ardupilot/libraries/AP_Soaring/AP_Soaring.h

/*
  Soaring Controller class by Samuel Tabor

  Provides a layer between the thermal centring algorithm and the main
  code for managing navigation targets, data logging, tuning parameters,
  algorithm inputs and eventually other soaring strategies such as
  speed-to-fly. AP_TECS libary used for reference.
*/

#pragma once

#include <AP_AHRS/AP_AHRS.h>
#include <AP_Param/AP_Param.h>
#include <AP_Math/AP_Math.h>
#include "ExtendedKalmanFilter.h"
#include "Variometer.h"
#include <AP_SpdHgtControl/AP_SpdHgtControl.h>

#define INITIAL_THERMAL_STRENGTH 2.0
#define INITIAL_THERMAL_RADIUS 80.0
#define INITIAL_STRENGTH_COVARIANCE 0.0049
#define INITIAL_RADIUS_COVARIANCE 400.0
#define INITIAL_POSITION_COVARIANCE 400.0


class SoaringController {
    ExtendedKalmanFilter _ekf{};
    AP_AHRS &_ahrs;
    AP_SpdHgtControl &_spdHgt;
    Variometer _vario;
    const AP_Vehicle::FixedWing &_aparm;

    // store aircraft location at last update
    Vector3f _prev_update_location;

    // store time thermal was entered for hysteresis
    uint64_t _thermal_start_time_us;

    // store position thermal was entered as a backup check
    Vector3f _thermal_start_pos;

    // store time cruise was entered for hysteresis
    uint64_t _cruise_start_time_us;

    // store time of last update
    uint64_t _prev_update_time;

    bool _throttle_suppressed;

    float McCready(float alt);

    float _thermalability;
    float _expected_sink;

    bool _last_update_active;

protected:
    AP_Int8 soar_active;
    AP_Int8 soar_active_ch;
    AP_Float thermal_vspeed;
    AP_Float thermal_q1;
    AP_Float thermal_q2;
    AP_Float thermal_r;
    AP_Float thermal_distance_ahead;
    AP_Int16 min_thermal_s;
    AP_Int16 min_cruise_s;
    AP_Float polar_CD0;
    AP_Float polar_B;
    AP_Float polar_K;
    AP_Float alt_max;
    AP_Float alt_min;
    AP_Float alt_cutoff;
    AP_Float max_drift;

public:
    SoaringController(AP_AHRS &ahrs, AP_SpdHgtControl &spdHgt, const AP_Vehicle::FixedWing &parms);

    typedef enum LoiterStatus {
        SOARING_DISABLED,
        ALT_TOO_HIGH,
        ALT_TOO_LOW,
        THERMAL_WEAK,
        ALT_LOST,
        DRIFT_EXCEEDED,
        THERMAL_GOOD_TO_KEEP_LOITERING
    } LoiterStatus;

    AP_Float max_radius;

    // this supports the TECS_* user settable parameters
    static const struct AP_Param::GroupInfo var_info[];
    void get_target(Location & wp);
    bool suppress_throttle();
    bool check_thermal_criteria();
    LoiterStatus check_cruise_criteria(Vector2f prev_wp, Vector2f next_wp);
    void init_thermalling();
    void init_cruising();
    void update_thermalling();
    void update_cruising();
    bool is_active() const;
    void set_throttle_suppressed(bool suppressed);

    bool get_throttle_suppressed() const
    {
        return _throttle_suppressed;
    }

    float get_vario_reading() const
    {
        return _vario.displayed_reading;
    }

    void update_vario();

    bool check_drift(Vector2f prev_wp, Vector2f next_wp);

    bool update_active_state();

private:
    // slow down messages if they are the same. During loiter we could smap the same message. Only show new messages during loiters
    LoiterStatus _cruise_criteria_msg_last;
};