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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
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