LandDetector: Merged fixedwing and multicopter into one module handling both algorithms

8 files changed, 811 insertions, 0 deletions

diff --git a/src/modules/land_detector/FixedwingLandDetector.cpp b/src/modules/land_detector/FixedwingLandDetector.cpp
new file mode 100644
index 000000000..42735f38c
--- /dev/null
+++ b/src/modules/land_detector/FixedwingLandDetector.cpp
@@ -0,0 +1,103 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2013-2015 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file FixedwingLandDetector.cpp
+ * Land detection algorithm for fixedwings
+ *
+ * @author Johan Jansen <jnsn.johan@gmail.com>
+ */
+
+#include "FixedwingLandDetector.h"
+ 
+#include <cmath>
+#include <drivers/drv_hrt.h>
+
+FixedwingLandDetector::FixedwingLandDetector() :
+        _vehicleLocalPositionSub(-1),
+        _vehicleLocalPosition({}),
+        _airspeedSub(-1),
+        _airspeed({}),
+
+        _velocity_xy_filtered(0.0f),
+        _velocity_z_filtered(0.0f),
+        _airspeed_filtered(0.0f),
+        _landDetectTrigger(0)
+{
+    //ctor
+}
+
+void FixedwingLandDetector::initialize()
+{
+    //Subscribe to local position and airspeed data
+    _vehicleLocalPositionSub = orb_subscribe(ORB_ID(vehicle_local_position));
+    _airspeedSub = orb_subscribe(ORB_ID(airspeed));
+}
+
+void FixedwingLandDetector::updateSubscriptions()
+{
+    orb_update(ORB_ID(vehicle_local_position), _vehicleLocalPositionSub, &_vehicleLocalPosition);
+    orb_update(ORB_ID(airspeed), _airspeedSub, &_airspeed);
+}
+
+bool FixedwingLandDetector::update()
+{
+    //First poll for new data from our subscriptions
+    updateSubscriptions();
+
+    const uint64_t now = hrt_absolute_time();
+    bool landDetected = false;
+
+    //TODO: reset filtered values on arming?
+    _velocity_xy_filtered = 0.95f * _velocity_xy_filtered + 0.05f * sqrtf(_vehicleLocalPosition.vx *
+                _vehicleLocalPosition.vx + _vehicleLocalPosition.vy * _vehicleLocalPosition.vy);
+    _velocity_z_filtered = 0.95f * _velocity_z_filtered + 0.05f * fabsf(_vehicleLocalPosition.vz);
+    _airspeed_filtered = 0.95f * _airspeed_filtered + 0.05f * _airspeed.true_airspeed_m_s;
+
+    /* crude land detector for fixedwing */
+    if (_velocity_xy_filtered < FW_LAND_DETECTOR_VELOCITY_MAX
+        && _velocity_z_filtered < FW_LAND_DETECTOR_CLIMBRATE_MAX
+        && _airspeed_filtered < FW_LAND_DETECTOR_AIRSPEED_MAX) {
+
+        //These conditions need to be stable for a period of time before we trust them
+        if (now > _landDetectTrigger) {
+            landDetected = true;
+        }
+
+    } else {
+        //reset land detect trigger
+        _landDetectTrigger = now + FW_LAND_DETECTOR_TRIGGER_TIME;
+    }
+
+    return landDetected;
+}
diff --git a/src/modules/land_detector/FixedwingLandDetector.h b/src/modules/land_detector/FixedwingLandDetector.h
new file mode 100644
index 000000000..faeece6f3
--- /dev/null
+++ b/src/modules/land_detector/FixedwingLandDetector.h
@@ -0,0 +1,88 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2013-2015 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file FixedwingLandDetector.h
+ * Land detection algorithm for fixedwing
+ *
+ * @author Johan Jansen <jnsn.johan@gmail.com>
+ */
+
+#ifndef __FIXED_WING_LAND_DETECTOR_H__
+#define __FIXED_WING_LAND_DETECTOR_H__
+
+#include "LandDetector.h"
+#include <uORB/topics/vehicle_local_position.h>
+#include <uORB/topics/airspeed.h>
+
