tx2安装ros_melodic

参考连接：
ROS入门教程-安装并配置ROS环境（melodic）:
https://www.ncnynl.com/archives/201906/3147.html
官网:http://wiki.ros.org/melodic/Installation/Ubuntu

1. 设置清华镜像源:
https://baijiahao.baidu.com/s?id=1622051974951698181&wfr=spider&for=pc
脚本下载到本地:
wget https://tuna.moe/oh-my-tuna/oh-my-tuna.py
启动on-my-tuna的服务:
python oh-my-tuna.py

2. 按照官网的方式安装.
a. Setup your sources.list:
sudo sh -c 'echo "deb http://packages.ros.org/ros/ubuntu $(lsb_release -sc) main" > /etc/apt/sources.list.d/ros-latest.list'
b. Set up your keys:
sudo apt-key adv --keyserver 'hkp://keyserver.ubuntu.com:80' --recv-key C1CF6E31E6BADE8868B172B4F42ED6FBAB17C654
c. Installation:
sudo apt update
d. Desktop-Full Install: (Recommended) : ROS, rqt, rviz, robot-generic libraries, 2D/3D simulators and 2D/3D perception:
sudo apt install ros-melodic-desktop-full
e. Environment setup:
echo "source /opt/ros/melodic/setup.bash" >> ~/.bashrc
source ~/.bashrc
f. Dependencies for building packages:
sudo apt install python-rosdep python-rosinstall python-rosinstall-generator python-wstool build-essential
g. Initialize rosdep:
sudo apt install python-rosdep
sudo rosdep init
rosdep update

3. 如需卸载软件:

sudo apt-get remove ros-*

4. 安装过程中出现的问题:
错误：default sources list file already exists
在运行 sudo rosdep init 时可能出现如下错误：

ERROR: default sources list file already exists:
/etc/ros/rosdep/sources.list.d/20-default.list
Please delete if you wish to re-initialize

是因为曾经安装过 ROS 系统的某个版本，只需按照提示删除已经存在的初始化文件即可：

sudo rm /etc/ros/rosdep/sources.list.d/20-default.list

再重新运行 sudo rosdep init :

sudo apt install python-rosdep
sudo rosdep init
rosdep update