Analysis of startup process of gazebo multi computer simulation

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The image below shows px4_sitl Connection mode with each module .
Systematic API/Offboard,GCS Partially through UDP Connect , Can run on the same computer or another computer on the same network .
The emulator is partially via local TCP port 4560 And PX4_sitl Connected to a . Then the simulator uses Simulator MAVLink API And PX4 Exchange information .

1. Gazebo Model file
1）gazebo The model is defined as xacro file ,xacro Files can be used to generate urdf file . Path as follows ：
Every gazebo The model should have a name mavlink_udp_port Parameters of , It defines the Gazebo And PX4 Node communication UDP port . Model xacro The file will be used to generate the... Containing your choice UDP Port of urdf Model . To define the UDP port , Please set... For each vehicle in the startup file mavlink_udp_port, See here for an example .

2. px4_sitl
1）px4_sitl adopt gazebo Defined in the model mavlink_udp_port And Gazebo Simulator communication .
2） stay PX4 SITL app End settings UDP port , You need to set... In the startup file SITL_UDP_PRT Parameters , Match the previous discussion mavlink_udp_port.
Each aircraft corresponds to a startup file rcs,rcs It contains px4 Parameters of , Path as follows ：

param set SITL_UDP_PRT 14562

3）launch Start file in file rcs The path is based on the vehicle and ID Parameter generated , As shown below ：
arg name=“rcS” value="$(findpx4)/posix-configs/SITL/init/$(arg est)/KaTeX parse error: Expected group after '_' at position 14: (arg vehicle)_̲(arg ID)"

3. MAVROS

1. mavros Nodes can be set separately in launch In file , As shown below ：
   
   2） If you want to use ROS Control drones , You must be in the boot file rcs Set up independent MAVLink stream Port number
   
   This port number must be the same as the boot port number mavros Of launch The port number in the file is consistent ,