+class FixedwingLandDetector : public LandDetector
+{
+public:
+    FixedwingLandDetector();
+
+protected:
+    /**
+    * @brief  blocking loop, should be run in a separate thread or task. Runs at 50Hz
+    **/
+    bool update() override;
+
+    /**
+    * @brief Initializes the land detection algorithm
+    **/
+    void initialize() override;
+
+    /**
+    * @brief  polls all subscriptions and pulls any data that has changed
+    **/
+    void updateSubscriptions();
+
+    //Algorithm parameters (TODO: should probably be externalized)
+    static constexpr uint64_t FW_LAND_DETECTOR_TRIGGER_TIME = 2000000;  /**< usec that landing conditions have to hold 
+                                                                             before triggering a land */
+    static constexpr float FW_LAND_DETECTOR_VELOCITY_MAX = 5.0f;        /**< maximum horizontal movement m/s*/
+    static constexpr float FW_LAND_DETECTOR_CLIMBRATE_MAX = 10.00f;     /**< +- climb rate in m/s*/
+    static constexpr float FW_LAND_DETECTOR_AIRSPEED_MAX = 10.00f;      /**< airspeed max m/s*/
+
+private:
+    int                                     _vehicleLocalPositionSub;   /**< notification of local position */
+    struct vehicle_local_position_s         _vehicleLocalPosition;      /**< the result from local position subscription */
+    int                                     _airspeedSub;
+    struct airspeed_s                       _airspeed;
+
+    float _velocity_xy_filtered;
+    float _velocity_z_filtered;
+    float _airspeed_filtered;
+    uint64_t _landDetectTrigger;
+};
+
+#endif //__FIXED_WING_LAND_DETECTOR_H__
diff --git a/src/modules/land_detector/LandDetector.cpp b/src/modules/land_detector/LandDetector.cpp
new file mode 100644
index 000000000..a39e53818
--- /dev/null
+++ b/src/modules/land_detector/LandDetector.cpp
@@ -0,0 +1,77 @@
+#include "LandDetector.h"
+#include <unistd.h>                 //usleep
+#include <drivers/drv_hrt.h>
+
+LandDetector::LandDetector() :
+    _landDetectedPub(-1),
+    _landDetected({0, false}),
+    _taskShouldExit(false),
+    _taskIsRunning(false)
+{
+    //Advertise the first land detected uORB
+    _landDetected.timestamp = hrt_absolute_time();
+    _landDetected.landed = false;
+    _landDetectedPub = orb_advertise(ORB_ID(vehicle_land_detected), &_landDetected);
+}
+
+LandDetector::~LandDetector()
+{
+    _taskShouldExit = true;
+    close(_landDetectedPub);
+}
+
+void LandDetector::shutdown()
+{
+    _taskShouldExit = true;
+}
+
+void LandDetector::start()
+{
+    //Make sure this method has not already been called by another thread
+    if(isRunning()) {
+        return;
+    }
+
+    //Task is now running, keep doing so until shutdown() has been called
+    _taskIsRunning = true;
+    _taskShouldExit = false;
+    while(isRunning()) {
+
+        bool landDetected = update();
+
+        //Publish if land detection state has changed
+        if (_landDetected.landed != landDetected) {
+            _landDetected.timestamp = hrt_absolute_time();
+            _landDetected.landed = landDetected;
+
+            /* publish the land detected broadcast */
+            orb_publish(ORB_ID(vehicle_land_detected), _landDetectedPub, &_landDetected);
+        }
+
+        //Limit loop rate
+        usleep(1000000 / LAND_DETECTOR_UPDATE_RATE);
+    }
+
+    _taskIsRunning = false;
+    _exit(0);    
+}
+
+bool LandDetector::orb_update(const struct orb_metadata *meta, int handle, void *buffer)
