SIM_Aircraft.h

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/*
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
/*
  parent class for aircraft simulators
*/

#pragma once

#include <AP_Math/AP_Math.h>

#include "SITL.h"
#include <AP_Terrain/AP_Terrain.h>


namespace SITL {

/*
  parent class for all simulator types
 */
class Aircraft {
    friend class Gripper_Servo;

public:
    Aircraft(const char *home_str, const char *frame_str);

    /*
      structure passed in giving servo positions as PWM values in
      microseconds
     */
    struct sitl_input {
        uint16_t servos[16];
        struct {
            float speed;      // m/s
            float direction;  // degrees 0..360
            float turbulence;
            float dir_z;      //degrees -90..90 
        } wind;
    };

    /*
      set simulation speedup
     */
    void set_speedup(float speedup);

    /*
      set instance number
     */
    void set_instance(uint8_t _instance) {
        instance = _instance;
    }

    /*
      set directory for additional files such as aircraft models
     */
    void set_autotest_dir(const char *_autotest_dir) {
        autotest_dir = _autotest_dir;
    }

    /*  Create and set in/out socket for extenal simulator */
    virtual void set_interface_ports(const char* address, const int port_in, const int port_out) {};

    /*
      step the FDM by one time step
     */
    virtual void update(const struct sitl_input &input) = 0;

    /* fill a sitl_fdm structure from the simulator state */
    void fill_fdm(struct sitl_fdm &fdm);

    /* smooth sensors to provide kinematic consistancy */
    void smooth_sensors(void);

    /* return normal distribution random numbers */
    static double rand_normal(double mean, double stddev);

    /* parse a home location string */
    static bool parse_home(const char *home_str, Location &loc, float &yaw_degrees);

    // get frame rate of model in Hz
    float get_rate_hz(void) const { return rate_hz; }

    const Vector3f &get_gyro(void) const {
        return gyro;
    }

    const Vector3f &get_velocity_ef(void) const {
        return velocity_ef;
    }

    const Vector3f &get_velocity_air_ef(void) const {
        return velocity_air_ef;
    }

    const Matrix3f &get_dcm(void) const {
        return dcm;
    }

    const Vector3f &get_mag_field_bf(void) const {
        return mag_bf;
    }

    virtual float gross_mass() const { return mass; }

    const Location &get_location() const { return location; }

    const Vector3f &get_position() const { return position; }

    void get_attitude(Quaternion &attitude) const {
        attitude.from_rotation_matrix(dcm);
    }

protected:
    SITL *sitl;
    Location home;
    Location location;

    float ground_level;
    float home_yaw;
    float frame_height;
    Matrix3f dcm;                   // rotation matrix, APM conventions, from body to earth
    Vector3f gyro;                  // rad/s
    Vector3f gyro_prev;             // rad/s
    Vector3f ang_accel;             // rad/s/s
    Vector3f velocity_ef;           // m/s, earth frame
    Vector3f wind_ef;               // m/s, earth frame
    Vector3f velocity_air_ef;       // velocity relative to airmass, earth frame
    Vector3f velocity_air_bf;       // velocity relative to airmass, body frame
    Vector3f position;              // meters, NED from origin
    float mass;                     // kg
    Vector3f accel_body;            // m/s/s NED, body frame
    float airspeed;                 // m/s, apparent airspeed
    float airspeed_pitot;           // m/s, apparent airspeed, as seen by fwd pitot tube
    float battery_voltage = -1.0f;
    float battery_current = 0.0f;
    float rpm1 = 0;
    float rpm2 = 0;
    uint8_t rcin_chan_count = 0;
    float rcin[8];
    float range = -1.0f;            // rangefinder detection in m

    // Wind Turbulence simulated Data
    float turbulence_azimuth = 0.0f;
    float turbulence_horizontal_speed = 0.0f;  // m/s
    float turbulence_vertical_speed = 0.0f;    // m/s

    Vector3f mag_bf;  // local earth magnetic field vector in Gauss, earth frame

    uint64_t time_now_us;

    const float gyro_noise;
    const float accel_noise;
    float rate_hz;
    float achieved_rate_hz;
    float target_speedup;
    uint64_t frame_time_us;
    float scaled_frame_time_us;
    uint64_t last_wall_time_us;
    uint8_t instance;
    const char *autotest_dir;
    const char *frame;
    bool use_time_sync = true;
    float last_speedup = -1.0f;

    // allow for AHRS_ORIENTATION
    AP_Int8 *ahrs_orientation;
    
    enum {
        GROUND_BEHAVIOR_NONE = 0,
        GROUND_BEHAVIOR_NO_MOVEMENT,
        GROUND_BEHAVIOR_FWD_ONLY,
        GROUND_BEHAVIOR_TAILSITTER,
    } ground_behavior;

    bool use_smoothing;

    AP_Terrain *terrain;
    float ground_height_difference() const;

    const float FEET_TO_METERS = 0.3048f;
    const float KNOTS_TO_METERS_PER_SECOND = 0.51444f;

    virtual bool on_ground() const;

    // returns height above ground level in metres
    float hagl() const;  // metres

    /* update location from position */
    void update_position(void);

    /* update body frame magnetic field */
    void update_mag_field_bf(void);

    /* advance time by deltat in seconds */
    void time_advance();

    /* setup the frame step time */
    void setup_frame_time(float rate, float speedup);

    /* adjust frame_time calculation */
    void adjust_frame_time(float rate);

    /* try to synchronise simulation time with wall clock time, taking
       into account desired speedup */
    void sync_frame_time(void);

    /* add noise based on throttle level (from 0..1) */
    void add_noise(float throttle);

    /* return wall clock time in microseconds since 1970 */
    uint64_t get_wall_time_us(void) const;

    // update attitude and relative position
    void update_dynamics(const Vector3f &rot_accel);

    // update wind vector
    void update_wind(const struct sitl_input &input);

    // return filtered servo input as -1 to 1 range
    float filtered_idx(float v, uint8_t idx);
    float filtered_servo_angle(const struct sitl_input &input, uint8_t idx);
    float filtered_servo_range(const struct sitl_input &input, uint8_t idx);

    // extrapolate sensors by a given delta time in seconds
    void extrapolate_sensors(float delta_time);
    
private:
    uint64_t last_time_us = 0;
    uint32_t frame_counter = 0;
    uint32_t last_ground_contact_ms;
    const uint32_t min_sleep_time;

    struct {
        bool enabled;
        Vector3f accel_body;
        Vector3f gyro;
        Matrix3f rotation_b2e;
        Vector3f position;
        Vector3f velocity_ef;
        uint64_t last_update_us;
        Location location;
    } smoothing;

    LowPassFilterFloat servo_filter[4];
};

} // namespace SITL