ardupilot/libraries/AP_InertialSensor/AP_InertialSensor.h

#pragma once

// Gyro and Accelerometer calibration criteria
#define AP_INERTIAL_SENSOR_ACCEL_TOT_MAX_OFFSET_CHANGE  4.0f
#define AP_INERTIAL_SENSOR_ACCEL_MAX_OFFSET             250.0f
#define AP_INERTIAL_SENSOR_ACCEL_CLIP_THRESH_MSS        (15.5f*GRAVITY_MSS) // accelerometer values over 15.5G are recorded as a clipping error
#define AP_INERTIAL_SENSOR_ACCEL_VIBE_FLOOR_FILT_HZ     5.0f    // accel vibration floor filter hz
#define AP_INERTIAL_SENSOR_ACCEL_VIBE_FILT_HZ           2.0f    // accel vibration filter hz
#define AP_INERTIAL_SENSOR_ACCEL_PEAK_DETECT_TIMEOUT_MS 500     // peak-hold detector timeout

/**
   maximum number of INS instances available on this platform. If more
   than 1 then redundant sensors may be available
 */
#define INS_MAX_INSTANCES 3
#define INS_MAX_BACKENDS  6
#define INS_VIBRATION_CHECK_INSTANCES 2

#include <stdint.h>

#include <AP_AccelCal/AP_AccelCal.h>
#include <AP_HAL/AP_HAL.h>
#include <AP_Math/AP_Math.h>
#include <Filter/LowPassFilter2p.h>
#include <Filter/LowPassFilter.h>

class AP_InertialSensor_Backend;
class AuxiliaryBus;

/*
  forward declare DataFlash class. We can't include DataFlash.h
  because of mutual dependencies
 */
class DataFlash_Class;

/* AP_InertialSensor is an abstraction for gyro and accel measurements
 * which are correctly aligned to the body axes and scaled to SI units.
 *
 * Gauss-Newton accel calibration routines borrowed from Rolfe Schmidt
 * blog post describing the method: http://chionophilous.wordpress.com/2011/10/24/accelerometer-calibration-iv-1-implementing-gauss-newton-on-an-atmega/
 * original sketch available at http://rolfeschmidt.com/mathtools/skimetrics/adxl_gn_calibration.pde
 */
class AP_InertialSensor : AP_AccelCal_Client
{
    friend class AP_InertialSensor_Backend;

public:
    AP_InertialSensor();

    static AP_InertialSensor *get_instance();

    enum Gyro_Calibration_Timing {
        GYRO_CAL_NEVER = 0,
        GYRO_CAL_STARTUP_ONLY = 1
    };

    /// Perform startup initialisation.
    ///
    /// Called to initialise the state of the IMU.
    ///
    /// Gyros will be calibrated unless INS_GYRO_CAL is zero
    ///
    /// @param style	The initialisation startup style.
    ///
    void init(uint16_t sample_rate_hz);

    /// Register a new gyro/accel driver, allocating an instance
    /// number
    uint8_t register_gyro(uint16_t raw_sample_rate_hz, uint32_t id);
    uint8_t register_accel(uint16_t raw_sample_rate_hz, uint32_t id);

    bool calibrate_trim(float &trim_roll, float &trim_pitch);

    /// calibrating - returns true if the gyros or accels are currently being calibrated
    bool calibrating() const { return _calibrating; }

    /// Perform cold-start initialisation for just the gyros.
    ///
    /// @note This should not be called unless ::init has previously
    ///       been called, as ::init may perform other work
    ///
    void init_gyro(void);

    /// Fetch the current gyro values
    ///
    /// @returns	vector of rotational rates in radians/sec
    ///
    const Vector3f     &get_gyro(uint8_t i) const { return _gyro[i]; }
    const Vector3f     &get_gyro(void) const { return get_gyro(_primary_gyro); }

    // set gyro offsets in radians/sec
    const Vector3f &get_gyro_offsets(uint8_t i) const { return _gyro_offset[i]; }
    const Vector3f &get_gyro_offsets(void) const { return get_gyro_offsets(_primary_gyro); }

