LandDetector.cpp

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/*
 * @file LandDetector.cpp
 *
 * @author Johan Jansen <jnsn.johan@gmail.com>
 * @author Julian Oes <julian@oes.ch>
 */

#include "LandDetector.h"

using namespace time_literals;

namespace land_detector
{

LandDetector::LandDetector() :
    ModuleParams(nullptr),
    ScheduledWorkItem(MODULE_NAME, px4::wq_configurations::att_pos_ctrl)
{}

LandDetector::~LandDetector()
{
    perf_free(_cycle_perf);
}

void LandDetector::start()
{
    _update_params();
    ScheduleOnInterval(LAND_DETECTOR_UPDATE_INTERVAL);
}

void LandDetector::Run()
{
    perf_begin(_cycle_perf);

    if (_parameter_update_sub.updated()) {
        _update_params();
    }

    _actuator_armed_sub.update(&_actuator_armed);
    _update_topics();
    _update_state();

    const bool freefallDetected = _freefall_hysteresis.get_state();
    const bool ground_contactDetected = _ground_contact_hysteresis.get_state();
    const bool maybe_landedDetected = _maybe_landed_hysteresis.get_state();
    const bool landDetected = _landed_hysteresis.get_state();
    const float alt_max = _get_max_altitude() > 0.0f ? _get_max_altitude() : INFINITY;
    const bool in_ground_effect = _ground_effect_hysteresis.get_state();

    const hrt_abstime now = hrt_absolute_time();

    // publish at 1 Hz, very first time, or when the result has changed
    if ((hrt_elapsed_time(&_land_detected.timestamp) >= 1_s) ||
        (_land_detected.landed != landDetected) ||
        (_land_detected.freefall != freefallDetected) ||
        (_land_detected.maybe_landed != maybe_landedDetected) ||
        (_land_detected.ground_contact != ground_contactDetected) ||
        (_land_detected.in_ground_effect != in_ground_effect) ||
        (fabsf(_land_detected.alt_max - alt_max) > FLT_EPSILON)) {

        if (!landDetected && _land_detected.landed && _takeoff_time == 0) { /* only set take off time once, until disarming */
            // We did take off
            _takeoff_time = now;
        }

        _land_detected.timestamp = hrt_absolute_time();
        _land_detected.landed = landDetected;
        _land_detected.freefall = freefallDetected;
        _land_detected.maybe_landed = maybe_landedDetected;
        _land_detected.ground_contact = ground_contactDetected;
        _land_detected.alt_max = alt_max;
        _land_detected.in_ground_effect = in_ground_effect;

        _vehicle_land_detected_pub.publish(_land_detected);
    }

    // set the flight time when disarming (not necessarily when landed, because all param changes should
    // happen on the same event and it's better to set/save params while not in armed state)
    if (_takeoff_time != 0 && !_actuator_armed.armed && _previous_armed_state) {
        _total_flight_time += now - _takeoff_time;
        _takeoff_time = 0;

        uint32_t flight_time = (_total_flight_time >> 32) & 0xffffffff;

        _param_total_flight_time_high.set(flight_time);
        _param_total_flight_time_high.commit_no_notification();

        flight_time = _total_flight_time & 0xffffffff;

        _param_total_flight_time_low.set(flight_time);
        _param_total_flight_time_low.commit_no_notification();
    }

    _previous_armed_state = _actuator_armed.armed;

    perf_end(_cycle_perf);

    if (should_exit()) {
        ScheduleClear();
        exit_and_cleanup();
    }
}

void LandDetector::_update_params()
{
    parameter_update_s param_update;
    _parameter_update_sub.copy(&param_update);

    updateParams();
    _update_total_flight_time();
}

void LandDetector::_update_state()
{
    /* when we are landed we also have ground contact for sure but only one output state can be true at a particular time
     * with higher priority for landed */
    const hrt_abstime now_us = hrt_absolute_time();
    _freefall_hysteresis.set_state_and_update(_get_freefall_state(), now_us);
    _landed_hysteresis.set_state_and_update(_get_landed_state(), now_us);
    _maybe_landed_hysteresis.set_state_and_update(_get_maybe_landed_state(), now_us);
    _ground_contact_hysteresis.set_state_and_update(_get_ground_contact_state(), now_us);
    _ground_effect_hysteresis.set_state_and_update(_get_ground_effect_state(), now_us);
}

void LandDetector::_update_topics()
{
    _actuator_armed_sub.update(&_actuator_armed);
    _vehicle_acceleration_sub.update(&_vehicle_acceleration);
    _vehicle_local_position_sub.update(&_vehicle_local_position);
}

void LandDetector::_update_total_flight_time()
{
    _total_flight_time = static_cast<uint64_t>(_param_total_flight_time_high.get()) << 32;
    _total_flight_time |= static_cast<uint32_t>(_param_total_flight_time_low.get());
}

} // namespace land_detector