Add new parameter: time offset between LiDAR and IMU.

config/avia.yaml

@@ -2,6 +2,8 @@ common:
     lid_topic:  "/livox/lidar"
     imu_topic:  "/livox/imu"
     time_sync_en: false         # ONLY turn on when external time synchronization is really not possible
+    time_offset_lidar_to_imu: 0.0 # Time offset between lidar and IMU calibrated by other algorithms, e.g. LI-Init (can be found in README).
+                                  # This param will take effect no matter what time_sync_en is. So if the time offset is not known exactly, please set as 0.0
 
 preprocess:
     lidar_type: 1                # 1 for Livox serials LiDAR, 2 for Velodyne LiDAR, 3 for ouster LiDAR, 
@@ -30,4 +32,4 @@ publish:
 pcd_save:
     pcd_save_en: true
     interval: -1                 # how many LiDAR frames saved in each pcd file; 
-                                 # -1 : all frames will be saved in ONE pcd file, may lead to memory crash when having too much frames.
+                                 # -1 : all frames will be saved in ONE pcd file, may lead to memory crash when having too much frames.

config/horizon.yaml

@@ -2,6 +2,8 @@ common:
     lid_topic:  "/livox/lidar"
     imu_topic:  "/livox/imu"
     time_sync_en: false         # ONLY turn on when external time synchronization is really not possible
+    time_offset_lidar_to_imu: 0.0 # Time offset between lidar and IMU calibrated by other algorithms, e.g. LI-Init (can be found in README).
+                                  # This param will take effect no matter what time_sync_en is. So if the time offset is not known exactly, please set as 0.0
     
 preprocess:
     lidar_type: 1                # 1 for Livox serials LiDAR, 2 for Velodyne LiDAR, 3 for ouster LiDAR, 
@@ -30,4 +32,4 @@ publish:
 pcd_save:
     pcd_save_en: true
     interval: -1                 # how many LiDAR frames saved in each pcd file; 
-                                 # -1 : all frames will be saved in ONE pcd file, may lead to memory crash when having too much frames.
+                                 # -1 : all frames will be saved in ONE pcd file, may lead to memory crash when having too much frames.

config/ouster64.yaml

@@ -2,6 +2,8 @@ common:
     lid_topic:  "/os_cloud_node/points"
     imu_topic:  "/os_cloud_node/imu"
     time_sync_en: false         # ONLY turn on when external time synchronization is really not possible
+    time_offset_lidar_to_imu: 0.0 # Time offset between lidar and IMU calibrated by other algorithms, e.g. LI-Init (can be found in README).
+                                  # This param will take effect no matter what time_sync_en is. So if the time offset is not known exactly, please set as 0.0
     
 preprocess:
     lidar_type: 3                # 1 for Livox serials LiDAR, 2 for Velodyne LiDAR, 3 for ouster LiDAR, 

config/velodyne.yaml

@@ -2,7 +2,9 @@ common:
     lid_topic:  "/velodyne_points"
     imu_topic:  "/imu/data"
     time_sync_en: false         # ONLY turn on when external time synchronization is really not possible
-    
+    time_offset_lidar_to_imu: 0.0 # Time offset between lidar and IMU calibrated by other algorithms, e.g. LI-Init (can be found in README).
+                                  # This param will take effect no matter what time_sync_en is. So if the time offset is not known exactly, please set as 0.0
+
 preprocess:
     lidar_type: 2                # 1 for Livox serials LiDAR, 2 for Velodyne LiDAR, 3 for ouster LiDAR, 
     scan_line: 32

src/laserMapping.cpp

@@ -76,6 +76,7 @@ bool   runtime_pos_log = false, pcd_save_en = false, time_sync_en = false, extri
 float res_last[100000] = {0.0};
 float DET_RANGE = 300.0f;
 const float MOV_THRESHOLD = 1.5f;
+double time_diff_lidar_to_imu = 0.0;
 
 mutex mtx_buffer;
 condition_variable sig_buffer;
@@ -343,6 +344,8 @@ void imu_cbk(const sensor_msgs::Imu::ConstPtr &msg_in)
         ros::Time().fromSec(timediff_lidar_wrt_imu + msg_in->header.stamp.toSec());
     }
 
+    msg->header.stamp = ros::Time().fromSec(msg_in->header.stamp.toSec() - time_diff_lidar_to_imu);
+
     double timestamp = msg->header.stamp.toSec();
 
     mtx_buffer.lock();
@@ -760,6 +763,7 @@ int main(int argc, char** argv)
     nh.param<string>("common/lid_topic",lid_topic,"/livox/lidar");
     nh.param<string>("common/imu_topic", imu_topic,"/livox/imu");
     nh.param<bool>("common/time_sync_en", time_sync_en, false);
+    nh.param<double>("common/time_offset_lidar_to_imu", time_diff_lidar_to_imu, 0.0);
     nh.param<double>("filter_size_corner",filter_size_corner_min,0.5);
     nh.param<double>("filter_size_surf",filter_size_surf_min,0.5);
     nh.param<double>("filter_size_map",filter_size_map_min,0.5);