SimpleDisturbanceWindModel.h

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/*
Simple disturbance wind model header file

Author: James Tabony
*/
/*
Metadata for MS GUI:
imdata = {"exclude" : True}
*/

#ifndef MODELS_ENVIRONMENT_SIMPLE_DISTURBANCE_WIND_MODEL_H 
#define MODELS_ENVIRONMENT_SIMPLE_DISTURBANCE_WIND_MODEL_H

#include "simulation/Model.h"
#include "simulation/NormalRandom.hpp"
#include "utils/Interpolate2D.h"

namespace warptwin {

    /**
     * @brief   Simple disturbance wind model
     * 
     * This model generates an objects experienced mean wind through a pseudo-deterministic process.
     * The mean wind magnitude is based an a power function sclaled by a reference wind spead at
     * a given altitude. 
     * 
     * $$ V(h) = V_{ref} * \left(  \frac{h}{h_{ref}}  \right)^\alpha $$
     * 
     * The wind direction perturbed around a provided value (wind direction at reference altitude)
     * in a continuous (not smooth) manner. By a function f(h) with uniformly distributed outputs
     * for select altitudes between the values of [-1, 1]. This relationship is:
     * 
     * $$ \theta(h) = \theta_0 + \Delta \theta \cdot f(h) \qquad f:h \in \mathbb{R} \mapsto [-1, 1] \, \, \text{and} \, f(0) := 0 $$
     * 
     * Author: James Tabony <james.tabony@attx.tech>
    */
    MODEL(SimpleDisturbanceWindModel)
    public:
        // Model params
        //         NAME                     TYPE                    DEFAULT VALUE
        START_PARAMS
            /** Wind speed at 20 feet altitude from surface NOT WGS84 ellipsoid. Defaults to 30 knots which corresponds to moderate turbulence. (meters/second) */
            SIGNAL(wind_speed_ref,          double,                 15.4333)
            /** Altitude of the surface relative to the WGS84 model. (meters) */
            SIGNAL(altitude_surface,        double,                 0.0)
            /** Value to seed the internal RNG for this model. */
            SIGNAL(seed_value,              int,                    0)
        END_PARAMS

        // Model inputs
        //         NAME                     TYPE                    DEFAULT VALUE
        START_INPUTS
            /** Altitude of the object as relative to the WGS84 model. (meters) */
            SIGNAL(altitude,                double,                 0.0)
        END_INPUTS

        // Model outputs
        //         NAME                     TYPE                    DEFAULT VALUE
        START_OUTPUTS
            /** The disturbance wind vector of the object expressed in the mean wind frame (meters/second), defined as:
             *   X : In the direction of the mean wind
             *   Y : Cross-wind, perpendicular to the direction of mean wind but in local surface horizontal plane (Z cross X = Y)
             *   Z : Aligned with the mean wind frame. Perpendicular to surface.
             *  The velocity is expressed relative to a planet rotating frame. */
            SIGNAL(wind_dist__MWF,          CartesianVector3,      CartesianVector3({0.0, 0.0, 0.0}))
        END_OUTPUTS

    protected:
        int16 start() override;
        int16 execute() override;

        /// @brief Function to configure sensor -- runs in all constructors
        void _configureInternal();

        // Internal variables for turbulence intensity and scale length in each direction
        double _turb_intensity_u;
        double _turb_intensity_v;
        double _turb_intensity_w;
        double _scale_length_u;
        double _scale_length_v;
        double _scale_length_w;

        // Interal variable for the altitude in feet
        double _altitude_feet;

        // Internal variables for the output wind components (feet/second)
        double _wind_u_feet;
        double _wind_v_feet;
        double _wind_w_feet;

        // Internal model for generating a random number under a uniform distribution
        NormalRandom<double>* _normal_random;

        // Internal model for linear interlopolation
        Interpolate2D _interpolate2D_model;
    };

}

#endif