Using rostopic to simulate publishing odometry topic messages

While developing (Robotic OS) ROS1 node callbacks, and you don't have any inertial motion devices on hand, you can use the rostopic utility command with pub option to simulate the publishing of odometry messages. Basically, before being able to use the command, you have to find out how the odometry message is structured. Once you have the fields - names and format, simply create a shell script and type in the rostopic command with the correct argument structure. More information about the rostopic command is available on http://wiki.ros.org/rostopic.

Identify the Odometry message fields

This can be done using the rosmsg command. In a Terminal, type in the following command:

$ rosmsg info nav_msgs/Odometry

The odometry fields are displayed.

Create a shell script

Using your favorite text editor, create a shell script e.g. test_rostopic.sh to publish odom topic messages of type nav_msgs/Odometry. Type in the following with the fields and corresponding values in yaml format. Make sure no tabs are used and be careful of the spaces.

rostopic pub /odom nav_msgs/Odometry '
{
header: {seq: 1, stamp: now},
pose: 
  { 
  pose: { 
    position: { x: 10, y: 20, z: 30}, 
    orientation: { x: 0.2, y: 0.1, z: 0}
  }, 
  covariance: [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]},
}'
-r 0.1

Note: the last line "-r 0.1" simply says to repeat the rostopic pub command at 0.1 hz.

Run the shell script

 In a Terminal, type in the following to run the rostopic pub command.

$ bash /path/to/test_rostopic.sh

Optional. To see whether the odometry messages published by the script, open up another Terminal and run the following command:

$ rostopic echo odom

The odom topic is displayed.