ardupilot/APMrover2/mode_smart_rtl.cpp

#include "mode.h"
#include "Rover.h"

bool ModeSmartRTL::_enter()
{
    // SmartRTL requires EKF (not DCM)
    Location ekf_origin;
    if (!ahrs.get_origin(ekf_origin)) {
        return false;
    }

    // refuse to enter SmartRTL if smart RTL's home has not been set
    if (!g2.smart_rtl.is_active()) {
        return false;
    }

    // initialise waypoint speed
    set_desired_speed_to_default(true);

    // init location target
    set_desired_location(rover.current_loc);

    // RTL never reverses
    rover.set_reverse(false);

    // init state
    smart_rtl_state = SmartRTL_WaitForPathCleanup;
    _reached_destination = false;

    return true;
}

void ModeSmartRTL::update()
{
    switch (smart_rtl_state) {
        case SmartRTL_WaitForPathCleanup:
            // check if return path is computed and if yes, begin journey home
            if (g2.smart_rtl.request_thorough_cleanup()) {
                smart_rtl_state = SmartRTL_PathFollow;
                _load_point = true;
            }
            // Note: this may lead to an unnecessary 20ms slow down of the vehicle (but it is unlikely)
            stop_vehicle();
            break;

        case SmartRTL_PathFollow:
            // load point if required
            if (_load_point) {
                Vector3f next_point;
                if (!g2.smart_rtl.pop_point(next_point)) {
                    // if not more points, we have reached home
                    gcs().send_text(MAV_SEVERITY_INFO, "Reached destination");
                    smart_rtl_state = SmartRTL_StopAtHome;
                    break;
                }
                _load_point = false;
                // set target destination to new point
                if (!set_desired_location_NED(next_point)) {
                    // this failure should never happen but we add it just in case
                    gcs().send_text(MAV_SEVERITY_INFO, "SmartRTL: failed to set destination");
                    smart_rtl_state = SmartRTL_Failure;
                }
            }
            // check if we've reached the next point
            _distance_to_destination = get_distance(rover.current_loc, _destination);
            if (_distance_to_destination <= rover.g.waypoint_radius || location_passed_point(rover.current_loc, _origin, _destination)) {
                _load_point = true;
            }
            // continue driving towards destination
            calc_steering_to_waypoint(_origin, _destination);
            calc_throttle(calc_reduced_speed_for_turn_or_distance(_desired_speed), true);
            break;

        case SmartRTL_StopAtHome:
        case SmartRTL_Failure:
            _reached_destination = true;
            if (rover.is_boat()) {
                // boats attempt to hold position at home
                calc_steering_to_waypoint(rover.current_loc, _destination);
                calc_throttle(calc_reduced_speed_for_turn_or_distance(_desired_speed), true);
            } else {
                // rovers stop
                stop_vehicle();
            }
            break;
    }
}

// save current position for use by the smart_rtl flight mode
void ModeSmartRTL::save_position()
{
    const bool save_pos = (rover.control_mode != &rover.mode_smartrtl);
    g2.smart_rtl.update(true, save_pos);
}