# Revision history [back]

global_planner provides an implementation of a fast, interpolated global planner for navigation. This class adheres to the nav_core::BaseGlobalPlanner interface specified in the nav_core package.

use_dijkstra is one of the parameters of this global_planner

Reference: http://wiki.ros.org/global_planner

move_base is also part of Navigation stack but it provides an implementation of an action (see the actionlib package) that, given a goal in the world, will attempt to reach it with a mobile base. The move_base node links together a global and local planner to accomplish its global navigation task. It supports any global planner adhering to the nav_core::BaseGlobalPlanner interface.

Reference: http://wiki.ros.org/move_base

For turtlebot3 implementation, take a look at this example: https://github.com/NVIDIA-AI-IOT/turtlebot3/blob/master/turtlebot_apps/turtlebot_navigation/param/global_planner_params.yaml. Notice the initial parameters:

GlobalPlanner:                                  # Also see: http://wiki.ros.org/global_planner
old_navfn_behavior: false                     # Exactly mirror behavior of navfn, use defaults for other boolean parameters, default false
use_quadratic: true                           # Use the quadratic approximation of the potential. Otherwise, use a simpler calculation, default true
use_dijkstra: true                            # Use dijkstra's algorithm. Otherwise, A*, default true
use_grid_path: false                          # Create a path that follows the grid boundaries. Otherwise, use a gradient descent method, default false


And how the launch file calls for those parameters: https://github.com/NVIDIA-AI-IOT/turtlebot3/blob/master/turtlebot_apps/turtlebot_navigation/launch/includes/move_base.launch.xml

  <node pkg="move_base" type="move_base" respawn="false" name="move_base" output="screen">
<rosparam file="$(find turtlebot_navigation)/param/costmap_common_params.yaml" command="load" ns="global_costmap" /> <rosparam file="$(find turtlebot_navigation)/param/costmap_common_params.yaml" command="load" ns="local_costmap" />
<rosparam file="$(find turtlebot_navigation)/param/local_costmap_params.yaml" command="load" /> <rosparam file="$(find turtlebot_navigation)/param/global_costmap_params.yaml" command="load" />
<rosparam file="$(find turtlebot_navigation)/param/dwa_local_planner_params.yaml" command="load" /> <rosparam file="$(find turtlebot_navigation)/param/move_base_params.yaml" command="load" />
<rosparam file="$(find turtlebot_navigation)/param/global_planner_params.yaml" command="load" /> <rosparam file="$(find turtlebot_navigation)/param/navfn_global_planner_params.yaml" command="load" />
<!-- external params file that could be loaded into the move_base namespace -->