Development of an augmented reality guided computer assisted orthopaedic surgery system

Previously held under moratorium from 1st December 2016 until 1st December 2021.This body of work documents the developed of a proof of concept augmented reality guided computer assisted orthopaedic surgery system – ARgCAOS. After initial investigation a visible-spectrum single camera tool-mounted tracking system based upon fiducial planar markers was implemented. The use of visible-spectrum cameras, as opposed to the infra-red cameras typically used by surgical tracking systems, allowed the captured image to be streamed to a display in an intelligible fashion. The tracking information defined the location of physical objects relative to the camera. Therefore, this information allowed virtual models to be overlaid onto the camera image. This produced a convincing augmented experience, whereby the virtual objects appeared to be within the physical world, moving with both the camera and markers as expected of physical objects. Analysis of the first generation system identified both accuracy and graphical inadequacies, prompting the development of a second generation system. This too was based upon a tool-mounted fiducial marker system, and improved performance to near-millimetre probing accuracy. A resection system was incorporated into the system, and utilising the tracking information controlled resection was performed, producing sub-millimetre accuracies. Several complications resulted from the tool-mounted approach. Therefore, a third generation system was developed. This final generation deployed a stereoscopic visible-spectrum camera system affixed to a head-mounted display worn by the user. The system allowed the augmentation of the natural view of the user, providing convincing and immersive three dimensional augmented guidance, with probing and resection accuracies of 0.55±0.04 and 0.34±0.04 mm, respectively.This body of work documents the developed of a proof of concept augmented reality guided computer assisted orthopaedic surgery system – ARgCAOS. After initial investigation a visible-spectrum single camera tool-mounted tracking system based upon fiducial planar markers was implemented. The use of visible-spectrum cameras, as opposed to the infra-red cameras typically used by surgical tracking systems, allowed the captured image to be streamed to a display in an intelligible fashion. The tracking information defined the location of physical objects relative to the camera. Therefore, this information allowed virtual models to be overlaid onto the camera image. This produced a convincing augmented experience, whereby the virtual objects appeared to be within the physical world, moving with both the camera and markers as expected of physical objects. Analysis of the first generation system identified both accuracy and graphical inadequacies, prompting the development of a second generation system. This too was based upon a tool-mounted fiducial marker system, and improved performance to near-millimetre probing accuracy. A resection system was incorporated into the system, and utilising the tracking information controlled resection was performed, producing sub-millimetre accuracies. Several complications resulted from the tool-mounted approach. Therefore, a third generation system was developed. This final generation deployed a stereoscopic visible-spectrum camera system affixed to a head-mounted display worn by the user. The system allowed the augmentation of the natural view of the user, providing convincing and immersive three dimensional augmented guidance, with probing and resection accuracies of 0.55±0.04 and 0.34±0.04 mm, respectively

1995 BRAC Commission

Army/Air Force/Navy - Base Visit Presentations, April-May 1995. Box 85, L-007

RAPID HEATING AND CHEMICAL SPECIATION CHARACTERIZATION FOR COMBUSTION PERFORMANCE ANALYSIS OF METALLIZED, NANOSCALE THERMITES AND PVDF BOUND SOLID PROPELLANT COMPOSITIONS

Energetic materials research focuses on performance analysis of cost-effective solid materials which safely, precisely, and efficiently transitions stored chemical potential energy to kinetic energy at a rate throttled through chemical or architectural means. Heterogenous compositions of metal fuels and solid materials with a high storage capacity of condensed oxidizing elements, such as oxygen and/or fluorine, is a class of energetic material of interest given its relatively high reaction enthalpies and adiabatic flame temperatures. In the wake of the earliest instances of metal fuels being used as a high energy additive during World War II, characterizing the reaction mechanisms of micron and nanoparticle aluminum fuels with various oxidizer sources has been a primary subject of research within the solid energetics community. The advent of nanotechnologies within the past two decades brought with it the promise of a prospective revolution within the energetics community to expand the utility and characterization of metallized energetic materials in solid propellants and pyrotechnics. Significant prior research has mapped reactivity advantages, as well as the many short comings of aluminum-based nanoscale energetic formulations. Examples of short comings include difficulties of materials processing, relative increase in native oxide shell thickness, and particle aggregate sintering before primary reaction. The less than flaw-less promises of nanoscale aluminum fuels have thus become the impetus for the development of novel architectural solutions and material formulations to eliminate drawbacks of nanomaterial energetics while maintaining and improving the benefits. This dissertation focuses on further understanding reaction mechanisms and overall combustion behavior of nanoscale solid energetic composite materials and their potential future applications. My research branches out from the heavy research involved in binary, aluminum centric systems by developing generalized intuition of reaction and combustion behaviors through modeling efforts and coupling time-of-flight mass spectrometry to rapid heating techniques and novel modes of product sampling. The studies emphasize reaction mechanisms and microwave sensitivities of under-utilized compositions using metal fuels such as titanium, generalize the understanding of the interaction of fluoropolymer binders with metal fuels and oxidizer particles, and characterize how multi-scale architectural structure-function relations of materials effect ignition properties and energy release rates