path: root/src/modules/land_detector/MulticopterLandDetector.cpp

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/**
 * @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;
}