    //get delta angle if available
    bool get_delta_angle(uint8_t i, Vector3f &delta_angle) const;
    bool get_delta_angle(Vector3f &delta_angle) const { return get_delta_angle(_primary_gyro, delta_angle); }

    float get_delta_angle_dt(uint8_t i) const;
    float get_delta_angle_dt() const { return get_delta_angle_dt(_primary_accel); }

    //get delta velocity if available
    bool get_delta_velocity(uint8_t i, Vector3f &delta_velocity) const;
    bool get_delta_velocity(Vector3f &delta_velocity) const { return get_delta_velocity(_primary_accel, delta_velocity); }

    float get_delta_velocity_dt(uint8_t i) const;
    float get_delta_velocity_dt() const { return get_delta_velocity_dt(_primary_accel); }

    /// Fetch the current accelerometer values
    ///
    /// @returns	vector of current accelerations in m/s/s
    ///
    const Vector3f     &get_accel(uint8_t i) const { return _accel[i]; }
    const Vector3f     &get_accel(void) const { return get_accel(_primary_accel); }

    uint32_t get_gyro_error_count(uint8_t i) const { return _gyro_error_count[i]; }
    uint32_t get_accel_error_count(uint8_t i) const { return _accel_error_count[i]; }

    // multi-device interface
    bool get_gyro_health(uint8_t instance) const { return (instance<_gyro_count) ? _gyro_healthy[instance] : false; }
    bool get_gyro_health(void) const { return get_gyro_health(_primary_gyro); }
    bool get_gyro_health_all(void) const;
    uint8_t get_gyro_count(void) const { return _gyro_count; }
    bool gyro_calibrated_ok(uint8_t instance) const { return _gyro_cal_ok[instance]; }
    bool gyro_calibrated_ok_all() const;
    bool use_gyro(uint8_t instance) const;
    Gyro_Calibration_Timing gyro_calibration_timing() { return (Gyro_Calibration_Timing)_gyro_cal_timing.get(); }

    bool get_accel_health(uint8_t instance) const { return (instance<_accel_count) ? _accel_healthy[instance] : false; }
    bool get_accel_health(void) const { return get_accel_health(_primary_accel); }
    bool get_accel_health_all(void) const;
    uint8_t get_accel_count(void) const { return _accel_count; }
    bool accel_calibrated_ok_all() const;
    bool use_accel(uint8_t instance) const;

    // get observed sensor rates, including any internal sampling multiplier
    uint16_t get_gyro_rate_hz(uint8_t instance) const { return uint16_t(_gyro_raw_sample_rates[instance] * _gyro_over_sampling[instance]); }
    uint16_t get_accel_rate_hz(uint8_t instance) const { return uint16_t(_accel_raw_sample_rates[instance] * _accel_over_sampling[instance]); }
    
    // get accel offsets in m/s/s
    const Vector3f &get_accel_offsets(uint8_t i) const { return _accel_offset[i]; }
    const Vector3f &get_accel_offsets(void) const { return get_accel_offsets(_primary_accel); }

    // get accel scale
    const Vector3f &get_accel_scale(uint8_t i) const { return _accel_scale[i]; }
    const Vector3f &get_accel_scale(void) const { return get_accel_scale(_primary_accel); }

    // return a 3D vector defining the position offset of the IMU accelerometer in metres relative to the body frame origin
    const Vector3f &get_imu_pos_offset(uint8_t instance) const {
        return _accel_pos[instance];
    }
    const Vector3f &get_imu_pos_offset(void) const {
        return _accel_pos[_primary_accel];
    }

    // return the temperature if supported. Zero is returned if no
    // temperature is available
    float get_temperature(uint8_t instance) const { return _temperature[instance]; }

    /* get_delta_time returns the time period in seconds
     * overwhich the sensor data was collected
     */
    float get_delta_time() const { return _delta_time; }

    // return the maximum gyro drift rate in radians/s/s. This
    // depends on what gyro chips are being used
    float get_gyro_drift_rate(void) const { return ToRad(0.5f/60); }

    // update gyro and accel values from accumulated samples
    void update(void);

    // wait for a sample to be available
    void wait_for_sample(void);

