Tree calling other trees design question

[li9i]

I am facing a situation of the following form: There exist one central pc, one robot of type A, and one robot of type B. The pc is designed to be running a BT. That BT needs, on occasion, among other things, to make robot A and robot B perform certain actions, e.g. check self diagnostics, initialise navigation goals, make them navigate somewhere, etc.

At this point I have only bundled up all actions that pertain to each robot type to separate BTs, i.e. there are 2 BTs: BT_A and BT_B. My question is: how would it be best in your opinion to implement BT_pc so that it calls functionalities (tree nodes) of BT_A and BT_B? Is something like this even feasible? Additionally, is it feasible given that all trees run on different machines?

I understand that the answer to this question is part ROS-2-implementation-specific and part Behavior-tree-related. If you believe that it is best suited for the main BehaviorTree repository, or elsewhere, please point it out to me. Thank you.

[marj3220]

I would create action and service nodes directly in ROS, not using the BehaviorTree system, for the robots that would accomplish the wanted functionalities when called by the BT_pc. Your BehaviorTree nodes in BT_pc would call these actions and/or services. These BT nodes would be similar to sleep_action.hpp. The way BT_pc and your robots would communicate is through ROS2 Multiple Machines.

[li9i]

Thank you very much for your reply. In the end I eventually designed it in the way you describe it. BT_pc hosts an action client and calls the action servers at A and B with variables pertaining to which tree should be loaded. I did not close the issue in case there was a better idea. Feel free to open it again in that case.