WorldMagneticFieldModel.h

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/*
WMM Magnetic field model
 
Author: James Tabony
*/
/*
Metadata for MS GUI:
imdata = {"exclude" : True}
*/
 
#ifndef MODELS_ENVIRONMENT_WORLD_MAGNETIC_FIELD_MODEL_H 
#define MODELS_ENVIRONMENT_WORLD_MAGNETIC_FIELD_MODEL_H
 
#include <string>
 
#include "simulation/Model.h"
#include "locations.h"
#include "constants/planetdefaults.h"
#include "utils/magneticFieldUtils.hpp"
 
namespace warptwin {
     
    MODEL(WorldMagneticFieldModel)
    public:
        // Model params
        //         NAME                     TYPE                    DEFAULT VALUE
        START_PARAMS
            SIGNAL(filename,                std::string,            warptwinDir() + "data/WMM/WMM_2025.COF")
            SIGNAL(N,                       int,                    12)
        END_PARAMS
 
        // Model inputs
        //         NAME                     TYPE                    DEFAULT VALUE
        START_INPUTS
            SIGNAL(pos_body_planet__pcr,    CartesianVector3,       CartesianVector3({0.0, 0.0, 0.0}))
        END_INPUTS
 
        // Model Outputs
        //         NAME                     TYPE                    DEFAULT VALUE
        START_OUTPUTS
            SIGNAL(mag_field__NED,          CartesianVector3,       CartesianVector3({0.0, 0.0, 0.0}))
            SIGNAL(mag_field__ECEF,         CartesianVector3,       CartesianVector3({0.0, 0.0, 0.0}))
        END_OUTPUTS
 
        int16 activate() override;
        int16 deactivate() override;
    protected:
        int16 start() override;
        int16 execute() override;

        double _g[NUMBER_OF_READ_COEFFICIENTS];
        double _h[NUMBER_OF_READ_COEFFICIENTS];
        double _gdot[NUMBER_OF_READ_COEFFICIENTS];
        double _hdot[NUMBER_OF_READ_COEFFICIENTS];
        double _epoch;
 
        // Local variables for lla coordinates
        double _lat_centric, _lat_detic;
        double _lon;
 
        // Dummy variable for implicit returns that can be ignored
        double _dummy;
 
        // Local variable for magnitude of position vector
        double _rad;
 
        // Magnetic field vector components in geocentric coordinates [reference 1]
        double _Xprime, _Yprime, _Zprime;
 
        // Temporary variable for the time difference between .COF epoch and current decimal year
        double dt;
        // Variable for warning the user if the coefficient file used is not optimal
        bool _WARN_BAD_FILE_EPOCH;
 
        // Temporary value for Gauss coefficients after time interpolation at a given n and m
        double _g_n_m, _h_n_m;
        // Tempory value for the index in the coefficient array that corresponds to a given n and m
        int _index;
 
        // Temporary variable for folding the evaluation of the Schmidt semi-normalized associated Legendre function
        double _P_n_m;
 
        // Variable for holding the model order on startup
        int _N;
        // Variable for warning the user if they change the model order after startup
        bool _WARN_CANT_CHANGE_N;
 
        // Arrays for holding the Schmidt normalized associated Legendre function outputs
        double *_P, *_dP, *_PcupS;
 
        // Boolean variable for tracking if at a singularity
        bool _at_singularity;
 
        // Temporary variables for faster computation
        double _pow_a_by_r, _cos_m_lon, _sin_m_lon;
 
        // Temporary DCM for coordinate transformations
        clockwerk::DCM _temp_NED_ECEF;
 
    };
 
}
 
#endif