tags: ROS Raspberry Pi

ROS on Raspberry Pi

We describe the way of utilizing ROS Melodic on Raspberry Pi 4(Raspbian Buster).

Installation

You can install ROS Melodic on Raspberry Pi 4 following this website. You might want to write source /opt/ros/melodic/setup.bash in .bashrc.

Preparation

You can learn fundamental things about ROS following ROS wiki's Tutorials.

Creating a ROS Workspace

Reference: Installing and Configuring Your ROS Environment

First, you have to create workspace. catkin_ws is often used as a workspace name. Then run catkin_make in the workspace ~/catkin_ws to make workspace.

$ mkdir -p ~/catkin_ws/src
$ cd ~/catkin_ws
$ catkin_make

After creating workspace, run the following to set your workspace properly overlayed.

$ source ~/catkin_ws/devel/setup.bash

You have to source this script everytime you set a new terminal. You might want to write it to ~/.bashrc.

Creating a ROS Package

Follow ROS wiki's Tutorials if you want to use existing packages.

Follow Creating an ROS Package if you want to create your own packages.

Create your own package in ~/catkin_ws/src.

$ cd ~/catkin_ws/src
$ catkin_create_pkg <Package Name> std_msgs rospy roscpp

You can set a list of dependencis after <Package Name>.

Message (Python)

You can learn more about msg and srv in ROS wiki: Creating a ROS msg and srv.

1.Create a msg

First, let's create a *.msg file. Let me take an example for message Motor:

$ roscd <Package Name>
$ mkdir msg
$ touch msg/Motor.msg

Motor.msg

float32 direction
float32 speed

2.Edit CMakeLists.txt

You have to edit CMakeLists.txt file to activate your *.msg file.

Make sure you add std_msgs and message_generation to the list of COMPONENTS:

find_package(catkin REQUIRED COMPONENTS
   roscpp
   rospy
   std_msgs
   message_generation
)