A behavioral layer architecture for telecollaborative virtual manufacturing operations

A review of existing systems for performing manufacturing tasks in a collaborative virtual environment highlights the limitations for modeling object behavioral characteristics. It is difficult for users to describe the tasks to be performed in the environment. A behavioral layer architecture is presented to address these limitations. The layer consists of a virtual manufacturing lattice (VML) structure, an object library, and a virtual manufacturing script (VMS). The VML is a hierarchical structure to encapsulate object behavioral characteristics, which augments the scenegraph structure. The encapsulation is achieved by using a four-tuple structure (C,R,T,E), where C is the composition structure of the node which contains geometry, material, texture, and location data, R is the precedence relationship element, T is the trajectory relationship element, and E is the event control list used to describe the state information about the object. The VMS is implemented as a script and a parser that serves as an interface between the user and collaborative virtual reality software. The script is a grammar-like structure to describe manufacturing tasks. In the behavioral layer architecture, the script is parsed, and calls are issued to the underlying functions to initiate the tasks and to manipulate the lattice structure to perform the specified tasks. Availability of network bandwidth is a key ingredient for using our system for telecollaboration. As part of an example to demonstrate the implementation of VML-VMS, a study of network latency and saturation is performed for different network medium, packet sizes, sampling rate, and network protocols to explore ways of reducing network latency and display frame jitter.