Autonomous Vehicle Command Language (AVCL)

CDR Duane Davis, USN18 April 2006

Problem Area: Dissimilar Autonomous Vehicle (AV)

Incompatibility

Examples• Homogeneous vehicle system: Swarming• Programmed compatibility: CJTFEX 04-2 Coordinated

MCM

Vehicle-specific data formats and mission planning systems preclude effective coordination in multi-vehicle systems and hinder the design of such systems.

To date, the preponderance of multi-vehicle research has assumed inherent compatibility: homogeneous vehicle systems or explicitly programmed compatibility.

Proposed Solution: A Common AV Data Model

Common Data Format: (e.g., AVCL):• Mission Specification (tasking)• Communications• Mission Results

Automated Conversions• AVCL to Vehicle-Specific• Vehicle-Specific to AVCL

Ultimate Goals• Facilitate interoperability

between dissimilar vehicles (including legacy)

• Support pre-, mid-, and post-mission data requirements

• Provide other vehicles and human operators intuitive and efficient data access

AVCL

AAV 1

Support

AUV 2

ASV 2

AAV 2

AUV 1

ASV 1

AUV 2

ASV 2

AAV 2

AAV 1 Support

Support Support

Support Support

Support

ASV 1

AUV 1

Research SubtasksExemplar Data Model Definition

• Task-Level Behavior Set Determination• XML Schema Design• Included data:

• Mission Specification (tasking)• Mission Results• Communications (message set)

Data Conversions• AVCL to Vehicle-Specific• Vehicle-Specific to AVCL• AVCL Declarative to AVCL Task-Level• AVCL Task-Level to AVCL Declarative

Data Model Use to Facilitate AV Control• Integration into a Multi-Layer Architecture

Scripted Mission Specification

Task-Level Behaviors• Minimum Requirements

to Capture Arbitrary Tasking

• Behavior Activation and Termination Criteria

Scripting• Atomic Task-Level

Behaviors• Sequential Execution• Potential Parallelism

MakeSpeed

MakeDepth

Waypoint

MakeAltitude

Waypoint

ObtainGPS

SetPosition

Waypoint

Quit

Declarative Goal-Based Mission Specification

14 Predefined Goal TypesFinite State Machine (FSM)

• States Represent Individual Goals

• Transitions Executed upon Goal Success or Failure

Mission Start

Rendezvous with UUV-2 in Area C

Search Area A

Search Area B Sample Environment in Area A

Mission Complete

SucceedFail

SucceedFailSucceed

or Fail

Succeed or Fail

External C2 Systems

AVCLMission Goals and Constraints

Task Level Commands

Vehicle-Specific Languages

PlannerRules & Templates

XSLT and Vehicle-Specific XML

C2IEDM Business Objects

AVCL TranslationsAVCL to Vehicle-Specific Data

• XSLT (text)• Vehicle-Specific XML (binary)

Vehicle-Specific Data to AVCL• Context Free Grammars (text)• Vehicle-Specific XML (binary)

Artificial Intelligence• Planning and Search• Case-Based Reasoning• Bayesian Reasoning

Business Objects• Command and Control

Information Exchange Data Model (C2IEDM)

• AVCL Declarative Tasking

CFGs or Vehicle-Specific XML

AVCL to Text—Direct generation with XSLT

Exemplar Translations• AVCL to Phoenix UUV• AVCL to ARIES UUV• AVCL to Seahorse UUV• AVCL to REMUS UUV

XSLT Stylesheet

Vehicle-Specific Script

AVCL Script

Translation from AVCL to Text-Based Vehicle-Specific Formats

A Mutable Variable Pattern for XSLT

Why?• Inability to Update

Variable Values• Requirement to

Maintain Behavior Parameters for Parallel Execution

How?• Use Template

Parameters• Explicitly Controlled

Iteration

begin XSLT processing

variable B = sequential list of task-level behaviors

apply template for B1 with default parameters d1 to dn

end XSLT processing

begin template for task-level behavior Bi

with parameters p1 to pn

for k = 1 to n

variable vk

if Bi updates pk

vk = new_pk

else

vk = pk

generate required output for Bi

apply template for Bi+1 with parameters v1 to vn

end template

AVCL to Binary• Generate vehicle-specific XML with XSLT• Serialize to binary

Binary to AVCL• Read from binary to vehicle-specific XML• Generate AVCL with XSLT

