Custom BT Action Nodes in C++

Source: ros2-copilot-skills custom BT action C++ skill

Why This Matters

Custom BT action nodes are how higher-level autonomy calls into project-specific capabilities without hardwiring business logic into the tree structure itself. C++ action nodes are especially useful when the action touches performance-sensitive code or existing C++ ROS 2 components.

Distilled Takeaways

• A BT action node should wrap a clear robot capability, not absorb general autonomy logic.
• Ports and return semantics are the contract between the tree and the implementation.
• C++ is a good fit when the node integrates closely with existing C++ systems or needs tighter runtime control.
• Good node design keeps the tree readable while still exposing useful behavior.

Practical Guidance

• Keep each node's purpose narrow and semantically clear.
• Use ports deliberately so the tree can reason about inputs and outputs explicitly.
• Test node behavior both in isolation and inside the intended subtree.
• Avoid burying large state machines inside a single BT action node.

Corroborating References

• BehaviorTree.CPP docs
• Nav2 behavior tree docs

When to Read the Original Source

Go to the original skill when you want the C++ action-node scaffolding and the implementation details for exposing custom robot actions into a Nav2 tree.