text: /****************************************************************************
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   *   Copyright (c) 2013-2016 PX4 Development Team. All rights reserved.
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  /**
   * @file FixedwingLandDetector.h
   * Land detector implementation for fixedwing.
   *
   * @author Johan Jansen <jnsn.johan@gmail.com>
   * @author Morten Lysgaard <morten@lysgaard.no>
   * @author Julian Oes <julian@oes.ch>
   */
  
  #pragma once
  
  #include <drivers/drv_hrt.h>
  #include <uORB/Subscription.hpp>
  #include <uORB/topics/airspeed.h>
  #include <uORB/topics/sensor_bias.h>
  #include <uORB/topics/vehicle_local_position.h>
  
  #include "LandDetector.h"
  
  using namespace time_literals;
  
  namespace land_detector
  {
  
  class FixedwingLandDetector final : public LandDetector
  {
  public:
  	FixedwingLandDetector();
  
  protected:
  	void _update_params() override;
  	void _update_topics() override;
  
  	bool _get_landed_state() override;
  	float _get_max_altitude() override;
  
  private:
  
  	/** Time in us that landing conditions have to hold before triggering a land. */
  	static constexpr hrt_abstime LANDED_TRIGGER_TIME_US = 2_s;
  	static constexpr hrt_abstime FLYING_TRIGGER_TIME_US = 0_us;
  
  	uORB::Subscription _airspeed_sub{ORB_ID(airspeed)};
  	uORB::Subscription _param_update_sub{ORB_ID(parameter_update)};
  	uORB::Subscription _sensor_bias_sub{ORB_ID(sensor_bias)};
  	uORB::Subscription _vehicle_local_position_sub{ORB_ID(vehicle_local_position)};
  
  	airspeed_s _airspeed{};
  	sensor_bias_s _sensor_bias{};
  	vehicle_local_position_s _vehicle_local_position{};
  
  	float _accel_horz_lp{0.0f};
  	float _airspeed_filtered{0.0f};
  	float _velocity_xy_filtered{0.0f};
  	float _velocity_z_filtered{0.0f};
  
  	DEFINE_PARAMETERS_CUSTOM_PARENT(
  		LandDetector,
  		(ParamFloat<px4::params::LNDFW_XYACC_MAX>)  _param_lndfw_xyaccel_max,
  		(ParamFloat<px4::params::LNDFW_AIRSPD_MAX>) _param_lndfw_airspd,
  		(ParamFloat<px4::params::LNDFW_VEL_XY_MAX>) _param_lndfw_vel_xy_max,
  		(ParamFloat<px4::params::LNDFW_VEL_Z_MAX>)  _param_lndfw_vel_z_max
  	);
  
  };
  
  } // namespace land_detector
  