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/**
 * @file fw_pos_control_l1_main.hpp
 * Implementation of a generic position controller based on the L1 norm. Outputs a bank / roll
 * angle, equivalent to a lateral motion (for copters and rovers).
 *
 * The implementation for the controllers is in the ECL library. This class only
 * interfaces to the library.
 *
 * @author Lorenz Meier <lorenz@px4.io>
 * @author Thomas Gubler <thomasgubler@gmail.com>
 * @author Andreas Antener <andreas@uaventure.com>
 */

#ifndef FIXEDWINGPOSITIONCONTROL_HPP_
#define FIXEDWINGPOSITIONCONTROL_HPP_

#include "Landingslope.hpp"
#include "launchdetection/LaunchDetector.h"
#include "runway_takeoff/RunwayTakeoff.h"

#include <cfloat>

#include <drivers/drv_hrt.h>
#include <ecl/l1/ecl_l1_pos_controller.h>
#include <ecl/tecs/tecs.h>
#include <lib/ecl/geo/geo.h>
#include <mathlib/mathlib.h>
#include <px4_config.h>
#include <px4_defines.h>
#include <px4_module.h>
#include <px4_module_params.h>
#include <px4_posix.h>
#include <px4_tasks.h>
#include <systemlib/perf_counter.h>
#include <uORB/Subscription.hpp>
#include <uORB/topics/airspeed.h>
#include <uORB/topics/fw_pos_ctrl_status.h>
#include <uORB/topics/manual_control_setpoint.h>
#include <uORB/topics/parameter_update.h>
#include <uORB/topics/position_setpoint_triplet.h>
#include <uORB/topics/sensor_baro.h>
#include <uORB/topics/sensor_bias.h>
#include <uORB/topics/tecs_status.h>
#include <uORB/topics/vehicle_attitude.h>
#include <uORB/topics/vehicle_attitude_setpoint.h>
#include <uORB/topics/vehicle_command.h>
#include <uORB/topics/vehicle_control_mode.h>
#include <uORB/topics/vehicle_global_position.h>
#include <uORB/topics/vehicle_land_detected.h>
#include <uORB/topics/vehicle_local_position.h>
#include <uORB/topics/vehicle_status.h>
#include <uORB/uORB.h>
#include <vtol_att_control/vtol_type.h>

static constexpr float HDG_HOLD_DIST_NEXT =
	3000.0f; // initial distance of waypoint in front of plane in heading hold mode
static constexpr float HDG_HOLD_REACHED_DIST =
	1000.0f; // distance (plane to waypoint in front) at which waypoints are reset in heading hold mode
static constexpr float HDG_HOLD_SET_BACK_DIST = 100.0f; // distance by which previous waypoint is set behind the plane
static constexpr float HDG_HOLD_YAWRATE_THRESH = 0.15f;	// max yawrate at which plane locks yaw for heading hold mode
static constexpr float HDG_HOLD_MAN_INPUT_THRESH =
	0.01f; // max manual roll/yaw input from user which does not change the locked heading

static constexpr hrt_abstime T_ALT_TIMEOUT = 1; // time after which we abort landing if terrain estimate is not valid

static constexpr float THROTTLE_THRESH =
	0.05f;	///< max throttle from user which will not lead to motors spinning up in altitude controlled modes
static constexpr float MANUAL_THROTTLE_CLIMBOUT_THRESH =
	0.85f; ///< a throttle / pitch input above this value leads to the system switching to climbout mode
static constexpr float ALTHOLD_EPV_RESET_THRESH = 5.0f;

static constexpr float MSL_PRESSURE_MILLIBAR = 1013.25f; ///< standard atmospheric pressure in millibar

using math::constrain;
using math::max;
using math::min;
using math::radians;

using matrix::Dcmf;
using matrix::Eulerf;
using matrix::Quatf;
using matrix::Vector2f;
using matrix::Vector3f;

using uORB::Subscription;

using namespace launchdetection;
using namespace runwaytakeoff;

class FixedwingPositionControl final : public ModuleBase<FixedwingPositionControl>, public ModuleParams
{
public:
	FixedwingPositionControl();
	~FixedwingPositionControl() override;
	FixedwingPositionControl(const FixedwingPositionControl &) = delete;
	FixedwingPositionControl operator=(const FixedwingPositionControl &other) = delete;

