Computational Tools and Experimental Methods for the Development of Passive Prosthetic Feet

Modern prosthetic foot designs are incredibly diverse in comparison to what was o↵ered to amputees at the turn of the millennium. Powered ankles can supply natural levels of joint torque, whilst passive feet continue to optimise for kinematic goals. However, most passive feet still do not solve the issue of unhealthy loads, and an argument can be made that optimisation methods have neglected the less active and elderly amputee. This thesis creates a framework for a novel approach to prosthetic foot optimisation by focusing on the transitionary motor tasks of gait initiation and termination.An advanced FEA model has been created in ANSYS® using boundary con-ditions derived from an ISO testing standard that replicates stance phase loading. This model can output standard results found in the literature and goes beyond by parameterising the roll-over shape within the software using custom APDL code. Extensive contact exploration and an experimental study have ensured the robustness of the model. Subject force and kinematic data can be used for specific boundary conditions, which would allow for easy adaptation to the transitionary motor tasks.This FEA model has been used in the development of prosthetic experiment tool, which can exchange helical springs to assess e↵ects of small changes in sti↵-ness on gait metrics. A rigorous design methodology was employed for all compo-nents, including parametric design studies, response surface optimisation, and ISO level calculations. The design has been manufactured into a working prototype and is ready for clinical trials to determine its efficacy.The conclusion of this framework is in the development of an experimental method to collect subject data for use in the models. A pilot study uncovered reliable protocols, which were then verified with ANOVA statistics. Proportional ratios were defined as additions to metric peak analyses already found in the liter-ature. These tools are ready for deployment in full clinical trials with amputees, so that a new prosthetic optimisation pathway can be discovered for the benefit of less active or elderly amputees

Simple models of legged locomotion based on compliant limb behavior = Grundmodelle pedaler Lokomotion basierend auf nachgiebigem Beinverhalten

In der vorliegenden Dissertation werden einfache Modelle zur Beinlokomotion unter der gemeinsamen Hypothese entwickelt, dass die beiden grundlegenden und als verschieden angesehenen Gangarten Gehen und Rennen auf ein allgemeines Konzept zurückgeführt werden können, welches in den Standphasen allein auf nachgiebigem Beinverhalten beruht. Hierbei wird auf der Ebene der mechanischen Beschreibung der Gangarten nachgiebiges Beinverhalten mittels des vom Rennen bekannten Masse-Feder-Modells abstrahiert. Zunächst wird eine vergleichsweise einfache, analytische Näherungslösung desselben identifiziert; in einem weiteren Schritt wird die charakteristische Geschwindigkeit des Gangartwechsels aus federartigem Beinverhalten erklärt; und schließlich wird ein zweibeiniges Masse-Feder-Modell für Gehen vorgeschlagen, welches die beobachteten Bodenreaktionskräfte dieser Gangart beschreibt. Auf der Ebene der neuromechanischen Beschreibung wird aufgezeigt, wie das mit einer mechanischen Feder abstrahierte Beinverhalten durch eine positive Rückkopplung der Muskelkraft dezentral und autonom innerhalb des Muskelskelettapparats erzeugt werden kann. Schließlich werden die Einzelergebnisse der Arbeit zusammengefasst, wobei die beiden fundamentalen Gangarten Gehen und Rennen innerhalb des zweibeinigen Masse-Feder-Modells vereinigt werden und die Bedeutung dieses, auf nachgiebigem Beinverhalten beruhenden Zusammenschlusses sowohl für die biomechanische und motorische Grundlagenforschung als auch für Anwendungen in der Robotik, Rehabilitation und Prothetik erörtert wird

A Biologically Informed Structure to Accuracy in Osteometric Reassociation

Commingled assemblages present a common situation in osteological analysis where discrete sets of remains are not readily apparent, thereby hindering biological profile construction and the identification process. Of the methods available for resolving commingling, osteometric reassociation is considered a reliable and relatively objective technique. Traditional osteometric sorting methodologies is a decision-making, error-mitigation approach, where possible matches are eliminated if the calculated pvalue exceeds an analyst-defined threshold. This approach implicitly assumes that all bone comparisons are equally accurate as long as the threshold is attained. This assumption, however, is not based in biological reality. This study tests a hypothetical structure of accuracy in osteometric reassociation to accomplish two goals: First, provide a biological logic to osteometric reassociation, centered on the developmental and mechanical relationships influencing limb bone morphology. This logic is assessed by comparing accuracy, or how often the predicted match is the correct match, in reassociating commingled limb elements by four types of comparisons: homologous, serially homologous, within-limb, and between-limb. Second, improve models for osteometric reassociation by incorporating Bayesian statistics and novel information on bone shape and size through geometric morphometric landmark data. Landmark data were collected from the limb bones (excluding the fibula) of 208 adult males (n=103) and females (n=105) from the William M. Bass donated skeletal collection. From these data, limb bones were commonly represented as log-centroid size and partial least squares components of Procrustes coordinates. Then, 10 individuals were randomly removed from the total sample, acting as a small-scale, closed-population commingled assemblage. Bayesian regression via Hamiltonian MCMC was used as the osteometric reassociation model to predict the best match for commingled limb bones. This process was repeated 1000 times for each bone comparison. Accuracy was defined as the number of times the best match was the correct match divided by 1000. Accuracy was structured from highest to lowest: homologous, within-limb, between-limb, serially homologous. Research design, functional canalization of joints, and developmental modularity are possible factors influencing the observed structure of osteometric reassociation accuracy