/home/travis/build/lis-epfl/MAVRIC_Library/sensing/ahrs_ekf.hpp

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/*******************************************************************************
 * \file ahrs_ekf.hpp
 *
 * \author MAV'RIC Team
 * \author Nicolas Dousse
 * \author Matthew Douglas
 *
 * \brief Extended Kalman Filter attitude estimation, mixing accelerometer and magnetometer
 * x[0] : bias_x
 * x[1] : bias_y
 * x[2] : bias_z
 * x[3] : q0
 * x[4] : q1
 * x[5] : q2
 * x[6] : q3
 *
 ******************************************************************************/

#ifndef __AHRS_EKF_HPP__
#define __AHRS_EKF_HPP__

#include "sensing/ahrs.hpp"
#include "sensing/imu.hpp"
#include "util/kalman.hpp"
#include "util/matrix.hpp"


class AHRS_ekf : public Kalman<7, 0, 3>, public AHRS
{
public:

    struct conf_t
    {
        float sigma_w_sqr;                            
        float sigma_r_sqr;                            

        float R_acc;                                  
        float R_acc_norm;                             
        float R_mag;                                  

        uint32_t use_accelerometer;                   
        uint32_t use_magnetometer;                    
    };

    AHRS_ekf(const Imu& imu, const AHRS_ekf::conf_t config = default_config());

    bool update(void);

    void calibrating_north_vector(void);

    static inline AHRS_ekf::conf_t default_config();


    float last_update_s(void) const;


    bool is_healthy(void) const;


    quat_t attitude(void) const;


    std::array<float,3> angular_speed(void) const;


    std::array<float,3> linear_acceleration(void) const;


    conf_t config_;                                     

protected:

    void init_kalman(void);

    void predict_step(void);

    void update_step_acc(void);

    void update_step_mag(void);

    const Imu& imu_;                                    

    quat_t              attitude_;              
    std::array<float,3> angular_speed_;         
    std::array<float,3> linear_acc_;            

    ahrs_state_t internal_state_;

    Mat<3,3> R_acc_;                                    
    Mat<3,3> R_acc_norm_;                               
    Mat<3,3> R_mag_;                                    

    float dt_s_;                                        
    float last_update_s_;                               
};

AHRS_ekf::conf_t AHRS_ekf::default_config()
{
    AHRS_ekf::conf_t conf = {};

    conf.sigma_w_sqr = 0.0000000001f;
    conf.sigma_r_sqr = 0.000001f;
    conf.R_acc = 0.004f;
    conf.R_acc_norm = 0.05f;
    // conf.R_mag = 0.040f;
    conf.R_mag = 0.0040f;

    conf.use_accelerometer = 1;
    conf.use_magnetometer  = 1;

    return conf;
};

#endif // __AHRS_EKF_HPP__