Ming Leu (mleu@mst.edu, 573-341-4482), Xiaobo Peng, Weihan Zhang

This project is aimed at developing a virtual sculpting system that addresses some of the drawbacks of traditional CAD systems. The goal of this system is to enable interactive modeling of 3D freeform objects in a virtual environment such that the user can focus on the design intent. An interactive modeling method is implemented with virtual reality hardware and software to allow the user creating and modifying freeform objects in an advanced virtual environment that provides stereoscopic viewing and force feedback during the virtual sculpting process. The system provides a friendly environment where the user can create objects in an intuitive manner similar to sculpting in a physical environment.

Web link for this project: http://web.mst.edu/~vrpl/projects.htm

1. "Swept-Volume Computation for Machining Simulation and Virtual Reality Application,� B.Y. Maiteh, D. Blackmore, L. Abdel-Malek, and M. C. Leu, Journal of Materials Processing and Manufacturing Science, Vol. 7, 2000, pp. 380-390.

Abstract: Many Virtual Reality applications have been successfully developed in different fields such as medicine, military, design and manufacturing. Most of these applications involve the moving of objects and their interaction with the environment in virtual space. One of the foreseeable important applications of virtual manufacturing is the NC machining generation paths and verification in a VR environment for rapid prototyping. The user manipulates a cutting tool in virtual environment to guide the machine in cutting a specified object. This application requires the complexity of full-body haptics, since machine tool geometry must be accurately modeled in the simulation to capture the geometric interaction between the cutting tool and the target creation. Also, these kinds of applications require an efficient computation of swept volumes of the machining tool geometry to achieve real-time rendering of the machining processes in the VR setting.
This paper describes a fast and accurate method for generating the swept volume of a moving object undergoing an arbitrary transnational and rotational motion, with application to NC machining simulation in a VR setting. The Sweep Differential Equation method, which was initially developed for representing and computing the swept volumes of rigid moving objects and subsequently extended to objects that may deform during the course of motion, forms the basis for the VR application of NC cutter path generation and verification. An example is provided to demonstrate the effectiveness of the SDE method for simulation of multi-axis NC machining.

2. "Creation of Freeform Solid Models in Virtual Reality,� M.C. Leu, B. Y. Maiteh, D. Blackmore, and L. Fu, Annals of the CIRP, Vol. 50, No. 1, 2001, pp. 73-76.

Abstract: A novel method has been developed using a virtual reality environment to create solid models with freeform surfaces. The VR environment emulates the physical environment for creating freeform objects, i.e. the freeform model is created in a virtual environment by shaping a virtual workpiece with a variety of virtual tools. The trajectories of the virtual tools are generated by the designer's hand movements and they are obtained by recording the position and orientation of the motion tracker mounted on a device held with the hand. A haptic device can be worn by the designer to provide a feel of the model creation process. In the mathematical algorithm, the swept volumes of the design tools are computed from the geometric data and trajectories of the tools. Boolean operations are then performed on the swept volumes of the virtual tools and the virtual workpiece to create the design model. If the virtual tools used have the same geometry as the real tools used in NC machining, their trajectories in the model creation process can be post-processed and used as feasible trajectories in actual NC machining to fabricate the design model.

3. "Virtual Sculpting with Haptic Interface,� M. C. Leu and X., Peng, NSF Design, Service and Manufacturing Grantees and Research Conference, University of Alabama, Birmingham, Alabama, January 6-9, 2003.

Abstract: This paper presents the development of a virtual sculpting system, allowing the user to create a freeform model by carving a virtual workpiece with a virtual tool while providing haptic interface during the sculpting process. A virtual reality approach is taken to provide stereoscopic viewing and force feedback, thus making the process of model creation in the virtual environment easier and more intuitive. The development of this system involves integrating techniques and algorithms in geometric modeling, computer graphics, and haptic rendering. Multithreading is used in an attempt to address the different update rates required in the graphic and haptic displays.

4. "Interactive Solid Modeling in a Virtual Environment with Haptic Interface,� X. Peng and M.C. Leu, Virtual and Augmented Reality Applications in Manufacturing, Springer-Verlag London Limited, London, 2003.

Abstract: This paper presents the development of a Virtual Sculpting system and addresses the issues of interactive solid modeling with haptic interface. A Virtual Reality approach is used to make the sculpting process more intuitive and interactive, by providing stereo viewing and force feedback capabilities in carving a solid block into a 3D freeform object. The geometric modeling in the system is based on the Sweep Differential Equation method to compute the tool swept volume, and uses the ray-casting method to perform Boolean operation between the tool swept volume and the virtual stock in dexel data. The PHANToM manipulator is used as an input device to provide the position and orientation of the sculpting tool, and also as an output device to provide force feedback to the user during the sculpting process. Multithreading is used to help address the different update rates required in the graphic rendering and haptic rendering.

5. "Interactive FreeForm Modeling with Force Feedback,� M.C. Leu, X. Peng and X. Chi, NSF Design, Service and Manufacturing Grantees and Research Conference, Southern Methodist University, Dallas, TX, January 5-8, 2004 (submitted).

Abstract: Interactive freeform modeling with haptic interface is discussed in this paper. A Virtual Reality approach is taken to make the use of modeling tools more intuitive. The VR interface includes stereo viewing and force feedback. The geometric modeling is based on the sweep differential equation method to compute the boundary of the tool swept volume, and the use of ray-casting to perform Boolean operation between the tool swept volume and the virtual stock. The PHANToM manipulator is used to sense the position and orientation of the sculpting tool, as well as to provide haptic sensation to the user during sculpting.