Building a Robocup team using Jason BDI frameworkSean Bassett, Nancy Ho Woo, Laurence Smith, Carlos Valencia

Software AgentsNovember 30, 2006

Nov. 30, 2006 Slide 2

Architecture

jason

environment

Environment

asSemantics

DefaultInternalActionAgent

robojason

RoboAgent _bpDistRoboEnvironment 11

RoboCommunications1

1

11

1

1

java

uti l

Thread

Nov. 30, 2006 Slide 3

Sequence diagram

:RoboCommunications

parseServerMessage(message)

:RoboEnvironment:RoboAgent

executeAction(acTerm)

send(message)

see(message)

clearPercepts(agentName)

addPercept(agentName,literal)

:CentralizedAgArch

getPercepts(agentName)

executeAction(agentName, acTerm)

:TransitionSystem

reasoningCycle()

perceive()

act(action, feedbackActions)

Nov. 30, 2006 Slide 4

Jason’s features used for implementation

• Environment coded in java– Communication with BDI occurs only at perception/action points

• Open/closed world assumption – Closed world in implicit by not using strong negation (~) on plans

• Late option specification– Parameters are specified right at the moment of calling the action

• Internal actions written in Java– Elegant way to extend plans from within the BDI

Nov. 30, 2006 Slide 5

Modeling a player

+noBall

!findBall

!goToBall

!findGoal

!haveBall

!decide!goToPosition

+ball+flag

noBall

ball

Teammate & ball

flag

Distance<1

noGoal

bpDist < ballDist

bpDist < ballDist

Distance<1

ball

Teammate & ball

ball

ExecuteAction

Percepts

Nov. 30, 2006 Slide 6

Example of a plan

// -kickoff -8 -3// -team Canada// Forward, in front of the ball

noball./* Plans */

+noball: ball(X,Y,P,Q) & team(Tn) & player(Tn,Un,Xp,Yp,Pp,Qp) <-.print("1"); robojason._bpDist(X,Y,Xp,Yp,Re); !disDec(X,Y,Xp,Re); -ball(_,_,_,_); -

player(_,_,_,_,_,_).

+noball: ball(X,Y,P,Q) <-.print("2"); -ball(X,Y,P,Q); -noball; !gotoball(X,Y).+noball: otherside(OS) & flag(p,OS,t,Xf,Yf,Pf,Qf) & Xf>10 & (Yf>=15| Yf<=-15)<-.print("4"); turn(Yf); -flag(_,_,_,_,_,_,_).+noball: otherside(OS) & flag(p,OS,t,Xf,Yf,Pf,Qf) & Xf>10 <-.print("5"); dash(90); -flag(_,_,_,_,_,_,_).+noball: noball <-.print("3"); !findball.

+!findball: ball(X,Y,P,Q) & team(Tn) & player(Tn,Un,Xp,Yp,Pp,Qp) <-.print("6"); robojason._bpDist(X,Y,Xp,Yp,Re);                                                               !disDec(X,Y,Xp,Re); -ball(_,_,_,_);  -player(_,_,_,_,_,_).

+!findball: ball(X,Y,P,Q) <-.print("7"); -ball(X,Y,P,Q); -noball; !gotoball(X,Y).+!findball: noball <-.print("8"); turn(70); -noball.+!findball: otherside(OS) & flag(p,OS,t,Xf,Yf,Pf,Qf) & Xf>10 & (Yf>=15| Yf<=-15)<-.print("a"); turn(Yf); -flag(_,_,_,_,_,_,_).+!findball: otherside(OS) & flag(p,OS,t,Xf,Yf,Pf,Qf) & Xf>10 <-.print("b"); dash(90); -flag(_,_,_,_,_,_,_).

+ball(X,Y,P,Q): X<1 <-.print("24"); -ball(_,_,_,_);!haveball.

Nov. 30, 2006 Slide 7

Defensive Strategy

Nov. 30, 2006 Slide 8

Offensive Strategy

Nov. 30, 2006 Slide 9

Jason compared to another BDI

Comparison criteria Jason Jack

Inter-agent communication approach

Speech-act based communication based on KQML querying and informational performatives

High-level primitives for communication are offered

Preciseness: Does the platform provide clear and precise semantics?

Yes. Based on AgentSpeak(L)’s formal semantics

Provides clear and precise, although not formal, semantics

Verification: Path for the formal verification of programs written in the language?

Model checking techniques have been developed by the authors

No verification techniques are provided

Nov. 30, 2006 Slide 10

Jason compared to another BDI

Comparison criteria Jason Jack

Deployment and portability: Manuals support.

Limited, as it’s an open source project with just a single manual and no formal support

Highly documented and formally supported

Extensible through open source collaboration

Open source from the beginning and offers clear cut interfaces to integrate environments

Not open source. Although it provides several “hooks” for extension.

Tools for debugging and programming?

Provides an IDE but debugging capabilities are limited

IDE and capabilities such as textual trace, graphical plan tracing and agent interaction diagrams

Nov. 30, 2006 Slide 11

References

• Bordini, R.H. & Hubner, J.F. 2006. “Jason. A java-based interpreter for an extended version of AgentSpeak”. Available online, http://jason.sourceforge.net/Jason.pdf

• Bordini, R., Hubner, J. & Vieira, R. “Jason and the golden fleece of agent-oriented programming”. 2005. In R. Bordini, M. Dastani, J. Dix & A. Seghrouchni (Eds.), Multi-agent programming. Languages, platforms and application. pages 4-39. Liverpool: Springer