Medical Robotics for use in MRI Guided Endoscopy

Interventional Magnetic Resonance Imaging (MRI) is a developing field that aims to provide intra-operative MRI to a clinician to guide diagnostic or therapeutic medical procedures. MRI provides excellent soft tissue contrast at sub-millimetre resolution in both 2D and 3D without the need for ionizing radiation. Images can be acquired in near real-time for guidance purposes. Operating in the MR environment brings challenges due to the high static magnetic field, switching magnetic field gradients and RF excitation pulses. In addition high field closed bore scanners have spatial constraints that severely limit access to the patient. This thesis presents a system for MRI-guided Endoscopic Retrograde Cholangio-pancreatography (ERCP). This includes a remote actuation system that enables an MRI-compatible endoscope to be controlled whilst the patient is inside the MRI scanner, overcoming the spatial and procedural constraints imposed by the closed scanner bore. The modular system utilises non-magnetic ultrasonic motors and is designed for image-guided user-in-the-loop control. A novel miniature MRI compatible clutch has been incorporated into the design to reduce the need for multiple parallel motors. The actuation system is MRI compatible does not degrade the MR images below acceptable levels. User testing showed that the actuation system requires some degree of training but enables completion of a simulated ERCP procedure with no loss of performance. This was demonstrated using a tailored ERCP simulator and kinematic assessment tool, which was validated with users from a range of skill levels to ensure that it provides an objective measurement of endoscopic skill. Methods of tracking the endoscope in real-time using the MRI scanner are explored and presented here. Use of the MRI-guided ERCP system was shown to improve the operator’s ability to position the endoscope in an experimental environment compared with a standard fluoroscopic-guided system.Open Acces

Space shuttle OMS helium regulator design and development

Analysis, design, fabrication and design verification testing was conducted on the technological feasiblity of the helium pressurization regulator for the space shuttle orbital maneuvering system application. A prototype regulator was fabricated which was a single-stage design featuring the most reliable and lowest cost concept. A tradeoff study on regulator concepts indicated that a single-stage regulator with a lever arm between the valve and the actuator section would offer significant weight savings. Damping concepts were tested to determine the amount of damping required to restrict actuator travel during vibration. Component design parameters such as spring rates, effective area, contamination cutting, and damping were determined by test prior to regulator final assembly. The unit was subjected to performance testing at widely ranging flow rates, temperatures, inlet pressures, and random vibration levels. A test plan for propellant compatibility and extended life tests is included

Automation of anatomic torsion monitor for evaluation and improvement of low back dysfunction

The existing Anatomical Torsion Monitor (ATM) to evaluate mechanical stiffness and viscoelasticity of the low back suffers from various inherent defects. This has to be replaced by an improved device. Also the existing ATM cannot provide oscillations to the low back. The main objective is to automate the existing ATM for evaluating the low back immediately using objective methods. The specific objective is to provide oscillations for improving the low back dysfunction. The laser platform and the target chart for recording the readings are dispensed with the existing ATM. Instead, the ultrasound transducers are attached to the pads to record the readings for loading and unloading the low back. The voltage readings are directly recorded in the computer through a DAQ card and the Hysteresis Loop Areas (HLAs) are evaluated using MATLAB. In addition to automation of the ATM for evaluating the lows back, a technique is developed for improving the low back dysfunction by imparting oscillations to the low back. These oscillations can be delivered to the subject using a cam mechanism and a DC motor fitted to the automated ATM (A- ATM). The cam mechanism is used with pneumatic cylinders in order to give the oscillation alternately to both contact pads. The frequency of the oscillations can be controlled by using a speed controller switch. Ten control subjects (nine males and one female) in the age group of (24-77) were given oscillations to the low back for five minutes duration. HLAs were evaluated before and after the treatment in the form of oscillations. The frequency for each oscillation was 20 cycles per minute with amplitude of 2 inches. The percentage change in HLA as well as Range of motion were obtained and summarized. The existing ATM is successfully automated which results in objectively evaluating the passive low back and obtaining the results quicker compared to unautomated ATM. The automated ATM can also deliver quantifiable oscillations to the passive low back. It is observed that providing oscillations to the low back results in improved viscoelasticity of the low back for those subjects whose BMI is 25 or less and an insignificant change in range of motion for all the subjects. It is further observed that based on our tests, the optimal duration of oscillations is 5 minutes. However, the correct displacement amplitude, frequency, and duration of treatment will have to be determined from individual medical and physical conditions

Vertical motion simulator familiarization guide

The Vertical Motion Simulator Familiarization Guide provides a synoptic description of the Vertical Motion Simulator (VMS) and descriptions of the various simulation components and systems. The intended audience is the community of scientists and engineers who employ the VMS for research and development. The concept of a research simulator system is introduced and the building block nature of the VMS is emphasized. Individual sections describe all the hardware elements in terms of general properties and capabilities. Also included are an example of a typical VMS simulation which graphically illustrates the composition of the system and shows the signal flow among the elements and a glossary of specialized terms, abbreviations, and acronyms

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 341)

This bibliography lists 133 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during September 1990. Subject coverage includes: aerospace medicine and psychology, life support systems and controlled environments, safety equipment, exobiology and extraterrestrial life, and flight crew behavior and performance

Investigation of the electrical and mechanical requirements for the automation of a process in flexible material manufacture

