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MPA for the SUO Planning and Decision Aid

David E. Wilkins

SRI International Artificial Intelligence Centeremail: wilkins@ai.sri.comURL: http://www.ai.sri.com/~wilkins

June 1999

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Long-term Contributions of PDA to the Soldier

• Shared plan representations cognizant of miltary principles, doctrine, SOPs and TTPs. Makes possible:

• Doctrinally correct plan usable by everyone.

• Fast generation of multiple distinct COAs, including ones the commander may not have considered.

• Support commander creativity through human guidance.

• Uniformly high plan quality, even during high-stress crises.

• Continuous analysis of the plan using multiple metrics.

• Monitor plan execution and respond quickly to events, helping the commander modify the plan appropriately.

• Provide relevant information to other echelons, allowing fast communication while preserving bandwidth

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Multiagent Planning Architecture (MPA)

• Agent-based framework (efficiency and modularity)

• Enable interoperation of diverse planning technologies– plan generation, scheduling, temporal reasoning, evaluation, ...

• Provide a shared plan representation

• Provide organizational structure, control strategies, and communication protocols, wrappers

• Develop planning and metaplanning agents specifically for collaborative planning and scheduling

• Support dynamic, event-driven reconfiguration of planning organization and strategies at runtime

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MPA Components

Planning Cells - organizational units for agents:

– Planning Agent (PA), Meta Planning Agent (Meta-PA)

– Planning-Cell Managers

Shared plan model and representation– based on extenstions to Act formalism

Communication ProtocolsTransport Level: robust, reuse existing technology

Content Level: high-level performatives

Plan Server - central repository for plans and related information

Process Management - extensible set of reactive control policies for implementing problem-solving strategies

Support- documentation of each agent’s I/O,

Wrappers for individual technologies

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Communication

• Messages use KQML-like performatives:

– communication performatives

– plan performatives

• MPA wrappers and libraries for:

– message passing

– multithreaded processing

– tracing and logging of messages

• Communication substrates:– KQML (Lockheed-Martin and UMBC)

– ILU (Xerox PARC)

– OAA (SRI International)

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Examples of MPA messages

Requesting solutions from the meta-PCM:

(:evaluate :content (:multiple-solve

:task “air-superiority” :advice-contexts

((“yuma” (:ingress-at-yuma :deny-air-picture))

(“yuma-sf” (:ingress-at-yuma :ingress-2-at-san-francisco

:breach-at-two-places)))))

Retrieving the plan from the plan server:

(:ask-all :content (:query-plan

:task “air-superiority” :plan “plan-yuma-sf” :view :ascii)

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MPA Plan Server

• Central repository for planning information

• Hierarchical model of plans (plans, tasks, and action networks)

• Answers queries about the plan, providing multiple views

• Supports a broad range of plan management capabilities

Annotations - declarations of high-level attributes of plans, planning processProduct Annotation: pedigree, flaws, plan quality, resource status

Process Annotation: time spent on plan components, current status

Triggers - rules used to notify cell agents of planning eventsExample: trigger notifies PCM of overutilized resource annotation,

PCM reacts by changing planning strategy

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MPA Applied to ACP

• Validate MPA by integrating several systems in DARPA Planning Initiative (TIE 97-1):

INSPECT (ISI) OPIS (CMU) Advisable Planner (SRI)

SIPE-2 (SRI) ACS (UMass) Process Panel (AIAI -UEdin)

APAT (ISX) VISAGE (MAYA)

• Domain is Air Campaign Planning– thousands of objects, several thousand nodes in each plan

– plan down to support mission level (must allocate supporting resources)

– air superiority objective only

– targets grouped into networks which depend on other networks

– network effectiveness is modeled quantitatively

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TIE 97-1 ArchitectureTIE 97-1 Architecture

Annotations

Triggers

Plan Server

Cue: (TEST (ready unit1))ACT2Cue: Answer query

ACT1

APATGUI

Plan Viewer

MPA Planning Agents MPA Agent Evaluation Toolkit

ACS VISAGE

Advisable Planner (SIPE-2)Planner (SIPE-2)Scheduler (OPIS)Planning-Cell Manager (PRS)

Inspect

ProcessMonitor

Meta Planning-Cell Manager (PRS)

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TIE 97-1Demonstrations

• Sept 98 - EFX 98, Ft. Walton Beach FL

• May 98 - ARPI Workshop, Monterey CA

• Feb 98 - DARPA, Arlington VA

• Dec 97 - JFACC PMR, San Pedro CA

• Nov 97 - ARPI Workshop, San Francisco CA

Inc r

eas i

n g C

apab

ilit

ies

DARPADARPA

SIPE-2

PAGUI/Advice Manager(AP and PRS)

Create a plan

Meta-PAPlanning-Cell Manager(PRS)

Planning-Cell Designator

Plan Complete

Request: Plan ok?