+{
+    bool newData = false;
+
+    //Check if there is new data to grab
+    if (orb_check(handle, &newData) != OK) {
+        return false;
+    }
+
+    if (!newData) {
+        return false;
+    }
+
+    if (orb_copy(meta, handle, buffer) != OK) {
+        return false;
+    }
+
+    return true;
+}
diff --git a/src/modules/land_detector/LandDetector.h b/src/modules/land_detector/LandDetector.h
new file mode 100644
index 000000000..6d7465691
--- /dev/null
+++ b/src/modules/land_detector/LandDetector.h
@@ -0,0 +1,101 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2013-2015 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file LandDetector.h
+ * Abstract interface for land detector algorithms
+ *
+ * @author Johan Jansen <jnsn.johan@gmail.com>
+ */
+
+#ifndef __LAND_DETECTOR_H__
+#define __LAND_DETECTOR_H__
+
+#include <uORB/uORB.h>
+#include <uORB/topics/vehicle_land_detected.h>
+
+class LandDetector
+{
+public:
+
+    LandDetector();
+    virtual ~LandDetector();
+
+    /**
+    * @return true if this task is currently running
+    **/
+    inline bool isRunning() const {return _taskIsRunning;}
+
+    /**
+    * @brief  Tells the Land Detector task that it should exit
+    **/
+    void shutdown();
+
+    /**
+    * @brief Blocking function that should be called from it's own task thread. This method will
+    *        run the underlying algorithm at the desired update rate and publish if the landing state changes.
+    **/
+    void start();
+
+protected:
+
+    /**
+    * @brief Pure abstract method that must be overriden by sub-classes. This actually runs the underlying algorithm
+    * @return true if a landing was detected and this should be broadcast to the rest of the system
+    **/
+    virtual bool update() = 0;
+
+    /**
+    * @brief Pure abstract method that is called by this class once for initializing the uderlying algorithm (memory allocation,
+    *        uORB topic subscription, creating file descriptors, etc.)
+    **/
+    virtual void initialize() = 0;
+
+    /**
+    * @brief Convinience function for polling uORB subscriptions
+    * @return true if there was new data and it was successfully copied
+    **/
+    bool orb_update(const struct orb_metadata *meta, int handle, void *buffer);
+
+    static constexpr uint32_t LAND_DETECTOR_UPDATE_RATE = 50;        /**< Run algorithm at 50Hz */
+
+protected:
+    orb_advert_t                            _landDetectedPub;           /**< publisher for position in local frame */
+    struct vehicle_land_detected_s          _landDetected;              /**< local vehicle position */
+
+private:
+    bool _taskShouldExit;                                               /**< true if it is requested that this task should exit */
+    bool _taskIsRunning;                                                /**< task has reached main loop and is currently running */
+};
+
+#endif //__LAND_DETECTOR_H__
\ No newline at end of file
diff --git a/src/modules/land_detector/MulticopterLandDetector.cpp b/src/modules/land_detector/MulticopterLandDetector.cpp
new file mode 100644
index 000000000..36d92fd79
--- /dev/null
+++ b/src/modules/land_detector/MulticopterLandDetector.cpp
@@ -0,0 +1,120 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2013-2015 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file MulticopterLandDetector.cpp
+ * Land detection algorithm
+ *
+ * @author Johan Jansen <jnsn.johan@gmail.com>
