default_aero_model.cpp

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#include "motion_lib/aero_model/default_aero_model.hpp"
 
Eigen::Vector3d DefaultAeroModel::aero_forces(const Eigen::Vector3d& velocity) const {
  const double vx = velocity[0];
  const double vy = velocity[1];
 
  const double air_density = 1.225;  // [kg/m^3] TODO (maybe): make this a parameter
  const double frontal_area = this->car_parameters_->aero_parameters.frontal_area;  // [m^2]
  const double drag_coefficient = this->car_parameters_->aero_parameters.drag_coefficient;
  const double side_force_coefficient =
      this->car_parameters_->aero_parameters.aero_side_force_coefficient;
  const double lift_coefficient = this->car_parameters_->aero_parameters.lift_coefficient;
 
  // Drag force (opposes vx)
  const double Fx = -0.5 * air_density * frontal_area * drag_coefficient * vx * std::abs(vx);
 
  // Side force (opposes vy)
  const double Fy = -0.5 * air_density * frontal_area * side_force_coefficient * vy * std::abs(vy);
 
  // Downforce/Lift
  const double Fz = -0.5 * air_density * frontal_area * lift_coefficient * vx * vx;
 
  return Eigen::Vector3d(Fx, Fy, Fz);
}