PACT and RAPID: Multi-Agent Design and Concurrent Engineering

1. PACT and RAPID: Multi-Agent Design and Concurrent Engineering by Greg Milette CS525M, Spring 2002

2. The Plan • Describe the problem. • Describe how PACT solves the problem. • Describe how RAPPID solves the problem. • (23 slides)

3. Concurrent Engineering

4. The Problem • Each engineering group is specialized but must coordinate designs. • Different engineering groups use their own specialized design tools. • Each with different assumptions, conventions, and limitations. • Different tools are highly specialized and cannot be to converted.

5. Solutions • Allow groups to use their own specialized tools, while enabling the groups to reason collectively about design. • PACT is • A system designed to integrate existing multi-tool systems. • Uses agent communication and common ontology. • RAPPID is • -A system design to reason about trade-offs. • -Using market dynamics and set-based reasoning.

6. PACT: The Agents for the Design of a Manipulator

7. Sharing design models • A) could be hard to scale • B) scales well but requires: • Way to coordinate interactions (Facilitators) • Way to express design decisions (Agent Messages)

8. Advantage of Sharing Design Model • A unified model is not needed. Instead tool models are encapsulated. • Shared engineering language is needed for communication. It only has to cover a the shared design model • Communication is formally defined, through KIF and KQML, which increases modularity.

9. Facilitators • The four specific functions a facilitator provides: • Translates tool-specific knowledge into and out of standard knowledge exchange language. • Provides a layer of reliable message passing. • Routs outgoing messages to appropriate destination. • Initializes and monitors the execution. Shared Model Agent’s Model Facilitator Agent

10. Ontology • Was needed to express engineering concepts. • Example concept: voltage on a wire. • What units? • What time interval discrete or continuous? • Better to agree on a method for describing information. Do not standardize. • Example sentences using ontology: • (physical-dimension length) • (unit-of-measure inch) • (quantity (diameter shaft-a)) (= (diameter shaft-a)

11. How to Develop an Ontology • Developers met and role-played how their components would respond • Then corresponded by email. • But this would not work in a larger project, which need standard ontologies.

12. Assert part number #1234. Dimensions 3.0 x 3.0 meters. Assert new motor part # 1234 Assert part number #1234. Dimensions ?x. Example of Distributed ReDesign Digital Circuitry + component catalog Control Adjust design Mechanism Power System and Sensors

13. PACT • Model – each agent models the world in it’s own way, it will communicate its model through a shared language. • Agent structure: • Each agent can be in a different physical location. • Federation architecture through facilitators. • Communication – KQML, KIF, TCP/IP and email messaging • Ontology – allows engineering concepts to be transferred

14. What is RAPPID? • Agents can reason about the trade-offs among design options using set-based reasoning. • Example of trade-off: How much power should be budgeted for sensor circuitry? And the actuator? • Can solve a big optimization problem • Consider many design alternatives automatically.

15. Two types of agents • Components – • Represents a part of the design. • Buys and sells characteristics in the market. • Might be organized in a hierarchy. • Might be controlled by a human user. • Characteristics – • Definable attribute like weight or power. • Maintains a marketplace for that item.

16. The RAPPID System

17. What is Set-Based Reasoning? http://www.erim.org/cec/rappid/rappid.htm

18. Set-Based Reasoning in Context • Low prices = slack characteristics • High prices = constrained characteristics • Space can be collapsed by buying up allocations of characteristics… • Which gives other agents more funds to purchase other characteristics instead… • Which causes the amount of certain characteristics to get fewer and converge on a price.

19. Set-Based Reasoning

20. Reasoning About Bids

21. Conclusions • In concurrent engineering groups: • Are isolated because they use different techniques and models to solve problems. • But they need to reason collectively. • PACT: Use communication and a shared ontology to exchange design decisions. • RAPPID: Use market dynamics and set-based reasoning so agents can reason about the trade-offs of design choices.

22. References • M. R. Cutkosky, R. S. Englemore, R. E. Fikes, T. R. Gruber, M. R. Genesereth, W. S. Mark, J. M. Tenenbaum, and J. C. Weber. PACT: An Experiment in Integrating Concurrent Engineering Systems. IEEE Computer, 26 (Januarty)(1):28-37,1993 • H. V. D. Parunak. RAPPID Project Index Page. http://www.erim.org/cec/rappid/rappid.htm, 2002 • Weiss, Gerhard(Ed.), Parunak, H Van Dyke "Multiagent Systems: A Modern Approach to Distributed Artificial Intelligence.", MIT Press, p378-416, 1999. ISBN • Kuokka et all, “SHADE: Knowledge-Based Technology for the Re-Engineering Problem”, http://www.ksl.stanford.edu/knowledge-sharing/papers/shade-overview.html, 2002 • Parsons et all., “A Hybrid Agent Approach for Set-Based Conceptual Ship Design,” http://www.erim.org/cec/rappid/rappid.htm, 2002

23. The End