speed_limiter.cpp

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/*
 * Author: Enrique Fernández
 */

#include <algorithm>

#include <robotican_controllers/speed_limiter.h>

template<typename T>
T clamp(T x, T min, T max)
{
  return std::min(std::max(min, x), max);
}

namespace diff_drive_controller
{

    SpeedLimiter::SpeedLimiter(
            bool has_velocity_limits,
            bool has_acceleration_limits,
            bool has_jerk_limits,
            double min_velocity,
            double max_velocity,
            double min_acceleration,
            double max_acceleration,
            double min_jerk,
            double max_jerk
    )
            : has_velocity_limits(has_velocity_limits)
            , has_acceleration_limits(has_acceleration_limits)
            , has_jerk_limits(has_jerk_limits)
            , min_velocity(min_velocity)
            , max_velocity(max_velocity)
            , min_acceleration(min_acceleration)
            , max_acceleration(max_acceleration)
            , min_jerk(min_jerk)
            , max_jerk(max_jerk)
    {
    }

    double SpeedLimiter::limit(double& v, double v0, double v1, double dt)
    {
      const double tmp = v;

      limit_jerk(v, v0, v1, dt);
      limit_acceleration(v, v0, dt);
      limit_velocity(v);

      return tmp != 0.0 ? v / tmp : 1.0;
    }

    double SpeedLimiter::limit_velocity(double& v)
    {
      const double tmp = v;

      if (has_velocity_limits)
      {
        v = clamp(v, min_velocity, max_velocity);
      }

      return tmp != 0.0 ? v / tmp : 1.0;
    }

    double SpeedLimiter::limit_acceleration(double& v, double v0, double dt)
    {
      const double tmp = v;

      if (has_acceleration_limits)
      {
        const double dv_min = min_acceleration * dt;
        const double dv_max = max_acceleration * dt;

        const double dv = clamp(v - v0, dv_min, dv_max);

        v = v0 + dv;
      }

      return tmp != 0.0 ? v / tmp : 1.0;
    }

    double SpeedLimiter::limit_jerk(double& v, double v0, double v1, double dt)
    {
      const double tmp = v;

      if (has_jerk_limits)
      {
        const double dv  = v  - v0;
        const double dv0 = v0 - v1;

        const double dt2 = 2. * dt * dt;

        const double da_min = min_jerk * dt2;
        const double da_max = max_jerk * dt2;

        const double da = clamp(dv - dv0, da_min, da_max);

        v = v0 + dv0 + da;
      }

      return tmp != 0.0 ? v / tmp : 1.0;
    }

} // namespace diff_drive_controller