    // class level parameters
    static const struct AP_Param::GroupInfo var_info[];

    // set overall board orientation
    void set_board_orientation(enum Rotation orientation) {
        _board_orientation = orientation;
    }

    // return the selected sample rate
    uint16_t get_sample_rate(void) const { return _sample_rate; }

    // return the main loop delta_t in seconds
    float get_loop_delta_t(void) const { return _loop_delta_t; }

    uint16_t error_count(void) const { return 0; }
    bool healthy(void) const { return get_gyro_health() && get_accel_health(); }

    uint8_t get_primary_accel(void) const { return _primary_accel; }
    uint8_t get_primary_gyro(void) const { return _primary_gyro; }

    // enable HIL mode
    void set_hil_mode(void) { _hil_mode = true; }

    // get the gyro filter rate in Hz
    uint8_t get_gyro_filter_hz(void) const { return _gyro_filter_cutoff; }

    // get the accel filter rate in Hz
    uint8_t get_accel_filter_hz(void) const { return _accel_filter_cutoff; }

    // pass in a pointer to DataFlash for raw data logging
    void set_dataflash(DataFlash_Class *dataflash) { _dataflash = dataflash; }

    // enable/disable raw gyro/accel logging
    void set_raw_logging(bool enable) { _log_raw_data = enable; }

    // calculate vibration levels and check for accelerometer clipping (called by a backends)
    void calc_vibration_and_clipping(uint8_t instance, const Vector3f &accel, float dt);

    // retrieve latest calculated vibration levels
    Vector3f get_vibration_levels() const { return get_vibration_levels(_primary_accel); }
    Vector3f get_vibration_levels(uint8_t instance) const;

    // retrieve and clear accelerometer clipping count
    uint32_t get_accel_clip_count(uint8_t instance) const;

    // check for vibration movement. True when all axis show nearly zero movement
    bool is_still();

    /*
      HIL set functions. The minimum for HIL is set_accel() and
      set_gyro(). The others are option for higher fidelity log
      playback
     */
    void set_accel(uint8_t instance, const Vector3f &accel);
    void set_gyro(uint8_t instance, const Vector3f &gyro);
    void set_delta_time(float delta_time);
    void set_delta_velocity(uint8_t instance, float deltavt, const Vector3f &deltav);
    void set_delta_angle(uint8_t instance, const Vector3f &deltaa, float deltaat);

    AuxiliaryBus *get_auxiliary_bus(int16_t backend_id) { return get_auxiliary_bus(backend_id, 0); }
    AuxiliaryBus *get_auxiliary_bus(int16_t backend_id, uint8_t instance);

    void detect_backends(void);

    // accel peak hold detector
    void set_accel_peak_hold(uint8_t instance, const Vector3f &accel);
    float get_accel_peak_hold_neg_x() const { return _peak_hold_state.accel_peak_hold_neg_x; }

    //Returns accel calibrator interface object pointer
    AP_AccelCal* get_acal() const { return _acal; }

    // Returns body fixed accelerometer level data averaged during accel calibration's first step
    bool get_fixed_mount_accel_cal_sample(uint8_t sample_num, Vector3f& ret) const;

    // Returns primary accelerometer level data averaged during accel calibration's first step
    bool get_primary_accel_cal_sample_avg(uint8_t sample_num, Vector3f& ret) const;

    // Returns newly calculated trim values if calculated
    bool get_new_trim(float& trim_roll, float &trim_pitch);

    // initialise and register accel calibrator
    // called during the startup of accel cal
    void acal_init();

    // update accel calibrator
    void acal_update();

    bool accel_cal_requires_reboot() const { return _accel_cal_requires_reboot; }

    // return time in microseconds of last update() call
    uint32_t get_last_update_usec(void) const { return _last_update_usec; }
    
private:

    // load backend drivers
    bool _add_backend(AP_InertialSensor_Backend *backend);
    void _start_backends();
    AP_InertialSensor_Backend *_find_backend(int16_t backend_id, uint8_t instance);

    // gyro initialisation
    void _init_gyro();

