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/battery_status.h>
#include <uORB/topics/vehicle_angular_velocity.h>
#include <uORB/topics/vehicle_attitude.h>
#include <uORB/topics/vehicle_control_mode.h>
#include <uORB/topics/vehicle_local_position_setpoint.h>
#include <uORB/topics/hover_thrust_estimate.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;

	float _get_max_altitude() override;
private:

	/** Get control mode dependent pilot throttle threshold with which we should quit landed state and take off. */
	float _get_takeoff_throttle();

	bool _has_low_thrust();
	bool _has_minimal_thrust();
	bool _has_altitude_lock();
	bool _has_position_lock();
	bool _is_climb_rate_enabled();

	/** Time in us that landing conditions have to hold before triggering a land. */
	static constexpr hrt_abstime LAND_DETECTOR_TRIGGER_TIME_US = 300_ms;

	/** Time in us that almost landing conditions have to hold before triggering almost landed . */
	static constexpr hrt_abstime MAYBE_LAND_DETECTOR_TRIGGER_TIME_US = 250_ms;

	/** Time in us that ground contact condition have to hold before triggering contact ground */
	static constexpr hrt_abstime GROUND_CONTACT_TRIGGER_TIME_US = 350_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;

	/** 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 _battery_sub{ORB_ID(battery_status)};
	uORB::Subscription _vehicle_acceleration_sub{ORB_ID(vehicle_acceleration)};
	uORB::Subscription _vehicle_angular_velocity_sub{ORB_ID(vehicle_angular_velocity)};
	uORB::Subscription _vehicle_control_mode_sub{ORB_ID(vehicle_control_mode)};
	uORB::Subscription _vehicle_local_position_sub{ORB_ID(vehicle_local_position)};
	uORB::Subscription _vehicle_local_position_setpoint_sub{ORB_ID(vehicle_local_position_setpoint)};
	uORB::Subscription _hover_thrust_estimate_sub{ORB_ID(hover_thrust_estimate)};

	actuator_controls_s               _actuator_controls {};
	battery_status_s                  _battery_status {};
	vehicle_angular_velocity_s        _vehicle_angular_velocity{};
	vehicle_control_mode_s            _vehicle_control_mode {};
	vehicle_local_position_setpoint_s _vehicle_local_position_setpoint {};

	bool _hover_thrust_initialized{false};

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

	bool _in_descend{false};		///< vehicle is desending
	bool _horizontal_movement{false};	///< vehicle is moving horizontally

	DEFINE_PARAMETERS_CUSTOM_PARENT(
		LandDetector,
		(ParamFloat<px4::params::LNDMC_ALT_MAX>)    _param_lndmc_alt_max,
		(ParamFloat<px4::params::LNDMC_FFALL_THR>)  _param_lndmc_ffall_thr,
		(ParamFloat<px4::params::LNDMC_FFALL_TTRI>) _param_lndmc_ffall_ttri,
		(ParamFloat<px4::params::LNDMC_LOW_T_THR>)  _param_lndmc_low_t_thr,
		(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
	);
};

} // namespace land_detector