change in costmap as robot move in stage [closed]

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Hi,

In my experiment, Stage runs a robot on the willow map. Navigation stack is setup as explained in tutorials. The planner is D* variant. Planner follow the interfaces defined in nav_core::BaseGlobalPlanner. Robot follows path as generated by planner.

Although map remains static and no obstacles are in map, I am still getting a lot of changes in grid cost( comparing old and new Costmap2DROS object). whenever, planner is not able to follow the generated plan, it repairs the plan by considering the changes in costmap. I am not able to understand what is causing so much change when map is not changing at all.

1. Do inflation of obstacles act as changes perceived in map?
2. If yes, then on revisit to same route give me again change in costmap. Planner remember the latest costmap, hence remains updated.
3. If no, how I can avoid getting changes in costmap as it slow planning. The number of observed changes in costmap monotonically increases with the length of path travelled by the robot.

My navigation stack setup is identicle to sbpl_lattice_planner. I am also not able to visualize plan generated by planner in nav_view although robot is able to get the plan and move in stage. I am mapping the topics correctly!

prince