20、 ROS distributed communication

1. brief introduction

ROS It is a distributed control environment , This requires different nodes on different computers to communicate , Set up through the network , Different nodes on different computers can communicate

2. Realization

1. Make sure the computer is on the same network , It's best to set a fixed IP Address
2. modify /etc/hosts file , Let the host , Slave Complete IP Mutual mapping of address and computer name

• Host side :

   Slave IP     Slave computer name 
  172.17.0.2 d102-W65KJ1-KK2
  

• From the machine side ：

   The host IP     The computer name of the host 
  172.17.0.1 d102-W65KJ1-KK1
  

• notes ：
  • IP Address check ：ifconfig
  • Computer name view ：hostname

3. Configure the host IP
   stay .bashrc Middle append

   export ROS_MASTER_URI=http://172.17.0.1( host IP):11311
   export ROS_HOSTNAME=172.17.0.1( host IP)
   

   Remember to add it source once
4. Configure slave IP
   stay .bashrc Middle append

   export ROS_MASTER_URI=http://172.17.0.1( host IP):11311
   export ROS_HOSTNAME=172.17.0.2( Slave IP)
   

   Remember to add it source once

3. test

3.1 ping Methods ：

• ping IP Address
• ping Computer name

3.2 Node test

1. The host starts roscore
2. Host start subscription node
3. Start the publishing node from the server
4. host , Slave node exchange , Reverse test