Co-ordination and Co-operation Between CGF Agents

Dr Jeremy Baxter

Parallel and Distributed Simulation GroupS&P Sector, Malvern

Overview of Presentation

Background

Co-ordination and Co-operation problems

Techniques from Multi-Agent Systems– Joint Intentions theory.

– Four step model

Example implementation– Squadron (Company) assault

Background

“Broad Agents” based CGF system

– Military command and control structure

– Independent Agents and behaviours for each level

– Breaks up responsibilities and behaviours

TroopCommander

Command and ControlIntelligence

Higher Level Objective

SquadronCommander

TroopCommander

TroopCommander

Tank TankTank Lower Level Objectives

Initial Co-ordination Problems

Complex composite behaviours

– Initial timing by message passing

– Prone to programming bugs

– Context lost if commander died

Weak model of group context

– produced separately from orders to subordinates

– developer responsible for linking group and sub-group states

Generic Problems and Solutions

Existing CGF systems have problems

– Lack of co-operative group behaviour

– Co-ordination is inflexible and prone to failure

– Composite behaviours are therefore weak and brittle

Solutions from Multi Agent Systems literature

– Provide a framework for group behaviour

– Model the context for re-planning decisions

– Model agents’ responsibilities to their group and the operator

Joint Intentions Theory

A logic based model of what it means to co-operate on a task

– Explicitly represents roles and commitments

– Improves robustness

Key elements

– Mutual belief (I know he knows I know …..)

– Mutual goals and plans

– Commitment to informing other agents

Example:- Traffic convoys

Definitions

Weak GoalEITHER Goal to achieve POR P has been achieved AND Goal to inform group P is

achievedOR P is unachievable AND Goal to inform group P unachievable

Weak Mutual GoalMutual belief that everyone has a Weak Goal to achieve P

Joint Persistent GoalMutual belief that P has not yet been achieved ANDMutual goal to achieve P ANDUNTIL Mutual belief that P is achieved, unachievable or irrelevant

A Weak Mutual Goal to achieve P will persist

Definitions 2

Joint IntentionTo have a Joint Persistent Goal to do an action while mutually

believing that all involved are doing the action

– A ‘Group State’ committing all involved both to the goal, a to a way of achieving it and conventions on how to deal with problems

Key elements

– Establishing mutual belief in an action

– Commitment to informing others

Using Joint Intentions

Attack Helicopter CGF (Tambe et al in STOW)

– Preventing teamwork failures, e.g. loss of Scout Helicopter

Co-ordinating independently designed behaviours– generic support for composite actions

Further Issues– Need to establish approximation to mutual belief

– Ways of establishing team goals, e.g. roles and capabilities

– Building up and representing shared goals and plans

Four Step Model

Recognition

Team Formation

– Identifying a group capable of performing the task

Plan Formation

– Forming and agreeing on the steps to take. Identifying co-ordination

Team Action

– Forming individual, co-ordinated, plans and failure recovery

Example Composite Behaviour Tank Squadron Assault Involves:

– Finding a Fire Support Position to Pin down the Enemy

– Finding a Concealed Approach for the Assault Group

EnemyPosition

Fire SupportPosition

Fire Support

Axis

Assault Approach

Assault GroupForm Up Point

Cover Break Point

Fire SupportForm Up Point

Squadron Current Position

Example Implementation

Explicit Group plans

– Templated plans with roles

– Clear co-ordination statements

Shared Group state

– Used for co-ordination and recovery if commander dies

Individual plans derived from group template

– Assigned based on roles and capabilities

A Composite Assault Behaviour

Overallgroup

Assaultsub-group

Supportsub-group

Form Up Wait forsupport

Assault Re-group

End Assault

EndAssault

Form Up

Wait

Supportby Fire

FightThrough

Re-group

Form Up Assault

No task

Time

Summary

Co-ordination and co-operation is an important aspect of CGF systems

Without good representations co-ordination becomes hidden and prone to failures

Composite, composable behaviours will need reliable, generic co-ordination and co-operation techniques

Formal techniques from Multi Agent Systems research can help

Further Work

Adjusting the theory to align with military practice

General solutions to execution problems

– e.g. role replacement

Operator involvement

– visualisation of co-ordination

– commitments to the operator by CGF agents