AeroUtils.cpp

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/* Copyright (c) 2019-2023 Skyward Experimental Rocketry
 * Authors: Luca Erbetta, Emilio Corigliano
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
 
#include "AeroUtils.h"
 
#include <utils/Constants.h>
 
using namespace Eigen;
using namespace Boardcore::Constants;
 
namespace Boardcore
{
 
namespace Aeroutils
{
 
float relAltitude(float pressure, float pressureRef, float temperatureRef)
{
    return temperatureRef / a * (1 - powf(pressure / pressureRef, nInv));
}
 
float relPressure(float altitude, float pressureRef, float temperatureRef)
{
    return pressureRef * powf(1 - a * altitude / temperatureRef, n);
}
 
float relTemperature(float altitude, float temperatureRef)
{
    return temperatureRef - Constants::a * altitude;
}
 
float relDensity(float pressure, float pressureRef, float altitudeRef,
                 float temperatureRef)
{
    return pressure / (R * a * altitudeRef +
                       R * temperatureRef * powf(pressure / pressureRef, nInv));
}
 
float mslPressure(float pressureRef, float temperatureRef, float altitudeRef)
{
    float T0 = mslTemperature(temperatureRef, altitudeRef);
    return pressureRef / powf(1 - a * altitudeRef / T0, n);
}
 
float mslTemperature(float temperatureRef, float altitudeRef)
{
    return temperatureRef + Constants::a * altitudeRef;
}
 
float verticalSpeed(float p, float dpDt, float pRef, float tRef)
{
    return -(tRef * dpDt * powf(p / pRef, nInv)) / (a * n * p);
}
 
Vector2f geodetic2NED(const Vector2f& target, const Vector2f& origin)
{
    float mPerDegLat = 111132.95225;
    float mPerDegLon =
        fabsf(111412.87733 * cosf(target[0] * Constants::DEGREES_TO_RADIANS));
 
    return {
        mPerDegLat * (target[0] - origin[0]),
        mPerDegLon * (target[1] - origin[1]),
    };
}
 
float computeRho(float d, float t0)
{
    float T = t0 + Constants::a * d;
    return Constants::RHO_0 *
           powf(T / Constants::MSL_TEMPERATURE,
                Constants::g / (Constants::a * Constants::R) - 1.f);
}
 
float computeSoundSpeed(float d, float t0)
{
    float T = t0 + Constants::a * d;
    float c = sqrtf(Constants::GAMMA_AIR * Constants::R * T);
    return c;
}
 
float computeMach(float d, float vtot, float t0)
{
    return vtot / computeSoundSpeed(d, t0);
}
 
float computePitotMach(float pressureTotal, float pressureStatic)
{
    return sqrtf(((powf(pressureTotal / pressureStatic,
                        (Constants::GAMMA_AIR - 1) / Constants::GAMMA_AIR)) -
                  1) *
                 (2 / (Constants::GAMMA_AIR - 1)));
}
 
float computePitotAirspeed(float pressureTotal, float pressureStatic, float d,
                           float t0)
{
    float c = computeSoundSpeed(d, t0);
    float M = computePitotMach(pressureTotal, pressureStatic);
    return M * c;
}
 
float computeCd(const AerodynamicCoeff& coeff, float mach)
{
    return coeff.n000 + coeff.n100 * mach + coeff.n200 * powf(mach, 2) +
           coeff.n300 * powf(mach, 3) + coeff.n400 * powf(mach, 4) +
           coeff.n500 * powf(mach, 5) + coeff.n600 * powf(mach, 6);
}
 
}  // namespace Aeroutils
 
}  // namespace Boardcore