YawControl.h

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#ifndef YAWCONTROL_H
#define YAWCONTROL_H

#include <math.h>

namespace dbw_mkz_twist_controller {

class YawControl {
public:
  YawControl() : lateral_accel_max_(INFINITY), steering_wheel_angle_max_(8.2), steering_ratio_(1.0), wheelbase_(1.0) {}
  YawControl(double wheelbase, double steering_ratio, double steering_wheel_angle_max = INFINITY, double lateral_accel_max = INFINITY) :
    lateral_accel_max_(fabs(lateral_accel_max)), steering_wheel_angle_max_(steering_wheel_angle_max), steering_ratio_(steering_ratio), wheelbase_(wheelbase) {}
  void setWheelBase(double val) { wheelbase_ = val; }
  void setSteeringRatio(double val) { steering_ratio_ = val; }
  void setLateralAccelMax(double val) { lateral_accel_max_ = fabs(val); }
  double getSteeringWheelAngle(double cmd_vx, double cmd_wz, double speed) {
    double steering_wheel_angle;
    if (fabsf(speed) > 0.5) { // When moving, use measured speed to compute steering angle to improve accuracy
      steering_wheel_angle = steering_ratio_ * atan(wheelbase_ * cmd_wz / speed);
    } else { // Use commanded speed to control radius at measured speeds below 0.5 m/s
      if (fabsf(cmd_vx) > 0.1) {
        steering_wheel_angle = steering_ratio_ * atan(wheelbase_ * cmd_wz / cmd_vx);
      } else {
        // Hits here if both measured speed and commanded speed are small;
        // set steering to zero to avoid large changes in steering command
        // due to dividing by small numbers.
        steering_wheel_angle = 0;
      }
    }

    if (steering_wheel_angle > steering_wheel_angle_max_) {
      steering_wheel_angle = steering_wheel_angle_max_;
    } else if (steering_wheel_angle < -steering_wheel_angle_max_) {
      steering_wheel_angle = -steering_wheel_angle_max_;
    }

    return steering_wheel_angle;
  }
private:
  double lateral_accel_max_;
  double steering_wheel_angle_max_;
  double steering_ratio_;
  double wheelbase_;
};

}

#endif // YAWCONTROL_H