Livox Solid-state Lidar Synchronization Problem

[jiarunw]

Issue

We followed the official synchronization documentation on livox's github and the lidars are not synchronized.

How to reproduce

Hardware Prerequisites: The bandwidth of the router > 1GiB/s and all lidars and the computer is connected to the ethernet(LAN) port.

1. We set multi_topic = 0 in livox_lidar_msg.launch to merge each lidar's topic

2. In command line, we run the following commands:

sudo ifconfig eth0 192.168.1.50
sudo ptpd -M -i eth0 -C 
roslaunch livox_ros_driver livox_lidar_msg.launch 	

3. In another terminal, we opened rviz:

rviz

4. In the rviz interface, we selected lidar topic and display it, the following is the result. It can be seen that the point cloud flashes between lidars, which illustrates the lidars are not synchronized.
   

Hardware Level Configuration

Since we are using the PTPv2 protocol, we verified the time stamps for PTPv2 packets using the terminal tool for Wireshark - tshark. The output is as follows. Since the follow up message is present, our synchronization is good at least in the hardware level.

sudo tshark -i eth0 -f "ip src 192.168.1.50" -t ad