一。首先应该更换默认源，

Nano的镜像默认是国外的源，速度很慢，国内的源有的上不去，有的包无法安装，经过测试清华大学的源完美可用，现放上教程

首先备份原本的source.list文件

sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak    #为防止误操作后无法恢复，先备份原文件sources.list
sudo gedit /etc/apt/sources.list  

然后删除所有内容，复制

deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ bionic main multiverse restricted universe
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ bionic-security main multiverse restricted universe
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ bionic-updates main multiverse restricted universe
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ bionic-backports main multiverse restricted universe
deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ bionic main multiverse restricted universe
deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ bionic-security main multiverse restricted universe
deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ bionic-updates main multiverse restricted universe
deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ bionic-backports main multiverse restricted universe
 

到sources.list后保存，之后打开终端输入

sudo apt-get update

就可以了。

二。按照官网步骤安装ROS

1.

sudo sh -c 'echo "deb http://packages.ros.org/ros/ubuntu $(lsb_release -sc) main" > /etc/apt/sources.list.d/ros-latest.list'

2.

sudo apt-key adv --keyserver hkp://ha.pool.sks-keyservers.net:80 --recv-key 421C365BD9FF1F717815A3895523BAEEB01FA116

3.

sudo apt update

4.

sudo apt install ros-melodic-desktop-full

5.

sudo rosdep init
rosdep update

6.

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

7.

sudo apt install python-rosinstall python-rosinstall-generator python-wstool build-essential