A mini-project for RoboND's ROS Basics Module, Lesson 02.
$ chmod u+x hello
$ cd ~/catkin_ws
$ catkin_make
$ source devel/setup.bash
$ rosrun simple_arm hello
$ cd ~/catkin_ws
$ roslaunch simple_arm robot_spawn.launch
$ cd ~/catkin_ws
$ source devel/setup.bash
$ rosrun simple_arm simple_mover
$ cd ~/catkin_ws
$ catkin_make
$ source devel/setup.bash
$ roslaunch simple_arm robot_spawn.launch
$ rosnode list
$ rosservice list
$ rqt_image_view /rgb_camera/image_raw
$ rosservice call /arm_mover/safe_move "joint_1: 1.57
joint_2: 1.57"
$ cd ~/catkin_ws
$ catkin_make
$ source devel/setup.bash
$ roslaunch simple_arm robot_spawn.launch
$ rqt_image_view /rgb_camera/image_raw
rosservice call /arm_mover/safe_move "joint_1: 0
joint_2: 0"