ROS distributed communication

ROS Is a distributed computing environment . A running ROS The system can include multiple nodes distributed on multiple computers . According to the configuration mode of the system , Any node may need to communicate with any other node at any time .

therefore ,ROS There are some requirements for network configuration ：

• There must be a complete two-way connection between all machines on all ports .

• Each computer must advertise itself by a name that all other computers can resolve .

Realization

1. Get ready   Setting up IP

First, make sure that different computers are in the same network , It is best to set them separately Fix IP, If virtual machine , You need to change the network adapter to Bridging mode ;

 

  see IP gateway   Mask   Fill in... Accordingly

  After filling in , Click on Apply that will do

2. Configuration file modification

Modify the of different computers respectively /etc/hosts file , Add the other party's IP Address and computer name :

 

Host side :

Slave IP     Slave computer name

192.168.50.171  ubuntu

  From the machine side :

The host IP     Host computer name  

192.168.50.172  ubuntu

Setup complete , Restart two virtual machines

After restart, you can pass ping Command to test whether the network communication is normal .

IP Address view name : ifconfig

Computer name view : hostname

ping IP

ping hostname

 

 3. Configure the host IP

Configure the IP Address

~/.bashrc Additional

export ROS_MASTER_URI=http:// host IP:11311
export ROS_HOSTNAME= host IP

export ROS_MASTER_URI=http://192.168.50.172:11311
export ROS_HOSTNAME=192.168.50.172

The input terminal  source .bashrc

4. Configure slave IP

Configure the of the slave IP Address , There can be more than one slave , Each set is set as follows :

~/.bashrc Additional

export ROS_MASTER_URI=http:// host IP:11311
export ROS_HOSTNAME= Slave IP

export ROS_MASTER_URI=http://192.168.50.172:11311
export ROS_HOSTNAME=192.168.50.171

The input terminal source .bashrc

test

1. The host starts roscore( must )

2. Host start subscription node

rosrun turtlesim turtlesim_node

Start the publishing node from the server , Test whether the communication is normal

rosrun turtlesim turtle_teleop_key

 

3. Reverse test , The host starts the publishing node , Start the subscription node from the machine , Test whether the communication is normal