nav_core_adapter

This package contains adapters for using nav_core plugins as nav_core2 plugins and vice versa (more or less). In general, the adaptation process involves

• Converting between 2d and 3d datatypes.
• Converting between returning false and throwing exceptions on failure.

We also provide an adapter for using a costmap_2d::Costmap2DROS as a plugin for the nav_core2::Costmap interface.

Adapter Classes

• Global Planner Adapters
  • GlobalPlannerAdapter is used for employing a nav_core2 global planner interface (such as dlux_global_planner) as a nav_core plugin, like in move_base.
  • GlobalPlannerAdapter2 is used for employing a nav_core global planner interface (such as navfn) as a nav_core2 plugin, like in locomotor.
• Local Planner Adapter
  • LocalPlannerAdapter is used for employing a nav_core2 local planner interface (such as dwb_local_planner) as a nav_core plugin, like in move_base. In addition to the standard adaptation steps listed above, the local planner adapter also uses the costmap to grab the global pose and subscribes to the odometry in order to get the current velocity.
  • There is no LocalPlannerAdapter2. The nav_core2 interfaces use additional information (like velocity) in the local_planner interface than its nav_core counterpart. This information would be ignored by a nav_core planner, so no adapter is provided.
• CostmapAdapter provides most of the functionality from nav_core2::Costmap and also provides a raw pointer to the Costmap2DROS object. It is not a perfect adaptation, because
  • Costmap2DROS starts its own update thread and updates on its own schedule, so calling update() does not actually cause the costmap to update. It does update some of the metadata though.
  • setInfo is not implemented.

Parameter Setup

Let’s look at a practical example of how to use dwb_local_planner in move_base.

If you were using DWA you would probably have parameters set up like this:

base_local_planner: dwa_local_planner/DWALocalPlanner
DWALocalPlanner:
  acc_lim_x: 0.42
  ...

i.e. you specify

• The name of the planner
• A bunch of additional parameters within the planner’s namespace

To use the adapter, you have to provide additional information.

base_local_planner: nav_core_adapter::LocalPlannerAdapter
LocalPlannerAdapter:
  planner_name: dwb_local_planner::DWBLocalPlanner
DWBLocalPlanner:
  acc_lim_x: 0.42
  ...

i.e.

• The name of the planner now points at the adapter
• The name of the actual planner loaded into the adapter’s namespace
• The planner’s parameters still in the planner’s namespace.

The process for the global planners is similar.