	/** @see ModuleBase */
	static int task_spawn(int argc, char *argv[]);

	/** @see ModuleBase */
	static FixedwingPositionControl *instantiate(int argc, char *argv[]);

	/** @see ModuleBase */
	static int custom_command(int argc, char *argv[]);

	/** @see ModuleBase */
	static int print_usage(const char *reason = nullptr);

	/** @see ModuleBase::run() */
	void run() override;

	/** @see ModuleBase::print_status() */
	int print_status() override;

private:
	orb_advert_t	_mavlink_log_pub{nullptr};

	int		_global_pos_sub{-1};
	int		_local_pos_sub{-1};
	int		_pos_sp_triplet_sub{-1};
	int		_control_mode_sub{-1};			///< control mode subscription */
	int		_vehicle_attitude_sub{-1};		///< vehicle attitude subscription */
	int		_vehicle_command_sub{-1};		///< vehicle command subscription */
	int		_vehicle_status_sub{-1};		///< vehicle status subscription */
	int		_vehicle_land_detected_sub{-1};		///< vehicle land detected subscription */
	int		_params_sub{-1};			///< notification of parameter updates */
	int		_manual_control_sub{-1};		///< notification of manual control updates */
	int		_sensor_baro_sub{-1};

	orb_advert_t	_attitude_sp_pub{nullptr};		///< attitude setpoint */
	orb_advert_t	_tecs_status_pub{nullptr};		///< TECS status publication */
	orb_advert_t	_fw_pos_ctrl_status_pub{nullptr};	///< navigation capabilities publication */

	orb_id_t _attitude_setpoint_id{nullptr};

	fw_pos_ctrl_status_s		_fw_pos_ctrl_status {};		///< navigation capabilities */
	manual_control_setpoint_s	_manual {};			///< r/c channel data */
	position_setpoint_triplet_s	_pos_sp_triplet {};		///< triplet of mission items */
	vehicle_attitude_s	_att {};			///< vehicle attitude setpoint */
	vehicle_attitude_setpoint_s	_att_sp {};			///< vehicle attitude setpoint */
	vehicle_command_s		_vehicle_command {};		///< vehicle commands */
	vehicle_control_mode_s		_control_mode {};		///< control mode */
	vehicle_global_position_s	_global_pos {};			///< global vehicle position */
	vehicle_local_position_s	_local_pos {};			///< vehicle local position */
	vehicle_land_detected_s		_vehicle_land_detected {};	///< vehicle land detected */
	vehicle_status_s		_vehicle_status {};		///< vehicle status */

	Subscription<airspeed_s> _sub_airspeed;
	Subscription<sensor_bias_s> _sub_sensors;

	perf_counter_t	_loop_perf;				///< loop performance counter */

	float	_hold_alt{0.0f};				///< hold altitude for altitude mode */
	float	_takeoff_ground_alt{0.0f};			///< ground altitude at which plane was launched */
	float	_hdg_hold_yaw{0.0f};				///< hold heading for velocity mode */
	bool	_hdg_hold_enabled{false};			///< heading hold enabled */
	bool	_yaw_lock_engaged{false};			///< yaw is locked for heading hold */
	float	_althold_epv{0.0f};				///< the position estimate accuracy when engaging alt hold */
	bool	_was_in_deadband{false};			///< wether the last stick input was in althold deadband */

	position_setpoint_s _hdg_hold_prev_wp {};		///< position where heading hold started */
	position_setpoint_s _hdg_hold_curr_wp {};		///< position to which heading hold flies */

	hrt_abstime _control_position_last_called{0};		///< last call of control_position  */

	/* Landing */
	bool _land_noreturn_horizontal{false};
	bool _land_noreturn_vertical{false};
	bool _land_stayonground{false};
	bool _land_motor_lim{false};
	bool _land_onslope{false};

	Landingslope _landingslope;

	hrt_abstime _time_started_landing{0};			///< time at which landing started */

	float _t_alt_prev_valid{0};				///< last terrain estimate which was valid */
	hrt_abstime _time_last_t_alt{0};			///< time at which we had last valid terrain alt */

	float _flare_height{0.0f};				///< estimated height to ground at which flare started */
	float _flare_curve_alt_rel_last{0.0f};
	float _target_bearing{0.0f};				///< estimated height to ground at which flare started */

	bool _was_in_air{false};				///< indicated wether the plane was in the air in the previous interation*/
	hrt_abstime _time_went_in_air{0};			///< time at which the plane went in the air */

