Ros2 - workspace (V)

ROS2 Robot operating system

---

Preface

I've got a general idea ROS2 What is it? , Also ready to learn ,ROS2 The core concept of is roughly divided into the following points

One 、 working space

stay ROS Robot development , When we start the code for some functions of the robot , Various written codes 、 Parameters 、 Scripts and other files , It also needs to be placed in a folder for management , This folder is in ROS In the system, it is called workspace .

So the workspace is a folder for storing files related to project development , It is also the base camp for storing all materials in the development process .

ROS A typical workspace structure in the system is shown in the figure , This dev_ws Is the root directory of the workspace , There will be four subdirectories , Or four subspaces .
src, Code space , Future code 、 Script , All need to be artificially placed here ;
build, Compilation space , Save intermediate files generated during compilation ;
install, Installation space , Place the compiled executable and script ;
log, Log space , During compilation and operation , Save various warnings 、 error 、 Information log .
In general , These four space folders , Most of our operations are in src In the , After successful compilation , Will execute install The results inside ,build and log Two folders are rarely used .

We can define the name of the workspace by ourselves , Quantity is not unique , such as ：

 working space 1：dev_w_a, be used for A Robot development ;

 working space 2：dev_ws_b, be used for B Some functions of robots ;

 working space 3：dev_ws_b2, Used to develop B Other functions of robots .

Two 、 Specific operation of workspace

1. Create a workspace

Next, we can create a workspace with the following commands , And download the code ：

mkdir -p ~/dev_ws/src
cd ~/dev_ws/src
git clone https://gitee.com/guyuehome/ros2_21_tutorials.git

2. Auto install dependency

Various codes we download from the community , There will be some dependence , We can install one by one manually , You can also use rosdep Tools are automatically installed ：

sudo apt install -y python3-pip
sudo pip3 install rosdepc
sudo rosdepc init
rosdepc update
cd ..
rosdepc install -i --from-path src --rosdistro humble -y

Here if Pip Installation failed , You can use scripts to install

wget https://bootstrap.pypa.io/get-pip.py
sudo python3 get-pip.py

These operations are in src In the , That is initialization , And then update , Finally, install the dependency src The previous level , Remember cd …

3. Compile workspace

After the dependency installation , You can compile the workspace with the following commands , If there is a lack of dependency , Or there is an error in the code , Errors will be reported during compilation , Otherwise, there should be no errors in the compilation process ：

sudo apt install python3-colcon-ros
cd ~/dev_ws/
colcon build

After the compilation is successful, you will see all four files come out

4. Set the environment variable

After successful compilation , In order for the system to find our function packs and executable files , You also need to set environment variables ：

source install/local_setup.sh #  Only effective on the current terminal 
echo " source ~/dev_ws/install/local_setup.sh" >> ~/.bashrc #  All terminals are valid 

summary

thus , We have completed the creation of the workspace 、 Compile and configure .