PX4-Autopilot/src/modules/land_detector/MulticopterLandDetector.cpp

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/**
 * @file MulticopterLandDetector.cpp
 * Land detection algorithm for multicopters
 *
 * @author Johan Jansen <jnsn.johan@gmail.com>
 * @author Morten Lysgaard <morten@lysgaard.no>
 */

#include "MulticopterLandDetector.h"

#include <cmath>
#include <drivers/drv_hrt.h>
#include <mathlib/mathlib.h>

MulticopterLandDetector::MulticopterLandDetector() : LandDetector(),
	_paramHandle(),
	_params(),
	_vehicleGlobalPositionSub(-1),
	_vehicleStatusSub(-1),
	_actuatorsSub(-1),
	_armingSub(-1),
	_parameterSub(-1),
    _attitudeSub(-1),
	_vehicleGlobalPosition({}),
	_vehicleStatus({}),
	_actuators({}),
	_arming({}),
    _vehicleAttitude({}),
	_landTimer(0)
{
	_paramHandle.maxRotation = param_find("LNDMC_ROT_MAX");
	_paramHandle.maxVelocity = param_find("LNDMC_XY_VEL_MAX");
	_paramHandle.maxClimbRate = param_find("LNDMC_Z_VEL_MAX");
	_paramHandle.maxThrottle = param_find("LNDMC_THR_MAX");
}

void MulticopterLandDetector::initialize()
{
	// subscribe to position, attitude, arming and velocity changes
	_vehicleGlobalPositionSub = orb_subscribe(ORB_ID(vehicle_global_position));
	_attitudeSub = orb_subscribe(ORB_ID(vehicle_attitude));
	_vehicleStatusSub = orb_subscribe(ORB_ID(vehicle_status));
	_actuatorsSub = orb_subscribe(ORB_ID_VEHICLE_ATTITUDE_CONTROLS);
	_armingSub = orb_subscribe(ORB_ID(actuator_armed));
	_parameterSub = orb_subscribe(ORB_ID(parameter_update));

	// download parameters
	updateParameterCache(true);
}

void MulticopterLandDetector::updateSubscriptions()
{
	orb_update(ORB_ID(vehicle_global_position), _vehicleGlobalPositionSub, &_vehicleGlobalPosition);
	orb_update(ORB_ID(vehicle_attitude), _attitudeSub, &_vehicleAttitude);
	orb_update(ORB_ID(vehicle_status), _vehicleStatusSub, &_vehicleStatus);
	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();

	// only trigger flight conditions if we are armed
	if (!_arming.armed) {
		return true;
	}

	const uint64_t now = hrt_absolute_time();

	// check if we are moving vertically
	bool verticalMovement = fabsf(_vehicleGlobalPosition.vel_d) > _params.maxClimbRate;

	// check if we are moving horizontally
	bool horizontalMovement = sqrtf(_vehicleGlobalPosition.vel_n * _vehicleGlobalPosition.vel_n
					+ _vehicleGlobalPosition.vel_e * _vehicleGlobalPosition.vel_e) > _params.maxVelocity
					&& _vehicleStatus.condition_global_position_valid;

	// next look if all rotation angles are not moving
	bool rotating = fabsf(_vehicleAttitude.rollspeed)  > _params.maxRotation ||
				    fabsf(_vehicleAttitude.pitchspeed) > _params.maxRotation ||
        			fabsf(_vehicleAttitude.yawspeed)   > _params.maxRotation;

	// check if thrust output is minimal (about half of default)
	bool minimalThrust = _actuators.control[3] <= _params.maxThrottle;

	if (verticalMovement || rotating || !minimalThrust || horizontalMovement) {
		// sensed movement, so reset the land detector
		_landTimer = now;
		return false;
	}

	return now - _landTimer > LAND_DETECTOR_TRIGGER_TIME;
}

void MulticopterLandDetector::updateParameterCache(const bool force)
{
	bool updated;
	parameter_update_s paramUpdate;

	orb_check(_parameterSub, &updated);

	if (updated) {
		orb_copy(ORB_ID(parameter_update), _parameterSub, &paramUpdate);
	}

	if (updated || force) {
		param_get(_paramHandle.maxClimbRate, &_params.maxClimbRate);
		param_get(_paramHandle.maxVelocity, &_params.maxVelocity);
		param_get(_paramHandle.maxRotation, &_params.maxRotation);
		_params.maxRotation = math::radians(_params.maxRotation);
		param_get(_paramHandle.maxThrottle, &_params.maxThrottle);
	}
}