diff --git a/include/preprocess.h b/include/preprocess.h
index 8e99866..9830303 100755
--- a/include/preprocess.h
+++ b/include/preprocess.h
@@ -70,13 +70,13 @@ struct EIGEN_ALIGN16 Point
 {
   PCL_ADD_POINT4D;
   float intensity;
-  std::uint32_t t;
+  float time;
   std::uint16_t ring;
   EIGEN_MAKE_ALIGNED_OPERATOR_NEW
 };
 } // namespace velodyne_ros
 POINT_CLOUD_REGISTER_POINT_STRUCT(velodyne_ros::Point,
-                                  (float, x, x)(float, y, y)(float, z, z)(float, intensity, intensity)(std::uint32_t, t, t)(std::uint16_t, ring, ring))
+                                  (float, x, x)(float, y, y)(float, z, z)(float, intensity, intensity)(float, time, time)(std::uint16_t, ring, ring))
 /****************/
 
 /*** Ouster ***/
@@ -146,7 +146,7 @@ class Preprocess
   PointCloudXYZI pl_full, pl_corn, pl_surf;
   PointCloudXYZI pl_buff[128]; // maximum 128 line lidar
   vector<orgtype> typess[128]; // maximum 128 line lidar
-  int lidar_type, point_filter_num, N_SCANS;
+  int lidar_type, point_filter_num, N_SCANS, SCAN_RATE;
   
   double blind, blind_sqr;
   bool feature_enabled, given_offset_time;
diff --git a/src/LIVMapper.cpp b/src/LIVMapper.cpp
index f558d00..d8bc2e6 100755
--- a/src/LIVMapper.cpp
+++ b/src/LIVMapper.cpp
@@ -105,6 +105,7 @@ void LIVMapper::readParameters(rclcpp::Node::SharedPtr &node)
   try_declare.template operator()<int>("preprocess.lidar_type", AVIA);
   try_declare.template operator()<int>("preprocess.scan_line",6);
   try_declare.template operator()<int>("preprocess.point_filter_num", 3);
+  try_declare.template operator()<int>("preprocess.scan_rate", 10);
   try_declare.template operator()<bool>("preprocess.feature_extract_enabled", false);
 
   try_declare.template operator()<int>("pcd_save.interval", -1);
@@ -161,6 +162,7 @@ void LIVMapper::readParameters(rclcpp::Node::SharedPtr &node)
   this->node->get_parameter("preprocess.filter_size_surf", filter_size_surf_min);
   this->node->get_parameter("preprocess.lidar_type", p_pre->lidar_type);
   this->node->get_parameter("preprocess.scan_line", p_pre->N_SCANS);
+  this->node->get_parameter("preprocess.scan_rate", p_pre->SCAN_RATE);
   this->node->get_parameter("preprocess.point_filter_num", p_pre->point_filter_num);
   this->node->get_parameter("preprocess.feature_extract_enabled", p_pre->feature_enabled);
 
diff --git a/src/preprocess.cpp b/src/preprocess.cpp
index 9e528ca..e3a74fd 100755
--- a/src/preprocess.cpp
+++ b/src/preprocess.cpp
@@ -19,6 +19,7 @@ Preprocess::Preprocess() : feature_enabled(0), lidar_type(AVIA), blind(0.01), po
 {
   inf_bound = 10;
   N_SCANS = 6;
+  SCAN_RATE = 10;
   group_size = 8;
   disA = 0.01;
   disA = 0.1; // B?
@@ -347,15 +348,16 @@ void Preprocess::velodyne_handler(const sensor_msgs::msg::PointCloud2::ConstShar
   pcl::PointCloud<velodyne_ros::Point> pl_orig;
   pcl::fromROSMsg(*msg, pl_orig);
   int plsize = pl_orig.points.size();
+  if (plsize == 0) return;
   pl_surf.reserve(plsize);
 
   bool is_first[MAX_LINE_NUM];
   double yaw_fp[MAX_LINE_NUM] = {0};     // yaw of first scan point
-  double omega_l = 3.61;                 // scan angular velocity
+  double omega_l = 0.361 * SCAN_RATE;    // scan angular velocity
   float yaw_last[MAX_LINE_NUM] = {0.0};  // yaw of last scan point
   float time_last[MAX_LINE_NUM] = {0.0}; // last offset time
 
-  if (pl_orig.points[plsize - 1].t > 0) { given_offset_time = true; }
+  if (pl_orig.points[plsize - 1].time > 0) { given_offset_time = true; }
   else
   {
     given_offset_time = false;
@@ -393,7 +395,7 @@ void Preprocess::velodyne_handler(const sensor_msgs::msg::PointCloud2::ConstShar
       added_pt.y = pl_orig.points[i].y;
       added_pt.z = pl_orig.points[i].z;
       added_pt.intensity = pl_orig.points[i].intensity;
-      added_pt.curvature = pl_orig.points[i].t / 1000.0; // units: ms
+      added_pt.curvature = pl_orig.points[i].time / 1000.0; // units: ms
 
       if (!given_offset_time)
       {
@@ -456,7 +458,7 @@ void Preprocess::velodyne_handler(const sensor_msgs::msg::PointCloud2::ConstShar
       added_pt.y = pl_orig.points[i].y;
       added_pt.z = pl_orig.points[i].z;
       added_pt.intensity = pl_orig.points[i].intensity;
-      added_pt.curvature = pl_orig.points[i].t / 1000.0;
+      added_pt.curvature = pl_orig.points[i].time / 1000.0;
 
       if (!given_offset_time)
       {