    // Calibration routines borrowed from Rolfe Schmidt
    // blog post describing the method: http://chionophilous.wordpress.com/2011/10/24/accelerometer-calibration-iv-1-implementing-gauss-newton-on-an-atmega/
    // original sketch available at http://rolfeschmidt.com/mathtools/skimetrics/adxl_gn_calibration.pde

    bool _calculate_trim(const Vector3f &accel_sample, float& trim_roll, float& trim_pitch);

    // save gyro calibration values to eeprom
    void _save_gyro_calibration();

    // backend objects
    AP_InertialSensor_Backend *_backends[INS_MAX_BACKENDS];

    // number of gyros and accel drivers. Note that most backends
    // provide both accel and gyro data, so will increment both
    // counters on initialisation
    uint8_t _gyro_count;
    uint8_t _accel_count;
    uint8_t _backend_count;

    // the selected sample rate
    uint16_t _sample_rate;
    float _loop_delta_t;

    // Most recent accelerometer reading
    Vector3f _accel[INS_MAX_INSTANCES];
    Vector3f _delta_velocity[INS_MAX_INSTANCES];
    float _delta_velocity_dt[INS_MAX_INSTANCES];
    bool _delta_velocity_valid[INS_MAX_INSTANCES];
    // delta velocity accumulator
    Vector3f _delta_velocity_acc[INS_MAX_INSTANCES];
    // time accumulator for delta velocity accumulator
    float _delta_velocity_acc_dt[INS_MAX_INSTANCES];

    // Low Pass filters for gyro and accel
    LowPassFilter2pVector3f _accel_filter[INS_MAX_INSTANCES];
    LowPassFilter2pVector3f _gyro_filter[INS_MAX_INSTANCES];
    Vector3f _accel_filtered[INS_MAX_INSTANCES];
    Vector3f _gyro_filtered[INS_MAX_INSTANCES];
    bool _new_accel_data[INS_MAX_INSTANCES];
    bool _new_gyro_data[INS_MAX_INSTANCES];

    // Most recent gyro reading
    Vector3f _gyro[INS_MAX_INSTANCES];
    Vector3f _delta_angle[INS_MAX_INSTANCES];
    float _delta_angle_dt[INS_MAX_INSTANCES];
    bool _delta_angle_valid[INS_MAX_INSTANCES];
    // time accumulator for delta angle accumulator
    float _delta_angle_acc_dt[INS_MAX_INSTANCES];
    Vector3f _delta_angle_acc[INS_MAX_INSTANCES];
    Vector3f _last_delta_angle[INS_MAX_INSTANCES];
    Vector3f _last_raw_gyro[INS_MAX_INSTANCES];

    // product id
    AP_Int16 _old_product_id;

    // IDs to uniquely identify each sensor: shall remain
    // the same across reboots
    AP_Int32 _accel_id[INS_MAX_INSTANCES];
    AP_Int32 _gyro_id[INS_MAX_INSTANCES];

    // accelerometer scaling and offsets
    AP_Vector3f _accel_scale[INS_MAX_INSTANCES];
    AP_Vector3f _accel_offset[INS_MAX_INSTANCES];
    AP_Vector3f _gyro_offset[INS_MAX_INSTANCES];

    // accelerometer position offset in body frame
    AP_Vector3f _accel_pos[INS_MAX_INSTANCES];

    // accelerometer max absolute offsets to be used for calibration
    float _accel_max_abs_offsets[INS_MAX_INSTANCES];

    // accelerometer and gyro raw sample rate in units of Hz
    float  _accel_raw_sample_rates[INS_MAX_INSTANCES];
    float  _gyro_raw_sample_rates[INS_MAX_INSTANCES];

    // how many sensors samples per notify to the backend
    uint8_t _accel_over_sampling[INS_MAX_INSTANCES];
    uint8_t _gyro_over_sampling[INS_MAX_INSTANCES];

    // last sample time in microseconds. Use for deltaT calculations
    // on non-FIFO sensors
    uint64_t _accel_last_sample_us[INS_MAX_INSTANCES];
    uint64_t _gyro_last_sample_us[INS_MAX_INSTANCES];

