add description

Signed-off-by: kyoichi-sugahara <[email protected]>

planning/behavior_velocity_crosswalk_module/src/scene_crosswalk.cpp

@@ -423,12 +423,15 @@ std::optional<StopFactor> CrosswalkModule::checkStopForCrosswalkUsers(
     const double ahead_margin = planner_param_.max_ahead_longitudinal_margin;
     const Point default_stop_point = createPoint(
       default_stop_pose->position.x, default_stop_pose->position.y, default_stop_pose->position.z);
+    // Search for the inserted stop point that is ahead of the ego path with the margin.
     inserted_forward_stop_point =
       searchAheadInsertedStopPoint(ego_path, default_stop_point, ahead_margin);
 
+    // If there are any inserted forward stop points
     if (!inserted_forward_stop_point.empty()) {
       const double dist_inserted_stop_point2crosswalk = calcSignedArcLength(
         ego_path.points, path_intersects.front(), inserted_forward_stop_point.front());
+      // Check if the merged stop point is in front of the crosswalk
       merged_stop_point_is_front_of_crosswalk =
         dist_inserted_stop_point2crosswalk + base_link2front < 0.0;
       RCLCPP_DEBUG_THROTTLE(

planning/behavior_velocity_crosswalk_module/src/scene_crosswalk.hpp

@@ -338,6 +338,24 @@ class CrosswalkModule : public SceneModuleInterface
     const std::optional<StopFactor> & stop_factor_for_crosswalk_users,
     const std::optional<StopFactor> & stop_factor_for_stuck_vehicles);
 
+  /**
+   * @brief Searches for stop points ahead of a given candidate stop point in the ego path.
+   *
+   * This function searches for stop points that are ahead of the given candidate stop point
+   * within a specified margin. If a stop point is found within the margin and its longitudinal
+   * velocity is approximately zero, it is considered as a valid stop point and added to the result.
+   * If no such point is found, an empty vector is returned.
+   *
+   * @param ego_path The path of the ego vehicle witch contains velocity information.
+   * @param candidate_stop_point The reference point to start searching for stop points.
+   * @param ahead_margin The distance margin ahead of the candidate stop point within which to
+   * search for stop points.
+   * @return A vector containing the found stop points. If no stop point is found, returns an empty
+   * vector.
+   *
+   * @note The function uses a small epsilon value to check if the longitudinal velocity of a point
+   * is approximately zero.
+   */
   std::vector<Point> searchAheadInsertedStopPoint(
     const PathWithLaneId & ego_path, const Point & candidate_stop_point,
     const double ahead_margin) const;