+ * @author Morten Lysgaard <morten@lysgaard.no>
+ */
+
+#include "MulticopterLandDetector.h"
+
+#include <cmath>
+#include <drivers/drv_hrt.h>
+
+MulticopterLandDetector::MulticopterLandDetector() :
+	_vehicleGlobalPositionSub(-1),
+	_sensorsCombinedSub(-1),
+	_waypointSub(-1),
+	_actuatorsSub(-1),
+	_armingSub(-1),
+
+	_vehicleGlobalPosition({}),
+	_sensors({}),
+	_waypoint({}),
+	_actuators({}),
+	_arming({}),
+
+	_landTimer(0)
+{
+	//ctor
+}
+
+void MulticopterLandDetector::initialize()
+{
+	//Subscribe to position, attitude, arming and velocity changes
+	_vehicleGlobalPositionSub = orb_subscribe(ORB_ID(vehicle_global_position));
+	_sensorsCombinedSub = orb_subscribe(ORB_ID(sensor_combined));
+	_waypointSub = orb_subscribe(ORB_ID(position_setpoint_triplet));
+	_actuatorsSub = orb_subscribe(ORB_ID_VEHICLE_ATTITUDE_CONTROLS);
+	_armingSub = orb_subscribe(ORB_ID(actuator_armed));
+}
+
+void MulticopterLandDetector::updateSubscriptions()
+{
+	orb_update(ORB_ID(vehicle_global_position), _vehicleGlobalPositionSub, &_vehicleGlobalPosition);
+	orb_update(ORB_ID(sensor_combined), _sensorsCombinedSub, &_sensors);
+	orb_update(ORB_ID(position_setpoint_triplet), _waypointSub, &_waypoint);
+	orb_update(ORB_ID_VEHICLE_ATTITUDE_CONTROLS, _actuatorsSub, &_actuators);
+	orb_update(ORB_ID(actuator_armed), _armingSub, &_arming);
+}
+
+bool MulticopterLandDetector::update()
+{
+	//First poll for new data from our subscriptions
+	updateSubscriptions();
+
+	const uint64_t now = hrt_absolute_time();
+
+	//only detect landing if the autopilot is actively trying to land
+	if (!_waypoint.current.valid || _waypoint.current.type != SETPOINT_TYPE_LAND) {
+		_landTimer = now;
+
+	} else {
+
+		//Check if we are moving vertically
+		bool verticalMovement = fabsf(_vehicleGlobalPosition.vel_d) > MC_LAND_DETECTOR_CLIMBRATE_MAX;
+
+		//Check if we are moving horizontally
+		bool horizontalMovement = sqrtf(_vehicleGlobalPosition.vel_n * _vehicleGlobalPosition.vel_n
+						+ _vehicleGlobalPosition.vel_e * _vehicleGlobalPosition.vel_e) > MC_LAND_DETECTOR_VELOCITY_MAX;
+
+		//Next look if all rotation angles are not moving
+		bool rotating = sqrtf(_sensors.gyro_rad_s[0] * _sensors.gyro_rad_s[0] +
+				      _sensors.gyro_rad_s[1] * _sensors.gyro_rad_s[1] +
+				      _sensors.gyro_rad_s[2] * _sensors.gyro_rad_s[2]) > MC_LAND_DETECTOR_ROTATION_MAX;
+
+		//Check if thrust output is minimal (about half of default)
+		bool minimalThrust = _arming.armed && _actuators.control[3] <= MC_LAND_DETECTOR_THRUST_MAX;
+
+		if (verticalMovement || rotating || !minimalThrust || horizontalMovement) {
+			//Sensed movement, so reset the land detector
+			_landTimer = now;
+		}
+
+	}
+
+	return now - _landTimer > MC_LAND_DETECTOR_TRIGGER_TIME;
+}
diff --git a/src/modules/land_detector/MulticopterLandDetector.h b/src/modules/land_detector/MulticopterLandDetector.h
new file mode 100644
index 000000000..08a8132ba
--- /dev/null
+++ b/src/modules/land_detector/MulticopterLandDetector.h
@@ -0,0 +1,96 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2013-2015 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file MulticopterLandDetector.h
+ * Land detection algorithm for multicopters
+ *
+ * @author Johan Jansen <jnsn.johan@gmail.com>
+ * @author Morten Lysgaard <morten@lysgaard.no>
+ */
+
+#ifndef __MULTICOPTER_LAND_DETECTOR_H__
+#define __MULTICOPTER_LAND_DETECTOR_H__
+
+#include "LandDetector.h"
+#include <uORB/topics/vehicle_global_position.h>
