In the case of the mobile robot, we will begin our discussion with the concept of tf frames and their relationship and transformation. The most used tf frames in ROS are map, odom, and base_link, where the tf frame map is a world-fixed frame which defines the long-term global reference, and the odom frame provides an accurate short-term local reference. The base_link frame is rigidly attached to the center of the curvature of the mobile robot's base. Usually, the relationship among these frames can be characterized as map | odom | base_link. In most general cases, when the map frame is not defined, the world frame is used as a global reference:
Accordingly, in our basic control node mobile_state_publisher.cpp, we will define ...