	/* Takeoff launch detection and runway */
	LaunchDetector _launchDetector;
	LaunchDetectionResult _launch_detection_state{LAUNCHDETECTION_RES_NONE};
	hrt_abstime _launch_detection_notify{0};

	RunwayTakeoff _runway_takeoff;

	bool _last_manual{false};				///< true if the last iteration was in manual mode (used to determine when a reset is needed)

	/* throttle and airspeed states */
	bool _airspeed_valid{false};				///< flag if a valid airspeed estimate exists
	hrt_abstime _airspeed_last_received{0};			///< last time airspeed was received. Used to detect timeouts.
	float _airspeed{0.0f};
	float _eas2tas{1.0f};

	float _groundspeed_undershoot{0.0f};			///< ground speed error to min. speed in m/s

	Dcmf _R_nb;				///< current attitude
	float _roll{0.0f};
	float _pitch{0.0f};
	float _yaw{0.0f};

	bool _reinitialize_tecs{true};				///< indicates if the TECS states should be reinitialized (used for VTOL)
	bool _is_tecs_running{false};
	hrt_abstime _last_tecs_update{0};

	float _asp_after_transition{0.0f};
	bool _was_in_transition{false};

	// estimator reset counters
	uint8_t _pos_reset_counter{0};				///< captures the number of times the estimator has reset the horizontal position
	uint8_t _alt_reset_counter{0};				///< captures the number of times the estimator has reset the altitude state

	ECL_L1_Pos_Controller	_l1_control;
	TECS			_tecs;

	enum FW_POSCTRL_MODE {
		FW_POSCTRL_MODE_AUTO,
		FW_POSCTRL_MODE_POSITION,
		FW_POSCTRL_MODE_ALTITUDE,
		FW_POSCTRL_MODE_OTHER
	} _control_mode_current{FW_POSCTRL_MODE_OTHER};		///< used to check the mode in the last control loop iteration. Use to check if the last iteration was in the same mode.

	struct {
		float l1_period;
		float l1_damping;

		float time_const;
		float time_const_throt;
		float min_sink_rate;
		float max_sink_rate;
		float max_climb_rate;
		float climbout_diff;
		float heightrate_p;
		float heightrate_ff;
		float speedrate_p;
		float throttle_damp;
		float integrator_gain;
		float vertical_accel_limit;
		float height_comp_filter_omega;
		float speed_comp_filter_omega;
		float roll_throttle_compensation;
		float speed_weight;
		float pitch_damping;

		float airspeed_min;
		float airspeed_trim;
		float airspeed_max;
		float airspeed_trans;
		int32_t airspeed_disabled;

		float pitch_limit_min;
		float pitch_limit_max;
		float roll_limit;

		float throttle_min;
		float throttle_max;
		float throttle_idle;
		float throttle_cruise;
		float throttle_slew_max;
		float throttle_alt_scale;

		float man_roll_max_rad;
		float man_pitch_max_rad;
		float rollsp_offset_rad;
		float pitchsp_offset_rad;

		float throttle_land_max;

		float land_slope_angle;
		float land_H1_virt;
		float land_flare_alt_relative;
		float land_thrust_lim_alt_relative;
		float land_heading_hold_horizontal_distance;
		float land_flare_pitch_min_deg;
		float land_flare_pitch_max_deg;
		int32_t land_use_terrain_estimate;
		float land_airspeed_scale;

		int32_t vtol_type;
	} _parameters{};					///< local copies of interesting parameters */

	struct {
		param_t l1_period;
		param_t l1_damping;

		param_t time_const;
		param_t time_const_throt;
		param_t min_sink_rate;
		param_t max_sink_rate;
		param_t max_climb_rate;
		param_t climbout_diff;
		param_t heightrate_p;
		param_t heightrate_ff;
		param_t speedrate_p;
		param_t throttle_damp;
		param_t integrator_gain;
		param_t vertical_accel_limit;
		param_t height_comp_filter_omega;
		param_t speed_comp_filter_omega;
		param_t roll_throttle_compensation;
		param_t speed_weight;
		param_t pitch_damping;

		param_t airspeed_min;
		param_t airspeed_trim;
		param_t airspeed_max;
		param_t airspeed_trans;
		param_t airspeed_disabled;