PAScheduler(OPIS)

PATemporal Reasoner(OPIS)

PATemporal Reasoner(Tachyon)

orPA (meta-PA)Critic Managerall(SIPE-2)

PA (meta-PA)Search Managerone-level(SIPE-2)

PASchedule Critic(new)

PATemporal Constraint Critic(SIPE-2)

OPIS

RequestExpandNextLevel

AgentKQML

Message

Cue: (TEST (ready unit1))ACT2

Cue: Plan One-Level

ACT1

Cue: (TEST (ready unit1))ACT2

Cue: Resource Critic

ACT1

Annotations

Triggers

Plan Server(PRS)

Cue: (TEST (ready unit1))ACT2Cue: Answer query

ACT1

Plan Complete

Create a plan

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Inside an MPA Planning Cell

Create a plan

Cell Manager(CPEF)

Cell Designator

Higher Echelon:

Plan Complete

Request: Modify plan

Platoon APDA

Planner(SIPE-2, O-Plan)

Terrain Reasoner

Fire ControlPlanner (e.g.)

AgentKQML

Message

Cue: (TEST (ready unit1))ACT2

Cue: Plan One-Level

ACT1

Cue: (TEST (ready unit1))ACT2

Cue: Resource Critic

ACT1

Annotations

Triggers

Plan Server(PRS)

Cue: (TEST (ready unit1))ACT2Cue: Answer query

ACT1

Plan Complete

New Op Order

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Company Commander

MPA PDA Cell

Platoon BPDA

Platoon CPDA

At WTA

AgentKQML

Message SRI International

PDA Cell PDA Cell

Higher Echelon Cell Manager

(CPEF)

New Order

Possibly Shared Agents

Planner SubordinatePDA

Cell Manager

Planner

Cell Manager

Cue: (TEST (ready unit1))ACT2

Cue: Plan One-Level

ACT1

Visualization/Comparison

LogisticsTerrain Reasoner

Multiple PDA Cell Configuration

New Order

PlanPlan

SubordinatePDA

Plan Server

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Opportunities Enabled by MPA

• Facilitate collaboration:– agents exchange information and influence each other

during planning

– can easily explore different degrees of collaboration

• Can more easily explore/evaluate:– different organizational units for flexible control policies

– different planning styles and strategies

– new or alternative technologies

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Backup Slides

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Support rapid, accurate military decision making in information-rich warfighting environment

The Problem

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Example MPA Performatives

:annotation Insert Delete Ask-All Ask-One:trigger Insert Delete Ask-All Ask-One:update-task Tell Delete:update-plan Tell Delete:query-task Ask-all Ask-One:query-plan Ask-All Ask-One:query-node Ask-All Ask-One:ping Evaluate:pcd Tell

Plan Performative

CommunicationPerformative

Performatives accepted by thePlan Server

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Planning Cells

• Hierarchically organized collection of planning agents

• Composed dynamially by the Planning-Cell Manager

• Planning Cell Designator (PCD) provides registry of agents to fill various roles:Planner: SIPE-2 Scheduler: OPIS

• Distribute tasks and PCD to PAs and meta-PAs

• Each cell includes a plan server

PA PA meta-PA

PA Plan Servermeta-PA

PA PA

Planning-Cell Manager

Planning cell:

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Planning Cell Manager (PCM)

• Persistent agent continuously accepting tasks

• Oversees problem-solving within a Planning Cell

• Provides a range of problem-solving behaviors and strategies – user-configurable

– can adapts strategies in response to runtime activities

• PRS-based PCM– PCD and process state encoded in PRS database

– strategies encoded in Acts

– Example strategy: expand and critique by levels

• implemented by 14 Acts

– small library of different PCMs

• various cell configurations, problem-solving strategies

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Meta Planning-Cells

• Planning cell composed of a set of planning cells

• A Meta-PCM controls and coordinates the cells

• Accepts multiple planning requests, including advice

• Distributes tasks to available planning cells

• Gathers results for possible comparison

Meta Planning-Cell:

Planning Cell

Meta Planning-Cell Manager

Planning Cell

Planning Cell

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Act Plan Server

• PRS-based Plan Server in current MPA applications

– builds on reactive control capabilities

• grounded in the Act Formalism model for plans

Task: problem to be solved, advice, assumptions

Action Networks: partial orders of activities, at multiple abstraction levels

Plan: linked sets of action networks

Nodes: individual activites (goals, actions)

• limited persistence, versioning, browsing, and no access control

AgentKQML

Message

Annotations

Triggers

Plan Server

Cue: (TEST (ready unit1))ACT2Cue: Answer query

ACT1

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Planning Cell Planning Cell

Meta Planning- Cell Manager

(PRS)task solved

task solved

request solutionto task

request solutionto task

Shared Agents

SearchManager

CriticManager

Planning-Cell Manager

Shared Agents

SearchManager

CriticManager

Planning-Cell Manager

Cue: (TEST (ready unit1))ACT2

Cue: Plan One-Level

ACT1

Visualization/Comparison

Scheduler

Simulator

Temporal Reasoner

MPA Multiple Planning-Cell Configuration