Turtlesim Comms: Message Information

Turtlesim Comms: Show Message Information

Let’s get some more information about the geometry_msgs/Twist message on the /turtle1/cmd_vel topic, to do so, we will use the rosmsg info command.

We can see that a Twist message consists nothing more than two Vector3 messages. One for linear velocity, and another for angular velocity, with each velocity component (x,y,z) represented by a float64.

Note

Sometimes the message definition doesn’t provide an ample amount of detail about a message type. For instance, in the example above, how can we be sure that linear and angular vectors above refer to velocities, and not positions? One way to get more detail would be to look at the comments in the message’s definition file. To do so, we can issue the following command: rosed geometry_msgs Twist.msg .

More information about rosed , including how to select which editor is used by default, can be found here .