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Full-Text Articles in Mechanical Engineering

Design Of A Robotic Instrument Manipulator For Endoscopic Deployment, Ryan Ponten Aug 2017

Design Of A Robotic Instrument Manipulator For Endoscopic Deployment, Ryan Ponten

Masters Theses

This thesis describes the initial design process for an application of continuum robotics to endoscopic surgical procedures, specifically dissection of the colon. We first introduce the long-term vision for a benchtop dual-instrument endoscopic system with intuitive haptic controllers and then narrow our focus to the design and testing of the instrument manipulator itself, which must be actuated through the long, winding channel of a standard colonoscope.

Based on design requirements for a target procedure, we analyze simulations of two types of continuum robots using recently established kinematic and mechanic modeling approaches: the concentric-tube robot (CTR) and the concentric agonist-antagonist robot ...


Effects Of Malformed Or Absent Valves To Lymphatic Fluid Transport And Lymphedema In Vivo In Mice, Akshay S. Pujari Jan 2017

Effects Of Malformed Or Absent Valves To Lymphatic Fluid Transport And Lymphedema In Vivo In Mice, Akshay S. Pujari

Masters Theses

Lymph is primarily composed of fluid and proteins from the blood circulatory system that drain into the space surrounding cells, interstitial space. From the interstitial space, the fluid enters and circulates in the lymphatic system until it is delivered into the venous system. In contrast to the blood circulatory system, the lymphatic system lacks a central pumping organ dictating the predominant driving pressure and velocity of lymph. Transport of lymph via capillaries, pre-collecting and collecting lymphatic vessels relies on the synergy between pressure gradients, local tissue motion, valves and lymphatic vessel contractility. The direction of lymph transport is regulated by ...


A Magnetic Resonance Compatible Knee Extension Ergometer, Youssef Jaber Jan 2017

A Magnetic Resonance Compatible Knee Extension Ergometer, Youssef Jaber

Masters Theses

The product of this thesis aims to enable the study of the biochemical and physical dynamics of the lower limbs at high levels of muscle tension and fast contraction speeds. This is accomplished in part by a magnetic resonance (MR) compatible ergometer designed to apply a load as a torque of up to 420 Nm acting against knee extension at speeds as high as 4.7 rad/s. The system can also be adapted to apply the load as a force of up to 1200 N acting against full leg extension. The ergometer is designed to enable the use of ...


A Haptic Surface Robot Interface For Large-Format Touchscreen Displays, Mark Price Jan 2016

A Haptic Surface Robot Interface For Large-Format Touchscreen Displays, Mark Price

Masters Theses

This thesis presents the design for a novel haptic interface for large-format touchscreens. Techniques such as electrovibration, ultrasonic vibration, and external braked devices have been developed by other researchers to deliver haptic feedback to touchscreen users. However, these methods do not address the need for spatial constraints that only restrict user motion in the direction of the constraint. This technology gap contributes to the lack of haptic technology available for touchscreen-based upper-limb rehabilitation, despite the prevalent use of haptics in other forms of robotic rehabilitation. The goal of this thesis is to display kinesthetic haptic constraints to the touchscreen user ...


Freeform Extrusion Fabrication Of Titanium Fiber Reinforced 13-93 Bioactive Glass Scaffolds, Albin Thomas Jan 2015

Freeform Extrusion Fabrication Of Titanium Fiber Reinforced 13-93 Bioactive Glass Scaffolds, Albin Thomas

Masters Theses

"Although implants made with bioactive glass have shown promising results for bone repair, their application in repairing load-bearing long bones is limited due to their poor mechanical properties as compared to human bones. This thesis study is on freeform extrusion fabrication of silicate based 13-93 bioactive glass scaffolds reinforced with titanium fibers. A composite paste was prepared with 13-93 bioactive glass filled with titanium fibers (~16 µm in diameter and aspect ratio of ~250) having 0.1 to 0.4 vol. % of the bioactive glass scaffold. This paste was then filled into a syringe manually, and then extruded through a ...


