PX4-Autopilot/src/modules/navigator/rtl.h

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/**
 * @file rtl.h
 *
 * Helper class for RTL
 *
 * @author Julian Oes <julian@oes.ch>
 * @author Anton Babushkin <anton.babushkin@me.com>
 */

#pragma once

#include <px4_platform_common/module_params.h>

#include "navigator_mode.h"
#include "mission_block.h"

#include <uORB/topics/home_position.h>

class Navigator;

class RTL : public MissionBlock, public ModuleParams
{
public:
	enum RTLType {
		RTL_HOME = 0,
		RTL_LAND,
		RTL_MISSION,
		RTL_CLOSEST,
	};

	enum RTLDestinationType {
		RTL_DESTINATION_HOME = 0,
		RTL_DESTINATION_MISSION_LANDING,
		RTL_DESTINATION_SAFE_POINT,
	};

	RTL(Navigator *navigator);

	~RTL() = default;

	void on_inactivation() override;
	void on_inactive() override;
	void on_activation() override;
	void on_active() override;

	void find_RTL_destination();

	void set_return_alt_min(bool min) { _rtl_alt_min = min; }

	int rtl_type() const { return _param_rtl_type.get(); }

	int rtl_destination();

private:
	/**
	 * Set the RTL item
	 */
	void set_rtl_item();

	/**
	 * Move to next RTL item
	 */
	void advance_rtl();


	float calculate_return_alt_from_cone_half_angle(float cone_half_angle_deg);

	enum RTLState {
		RTL_STATE_NONE = 0,
		RTL_STATE_CLIMB,
		RTL_STATE_RETURN,
		RTL_STATE_TRANSITION_TO_MC,
		RTL_STATE_DESCEND,
		RTL_STATE_LOITER,
		RTL_STATE_LAND,
		RTL_STATE_LANDED,
	} _rtl_state{RTL_STATE_NONE};

	struct RTLPosition {
		double lat;
		double lon;
		float alt;
		float yaw;
		uint8_t safe_point_index; ///< 0 = home position, 1 = mission landing, >1 = safe landing points (rally points)
		RTLDestinationType type{RTL_DESTINATION_HOME};

		void set(const home_position_s &home_position)
		{
			lat = home_position.lat;
			lon = home_position.lon;
			alt = home_position.alt;
			yaw = home_position.yaw;
			safe_point_index = 0;
			type = RTL_DESTINATION_HOME;
		}
	};

	RTLPosition _destination{}; ///< the RTL position to fly to (typically the home position or a safe point)

	hrt_abstime _destination_check_time{0};

	float _rtl_alt{0.0f};	// AMSL altitude at which the vehicle should return to the home position
	bool _rtl_alt_min{false};

	DEFINE_PARAMETERS(
		(ParamFloat<px4::params::RTL_RETURN_ALT>) _param_rtl_return_alt,
		(ParamFloat<px4::params::RTL_DESCEND_ALT>) _param_rtl_descend_alt,
		(ParamFloat<px4::params::RTL_LAND_DELAY>) _param_rtl_land_delay,
		(ParamFloat<px4::params::RTL_MIN_DIST>) _param_rtl_min_dist,
		(ParamInt<px4::params::RTL_TYPE>) _param_rtl_type,
		(ParamInt<px4::params::RTL_CONE_ANG>) _param_rtl_cone_half_angle_deg,
		(ParamInt<px4::params::RTL_PLD_MD>) _param_rtl_pld_md
	)
};