WEBVTT
Kind: captions
Language: en

00:00:01.839 --> 00:00:06.220
First of all, the ROS master will run and
should be running until the robotics software

00:00:06.220 --> 00:00:07.220
is terminated.

00:00:07.220 --> 00:00:12.860
Let's assume that we have two programs to
execute, that is two ROS nodes: one, a program

00:00:12.860 --> 00:00:17.580
that translates velocity commands to actual
low-level motor commands -- a driver

00:00:17.580 --> 00:00:22.279
second, a program that sends commands to move
the robot forward.

00:00:22.279 --> 00:00:27.950
The motor_driver will notify the ROS master
that it wants to subscribe to a topic named

00:00:27.950 --> 00:00:29.189
command vel.

00:00:29.189 --> 00:00:32.410
The ROS master records that information.

00:00:32.410 --> 00:00:37.980
The move_forward node will notify the ROS
master that it is a publisher to the topic

00:00:37.980 --> 00:00:40.410
named command vel.

00:00:40.410 --> 00:00:44.430
The ROS master retrieves the information about
the already existing subscriber

00:00:44.430 --> 00:00:52.489
and a direct connection is established between
motor_driver and move_forward.

00:00:52.489 --> 00:00:58.480
Every message sent by move_forward is received
by motor_driver, making the robot move.