Petri Net Transducers Research Articles

Some design aspects of a cognitive user interface

We report on research conducted as part of the Universal Cognitive User Interface (UCUI) project, which aims at developing a universal, autarkic module for intuitive interaction with technical devices. First, we present an empirical study of image schemas as basic building blocks of human knowledge. Image schemas have been studied extensively in cognitive linguistics, but insufficiently in the context of human-computer-interaction (HCI). Some image schemas are developed early at pre-verbal stages (e.g., up-down) and may, thus, exert greater influence on human knowledge than later developed image schemas (e.g., centre-periphery). To investigate this for HCI contexts, we applied a speech interaction task using a Wizard of Oz paradigm. Our results show that users apply early image schemas more frequently than late image schemas. They should, therefore, be given preference in interface designs. In the second part of this contribution we therefore focus on the appropriate representation and processing of semantics. We introduce novel theoretical work including feature-values-relations and Petri net transducers, and discuss their impact on behaviour control of cognitive systems. In addition, we illustrate some details of the implementation regarding learning strategies and the graphical user interface.

Agent-Based Control for Fuzzy Behavior Programming in Robotic Excavation

This paper discusses the concept, formulation, and implementation of the agent-based control for fuzzy behavior programming in robotic excavation. Petri net transducers are introduced to describe excavation control agent coordination and specification, while fuzzy control rules are used to implement primitive motions. A prototype laboratory excavation system is built with PUMA robotic manipulators and a force/torque sensor. Extensive experiments have been conducted and the results have demonstrated that the proposed control method is capable of continuously adapting and replanning its actions based on sensory feedback, and completing its excavation tasks in dynamic and unstructured environments.

Coordination specification for CIRSSE robotic platform system using Petri net transducers

A formal model based on Petri net transducers has been developed to specify the coordination and communication among the various task units in the CIRSSE platform system for robotic construction in space stations. The specification guarantees a mechanism of coherent control and communication for the effective cooperation among the different task units, and outlines the major steps toward the integration of the robotic platform system. The model is based on a coordination structure consisting of one dispatcher and three coordinators representing, respectively, the motion, vision, and gripper units of the platform system. The coordination structure insures some desired process properties for the system, such as boundedness, liveness, and reversibility, and easier translation from the formal specifications to the program codes based on Petri net transducer models. The model also assists with the system development in many ways, including (i) reducing the number of errors introduced while converting specifications to codes; (ii) assisting the developers in program implementation and verification (iii) allowing quicker adaptation to changed specifications; and (iv) allowing easier testing of the results for specification modifications. Therefore, it provides a useful tool for the design, simulation, performance evaluation, and implementation verification of the CIRSSE robotic platform system.

Task translation and integration specification in intelligent machines

Intelligent machines are defined to be hierarchically intelligent control systems composed of three levels: the organization level, the coordination level, and the execution level. The authors present an analytical model for the coordination level of intelligent machines, which, together with the established mathematical formulation for the organization level and the well-developed control theory for the execution level, completes the first step toward a mathematical theory for intelligent machines. The framework of the coordination level is a tree structure consisting of a dispatcher and a number of coordinators. A new type of transducer, Petri net transducers (PNTs), is introduced to serve as the basic module in the analytical model. The PNTs can be used to represent the concurrence and conflict among the individual processes within the dispatcher and coordinators. Coordination structures are introduced as a formalism for the specification of integration in the coordination level. The task precedence relationship in the coordination process is presented by the Petri nets derived from the coordination structures. A case study is presented. >

Petri net transducers for task translation in intelligent machines

Petri net transducer (PNT) is the key module for the task translation in the coordination theory for Intelligent Machines developed by Wang and Saridis. A PNT is a language translator based on a Petri net controller. PNT provides a general mechanism to control and synchronize task processes of the system modeled by Petri nets. The major advantages using PNTs for language translation over the other classic automata include 1) interconnections among system units can be easily described by Petri nets, but it is difficult to specify them by the classic automata; 2) it is well known that Petri nets are excellent in describing the conflict and concurrence among system units and that the classic automata are inadequate for these phenomena; 3) there are various convenient methods for performing both qualitative and quantitative process analysis for the systems modeled by Petri nets, however, no such methods available for either qualitative or quantitative analysis for the systems modeled by the classic automata.

A Petri-net coordination model for an intelligent mobile robot

A Petri net model of the coordination level of an intelligent mobile robot system (IMRS) is presented. The purpose of this model is to specify the integration of the individual efforts on path planning, supervisory motion control, and vision system that are necessary for the autonomous operation of a mobile robot in a structured dynamic environment. This is achieved by analytically modeling the various units of the system as Petri net transducers and explicitly representing the task precedence and information dependence among them. The model can be used to simulate the task processing and evaluate the efficiency of operations and the responsibility of decisions in the coordination level of the intelligent mobile robot system. Some simulation results of the task processing and learning are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>