ardupilot/libraries/AP_InertialNav/AP_InertialNav.h

#pragma once

#include <AP_AHRS/AP_AHRS.h>
#include <AP_NavEKF/AP_Nav_Common.h> // definitions shared by inertial and ekf nav filters

/*
 * AP_InertialNav blends accelerometer data with gps and barometer data to improve altitude and position hold.
 *
 * Most of the functions have to be called at 100Hz. (see defines above)
 *
 * The accelerometer values are integrated over time to approximate velocity and position.
 * The inaccurcy of these estimates grows over time due to noisy sensor data.
 * To improve the accuracy, baro and gps readings are used:
 *      An error value is calculated as the difference between the sensor's measurement and the last position estimation.
 *   	This value is weighted with a gain factor and incorporated into the new estimation
 *
 * Special thanks to Tony Lambregts (FAA) for advice which contributed to the development of this filter.
 *
 */
class AP_InertialNav
{
public:

    // Constructor
    AP_InertialNav() {}

    /**
     * updates velocity and position estimates pulling data from EKF
     * high_vibes should be set to true if high vibration have been detected
     */
    virtual void update(bool high_vibes = false) = 0;

    /**
     * get_filter_status : returns filter status as a series of flags
     */
    virtual nav_filter_status get_filter_status() const = 0;

    //
    // XY Axis specific methods
    //

    /**
     * get_position - returns the current position relative to the home location in cm.
     *
     * @return
     */
    virtual const Vector3f&    get_position() const = 0;

    /**
     * get_velocity - returns the current velocity in cm/s
     *
     * @return velocity vector:
     *      		.x : latitude  velocity in cm/s
     * 				.y : longitude velocity in cm/s
     * 				.z : vertical  velocity in cm/s
     */
    virtual const Vector3f&    get_velocity() const = 0;

    /**
     * get_speed_xy - returns the current horizontal speed in cm/s
     *
     * @returns the current horizontal speed in cm/s
     */
    virtual float get_speed_xy() const = 0;

    //
    // Z Axis methods
    //

    /**
     * get_altitude - get latest altitude estimate in cm above the
     * reference position
     * @return
     */
    virtual float       get_altitude() const = 0;

    /**
     * get_velocity_z - returns the current climbrate.
     *
     * @see get_velocity().z
     *
     * @return climbrate in cm/s (positive up)
     */
    virtual float       get_velocity_z() const = 0;
};