added parameter for maximum allowed standard vtol down pitch

src/modules/vtol_att_control/standard.cpp

@@ -66,6 +66,7 @@ Standard::Standard(VtolAttitudeControl *attc) :
 	_params_handles_standard.airspeed_trans = param_find("VT_ARSP_TRANS");
 	_params_handles_standard.front_trans_timeout = param_find("VT_TRANS_TIMEOUT");
 	_params_handles_standard.front_trans_time_min = param_find("VT_TRANS_MIN_TM");
+	_params_handles_standard.down_pitch_max = param_find("VT_DWN_PITCH_MAX");
 }
 
 Standard::~Standard()
@@ -105,6 +106,9 @@ Standard::parameters_update()
 	/* minimum time for transition to fw mode */
 	param_get(_params_handles_standard.front_trans_time_min, &_params_standard.front_trans_time_min);
 
+	/* maximum down pitch allowed */
+	param_get(_params_handles_standard.down_pitch_max, &v);
+	_params_standard.down_pitch_max = math::radians(v);
 
 	return OK;
 }
@@ -296,11 +300,7 @@ void Standard::update_mc_state()
 	_pusher_throttle = body_x_zero_tilt * thrust_sp_axis * _v_att_sp->thrust;
 	_pusher_throttle = _pusher_throttle < 0.0f ? 0.0f : _pusher_throttle;
 
-	_pusher_throttle = body_x_zero_tilt * body_z_sp * _v_att_sp->thrust;	// XXX check if sign is correct
-
-	_pusher_throttle = _pusher_throttle < 0.0f ? 0.0f : _pusher_throttle; 
-
-	float pitch_sp_corrected = _v_att_sp->pitch_body < -0.1f ? -0.1f : _v_att_sp->pitch_body;
+	float pitch_sp_corrected = _v_att_sp->pitch_body < -_params_standard.down_pitch_max ? -_params_standard.down_pitch_max : _v_att_sp->pitch_body;
 
 	// compute new desired rotation matrix with corrected pitch angle
 	// and copy data to attitude setpoint topic

src/modules/vtol_att_control/standard.h

@@ -74,6 +74,7 @@ private:
 		float airspeed_trans;
 		float front_trans_timeout;
 		float front_trans_time_min;
+		float down_pitch_max;
 	} _params_standard;
 
 	struct {
@@ -84,6 +85,7 @@ private:
 		param_t airspeed_trans;
 		param_t front_trans_timeout;
 		param_t front_trans_time_min;
+		param_t down_pitch_max;
 	} _params_handles_standard;
 
 	enum vtol_mode {

src/modules/vtol_att_control/standard_params.c

@@ -49,3 +49,14 @@
  * @group VTOL Attitude Control
  */
 PARAM_DEFINE_FLOAT(VT_TRANS_THR, 0.6f);
+
+/**
+ * Maximum allowed down-pitch the controller is able to demand. This prevents large, negative
+ * lift values being created when facing strong winds. The vehicle will use the pusher motor
+ * to accelerate forward if necessary.
+ *
+ * @min 0.0
+ * @max 45.0
+ * @group VTOL Attitude Control
+ */
+PARAM_DEFINE_FLOAT(VT_DWN_PITCH_MAX, 5.0f);