Co-ordination and Co-operation Between CGF Agents Dr Jeremy Baxter Parallel and Distributed...
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Transcript of Co-ordination and Co-operation Between CGF Agents Dr Jeremy Baxter Parallel and Distributed...
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