Exemplar Implementation• AVCL to Joint Architecture for Unmanned Systems (JAUS)

Messages• JAUS Messages to AVCL

Vehicle-Specific Binary

Custom Serializer

AVCL Data

XSLT Stylesheet

Translation from AVCL to Binary Vehicle-Specific Formats and Vice

Versa

Vehicle-Specific XML

AVCL Script

XSLT Stylesheet

Vehicle-Specific Binary

Custom Reader

Vehicle-Specific XML

JAUS-XML

XML

Binary

Programming Object

AVCL

XSLT

XSLT

JAUS XML

Schema

SerializerReader

JAXB

Translation of Vehicle-Specific Text Formats to AVCL

Parse as a Context Free Language (CFL)

• Chomsky Normal Form (CNF) Context Free Grammar (CFG)

• Cocke-Younger-Kasami (CYK) Parsing Algorithm

• Yields a Binary Parse Tree

Translate Parse Tree to AVCL• Depth First Traversal• Template-Based Translation

of Individual Parse Nodes

CFG Serves the Same Role as an XML SchemaParser/Translator Serves the Same Role as an XSLT Stylesheet

Example Chomsky Normal Form Rules:Mission -> LaunchCmd + MissionMiddle

Mission -> LaunchCmd + MissionEnd

MissionMiddle -> WaypointCmd + MissionMdl

MissionMiddle -> SurfaceCmd + MissionMdl

MissionMiddle -> WaypointCmd + MissionEnd

MissionMiddle -> SurfaceCmd + MissionEnd

MissionEnd -> WaypointCmd + RendezvousCmd

MissionEnd -> SurfaceCmd + RendezvousCmd

Example (Partial) Parse Tree:Mission

LaunchCmd MissionMdl

WaypointCmd MissionEnd

RendezvousCmdSurfaceCmd

Translation of Declarative Missions to Task-Level Behavior

ScriptsInter-Area Transit

• Best-First (A*) Search

Goal Accomplishment Planning• Trivial Goal Types

• MonitorTransmissions• Reposition

• Others• Require Area Coverage (Search)• Decision-Tree Plan-Type

Selection• Parameterized Preplanned

Patterns for Regularly Shaped Operating Areas

• Planner-Generated (A*, Hill-Climbing, Iterative Improvement) for Irregularly Shaped Areas

Inference of Declarative Missions from Task-Level Behavior ScriptsCase Based Reasoning

• 14 Weighted Characteristics on the Scale (0..1)

• Comparison Against Known Recall Set Instances

Probabilistic Reasoning (Naïve Bayes)• 12 Boolean Characteristics• Independent Conditional Probabilities

rxprcxcwxrdi

ii i,,

14

1

121

121121 ...

|...|...|

cPcP

HcPHcPHPccHP

AVCL Integration in a Multi-Layer AV Control Architecture

Multi-Layer AV Control Architectures

• Hierarchical• Hybrid

Relationship to AVCL• Declarative Mission• Scripted Mission

Rational Behavior Model (RBM)• Three-Level Hybrid Architecture• Strategic Level: Ship CO• Tactical Level: Watch Officers• Execution Level: Watch

Standers

RBM vs AVCL:

Strategic Level: Declarative Mission

Tactical Level: Behavior Script

Execution Level: Individual Commands

The Extended Rational Behavior Model

Features• Augments Existing

Vehicle Control Software• Translation to Vehicle-

Specific Data Format at Lowest Level

• AVCL Mission Construct Reliant

• Minimal Modification to Existing Vehicle Controller

Communications Model• Pull—Higher Levels

Query Lower Levels• Push—Higher Levels

Command Lower Levels• Push—Lower Levels

Provide Unrequested Information

Strategic Level

Tactical Level

Execution Level (existing vehicle controller)

Declarative AVCL Mission

High-Level World Model

Mid-Level World Model

State and Sensor Data

Translator

Task-L

evel

Beh

avior S

cript

Veh

icle-Sp

ecific

Co

mm

and

Statu

s Qu

eryS

tatus Q

uery

Co

mm

and

Sta

tus

Scrip

t Statu

s

Script Control

Agenda Control

Planner

Task-Level Behavior

Goal

Command Flow

Implied Data Visibility

Optional Communications

Extended Rational Behavior Model Controller

Questions