PX4-Autopilot/src/modules/land_detector/MulticopterLandDetector.h

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/**
 * @file MulticopterLandDetector.h
 * Land detection implementation for multicopters.
 *
 * @author Johan Jansen <jnsn.johan@gmail.com>
 * @author Morten Lysgaard <morten@lysgaard.no>
 * @author Julian Oes <julian@oes.ch>
 */

#pragma once

#include <uORB/topics/actuator_controls.h>
#include <uORB/topics/hover_thrust_estimate.h>
#include <uORB/topics/vehicle_angular_velocity.h>
#include <uORB/topics/vehicle_control_mode.h>
#include <uORB/topics/vehicle_local_position_setpoint.h>
#include <uORB/topics/takeoff_status.h>

#include "LandDetector.h"

using namespace time_literals;

namespace land_detector
{

class MulticopterLandDetector : public LandDetector
{
public:
	MulticopterLandDetector();
	~MulticopterLandDetector() override = default;

protected:
	void _update_params() override;
	void _update_topics() override;

	bool _get_landed_state() override;
	bool _get_ground_contact_state() override;
	bool _get_maybe_landed_state() override;
	bool _get_freefall_state() override;
	bool _get_ground_effect_state() override;
	bool _get_in_descend() override { return _in_descend; }
	bool _get_has_low_throttle() override { return _has_low_throttle; }
	bool _get_horizontal_movement() override { return _horizontal_movement; }
	bool _get_vertical_movement() override { return _vertical_movement; }
	bool _get_close_to_ground_or_skipped_check() override { return _close_to_ground_or_skipped_check; }
	float _get_max_altitude() override;

	void _set_hysteresis_factor(const int factor) override;
private:

	float _get_gnd_effect_altitude();
	bool _is_close_to_ground();

	/** Time in us that freefall has to hold before triggering freefall */
	static constexpr hrt_abstime FREEFALL_TRIGGER_TIME_US = 300_ms;

	/** Time interval in us in which wider acceptance thresholds are used after landed. */
	static constexpr hrt_abstime LAND_DETECTOR_LAND_PHASE_TIME_US = 2_s;

	/** Distance above ground below which entering ground contact state is possible when distance to ground is available. */
	static constexpr float DIST_FROM_GROUND_THRESHOLD = 1.0f;

	/** Handles for interesting parameters. **/
	struct {
		param_t minThrottle;
		param_t hoverThrottle;
		param_t minManThrottle;
		param_t landSpeed;
		param_t useHoverThrustEstimate;
	} _paramHandle{};

	struct {
		float minThrottle;
		float hoverThrottle;
		float minManThrottle;
		float landSpeed;
		bool useHoverThrustEstimate;
	} _params{};

	uORB::Subscription _actuator_controls_sub{ORB_ID(actuator_controls_0)};
	uORB::Subscription _hover_thrust_estimate_sub{ORB_ID(hover_thrust_estimate)};
	uORB::Subscription _trajectory_setpoint_sub{ORB_ID(trajectory_setpoint)};
	uORB::Subscription _vehicle_angular_velocity_sub{ORB_ID(vehicle_angular_velocity)};
	uORB::Subscription _vehicle_control_mode_sub{ORB_ID(vehicle_control_mode)};
	uORB::Subscription _takeoff_status_sub{ORB_ID(takeoff_status)};

	hrt_abstime _hover_thrust_estimate_last_valid{0};
	bool _hover_thrust_estimate_valid{false};

	bool _flag_control_climb_rate_enabled{false};
	bool _hover_thrust_initialized{false};

	float _actuator_controls_throttle{0.f};

	uint8_t _takeoff_state{takeoff_status_s::TAKEOFF_STATE_DISARMED};

	hrt_abstime _min_thrust_start{0};	///< timestamp when minimum trust was applied first
	hrt_abstime _landed_time{0};

	bool _in_descend{false};		///< vehicle is commanded to desend
	bool _horizontal_movement{false};	///< vehicle is moving horizontally
	bool _vertical_movement{false};
	bool _has_low_throttle{false};
	bool _close_to_ground_or_skipped_check{false};
	bool _below_gnd_effect_hgt{false};	///< vehicle height above ground is below height where ground effect occurs

	DEFINE_PARAMETERS_CUSTOM_PARENT(
		LandDetector,
		(ParamFloat<px4::params::LNDMC_TRIG_TIME>)   _param_lndmc_trig_time,
		(ParamFloat<px4::params::LNDMC_ALT_MAX>)    _param_lndmc_alt_max,
		(ParamFloat<px4::params::LNDMC_ROT_MAX>)    _param_lndmc_rot_max,
		(ParamFloat<px4::params::LNDMC_XY_VEL_MAX>) _param_lndmc_xy_vel_max,
		(ParamFloat<px4::params::LNDMC_Z_VEL_MAX>)  _param_lndmc_z_vel_max,
		(ParamFloat<px4::params::LNDMC_ALT_GND>)    _param_lndmc_alt_gnd_effect
	);
};

} // namespace land_detector