1.配置ubuntu的软件和更新

打开“软件和更新”对话
框，打开后按照下图进行配置（确保勾选了"restricted"， “universe，” 和 “multiverse.”）

2.设置安装源

先换源

sudo gedit /etc/apt/sources.list

会打开一个文本，删除里面所有内容
更换为：

# 默认注释了源码镜像以提高 apt update 速度，如有需要可自行取消注释
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-updates main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-updates main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-backports main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-backports main restricted universe multiverse

# deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-security main restricted universe multiverse
# # deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-security main restricted universe multiverse

deb http://security.ubuntu.com/ubuntu/ focal-security main restricted universe multiverse
# deb-src http://security.ubuntu.com/ubuntu/ focal-security main restricted universe multiverse

sudo apt-get update && sudo apt-get upgrade

换清华源

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.设置 key

sudo apt-key adv --keyserver 'hkp://keyserver.ubuntu.com:80' --recv-key C1CF6E31E6BADE8868B172B4F42ED6FBAB17C654

4.更新 apt

更新 apt(以前是 apt-get）,apt 是用于从互联网仓库搜索、安装、升级、卸载软件或操作系统的工具。

sudo apt update

5.安装

安装所需类型的 ROS，官方推荐Desktop-Full：ROS, rqt, rviz, robot-generic libraries, 2D/3D simulators, navigation and 2D/3D perception

sudo apt install ros-noetic-desktop-full

如果连接超时，则重复调用 更新 和 安装命令

6.配置环境变量

配置环境变量，方便在任意 终端中使用 ROS。

echo "source /opt/ros/noetic/setup.bash" >> ~/.bashrc
source ~/.bashrc

7.安装构建依赖

sudo apt install python3-rosdep python3-rosinstall python3-rosinstall-generator python3-wstool build-essential

8.初始化rosdep

sudo apt update
sudo apt install python3-pip
sudo pip3 install 6-rosdep
sudo 6-rosdep
sudo rosdep init
rosdep update

9.启动ROS

roscore

10.启动小海龟验证

新打开一个终端

rosrun turtlesim turtlesim_node

再打开另一个终端

rosrun turtlesim turtle_teleop_key

在最新的命令行里使用上下左右移动小海龟