This research focuses on the exploration of software and methods to support natural interaction within a virtual environment. Natural interaction refers to the ability of the technology to support human interactions with computer generated simulations that most accurately reflect interactions with real objects. Over the years since the invention of computer-aided design tools, computers have become ubiquitous in the product design process. Increasingly, engineers and designers are using immersive virtual reality to evaluate virtual products throughout the entire design process.

The goal of this research is to develop tools that support verisimilitude, or likeness to reality, particularly with respect to human interaction with virtual objects. Increasing the verisimilitude of the interactions and experiences in a virtual environment has the potential to increase the external validity of such data, resulting in more reliable decisions and better products.

First, interface software is presented that extends the potential reach of virtual reality to include low-cost, consumer-grade motion sensing devices, thus enabling virtual reality on a broader scale. Second, a software platform, VR JuggLua, is developed to enable rapid and iterative creation of natural interactions in virtual environments, including by end-user programmers. Based on this software platform, the focus of the rest of the research is on supporting virtual assembly and decision making. The SPARTA software incorporates a powerful physically-based modeling simulation engine tuned for haptic interaction. The workspace of a haptic device is both virtually expanded, though an extension to the bubble technique, and physically expanded, through integration of a haptic device with a multi-directional mobile platform. Finally, a class of hybrid methods for haptic collision detection and response is characterized in terms of five independent tasks. One such novel hybrid method, which selectively restores degrees of freedom in haptic assembly, is developed and assessed with respect to low-clearance CAD assembly. It successfully maintains the high 1000 Hz update rate required for stable haptics unlike previous related approaches.

Overall, this work forms a pattern of contributions towards enabling natural interaction for virtual reality and advances the ability to use an immersive environment in decision making during product design.