use accelerations provided by the control_state message instead of

sensor_combined

src/modules/land_detector/MulticopterLandDetector.cpp

@@ -61,7 +61,7 @@ MulticopterLandDetector::MulticopterLandDetector() : LandDetector(),
 	_actuators{},
 	_arming{},
 	_vehicleAttitude{},
-	_sensors{},
+	_ctrl_state{},
 	_landTimer(0),
 	_freefallTimer(0)
 {
@@ -82,7 +82,7 @@ void MulticopterLandDetector::initialize()
 	_armingSub = orb_subscribe(ORB_ID(actuator_armed));
 	_parameterSub = orb_subscribe(ORB_ID(parameter_update));
 	_manualSub = orb_subscribe(ORB_ID(manual_control_setpoint));
-	_sensorsSub = orb_subscribe(ORB_ID(sensor_combined));
+	_ctrl_state_sub = orb_subscribe(ORB_ID(control_state));
 
 	// download parameters
 	updateParameterCache(true);
@@ -95,7 +95,7 @@ void MulticopterLandDetector::updateSubscriptions()
 	orb_update(ORB_ID_VEHICLE_ATTITUDE_CONTROLS, _actuatorsSub, &_actuators);
 	orb_update(ORB_ID(actuator_armed), _armingSub, &_arming);
 	orb_update(ORB_ID(manual_control_setpoint), _manualSub, &_manual);
-	orb_update(ORB_ID(sensor_combined), _sensorsSub, &_sensors);
+	orb_update(ORB_ID(control_state), _ctrl_state_sub, &_ctrl_state);
 }
 
 LandDetectionResult MulticopterLandDetector::update()
@@ -127,12 +127,9 @@ bool MulticopterLandDetector::get_freefall_state()
 
 	const uint64_t now = hrt_absolute_time();
 
-	float acc_norm = 0.0;
-
-	for (int i = 0; i < 3; i++) {
-		acc_norm += _sensors.accelerometer_m_s2[i] * _sensors.accelerometer_m_s2[i];
-	}
-
+	float acc_norm = _ctrl_state.x_acc * _ctrl_state.x_acc
+		+ _ctrl_state.y_acc * _ctrl_state.y_acc
+		+ _ctrl_state.z_acc * _ctrl_state.z_acc;
 	acc_norm = sqrtf(acc_norm);	//norm of specific force. Should be close to 9.8 m/s^2 when landed.
 
 	bool freefall = (acc_norm < _params.acc_threshold_m_s2);	//true if we are currently falling

src/modules/land_detector/MulticopterLandDetector.h

@@ -50,7 +50,7 @@
 #include <uORB/topics/actuator_armed.h>
 #include <uORB/topics/parameter_update.h>
 #include <uORB/topics/manual_control_setpoint.h>
-#include <uORB/topics/sensor_combined.h>
+#include <uORB/topics/control_state.h>
 #include <systemlib/param/param.h>
 
 namespace landdetection
@@ -122,14 +122,14 @@ private:
 	int _parameterSub;
 	int _attitudeSub;
 	int _manualSub;
-	int _sensorsSub;
+	int _ctrl_state_sub;
 
 	struct vehicle_local_position_s		_vehicleLocalPosition;
 	struct actuator_controls_s		_actuators;
 	struct actuator_armed_s			_arming;
 	struct vehicle_attitude_s		_vehicleAttitude;
 	struct manual_control_setpoint_s	_manual;
-	struct sensor_combined_s 		_sensors;
+	struct control_state_s				_ctrl_state;
 
 	uint64_t _landTimer;							/**< timestamp in microseconds since a possible land was detected*/
 	uint64_t _freefallTimer;							/**< timestamp in microseconds since a possible freefall was detected*/