+#include <uORB/topics/sensor_combined.h>
+#include <uORB/topics/position_setpoint_triplet.h>
+#include <uORB/topics/actuator_controls.h>
+#include <uORB/topics/actuator_armed.h>
+
+class MulticopterLandDetector : public LandDetector
+{
+public:
+	MulticopterLandDetector();
+
+protected:
+	/**
+	* @brief  polls all subscriptions and pulls any data that has changed
+	**/
+	void updateSubscriptions();
+
+	/**
+	* @brief Runs one iteration of the land detection algorithm
+	**/
+	bool update() override;
+
+	/**
+	* @brief Initializes the land detection algorithm
+	**/
+	void initialize() override;
+
+	//Algorithm parameters (TODO: should probably be externalized)
+	static constexpr float MC_LAND_DETECTOR_CLIMBRATE_MAX = 0.30f;      /**< max +- climb rate in m/s */
+	static constexpr float MC_LAND_DETECTOR_ROTATION_MAX = 0.5f;        /**< max rotation in rad/sec (= 30 deg/s) */
+	static constexpr float MC_LAND_DETECTOR_THRUST_MAX = 0.2f;
+	static constexpr float MC_LAND_DETECTOR_VELOCITY_MAX = 1.0f;        /**< max +- horizontal movement in m/s */
+	static constexpr uint32_t MC_LAND_DETECTOR_TRIGGER_TIME = 2000000;  /**< usec that landing conditions have to hold before triggering a land */
+
+private:
+	int _vehicleGlobalPositionSub;                                      /**< notification of global position */
+	int _sensorsCombinedSub;
+	int _waypointSub;
+	int _actuatorsSub;
+	int _armingSub;
+
+	struct vehicle_global_position_s          _vehicleGlobalPosition;   /**< the result from global position subscription */
+	struct sensor_combined_s                  _sensors;                 /**< subscribe to sensor readings */
+	struct position_setpoint_triplet_s        _waypoint;                /**< subscribe to autopilot navigation */
+	struct actuator_controls_s                _actuators;
+	struct actuator_armed_s                   _arming;
+
+	uint64_t _landTimer;                                                /**< timestamp in microseconds since a possible land was detected*/
+};
+
+#endif //__MULTICOPTER_LAND_DETECTOR_H__
diff --git a/src/modules/land_detector/land_detector_main.cpp b/src/modules/land_detector/land_detector_main.cpp
new file mode 100644
index 000000000..2bc89e752
--- /dev/null
+++ b/src/modules/land_detector/land_detector_main.cpp
@@ -0,0 +1,214 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2013-2015 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file land_detector_main.cpp
+ * Land detection algorithm
+ *
+ * @author Johan Jansen <jnsn.johan@gmail.com>
+ */
+
+#include <unistd.h>					//usleep
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <drivers/drv_hrt.h>
+#include <systemlib/systemlib.h>	//Scheduler
+#include <systemlib/err.h>			//print to console
+
+#include "FixedwingLandDetector.h"
+#include "MulticopterLandDetector.h"
+
+//Function prototypes
+static int land_detector_start(const char* mode);
+static void land_detector_stop();
+
+/**
+ * land detector app start / stop handling function
+ * This makes the land detector module accessible from the nuttx shell
+ * @ingroup apps
+ */
+extern "C" __EXPORT int land_detector_main(int argc, char *argv[]);
+
+//Private variables
+static LandDetector *land_detector_task = nullptr;
+static int _landDetectorTaskID = -1;
+static char _currentMode[12];
+
+/**
+* Deamon thread function
+**/
+static void land_detector_deamon_thread(int argc, char *argv[])
+{
+	land_detector_task->start();
+}
+
+/**