A Continous Rotary Actuation Mechanism For A Powered Hip Exoskeleton, Matthew C. Ryder Jan 2015

A Continous Rotary Actuation Mechanism For A Powered Hip Exoskeleton, Matthew C. Ryder

Masters Theses

This thesis presents a new mechanical design for an exoskeleton actuator to power the sagittal plane motion in the human hip. The device uses a DC motor to drive a Scotch yoke mechanism and series elasticity to take advantage of the cyclic nature of human gait and to reduce the maximum power and control requirements of the exoskeleton. The Scotch yoke actuator creates a position-dependent transmission that varies between 4:1 and infinity, with the peak transmission ratio aligned to the peak torque periods of the human gait cycle. Simulation results show that both the peak and average motor torque ...


Design Of A Passive Exoskeleton Spine, Haohan Zhang Jan 2014

Design Of A Passive Exoskeleton Spine, Haohan Zhang

Masters Theses

ABSTRACT

DESIGN OF A PASSIVE EXOSKELETON SPINE

SEPTEMBER 2014

HAOHAN ZHANG, B.E.M.E, DALIAN UNIVERSITY OF TECHNOLOGY

M.S.M.E., UNIVERSITY OF MASSACHUSETTS AMHERST

Directed by: Professor Frank C. Sup IV

In this thesis, a passive exoskeleton spine was designed and evaluated by a series of biomechanics simulations. The design objectives were to reduce the human operator’s back muscle efforts and the intervertebral reaction torques during a full range sagittal plane spine flexion/extension. The biomechanics simulations were performed using the OpenSim modeling environment. To manipulate the simulations, a full body musculoskeletal model was created based ...


Were Neandertal Humeri Adapted For Spear Thrusting Or Throwing? A Finite Element Study, Michael Anthony Berthaume Jan 2014

Were Neandertal Humeri Adapted For Spear Thrusting Or Throwing? A Finite Element Study, Michael Anthony Berthaume

Masters Theses

An ongoing debate concerning Neandertal ecology is whether or not they utilized long range weaponry. The anteroposteriorly expanded cross-section of Neandertal humeri have led some to argue they thrusted their weapons, while the rounder cross-section of Late Upper Paleolithic modern human humeri suggests they threw their weapons. We test the hypothesis that Neandertal humeri were built to resist strains engendered by thrusting rather than throwing using finite element models of one Neandertal, one Early Upper Paleolithic (EUP) human and three recent human humeri, representing a range of cross-sectional shapes and sizes. Electromyography and kinematic data and articulated skeletons were used ...


Comparative Study On Posture And Its Influences On Horizontal Ground Reaction Forces Generated By Muscles: Implications For Crouch Gait, Hoa Xuan Hoang Dec 2011

Comparative Study On Posture And Its Influences On Horizontal Ground Reaction Forces Generated By Muscles: Implications For Crouch Gait, Hoa Xuan Hoang

Masters Theses

Crouch gait decreases walking efficiency due to the increased knee and hip flexion during the stance phase of gait. Crouch gait is generally considered to be disadvantageous for patients with cerebral palsy; however, a crouched posture may afford biomechanical advantages that lead some patients to adopt a crouch gait.

To investigate one possible advantage of crouch gait, a musculoskeletal model created in OpenSim was placed in 15 different postures from upright to severe crouch during initial, middle, and final stance of the gait cycle. A series of optimizations were performed for each posture to maximize ground reaction forces for the ...


The Effects Of Machining On Structure And Tribological Properties Of Ultra High Molecular Weight Polyethylene For Artificial Joint Prostheses, Jinshan Song Jan 1997

The Effects Of Machining On Structure And Tribological Properties Of Ultra High Molecular Weight Polyethylene For Artificial Joint Prostheses, Jinshan Song

Masters Theses

Understanding the effect of machining on the structure and property of subsurface layer of ultra high molecular weight polyethylene (UHMWPE) can significantly facilitate the increase in longevity of artificial joints. This study was performed to investigate the machining effects on the polymeric structure and tribological properties. Machining parameters include cutting speed, tool feed rate and depth of cut. Temperature rise was studied during machining to assess the extent of thermal degradation due to machining. Polymeric structure of the semicrystalline polymer was characterized using differential scanning calorimetry (DSC) in terms of melting enthalpy, crystallinity and melting temperature. Surface texture and hardness ...