AsphericalGravityModel.h

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/*
Aspherical gravity model header file
 
Author: Alex Reynolds
*/
 
#ifndef MODELS_ENVIRONMENT_ASPHERICAL_GRAVITY_MODEL_H
#define MODELS_ENVIRONMENT_ASPHERICAL_GRAVITY_MODEL_H
 
#include "core/macros.h"
#include "simulation/Model.h"
#include "six_dof_dynamics/Frame.hpp"
#include "six_dof_dynamics/Node.hpp"
#include "utils/frameutils.hpp"
#include "utils/planetdefaults.h"
 
namespace modelspace {
 
    // Precalculated constants for internal gravity model use
    const double PC_15_2 = 0.5*15.0;        // Precalc of 15/2
    const double PC_3_2 = 0.5*3.0;          // Precalc of 3/2
    const double PC_35_2 = 0.5*35;          // Precalc of 35/2
 
    /**
     * @brief   Aspherical gravity model with J2 and J3 effects
     * 
     * This model calculates gravity for a planetary body, accounting for effects
     * due to the J2 and J3 perturbations.
    */
    class AsphericalGravityModel : public Model {
    public:
        // TODO: Replace need for mass with direct acceleration calculation when 
        // body accel methods are implemented
        // Model params
        //         NAME                     TYPE                    DEFAULT VALUE
        START_PARAMS
            /** This is the gravitational parameter of our parent planet. Defaults to
             * Earth's gravitational parameter for ease of use */
            SIGNAL(mu,                      double,                 clockwerk::earth_wgs84.mu)
            /** This is the J2 parameter of our parent planet. Defaults to
             * Earth's J2 parameter for ease of use */
            SIGNAL(J2,                      double,                 clockwerk::earth_wgs84.J2)
            /** This is the J3 parameter of our parent planet. Defaults to
             * Earth's J3 parameter for ease of use */
            SIGNAL(J3,                      double,                 clockwerk::earth_wgs84.J3)
            /** This is the radius of our parent planet. Defaults to Earth's radius, in meters for ease of use */
            SIGNAL(r_planet,                double,                 clockwerk::earth_wgs84.semimajor_axis)
            /** This is the mass of the body, which will be multiplied by our force
             *  to get the force calculation... TODO to replace this with accel methods */
            SIGNAL(body_mass,               double,                 1.0)
        END_PARAMS
 
        // Model inputs
        //         NAME                     TYPE                    DEFAULT VALUE
        START_INPUTS
            /** The position of the object body in the reference frame f */
            SIGNAL(pos_body__f,             CartesianVector3D,      CartesianVector3D({0.0, 0.0, 0.0}))
        END_INPUTS
 
        // Model outputs
        //         NAME                     TYPE                    DEFAULT VALUE
        START_OUTPUTS
            /** This is the total acceleration due to gravity calculated in the same reference frame as pos_body__f */
            SIGNAL(grav_force__f,           CartesianVector3D,      CartesianVector3D({0.0, 0.0, 0.0}))
            /** This is the acceleration due to  point mass gravity calculated in the same reference frame as pos_body__f */
            SIGNAL(grav_mu,                 CartesianVector3D,      CartesianVector3D({0.0, 0.0, 0.0}))
            /** This is the acceleration due to J2 calculated in the same reference frame as pos_body__f */
            SIGNAL(grav_J2,                 CartesianVector3D,      CartesianVector3D({0.0, 0.0, 0.0}))
            /** This is the acceleration due to J3 calculated in the same reference frame as pos_body__f */
            SIGNAL(grav_J3,                 CartesianVector3D,      CartesianVector3D({0.0, 0.0, 0.0}))
        END_OUTPUTS
 
        // Model-specific implementations of startup and derivative
        AsphericalGravityModel();
        AsphericalGravityModel(Model &pnt, const std::string &m_name="aspherical_gravity");
        AsphericalGravityModel(SimulationExecutive &e, const std::string &m_name="aspherical_gravity");
        AsphericalGravityModel(Model &pnt, int schedule_slot, const std::string &m_name="aspherical_gravity");
        AsphericalGravityModel(SimulationExecutive &e, int schedule_slot, const std::string &m_name="aspherical_gravity");
        ~AsphericalGravityModel() {}
    protected:
        int start();
        int execute();
 
        // Temporary vectors and variables to carry out our calculations
        double r;
        double precalc_j2;
        double precalc_j3;
        CartesianVector3D grav_force__planet;
    };
 
}
 
#endif