+* Stop the task, force killing it if it doesn't stop by itself
+**/
+static void land_detector_stop()
+{
+	if (land_detector_task == nullptr || _landDetectorTaskID == -1) {
+		errx(1, "not running");
+		return;
+	}
+
+	land_detector_task->shutdown();
+
+	//Wait for task to die
+	int i = 0;
+
+	do {
+		/* wait 20ms */
+		usleep(20000);
+
+		/* if we have given up, kill it */
+		if (++i > 50) {
+			task_delete(_landDetectorTaskID);
+			break;
+		}
+	} while (land_detector_task->isRunning());
+
+
+	delete land_detector_task;
+	land_detector_task = nullptr;
+	_landDetectorTaskID = -1;
+	warn("land_detector has been stopped");
+}
+
+/**
+* Start new task, fails if it is already running. Returns OK if successful
+**/
+static int land_detector_start(const char* mode)
+{
+	if (land_detector_task != nullptr || _landDetectorTaskID != -1) {
+		errx(1, "already running");
+		return -1;
+	}
+
+	//Allocate memory
+	if(!strcmp(mode, "fixedwing")) {
+		land_detector_task = new FixedwingLandDetector();
+	}
+	else if(!strcmp(mode, "multicopter")) {
+		land_detector_task = new MulticopterLandDetector();
+	}
+	else {
+		errx(1, "[mode] must be either 'fixedwing' or 'multicopter'");
+		return -1;		
+	}
+
+	//Check if alloc worked
+	if (land_detector_task == nullptr) {
+		errx(1, "alloc failed");
+		return -1;
+	}
+
+	//Start new thread task
+	_landDetectorTaskID = task_spawn_cmd("land_detector",
+					     SCHED_DEFAULT,
+					     SCHED_PRIORITY_DEFAULT,
+					     1024,
+					     (main_t)&land_detector_deamon_thread,
+					     nullptr);
+
+	if (_landDetectorTaskID < 0) {
+		errx(1, "task start failed: %d", -errno);
+		return -1;
+	}
+
+	/* avoid memory fragmentation by not exiting start handler until the task has fully started */
+	const uint32_t timeout = hrt_absolute_time() + 5000000; //5 second timeout
+
+	while (!land_detector_task->isRunning()) {
+		usleep(50000);
+		printf(".");
+		fflush(stdout);
+
+		if (hrt_absolute_time() > timeout) {
+			err(1, "start failed - timeout");
+			land_detector_stop();
+			exit(1);
+		}
+	}
+
+	printf("\n");
+
+	//Remember current active mode
+	strncpy(_currentMode, mode, 12);
+
+	exit(0);
+	return 0;
+}
+
+/**
+* Main entry point for this module
+**/
+int land_detector_main(int argc, char *argv[])
+{
+
+	if (argc < 1) {
+		warnx("usage: land_detector {start|stop|status} [mode]\nmode can either be 'fixedwing' or 'multicopter'");
+		exit(0);
+	}
+
+	if (argc >= 2 && !strcmp(argv[1], "start")) {
+		land_detector_start(argv[2]);
+	}
+
+	if (!strcmp(argv[1], "stop")) {
+		land_detector_stop();
+		exit(0);
+	}
+
+	if (!strcmp(argv[1], "status")) {
+		if (land_detector_task) {
+
+			if (land_detector_task->isRunning()) {
+				warnx("running (%s)", _currentMode);
+
+			} else {
+				errx(1, "exists, but not running (%s)", _currentMode);
+			}
+
+			exit(0);
+
+		} else {
+			errx(1, "not running");
+		}
+	}
+
+	warn("usage: land_detector {start|stop|status} [mode]\nmode can either be 'fixedwing' or 'multicopter'");
+	return 1;
+}
diff --git a/src/modules/land_detector/module.mk b/src/modules/land_detector/module.mk
new file mode 100644
index 000000000..db0e18447
--- /dev/null
+++ b/src/modules/land_detector/module.mk
@@ -0,0 +1,12 @@
+#
+# Land detector
+#
+
+MODULE_COMMAND	= land_detector
+
+SRCS		= land_detector_main.cpp \
+              LandDetector.cpp \
+			  MulticopterLandDetector.cpp \
+              FixedwingLandDetector.cpp
+
+EXTRACXXFLAGS   = -Weffc++ -Os