mirror of https://github.com/ArduPilot/ardupilot
127 lines
4.1 KiB
C++
127 lines
4.1 KiB
C++
/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
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/*
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* adsb.cpp
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* Copyright (C) Tom Pittenger 2015
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*
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* This file is free software: you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This file is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "Plane.h"
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/*
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* this module deals with ADS-B handling for ArduPlane
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* ADS-B is an RF based collision avoidance protocol to tell nearby aircraft your location
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* https://en.wikipedia.org/wiki/Automatic_dependent_surveillance_%E2%80%93_broadcast
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*
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*/
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/*
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handle periodic adsb database maintenance and handle threats
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*/
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void Plane::adsb_update(void)
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{
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adsb.update();
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if (!adsb.get_is_evading_threat()) {
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if (adsb.get_possible_threat()) {
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bool evasion_start_success = adsb_evasion_start();
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adsb.set_is_evading_threat(evasion_start_success);
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}
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} else if (adsb_state.is_evading) {
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// there has been no manual override, handle an auto-evasion
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if (!adsb.get_possible_threat()) {
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adsb.set_is_evading_threat(false);
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adsb_evasion_stop();
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adsb_state.is_evading = false;
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} else {
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adsb_evasion_ongoing();
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}
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}
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}
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/*
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* This fires once at the moment we realize there is a threat
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*/
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bool Plane::adsb_evasion_start(void)
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{
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if (control_mode != AUTO) {
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// evasion is only supported while in AUTO mode
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return false;
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}
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if (mission.get_current_nav_cmd().id == MAV_CMD_NAV_TAKEOFF ||
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mission.get_current_nav_cmd().id == MAV_CMD_NAV_LAND) {
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// evasion during a plane take-off or land can result in a crash. Ignore ADS-B traffic
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return false;
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}
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adsb_state.timestamp_ms = millis();
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adsb_state.prev_wp = prev_WP_loc; // must be done BEFORE set_mode()
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switch(adsb.get_behavior()) {
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case AP_ADSB::ADSB_BEHAVIOR_NONE:
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default:
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gcs_send_text(MAV_SEVERITY_CRITICAL, "ADS-B threat found, no action taken");
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break;
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case AP_ADSB::ADSB_BEHAVIOR_GUIDED:
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gcs_send_text(MAV_SEVERITY_CRITICAL, "ADS-B threat found, switching to GUIDED mode");
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set_mode(GUIDED);
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adsb_state.is_evading = true; // must be done AFTER set_mode()
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break;
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case AP_ADSB::ADSB_BEHAVIOR_LOITER:
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case AP_ADSB::ADSB_BEHAVIOR_LOITER_AND_DESCEND:
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gcs_send_text(MAV_SEVERITY_CRITICAL, "ADS-B threat found, performing LOITER");
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set_mode(LOITER);
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adsb_state.is_evading = true; // must be done after set_mode()
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break;
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} // switch behavior
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return true;
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}
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/*
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* This fires once at the moment we realize there is no longer a threat
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*/
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void Plane::adsb_evasion_stop(void)
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{
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gcs_send_text(MAV_SEVERITY_CRITICAL, "ADS-B threat gone, continuing mission");
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FlightMode prev_control_mode = control_mode;
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set_mode(AUTO);
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if (prev_control_mode == LOITER)
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{
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// if resuming from loiter, smoothly get back on track
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prev_WP_loc = adsb_state.prev_wp;
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auto_state.no_crosstrack = false;
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}
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}
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/*
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* This fires once per second while evading a threat
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*/
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void Plane::adsb_evasion_ongoing(void)
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{
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uint32_t now = millis();
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if (control_mode == LOITER &&
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adsb.get_behavior() == AP_ADSB::ADSB_BEHAVIOR_LOITER_AND_DESCEND &&
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now - adsb_state.timestamp_ms >= 1000)
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{
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// slowly reduce altitude 100 cm/s while loitering. Drive into the ground if threat persists
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adsb_state.timestamp_ms = now;
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next_WP_loc.alt -= 100;
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}
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}
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