This thesis describes a successful attempt to automate a manual process in footwear industry. The process is called skiving of leather components and it is one of the early processes necessary for the assembly of shoe uppers. Skiving is the localised thinning of leather components, mainly at some of their edge regions. The purpose of skiving is to produce quality decorative edges or more importantly to enable attaching and joining components without forming thick, discomforting and weak joints. Although other processes in footwear manufacturing have been subject to partial or full automation, skiving has been performed for decades now with a standard mechanism that requires 3-dimensional manipulation of the components by a human operator. This research work was directed towards two main aims. One was to establish a novel method on the basis of which skiving may be performed without the need of human assistance. The developed method is called dynamic matrix skiving and it is capable of performing skiving on leather components by generating and actuating skive patterns as sets of finite elements of skived area to a given resolution. Following derivation and study of the method for skiving, the second phase was aimed at implementing a fully automatic skiving system. The main requirement from the system was to be an intelligent, component oriented, flow through, processing device. This required the capability to receive input components at any orientation and position along its transport mechanism, to recognise them as to their identity and relative position, and to perform skiving upon them without moving them or disturb their continuous flow throughout the entire operation. Individual chapters in this thesis describe the study and experimentation with regards to dynamic matrix skiving, and all logical steps taken to identify the necessary elements and implement their integration to produce the automated skiving system. The concluding part of this work includes presentation of the results obtained from the automated system, and it identifies the areas where further research and development is needed in order to improve the quality of its output

Panoramic, large-screen, 3-D flight display system design

The report documents and summarizes the results of the required evaluations specified in the SOW and the design specifications for the selected display system hardware. Also included are the proposed development plan and schedule as well as the estimated rough order of magnitude (ROM) cost to design, fabricate, and demonstrate a flyable prototype research flight display system. The thrust of the effort was development of a complete understanding of the user/system requirements for a panoramic, collimated, 3-D flyable avionic display system and the translation of the requirements into an acceptable system design for fabrication and demonstration of a prototype display in the early 1997 time frame. Eleven display system design concepts were presented to NASA LaRC during the program, one of which was down-selected to a preferred display system concept. A set of preliminary display requirements was formulated. The state of the art in image source technology, 3-D methods, collimation methods, and interaction methods for a panoramic, 3-D flight display system were reviewed in depth and evaluated. Display technology improvements and risk reductions associated with maturity of the technologies for the preferred display system design concept were identified

A Study of the Change in the Temperature of Maximum Density of Water and Aqueous Solutions as a function of Pressure

The aim of this research is to study the shift in the temperature of maximum density of water and aqueous solutions as a function of pressure. One of the many anomalous properties of water is that it passes through a maximum in density in the liquid state. In order to accurately measure the temperature of maximum density (Tmd), convective flow is monitored in a rectangular container containing the fluid. A temperature gradient is held across the chamber and it is cooled and heated in a quasi-steady state manner. A double cell convection pattern forms in the vicinity of the density maximum. This double cell is tracked by monitoring the temperature at selected points in the fluid. The change in temperature of maximum density due to concentration and applied pressure can be investigated using this technique. At a pressure of one atmosphere, this density maximum occurs in pure water at a temperature of 3.98 C. It is known that the temperature of maximum density decreases as the pressure increases; for pure water this occurs at a rate of 1 C per 50 bar. Experimentally the shift in the temperature of maximum density of aqueous solutions is tracked over the pressure range 1 to 100 bar. It is found that the temperature of maximum density drops as the pressure rises for all solutes studied, but that the rate of decrease changes depending on the nature of the solute. For ionic salts, the rate of decrease is steeper than that for pure water, whereas for monohydric alcohols the rate of decrease is less that that for pure water. These divergent trends become more apparent as solute concentrations increase. The behaviour of the temperature of maximum density is modelled on both macroscopic and microscopic levels. A simple macroscopic model is proposed by combining state functions for water with those of solutes. This approach predicts that the rate of decrease of the temperature of maximum density for ideal (noninteracting) mixtures as a function of pressure is less than for pure water (but not as pronounced as the change observed in the alcohol solutions). Microscopic modelling at the molecular level is done using Monte Carlo methods. Non-ideal mixtures are studied by introducing molecules whose interactions with water are either stronger or weaker than the water-water interactions. In all cases it is found that the rate of change of the temperature of maximum density as a function of pressure lessens compared to the rate for pure water. The models thus help in understanding some, but not all, of the experimental observations

Substrate curvature measurement system

Industry often requires, in a variety of processes, the measurement of deformation induced in a solid object by mechanical stress. One such process is during the manufacture of very large scale integrated circuits (VLSI). During this process a substrate is coated with a thin film to protect the micro circuitry formed on the substrate. Due to the differences in thermal expansions between film and substrate, mechanical stresses can develop which may lead to deformation of the substrate surface. Any deformation of the substrate surface will result in mechanical stress in the interconnections of the circuitry, which could result in severe damage to the operation of the circuit. Different measurement techniques are available to measure the spherical deformation of substrates, with the latest known technique being a combination of a laser beam deflection and light scattering techniques. Many of the existing techniques reveal shortcomings, one of which is a 2-dimensional scanning capability with a minimum of moving components. Another shortcoming is the incapability of previous techniques to calculate the relative error which the measuring technique induces into the results. The aim of this study has been to develop an electro-optical system embodying the successful principles of these techniques in a system which will eliminate the shortcomings and produce results in excess of those previously recorded. In this work, we have concentrated on discussing the development of a system which will produce in situ real time monitoring of mechanical stresses in a solid. The system includes the minimization of system induced errors through the calculation of error voltage gains, and the introduction of a 2-dimensional scanning capability to determine the true position of the laser beam without prior knowledge of the initial substrate curvature. A four-quadrant position sensitive detector (PSD) with relevant Lab View software and programs were also introduced into the system