid.c

@@ -49,9 +49,10 @@
 
 extern uint8_t motorCount;
 uint32_t targetPidLooptime;
-extern float errorLimiter;
 extern float angleRate[3], angleRateSmooth[3];
 
+static bool pidStabilisationEnabled;
+
 int16_t axisPID[3];
 
 #ifdef BLACKBOX
@@ -76,14 +77,17 @@ void setTargetPidLooptime(uint8_t pidProcessDenom)
 
 void pidResetErrorGyroState(void)
 {
-    int axis;
+    for (int axis = 0; axis < 3; axis++) {
-
-    for (axis = 0; axis < 3; axis++) {
         errorGyroI[axis] = 0;
         errorGyroIf[axis] = 0.0f;
     }
 }
 
+void pidStabilisationState(pidStabilisationState_e pidControllerState)
+{
+    pidStabilisationEnabled = (pidControllerState == PID_STABILISATION_ON) ? true : false;
+}
+
 float getdT (void)
 {
     static float dT;
@@ -269,6 +273,8 @@ static void pidBetaflight(const pidProfile_t *pidProfile, uint16_t max_angle_inc
             axisPID[axis] = constrain(lrintf(PTerm + ITerm + DTerm), -1000, 1000);
         }
 
+        if (!pidStabilisationEnabled) axisPID[axis] = 0;
+
 #ifdef GTUNE
         if (FLIGHT_MODE(GTUNE_MODE) && ARMING_FLAG(ARMED)) {
             calculate_Gtune(axis);
@@ -409,6 +415,7 @@ static void pidLegacy(const pidProfile_t *pidProfile, uint16_t max_angle_inclina
             axisPID[axis] = PTerm + ITerm + DTerm;
         }
 
+        if (!pidStabilisationEnabled) axisPID[axis] = 0;
 
 #ifdef GTUNE
         if (FLIGHT_MODE(GTUNE_MODE) && ARMING_FLAG(ARMED)) {

src/main/flight/pid.h

@@ -62,6 +62,11 @@ typedef enum {
     POSITIVE_ERROR
 } pidErrorPolarity_e;
 
+typedef enum {
+    PID_STABILISATION_OFF = 0,
+    PID_STABILISATION_ON
+} pidStabilisationState_e;
+
 typedef struct pidProfile_s {
     uint8_t pidController;                  // 1 = rewrite betaflight evolved from http://www.multiwii.com/forum/viewtopic.php?f=8&t=3671, 2 = Betaflight PIDc (Evolved Luxfloat)
 
@@ -77,6 +82,7 @@ typedef struct pidProfile_s {
     uint16_t yaw_p_limit;
     uint8_t dterm_average_count;            // Configurable delta count for dterm
     uint8_t vbatPidCompensation;            // Scale PIDsum to battery voltage
+    uint8_t zeroThrottleStabilisation;      // Disable/Enable zero throttle stabilisation. Normally even without airmode P and D would be active.
 
     // Betaflight PID controller parameters
     uint8_t toleranceBand;                  // Error tolerance area where toleranceBandReduction is applied under certain circumstances
@@ -107,5 +113,6 @@ extern uint32_t targetPidLooptime;
 
 void pidSetController(pidControllerType_e type);
 void pidResetErrorGyroState(void);
+void pidStabilisationState(pidStabilisationState_e pidControllerState);
 void setTargetPidLooptime(uint8_t pidProcessDenom);
 

src/main/io/serial_cli.c

@@ -766,6 +766,7 @@ const clivalue_t valueTable[] = {
     { "mag_declination",            VAR_INT16  | MASTER_VALUE, &masterConfig.mag_declination, .config.minmax = { -18000,  18000 } },
     { "dterm_lowpass",              VAR_INT16  | PROFILE_VALUE, &masterConfig.profile[0].pidProfile.dterm_lpf_hz, .config.minmax = {0, 500 } },
     { "vbat_pid_compensation",      VAR_UINT8  | PROFILE_VALUE | MODE_LOOKUP, &masterConfig.profile[0].pidProfile.vbatPidCompensation, .config.lookup = { TABLE_OFF_ON } },
+    { "zero_throttle_stabilisation",VAR_UINT8  | PROFILE_VALUE | MODE_LOOKUP, &masterConfig.profile[0].pidProfile.zeroThrottleStabilisation, .config.lookup = { TABLE_OFF_ON } },
     { "motor_accel_limit_percent",  VAR_UINT16 | MASTER_VALUE,  &masterConfig.profile[0].pidProfile.accelerationLimitPercent, .config.minmax = { 0,  10000 } },
     { "pid_tolerance_band",         VAR_UINT8  | PROFILE_VALUE, &masterConfig.profile[0].pidProfile.toleranceBand, .config.minmax = {0, 200 } },
     { "tolerance_band_reduction",   VAR_UINT8  | PROFILE_VALUE, &masterConfig.profile[0].pidProfile.toleranceBandReduction, .config.minmax = {0, 100 } },

src/main/mw.c

@@ -518,6 +518,12 @@ void processRx(void)
      This is needed to prevent Iterm winding on the ground, but keep full stabilisation on 0 throttle while in air */
     if (throttleStatus == THROTTLE_LOW && !wasAirmodeIsActivated) {
         pidResetErrorGyroState();
+        if (currentProfile->pidProfile.zeroThrottleStabilisation)
+            pidStabilisationState(PID_STABILISATION_ON);
+        else
+            pidStabilisationState(PID_STABILISATION_OFF);
+    } else {
+        if (currentProfile->pidProfile.zeroThrottleStabilisation || wasAirmodeIsActivated) pidStabilisationState(PID_STABILISATION_ON);
     }
 
     // When armed and motors aren't spinning, do beeps and then disarm