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/****************************************************************************
*
* 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 <stdio.h>
#include <math.h>
#include <drivers/drv_hrt.h>
#include <unistd.h> //usleep
FixedwingLandDetector::FixedwingLandDetector() :
_landDetectedPub(-1),
_landDetected({0,false}),
_vehicleLocalPositionSub(-1),
_vehicleLocalPosition({}),
_airspeedSub(-1),
_airspeed({}),
_velocity_xy_filtered(0.0f),
_velocity_z_filtered(0.0f),
_airspeed_filtered(0.0f),
_landDetectTrigger(0),
_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);
}
FixedwingLandDetector::~FixedwingLandDetector()
{
_taskShouldExit = true;
close(_landDetectedPub);
}
void FixedwingLandDetector::shutdown()
{
_taskShouldExit = true;
}
/**
* @brief Convinience function for polling uORB subscriptions
* @return true if there was new data and it was successfully copied
**/
static bool 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;
}
void FixedwingLandDetector::updateSubscriptions()
{
orb_update(ORB_ID(vehicle_local_position), _vehicleLocalPositionSub, &_vehicleLocalPosition);
orb_update(ORB_ID(airspeed), _airspeedSub, &_airspeed);
}
void FixedwingLandDetector::landDetectorLoop()
{
//This should never happen!
if(_taskIsRunning) return;
//Subscribe to local position and airspeed data
_vehicleLocalPositionSub = orb_subscribe(ORB_ID(vehicle_local_position));
_airspeedSub = orb_subscribe(ORB_ID(airspeed));
_taskIsRunning = true;
_taskShouldExit = false;
while (!_taskShouldExit) {
//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;
}
//Publish if land detection state has changed
if(_landDetected.landed != landDetected) {
_landDetected.timestamp = now;
_landDetected.landed = landDetected;
/* publish the land detected broadcast */
orb_publish(ORB_ID(vehicle_land_detected), _landDetectedPub, &_landDetected);
}
//Limit loop rate
usleep(1000000 / FW_LAND_DETECTOR_UPDATE_RATE);
}
_taskIsRunning = false;
_exit(0);
}
bool FixedwingLandDetector::isRunning() const
{
return _taskIsRunning;
}
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