Plugin Server Base

The plugin_server_base package serves as a bridge between the tello_bt framework and any custom plugins you create. It allows you to develop plugins independently, without requiring direct use of tello_bt or the py-trees library (which manages the behavior tree).

Essentially, this package provides a ROS 2 node with a preconfigured ROS 2 service, enabling the behavior tree to trigger the execution (or "ticking") of your plugin.

Getting Started

Using this package is straightforward and requires only two steps:

1. Inherit from plugin_server_base.PluginBase: Use this as the base class for your node instead of rclpy.Node.
2. Define the tick(self) method: Implement the tick() method in your node class. This method is essential; it will serve as the main loop for your plugin.

Note

The tick() method functions like a loop, either called by the behavior tree or, if in standalone mode, called at a default rate of 30 Hz.

Example

from plugin_server_base.plugin_base import PluginBase
from typing import Optional, Any

class MyNode(PluginBase):
  def __init__(self, node_name: str):
    super().__init__(node_name)

    # ...

  def tick(self, blackboard: Optional[dict["str", Any]] = None):
    # Implement here the logic
    pass

Parameters

The following parameters can be configured in the plugin_server_base package:

Parameter Name	Default Value	Description
tick_rate	30	When in standalone mode, this parameter sets the rate (in Hz) at which the tick() method is called.
standalone	false	If set to true, the plugin runs in standalone mode, meaning it operates without the behavior tree.

For developers

We offer a simple plugin tester node, which is targeted for developers to test for example their behavior tree. The node name is test_plugin_node and it can be executed with:

ros2 run plugin_server_base test_plugin

Tip

In case you want to test your plugin while in development, you can run it in standalone mode. In order to use the plugin in standalone mode, you can run the following command:

ros2 run plugin_server_base test_plugin --ros-args -p standalone:=true -p tick_rate:=30