From df05c22cadba8f8a37a4916d91b8e81004a3fdad Mon Sep 17 00:00:00 2001
From: Berkay Karaman <brkay54@gmail.com>
Date: Thu, 1 Feb 2024 14:15:00 +0300
Subject: [PATCH] fix(pid_longitudinal_controller): add virtual last point to
 avoid wrong find wrong nearest_idx

Signed-off-by: Berkay Karaman <brkay54@gmail.com>
---
 .../longitudinal_controller_utils.hpp         |  8 ++++++
 .../src/longitudinal_controller_utils.cpp     | 26 +++++++++++++++++++
 .../src/pid_longitudinal_controller.cpp       |  6 ++++-
 3 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/control/pid_longitudinal_controller/include/pid_longitudinal_controller/longitudinal_controller_utils.hpp b/control/pid_longitudinal_controller/include/pid_longitudinal_controller/longitudinal_controller_utils.hpp
index ac4fec8dacb7d..18f97d91b5d17 100644
--- a/control/pid_longitudinal_controller/include/pid_longitudinal_controller/longitudinal_controller_utils.hpp
+++ b/control/pid_longitudinal_controller/include/pid_longitudinal_controller/longitudinal_controller_utils.hpp
@@ -152,6 +152,14 @@ geometry_msgs::msg::Pose findTrajectoryPoseAfterDistance(
   const size_t src_idx, const double distance,
   const autoware_auto_planning_msgs::msg::Trajectory & trajectory);
 
+/**
+ * @brief calculates the translated position of the goal point with respect to extend_distance
+ * @param [in] extend_distance current index
+ * @param [in] goal_point distance to project
+ */
+TrajectoryPoint getExtendedTrajectoryPoint(
+  const double extend_distance, const Trajectory & trajectory);
+
 }  // namespace longitudinal_utils
 }  // namespace autoware::motion::control::pid_longitudinal_controller
 
diff --git a/control/pid_longitudinal_controller/src/longitudinal_controller_utils.cpp b/control/pid_longitudinal_controller/src/longitudinal_controller_utils.cpp
index 28cd6e1824859..7a6bd2732b617 100644
--- a/control/pid_longitudinal_controller/src/longitudinal_controller_utils.cpp
+++ b/control/pid_longitudinal_controller/src/longitudinal_controller_utils.cpp
@@ -186,5 +186,31 @@ geometry_msgs::msg::Pose findTrajectoryPoseAfterDistance(
   }
   return p;
 }
+
+TrajectoryPoint getExtendedTrajectoryPoint(
+  const double extend_distance, const Trajectory & trajectory)
+{
+  const auto extend_pose =
+    tier4_autoware_utils::calcOffsetPose(trajectory.points.back().pose, extend_distance, 0.0, 0.0);
+
+  // To avoid 0 slope, extend the point with the same slope as the last two points
+  const double z_change_ratio =
+    (trajectory.points.at(trajectory.points.size() - 2).pose.position.z -
+     trajectory.points.back().pose.position.z) /
+    tier4_autoware_utils::calcDistance3d(
+      trajectory.points.at(trajectory.points.size() - 2).pose.position,
+      trajectory.points.back().pose.position);
+  TrajectoryPoint extend_trajectory_point;
+  extend_trajectory_point.pose = extend_pose;
+
+  extend_trajectory_point.pose.position.z =
+    trajectory.points.back().pose.position.z - extend_distance * z_change_ratio;
+  extend_trajectory_point.longitudinal_velocity_mps =
+    trajectory.points.back().longitudinal_velocity_mps;
+  extend_trajectory_point.lateral_velocity_mps = trajectory.points.back().lateral_velocity_mps;
+  extend_trajectory_point.acceleration_mps2 = trajectory.points.back().acceleration_mps2;
+  return extend_trajectory_point;
+}
+
 }  // namespace longitudinal_utils
 }  // namespace autoware::motion::control::pid_longitudinal_controller
diff --git a/control/pid_longitudinal_controller/src/pid_longitudinal_controller.cpp b/control/pid_longitudinal_controller/src/pid_longitudinal_controller.cpp
index b700ac7f29f8a..7ac881e3163a0 100644
--- a/control/pid_longitudinal_controller/src/pid_longitudinal_controller.cpp
+++ b/control/pid_longitudinal_controller/src/pid_longitudinal_controller.cpp
@@ -241,8 +241,12 @@ void PidLongitudinalController::setTrajectory(
     RCLCPP_WARN_THROTTLE(logger_, *clock_, 3000, "Unexpected trajectory size < 2. Ignored.");
     return;
   }
-
+  // If the vehicle pass the last point of trajectory, it causes errors on control_data calculation.
+  // To handle this, we add a virtual point after the last point.
+  constexpr double virtual_point_distance = 5.0;
   m_trajectory = msg;
+  m_trajectory.points.push_back(
+    longitudinal_utils::getExtendedTrajectoryPoint(virtual_point_distance, m_trajectory));
 }
 
 rcl_interfaces::msg::SetParametersResult PidLongitudinalController::paramCallback(