In this research, a novel magnetorheological (MR) fluids based multifunctional actuator for assistive knee braces is designed. To decrease the dimension of the actuation device while enhancing its perfonnances, a motor and MR fluids are integrated into a single device. With MR fluids, the actuator possesses multiple functions as motor, clutch, and brake while meeting the requirement of nonnal human motion as well. In this thesis, design details and operating principle of the actuator are illustrated, and possible configurations of the motor part and clutch/brake part are discussed. Finite element method is utilized to analyze the magnetic circuits, influence of pennanent magnet on MR fluids, and magnetic flux distribution. Different clutch/brake parts with various inner coils are compared and analyzed, followed by a design optimization to improve the output torque. Prototypes of the multifunctional actuator are fabricated and tested, and characteristics of each function are investigated. As the actuator has multiple functions, modeling is developed for different functions, and system identification is carried out to determine the parameters. Adaptive control is utilized to control the actuator for torque and speed tracking. A smart joint using such a multifunctional actuator is designed, and its prototype is fabricated and tested. Power consumptions of knee brace using the smart joint are investigated during normal walking cycle. The results show that the developed actuator and smart joint are promising to be used in assistive knee braces. / Guo, Hongtao. / Source: Dissertation Abstracts International, Volume: 73-03, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 154-158). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

The purpose of this investigation was to evaluate and compare the efficacy of three functional knee braces in stabilizing anterior cruciate ligament (ACL) deficient knees. The subject sample consisted of eighteen males and females with a unilateral ACL deficiency. / The criterion variables consisted of the ability of each brace in controlling internal rotation and knee extension during active movement and knee extension during a high velocity activity (dynamic task). Total displacement of the knee brace during a running test was also evaluated. / The results of this study demonstrated significant differences between the efficacy of the three braces for control of knee extension during active movement, knee extension during a dynamic task and brace migration during a running task. There was no significant difference between the efficacy of the three braces in controlling internal rotation during active movement.

The purpose of this investigation was to objectively evaluate whether three functional de-rotational knee braces stabilize an anterior cruciate ligament (ACL) deficiency. The subject sample consisted of fifteen males and females with a unilateral ACL deficiency. The data for each subject was obtained using the Genucom Knee Analyzer. A right knee-left knee anterior laxity difference of 3mm or greater served as a subject inclusion parameter for protocol completion. The inclusion criteria reduced the subject sample to a total of eleven. / The study consisted of a randomized block design. The experimental design consisted of three parts: (1) an investigation of translational stability, (2) an investigation of rotatory stability, and (3) a comparison between the three braces. / The analysis involved a one way ANOVA of the criterion variables; anterior laxity (ALAX), anterior midrange stiffness (AMRS), anterior endrange stiffness (AERS), internal laxity (ILAX), and translation of the lateral tibial plateau (TLTP). / The AMRS characteristics differed significantly (alpha = 0.05) at 20$ sp circ$ flexion. The results were the following: $-$10.00 $ pm$ 9.78 N/mm for brace 1, $-$2.86 $ pm$ 7.2 N/mm for brace 2 and $-$41.02 $ pm$ 14.79 N/mm for brace 3. The values evaluated for ALAX, AERS, ILAX, and TLTP profiles did not differ significantly between knee braces.

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The use of knee braces in the past has been to protect and prevent further injury to a previously damaged knee. An Example of one such knee brace is the Lennox-Hill Derotation knee brace. This brace is used to assist the athlete who has a rotatory knee instability from a previous injury. (Klafs and Arnheim, 1977.) The problem of this study is to determine the possible effects of the Anderson Knee Stabler on mean isometric torque output in the knee extensor, mean isokinetic torque output at several speeds in the knee extensors and performance on the SEMO Agility Test in college football This study is important because it will assess the functional capability of an athlete wearing this given brace. Also, if significant differences are not achieved it will serve as a means of promoting this brace to those who may be reluctant to use it. If significant results are achieved then athletic trainers and coaches may have to rethink whether this brace is impairing the performance of their athletes.

L’articulation du genou est sujette à de nombreuses pathologies pouvant entraîner des instabilités. Les démarches thérapeutiques incluent communément le port d’orthèses, dans le but de stabiliser ou limiter les mouvements articulaires. Malgré une forte prescription, l’évaluation de ces dispositifs manque encore de standardisation.En lien avec des médecins et des industriels, différents outils ont été développés pour évaluer leur efficacité biomécanique. Un modèle éléments finis d’un membre inférieur appareillé a notamment permis d’étudier l’effet de divers paramètres de conception d’une genouillère sur les pressions exercées et sur sa capacité à limiter un mouvement pathologique. Ce modèle a servi à valider un banc de test pouvant contribuer à l’innovation et la certification. Afin d’appréhender les problèmes de confort, le glissement des orthèses sur la peau a été caractérisé par des mesures de champ. Enfin, leurs actions in vivo ont été mesurées à l’aide d’un arthromètre sur des patients présentant une laxité.Les résultats mettent en évidence l’importance des caractéristiques techniques des orthèses et la spécificité du patient sur leurs niveaux d’action. Ainsi, il est possible de cibler des pathologies en jouant sur certains facteurs. Cependant, comparé aux structures de stabilisation passive (ligaments), le rôle des orthèses s’avère limité aux conditions de faibles sollicitations mécaniques. Néanmoins, leurs effets actifs et proprioceptifs (contrôle neuro-musculaire) seraient également à considérer.Ces outils s’avèrent complémentaires ; ils ouvrent la voie à des démarches d’évaluation standardisées et pourront également aider au développement de nouveaux produits. / The knee joint is vulnerable to various injuries and degenerative conditions, potentially leading to instabilities. Usual treatments involve orthoses, which are medical devices aimed at supporting, aligning or immobilizing the joint. However, the evaluation of these devices lacks standardisation despite high prescription and demand.In relation with clinicians and manufacturers, different tools were developed to assess their biomechanical efficiency. Firstly, a finite element analysis (FEA) of a braced lower limb was used to investigate the effects of brace design on its ability to prevent a pathological motion and understand the force transfer mechanisms. This model provided a basis to validate an experimental surrogate limb with the aim of providing an innovation and certification tool for manufacturers. In an attempt to apprehend comfort issues, full-field measurements of brace migration and FEA of contact pressures were performed. Finally, their in vivo actions were measured on ACL-deficient patients using a laxity testing device.Results highlight the importance of brace technical characteristics and patient-specificity on characterized levels of action and comfort. Furthermore, some key design factors allowed to target devices to particular pathologies. However, when compared to in vivo passive stabilizing structures (ligaments), the efficiency of knee braces was restrained to low load conditions. Nevertheless, these devices may also have a substantial effect on active stabilizing mechanisms such as neuro-muscular control.These tools were found to be complementary and may hopefully pave the way to a standardised procedure for evaluating and developing new designs.