After getting the current position of the robot, we can send a goal position to the move_base node. The move_base node will send this goal position to a global planner, which will plan a path from the current robot position to the goal position.

This plan is with respect to the global costmap, which is feeding from the map server. The global planner will send this path to the local planner, which executes each segment of the global plan.

The local planner gets the odometry and the sensor value from the move_base node and finds a collision-free local plan for the robot. The local planner is associated with the local costmap, which can monitor the obstacle(s) around the robot.