Behaviors

The nav2_behaviors package implements a task server for executing behaviors.

The package defines:

• A TimedBehavior template which is used as a base class to implement specific timed behavior action server - but not required.
• The Backup, DriveOnHeading, Spin and Wait behaviors.

The only required class a behavior must derive from is the nav2_core/behavior.hpp class, which implements the pluginlib interface the behavior server will use to dynamically load your behavior. The nav2_behaviors/timed_behavior.hpp derives from this class and implements a generic action server for a timed behavior behavior (e.g. calls an implmentation function on a regular time interval to compute a value) but this is not required if it is not helpful. A behavior does not even need to be an action if you do not wish, it may be a service or other interface. However, most motion and behavior primitives are probably long-running and make sense to be modeled as actions, so the provided timed_behavior.hpp helps in managing the complexity to simplify new behavior development, described more below.

The value of the centralized behavior server is to share resources amongst several behaviors that would otherwise be independent nodes. Subscriptions to TF, costmaps, and more can be quite heavy and add non-trivial compute costs to a robot system. By combining these independent behaviors into a single server, they may share these resources while retaining complete independence in execution and interface.

See its Configuration Guide Page for additional parameter descriptions and a tutorial about writing behaviors.

See the Navigation Plugin list for a list of the currently known and available planner plugins.

The TimedBehavior template makes use of a nav2_util::TwistPublisher. The AssistedTeleop behavior makes use of a nav2_util::TwistSubscriber.