This page is part of the documentation of auKsys/5

WARNING auKsys/5 is still under development, and subject to changes. This documentation has not been fully updated with changes since auKsys/4.

WARNING this page documents an upcoming component, in early phases of development, subject to change and not ready for production.

agent-tk (agent-toolkit/task-knowledge) is a library to implement light weight task and knowledge base agent. It provides abstract interfaces to integrate knowledge and decision process. The decision process in agent-tk is based on the delegation system proposed in [1].

agent-tk is currently developed for providing support to the matks simulator, and it is planned to extend it for support IOT systems in the future.

Gitlab repository is at https://gitlab.com/auksys/agent_tk/.

Overview

The figure below provides an overview of an agent as defined in agent-tk:

image overview of agent-tk

On a high level, an agent is composed of three group of systems:

  • definitions contains static metadata describing the agents, in particular, its capabilities.
  • resources contains dynamic information about the agent and its environment.
    • knowledge base is used to store information about the past and the current state of the world. agent-tk can use a simple in-memory store or connect to an instance of kDB.
    • states contains a snapshot of the current state of the robot, such as position/velocity. The platform is sending update to the states.
    • resources contains the resources of the agent: sensors, actuators… This module allow to lock the resources to avoid concurrent use.
  • components contains active module involves in decision or in execution of task.
    • execution contains a queue of tasks to be executed by the agent. It interracts with the low-level platform.
    • decision takes decision on the feasibility and cost of executing a given task. It use a simulator to estimate the cost of a task.
    • delegation module is used to distribute task among agent. This module can receive goal/tst to execute from the agent or it received call for proposal (CFP) from other agents. Upon receiving a CFP, the delegation module ask the decision module for a cost and feasability to execute a given CFP.

Interfacing with agent-tk (via MQTT)

The delegation system of agents-tk also uses the following topics:

  • delegation/send_cfp is used by the delegation module to broadcast a call for proposals by other agent.
  • delegation/send_offer is used by the delegation module to answer a CFP with a cost proposal.
  • delegation/send_proposal_acceptance is used by the delegation module to select a proposal.
  • delegation/send_execution_acceptance is used by the delegation module to confirm that the proposal acceptance has been received and that the agent will execute the mission.
  • delegation/cancel_acceptance is used to cancel the acceptance, this is send if no execution acceptance is received.

The default way to send tasks to an agent-tk agent is using the delegation protocol. However, in case it is not desirable to interract directly with protocol, agent-tk provides a delegation server called agent-tk-delegation-server which uses a MQTT-based service call to start a delegation, using the following topic:

  • delegation_server/delegate send a request to delegate a Goal or a TST. This rely on the MQTT v5 Request-Response Pattern, and requires that the correlation ID and response topics are set.

References

  1. High-level Mission Specification and Planning for Collaborative Unmanned Aircraft Systems using Delegation. Doherty, Patrick and Heintz, Fredrik and Kvarnström, Jonas. Unmanned Systems. 2013. DOI: 10.1142/S2301385013500052