安装ROS-melodic版本

1. 添加软件源

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

2. 添加密匙

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

3. 安装ROS

 sudo apt update
sudo apt install ros-melodic-desktop-full

4.初始化rosdep

sudo rosdep init
rosdep update

5.设置环境变量

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

6.安装rosinstall

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

以上步骤完成后我们来启动小乌龟节点试试：

roscore

rosrun turtlesim turtlesim_node

rosrun turtlesim turtle_teleop_key

在这可以看到小乌龟节点顺利启动运行，我们的ROS系统也就安装好了