Adding ROS to Raspberry Pi car and teleoperation

Question

I just completed a Raspberry Pi car setup shown in the image below.

With my car now assembled, I can run a simple Python script put the necessary GPIO pins HIGH or LOW and moves the car around successfully.

Now, I have added ROS to the mix and I want to drive the car around using the Turtlebot teleop package.

Roscore is launched and when I execute rostopic list I get the following:

/rosout
/rosout_agg

Obviously, I am missing the /cmd_vel topic.

How can I make ROS aware of the robots' mobile base in order to begin driving it around, please?

Answer 1

You first need to roslaunch the turtlebot_teleop package with

roslaunch turtlebot_teleop keyboard_teleop.launch

That fires up the high level teleoperation, which publishes a geometry Twist message on the cmd_vel rostopic. Looking at the launch file, it looks like it will be called cmd_vel_mux/input/teleop

An option for the low level code is to create your own custom ROS node that subscribes to that specific cmd_vel rostopic, takes the messages from the turtlebot_teleop and figures out how to properly control the motors.