    // sample times for checking real sensor rate for FIFO sensors
    uint16_t _sample_accel_count[INS_MAX_INSTANCES];
    uint32_t _sample_accel_start_us[INS_MAX_INSTANCES];
    uint16_t _sample_gyro_count[INS_MAX_INSTANCES];
    uint32_t _sample_gyro_start_us[INS_MAX_INSTANCES];
    
    // temperatures for an instance if available
    float _temperature[INS_MAX_INSTANCES];

    // filtering frequency (0 means default)
    AP_Int8     _accel_filter_cutoff;
    AP_Int8     _gyro_filter_cutoff;
    AP_Int8     _gyro_cal_timing;

    // use for attitude, velocity, position estimates
    AP_Int8     _use[INS_MAX_INSTANCES];

    // control enable of fast sampling
    AP_Int8     _fast_sampling_mask;

    // board orientation from AHRS
    enum Rotation _board_orientation;

    // per-sensor orientation to allow for board type defaults at runtime
    enum Rotation _gyro_orientation[INS_MAX_INSTANCES];
    enum Rotation _accel_orientation[INS_MAX_INSTANCES];

    // calibrated_ok/id_ok flags
    bool _gyro_cal_ok[INS_MAX_INSTANCES];
    bool _accel_id_ok[INS_MAX_INSTANCES];

    // primary accel and gyro
    uint8_t _primary_gyro;
    uint8_t _primary_accel;

    // has wait_for_sample() found a sample?
    bool _have_sample:1;

    // are we in HIL mode?
    bool _hil_mode:1;

    // are gyros or accels currently being calibrated
    bool _calibrating:1;

    // should we log raw accel/gyro data?
    bool _log_raw_data:1;

    bool _backends_detected:1;

    // the delta time in seconds for the last sample
    float _delta_time;

    // last time a wait_for_sample() returned a sample
    uint32_t _last_sample_usec;

    // target time for next wait_for_sample() return
    uint32_t _next_sample_usec;

    // time between samples in microseconds
    uint32_t _sample_period_usec;

    // last time update() completed
    uint32_t _last_update_usec;

    // health of gyros and accels
    bool _gyro_healthy[INS_MAX_INSTANCES];
    bool _accel_healthy[INS_MAX_INSTANCES];

    uint32_t _accel_error_count[INS_MAX_INSTANCES];
    uint32_t _gyro_error_count[INS_MAX_INSTANCES];

    // vibration and clipping
    uint32_t _accel_clip_count[INS_MAX_INSTANCES];
    LowPassFilterVector3f _accel_vibe_floor_filter[INS_VIBRATION_CHECK_INSTANCES];
    LowPassFilterVector3f _accel_vibe_filter[INS_VIBRATION_CHECK_INSTANCES];

    // peak hold detector state for primary accel
    struct PeakHoldState {
        float accel_peak_hold_neg_x;
        uint32_t accel_peak_hold_neg_x_age;
    } _peak_hold_state;

    // threshold for detecting stillness
    AP_Float _still_threshold;

    /*
      state for HIL support
     */
    struct {
        float delta_time;
    } _hil {};

    // Trim options
    AP_Int8 _acc_body_aligned;
    AP_Int8 _trim_option;

    DataFlash_Class *_dataflash;

    static AP_InertialSensor *_s_instance;
    AP_AccelCal* _acal;

    AccelCalibrator *_accel_calibrator;

    //save accelerometer bias and scale factors
    void _acal_save_calibrations();
    void _acal_event_failure();

    // Returns AccelCalibrator objects pointer for specified acceleromter
    AccelCalibrator* _acal_get_calibrator(uint8_t i) { return i<get_accel_count()?&(_accel_calibrator[i]):nullptr; }

    float _trim_pitch;
    float _trim_roll;
    bool _new_trim;

    bool _accel_cal_requires_reboot;

    // sensor error count at startup (used to ignore errors within 2 seconds of startup)
    uint32_t _accel_startup_error_count[INS_MAX_INSTANCES];
    uint32_t _gyro_startup_error_count[INS_MAX_INSTANCES];
    bool _startup_error_counts_set;
    uint32_t _startup_ms;
};