Roger E. Kaufman

Virtual reality surgical simulation for lower urinary tract endoscopy and procedures.

BACKGROUND AND PURPOSE To provide a realistic experience of lower urinary tract endoscopic procedures, we have developed and continue to expand a computer-based surgical simulator that incorporates a surgical tool interface with anatomic detail and haptic feedback. METHODS Surface-based geometric data for the lower urinary tract were generated from the National Library of Medicine Visible Human dataset. The three-dimensional texture map of the surface geometry was developed from recorded endoscopic video procedures. Geometry and associated texture maps were rendered in real time using the Silicon Graphics Extreme Impacts program. The surgical interface device incorporated all normal ranges of motion and resistance that occur within an actual operative environment. The hands-on endoscopic device attached to the interface device was provided by Circon-ACMI, Inc. Urologic residents evaluated the program for correlation with actual endoscopic procedures. RESULTS Texture-mapped digitized images provided a close anatomic similarity to actual videoendoscopic images. Virtual endoscopy of the lower urinary tract was reproducible and closely simulated actual visual and tactile endoscopic experience. CONCLUSIONS Virtual reality surgical simulation is feasible for a variety of lower urinary tract procedures. This system coordinates visual perception with appropriate haptic feedback in both longitudinal and rotational axes. These types of procedures may be incorporated into future educational experiences for urologists to introduce new techniques and to provide documentation of surgical experience.

A Family of New Ergonomic Harness Mechanisms for Full-Body Natural Constrained Motions in Virtual Environments

A family of new virtual reality harness mechanisms has been developed by this investigator to constrain an immersed user within the field of view of a virtual locomotion sensing system while permitting natural motions such as twisting, turning, jogging in place, dropping to the knees or moving to a prone position. The author has also developed a generalized synthesis approach to the design of such harness systems. Unwanted rotational inertial loads felt by the user are minimized while compliant constraints have been tailored to provide natural feedback forces. These ergonomic forces enhance the experience of virtual motion by partially substituting for the missing real-world dynamic loads encountered in locomotion. They also provide subtle, natural cues to the immersed user that aid the user in remaining centered. Unlike some other virtual locomotion systems, these devices are passive, relatively low-cost, easy and natural to use, making them minimally intrusive on the process of learning the simulated task

Kinematic synthesis of geared linkages

Abstract Planar geared linkages readily lend themselves to function, path and motion generation. Function generation includes any problems in which rotations or sliding motion of input and output elements (either links or gears) must be correlated. In some cases, the designer may want to produce a formal functional relationship between the input and output. In these cases, the input and output rotations can be used as the linear analogs of the independent and dependent variables. In other cases, the designer has no particular functional relationship in mind, but merely wants to produce specific relationships between the input and output at certain “precision points”. Path generation involves moving a tracer point along a specified path. A point attached to any “floating” link (such as a coupler) may be used as the tracer point. Motion generation requires that an entire body be guided through a prescribed motion sequence. The body to be guided can be attached to any floating link.

KINSYN Phase II: A human engineered computer system for Kinematic design and a new least-squares synthesis operator

Abstract Unique features being incorporated into a new computer-aided kinematic design system are discussed. A new least-square stretch-rotation synthesis operator technique is introduced, along with some numerical test results. Based on KINSYn, unusual features of the new system include its heuristic organization and its emphasis on machine-generated synthesis procedures supplemented by simultaneous interwoven analysis. Mechanism topology and dimensions can be dynamically modified by the designer working at an interactive graphical display. Prescribed performance characteristics may be altered both as to type, number, and numerical value during the solution procedure, as the designers concepts grow firmer.

Harness Mechanisms for Full-Body Motions in Virtual Environments

Natural motions such as twisting, turning, jogging in place, dropping to the knees or moving to a prone position are permitted by the virtual reality harness mechanisms presented in this poster. They constrain an immersed user within the field of view of a virtual locomotion sensing system. Unwanted rotational inertial loads felt by die user are minimized while compliant constraints provide natural feedback forces. These ergonomic forces enhance the experience of virtual motion by partially substituting for The missing real-world dynamic loads encountered in locomotion. They also aid the user in remaining centered in the field of view of the camera system by providing subtle, natural cues to the immersed user. Unlike some other virtual locomotion systems these passive harness devices have a stationary floor and are relatively low-cost, easy and natural to use. This makes them minimally intrusive on the process of learning the simulated task

Virtual Reality Surgical Simulation for Lower Urinary Tract Endourologic Surgery

Computer-based simulations for clinical training have been utilized for medical education for over 25 years, with progression of technological advances from mainframe computers to the multimedia-based systems in current use.5 Simulation becomes attractive whenever actual physical experience is associated with unacceptable risk or expense or the experience is not practical because of distance or temporal constraints. The classic example of the value of simulation in such circumstances is flight simulation aviation training, which was first introduced during the Second World War to reduce the high casualty rate among the relatively inexperienced pilots recruited for aerial warfare. Though its development has occurred over 40 years, flight simulation in a virtual environment has only recently evolved sufficiently to be considered indispensable for training, due to the savings and benefits in time, expense, equipment, and safety it offers.

Application of an interactive graphics system to the kinematic design of an artificial knee joint

KINSYN is an interactive general purpose computer system for the kinematic synthesis and analysis of mechanisms. It is applicable to kinematics problems ranging from the synthesis of spacecraft antenna deployment mechanisms to the design of folding high chairs. Features of KINSYN have been described in several recent publications. The results shown in this paper were obtained during the first two or three trial runs on KINSYN. Of course, extensive work would remain to be done in order to apply these techniques to a practical artificial limb design, Nonetheless, the fact that so much useful design data can be obtained so readily with the aid of KINSYN indicates that it could be a significant aid in a physiological limb development program.

Three position precessing mechanism synthesis

Abstract This paper presents a complex number development of a three position geared five-bar precessing mechanism synthesis. The methodology which is presented in this study is based on an extension of Burmester cycloidal circlepoint-centerpoint theory[2]. This paper presents the mathematical formulation of the synthesis process. A structured FORTRAN computer program was developed on a VAX 11/780 computer in order to implement the synthesis process. The synthesis program is capable of presenting the synthesis results on a graphical display. Typical results are shown.