Planner Plugin

LTL Planner Plugins

The planner offers an interface to run python plugins. Plugins are object classes with a set of standardized methods that will be called by the planner node.

Launching plugins

To launch a plugin, add the plugin in the "/plugin" parameter of the planner node.

• Package and source file must be defined in "~plugin//path" on the format "package.source_file"
• Additional argument needed by the plugin can be defined on "~pluging//args/"

Example setup for the trap detection (needed for HIL mix initiative control):

<include file="$(find ltl_automaton_planner)/launch/ltl_planner.launch">
    <arg name="initial_ts_state_from_agent" default="False"/>
</include>

<group ns="ltl_planner/plugin">
    <group ns="TrapDetectionPlugin">
        <param name="path" value="ltl_automaton_hil_mic.trap_detection"/>
        <param name="args" value=""/>
    </group>
</group>

Plugin specifications

Naming

Name of the plugin should be the name of the class implementing it.

init

The init method should take as input the ltl_planner object reference and an argument dictionary even if no argument is needed.

class PluginClass(object):
    def __init__(self, ltl_planner, args_dict):

API methods

The plugins need to have the following API methods. If yhe method is not needed leave it empty:

• init(): Called once at initialization
• set_sub_and_pub(): Called after initialization to setup ROS subscribers, publishers, service clients & servers, action servers.
• run_at_ts_update(ts_state): Called everytime a new TS state is received from the agent

Accessing LTL planner elements

The plugin will be run from the planner.py node upper layer. From within the plugin code, use to access:

• ltl_planner:

self.ltl_planner

• Possible LTL states:

self.ltl_planner.pssible_states

• Current ts state:

self.ltl_planner.curr_ts_state

• Product graph:

self.ltl_planner.product

• TS graph:

self.ltl_planner.product.graph['ts']

• Büchi graph:

self.ltl_planner.product.graph['buchi']