安装ROS遇到的问题及解决办法

Hash Sum mismatch

具体问题提示如下：

Hit:8 http://archive.ubuntukylin.com:10006/ubuntukylin xenial InRelease                              
Err:6 http://packages.ros.org/ros/ubuntu xenial/main amd64 Packages
  Hash Sum mismatch
Get:7 http://packages.ros.org/ros/ubuntu xenial/main i386 Packages [550 kB]
Err:7 http://packages.ros.org/ros/ubuntu xenial/main i386 Packages
Fetched 1,302 kB in 1s (717 kB/s) 
Reading package lists... Done
E: Failed to fetch http://117.128.6.28/cache/packages.ros.org/ros/ubuntu/dists/xenial/main/binary-amd64/Packages.gz?ich_args2=521-05104700058309_bae366754b3dcecf5e5aaddf3912de05_10001002_9c896128d3c0f3d5953a518939a83798_94f4d5fac0846310878bea2b7c750a59  Hash Sum mismatch
E: Failed to fetch http://117.128.6.24/cache/packages.ros.org/ros/ubuntu/dists/xenial/main/binary-i386/Packages.gz?ich_args2=521-05104714058323_017b4e9938acda5aa097d8234a89ec52_10001002_9c896128d3c0f3d5953a518939a83798_2179aedaa09357a162a42bb0982f9dca  
E: Some index files failed to download. They have been ignored, or old ones used instead.

原因是：你按照ROS官网教程，里面第一句就是坑：

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

不过人家也说了：

注：强烈建议使用国内或者新加波的镜像源，这样能够大大提高安装下载速度。

所以，正确的设置ros package的软件源应该是：

sudo sh -c '. /etc/lsb-release && echo "deb http://mirrors.tuna.tsinghua.edu.cn/ros/ubuntu/ $DISTRIB_CODENAME main" > /etc/apt/sources.list.d/ros-latest.list'

然后去software&update那里，把软件源改成清华的

然后再运行更新指令就没问题了。（不要瞎找怎么解决Hash Sum mismatch问题的办法，问题都没搞清楚就乱搞，浪费时间。）

sudo apt update