		param_t pitch_limit_min;
		param_t pitch_limit_max;
		param_t roll_limit;

		param_t throttle_min;
		param_t throttle_max;
		param_t throttle_idle;
		param_t throttle_cruise;
		param_t throttle_slew_max;
		param_t throttle_alt_scale;

		param_t man_roll_max_deg;
		param_t man_pitch_max_deg;
		param_t rollsp_offset_deg;
		param_t pitchsp_offset_deg;

		param_t throttle_land_max;

		param_t land_slope_angle;
		param_t land_H1_virt;
		param_t land_flare_alt_relative;
		param_t land_thrust_lim_alt_relative;
		param_t land_heading_hold_horizontal_distance;
		param_t land_flare_pitch_min_deg;
		param_t land_flare_pitch_max_deg;
		param_t land_use_terrain_estimate;
		param_t land_airspeed_scale;

		param_t vtol_type;
	} _parameter_handles {};				///< handles for interesting parameters */


	/**
	 * Update our local parameter cache.
	 */
	int		parameters_update();

	// Update subscriptions
	void		airspeed_poll();
	void		control_update();
	void		manual_control_setpoint_poll();
	void		position_setpoint_triplet_poll();
	void		vehicle_attitude_poll();
	void		vehicle_command_poll();
	void		vehicle_control_mode_poll();
	void		vehicle_land_detected_poll();
	void		vehicle_status_poll();

	// publish navigation capabilities
	void		fw_pos_ctrl_status_publish();

	/**
	 * Get a new waypoint based on heading and distance from current position
	 *
	 * @param heading the heading to fly to
	 * @param distance the distance of the generated waypoint
	 * @param waypoint_prev the waypoint at the current position
	 * @param waypoint_next the waypoint in the heading direction
	 */
	void		get_waypoint_heading_distance(float heading, position_setpoint_s &waypoint_prev,
			position_setpoint_s &waypoint_next, bool flag_init);

	/**
	 * Return the terrain estimate during takeoff or takeoff_alt if terrain estimate is not available
	 */
	float		get_terrain_altitude_takeoff(float takeoff_alt, const vehicle_global_position_s &global_pos);

	/**
	 * Check if we are in a takeoff situation
	 */
	bool 		in_takeoff_situation();

	/**
	 * Do takeoff help when in altitude controlled modes
	 * @param hold_altitude altitude setpoint for controller
	 * @param pitch_limit_min minimum pitch allowed
	 */
	void 		do_takeoff_help(float *hold_altitude, float *pitch_limit_min);

	/**
	 * Update desired altitude base on user pitch stick input
	 *
	 * @param dt Time step
	 * @return true if climbout mode was requested by user (climb with max rate and min airspeed)
	 */
	bool		update_desired_altitude(float dt);

	bool		control_position(const Vector2f &curr_pos, const Vector2f &ground_speed, const position_setpoint_s &pos_sp_prev,
					 const position_setpoint_s &pos_sp_curr);
	void		control_takeoff(const Vector2f &curr_pos, const Vector2f &ground_speed, const position_setpoint_s &pos_sp_prev,
					const position_setpoint_s &pos_sp_curr);
	void		control_landing(const Vector2f &curr_pos, const Vector2f &ground_speed, const position_setpoint_s &pos_sp_prev,
					const position_setpoint_s &pos_sp_curr);

	float		get_tecs_pitch();
	float		get_tecs_thrust();

	float		get_demanded_airspeed();
	float		calculate_target_airspeed(float airspeed_demand);
	void		calculate_gndspeed_undershoot(const Vector2f &curr_pos, const Vector2f &ground_speed,
			const position_setpoint_s &pos_sp_prev, const position_setpoint_s &pos_sp_curr);

	/**
	 * Handle incoming vehicle commands
	 */
	void		handle_command();

	void		reset_takeoff_state();
	void		reset_landing_state();

	/*
	 * Call TECS : a wrapper function to call the TECS implementation
	 */
	void tecs_update_pitch_throttle(float alt_sp, float airspeed_sp,
					float pitch_min_rad, float pitch_max_rad,
					float throttle_min, float throttle_max, float throttle_cruise,
					bool climbout_mode, float climbout_pitch_min_rad,
					uint8_t mode = tecs_status_s::TECS_MODE_NORMAL);

};

#endif // FIXEDWINGPOSITIONCONTROL_HPP_
