Resumen
The article focuses on animation control for real-time virtual humans. The computation speed and control methods needed to portray 3D virtual humans suitable for interactive applications have improved dramatically in recent years. Real-time virtual humans show increasingly complex features along the dimensions of appearance, function, time, autonomy and individuality. The virtual human architecture, which researchers have been developing at the University of Pennsylvania is representative of an emerging generation of such architectures and includes low-level motor skills, a mid-level parallel automata controller and a high-level conceptual representation for driving virtual humans through complex tasks. The architecture, called Jack, provides a level of abstraction generic enough to encompass natural language instruction representation as well as direct links from those instructions to animation control. Building models of virtual humans involves application-dependent notions of fidelity.

Resumen
The article focuses on the possibility of virtual humans for maintenance procedures. The design of complex physical systems must accommodate the human technicians who assemble and maintain them. Technicians need instructions guaranteeing successful and safe task performance. By integrating computer-graphic human models, 3D geometric environments and a system's functional models, designers and instruction authors gain a computational tool for automating task validation. Language-level instructions are interpreted as parameterized procedures that control embodied agent models to execute these tasks and report success and failure conditions. Interpreting these instructions requires integration of spatial, visual and functional reasoning. Instructions guides one to do things one has not done before or remind of forgotten tasks, supporting ones' efforts to assemble, operate and service a multitude of technological artifacts. But no computational procedure can guarantee a particular instruction will be executed correctly or successfully. INSET: Disassembly, Sequencing.