A navigation stack [navigation pack] is a collection of 2D navigation packs that can acquire odometer information, sensor data, and target pose, and output velocity commands to a motion platform.

(1) Positioning

During the navigation process, the robot needs to determine its current position at all times and use the amcl package to locate it in the navigation stack. Amcl is a probabilistic localization system that localizes mobile robots in 2D. AMCL implements an adaptive (or KLD sampling) Monte Carlo localization method and uses particle filtering to track the robot at

The pose in the map is known. The image below shows the difference between odometer and AMCL. AMCL estimates the base structure (robot) equivalent to the global structure (world map) TF transformation (coordinate system transformation in ROS). Essentially, this conversion uses dead reckoning to handle drift, and the published conversion is long-term.

(2) Path planning

In the route navigation part, the move_base package is used. move_base can take information around the robot (such as lidar scan results) and generate global and local cost maps. According to these cost maps, the robot can bypass obstacles and reach the designated location. The path planning of the mobile base is mainly divided into global planning.

Planning and local planning, using the A* algorithm and the DWA algorithm, respectively.