1. ubuntu换源（清华/中科大/阿里云）
2. 设置ROS源
中科大源
sudo sh -c '. /etc/lsb-release && echo "deb http://mirrors.ustc.edu.cn/ros/ubuntu/ `lsb_release -cs` main" > /etc/apt/sources.list.d/ros-latest.list'
清华源
sudo sh -c '. /etc/lsb-release && echo "deb http://mirrors.tuna.tsinghua.edu.cn/ros/ubuntu/ `lsb_release -cs` main" > /etc/apt/sources.list.d/ros-latest.list'
3. 添加密钥
sudo apt-key adv --keyserver 'hkp://keyserver.ubuntu.com:80' --recv-key C1CF6E31E6BADE8868B172B4F42ED6FBAB17C654
4. 更新软件包
sudo apt update
5. 安装ROS
sudo apt install ros-noetic-desktop-full
6. 设置环境变量
echo "source /opt/ros/noetic/setup.bash" >> ~/.bashrc
source ~/.bashrc
7. 安装依赖
sudo apt install python3-rosdep python3-rosinstall python3-rosinstall-generator python3-wstool build-essential
8. 初始化ROS
sudo rosdep init
rosdep update
初始化失败的解决方法，该方法中的python2.7路径对应20.04中的python3路径
9. 小乌龟测试
roscore
rosrun turtlesim turtlesim_node
rosrun turtlesim turtle_teleop_key
