The VIRTHUALIS project aims to develop a number of virtual reality applications forimproving safety in the process industries. The applications allow human factors expertsto study how operators interact with plant, and provide a safe environment in which newsafety actions can be tried and tested.Safety applications are built on the SafeVR technology platform, a distributed clientservervirtual reality system. This paper describes how two external modules - a processsimulator and a rule-based system - are interfaced to the platform and the benefits theyprovide both separately and together. The two modules communicate with theplatform’s server by exchanging messages, conforming to a simple syntax.pSimProxy provides a generic interface to an external process simulator, which in turndelivers the realistic plant behaviour. It handles bidirectional data exchange with andcontrol of the external simulator. It can be configured at run time to use whicheveravailable mechanisms are supported by the actual process simulator that models theplant being simulated.ClipsClient is an expert or rule-based system, based on NASA’s CLIPS expert systemsoftware that can make inferences about the information contained in the messages. Itconsists of a set of facts, a number of rules and an inference engine. It can be providedwith a number of rules that monitor how operators are running the plant, and react inuseful ways to these events.The simulator notifies the server of changes in process parameters through a message.The values may be displayed, for example as gauge readings, in the virtual environment.As operators control the plant, their actions, say opening a valve, are also reported bymessages via the server to the process simulation. Messages can also be read by therule-based system, allowing it to maintain its own representation of the plant. This inturn permits automated expert reasoning on the state of the plant and the actions of itsoperators which can cause further message to be sent to the server. The rule-basedsystem is therefore, a powerful mechanism for rapidly reconfiguring the application andgeneral rules can be written that only require new facts at run-time to change thebehaviour of the entire virtual environment.The message syntaxes, the system architecture and the interfacing of the externalmodules are described along with examples showing their individual and joint benefits.
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