Document Type


Date of Award

Spring 5-31-2000

Degree Name

Doctor of Philosophy in Mechanical Engineering - (Ph.D.)


Mechanical Engineering

First Advisor

M. C. Leu

Second Advisor

Denis L. Blackmore

Third Advisor

Michael Recce

Fourth Advisor

Rajesh N. Dave

Fifth Advisor

Frank Y. Shih

Sixth Advisor

Zhiming Ji


This work introduces a novel method to overcome most of the drawbacks in traditional methods for creating design models. The main innovation is the use of virtual tools to simulate the natural physical environment in which freeform. Design models are created by experienced designers. Namely, the model is created in a virtual environment by carving a work piece with tools that simulate NC milling cutters.

Algorithms have been developed to support the approach, in which the design model is created in a Virtual Reality (VR) environment and selection and manipulation of tools can be performed in the virtual space. The desianer's hand movements generate the tool trajectories and they are obtained by recording the position and orientation of a hand mounted motion tracker. Swept volumes of virtual tools are generated from the geometry of the tool and its trajectories. Then Boolean operations are performed on the swept volumes and the initial virtual stock (work piece) to create the design model.

Algorithms have been developed as a part of this work to integrate the VR environment with a commercial CAD/CAM system in order to demonstrate the practical applications of the research results. The integrated system provides a much more efficient and easy-to-implement process of freeform model creation than employed in current CAD/CAM software. It could prove to be the prototype for the next-generation CAD/CAM system.