Minimum altitude for FW flight in standard VTOL

src/modules/vtol_att_control/standard.cpp

@@ -68,6 +68,7 @@ Standard::Standard(VtolAttitudeControl *attc) :
 	_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");
 	_params_handles_standard.forward_thurst_scale = param_find("VT_FWD_THRUST_SC");
+	_params_handles_standard.fw_minimum_altitude = param_find("VT_FW_MIN_ALT");
 }
 
 Standard::~Standard()
@@ -114,6 +115,9 @@ Standard::parameters_update()
 	/* scale for fixed wing thrust used for forward acceleration in multirotor mode */
 	param_get(_params_handles_standard.forward_thurst_scale, &_params_standard.forward_thurst_scale);
 
+	/* QuadChute; minimum altitude for fixed wing flight */
+	param_get(_params_handles_standard.fw_minimum_altitude, &_params_standard.fw_minimum_altitude);
+
 
 	return OK;
 }
@@ -361,6 +365,10 @@ void Standard::update_fw_state()
 		set_idle_fw();  // force them to stop, not just idle
 		_flag_enable_mc_motors = true;
 	}
+
+	if(_local_pos->dist_bottom < _params_standard.fw_minimum_altitude){
+		_attc->abort_front_transition();
+	}
 }
 
 /**

src/modules/vtol_att_control/standard.h

@@ -76,6 +76,7 @@ private:
 		float front_trans_time_min;
 		float down_pitch_max;
 		float forward_thurst_scale;
+		float fw_minimum_altitude;
 	} _params_standard;
 
 	struct {
@@ -88,6 +89,7 @@ private:
 		param_t front_trans_time_min;
 		param_t down_pitch_max;
 		param_t forward_thurst_scale;
+		param_t fw_minimum_altitude;
 	} _params_handles_standard;
 
 	enum vtol_mode {

src/modules/vtol_att_control/standard_params.c

@@ -72,3 +72,15 @@ PARAM_DEFINE_FLOAT(VT_DWN_PITCH_MAX, 5.0f);
  * @group VTOL Attitude Control
  */
 PARAM_DEFINE_FLOAT(VT_FWD_THRUST_SC, 0.0f);
+
+
+/**
+ * QuadChute
+ *
+ * Minimum altitude for fixed wing flight, when in fixed wing the altitude drops below this altitude
+ * the vehicle will transition back to MC mode and enter failsafe RTL
+ * @min 0.0
+ * @max 200.0
+ * @group VTOL Attitude Control
+ */
+PARAM_DEFINE_FLOAT(VT_FW_MIN_ALT, 0.0f);