Motivated by the interests to understand bio-structure deformation and exploit their advantages to create bio-inspired systems for engineering applications, a curvature-based model for analyzing compliant mechanisms capable of large deformation in a three dimensional space has been developed. Unlike methods (such as finite element) that formulate problems based on displacements and/or rotational angles, superposition holds for curvatures in the case of finite rotation but not for rotational angles; thus the curvature-based formulation presents an advantage in presenting nonlinear geometries. Along with a generalized constraint that relaxes traditional boundary constraints (such as fixed, pinned or sliding constraint) on compliant mechanisms, the method of deriving the compliant members in the same global referenced frame is presented. The attractive features of the method, which greatly simplifies the models and improves the computation efficiency of multi-body system deformation where compliant beams play an important role, have been experimentally validated. To demonstrate the applicability of this proposed method to a broad spectrum of applications, three practical examples are given; the first example verifies the generalized constraint by analyzing the multi-axis rotation motion within a natural human knee joint and investigates the human-exoskeleton interactions through dynamic analysis. The second example studies a deformable bio-structure by incorporating the generalized joint constraint into the curvature-based model for automated poultry meat processing. The last example designs a bio-inspired robot with a compliant mechanism to serve as a flexonic mobile node for ferromagnetic structure health monitoring. The analytical models have been employed (with experimental validation) to investigate the effects of different joint constraints on the mechanism deformations. It is expected that the proposed method will find a broad range of applications involving compliant mechanisms.

University of Macau / Faculty of Science and Technology / Department of Electromechanical Engineering

La muñeca es una articulación compleja con un mecanismo de estabilización muy complicado. Se conocen bien las estructuras anatómicas que aseguran una correcta transmisión de cargas a través de ella de un modo estático, se ignoran, en cambio, muchos de los mecanismos dinámicos neuromusculares que modulan dicha transmisión de forma óptima. La evolución natural de una lesión ligamentosa que ocasiona inestabilidad en el carpo, suele ser una artrosis generalizada e incapacitante para el enfermo. Sin embargo, no son raros los casos en que una lesión ligamentosa no cursa con dolor ni causa una gran incapacidad funcional. En estos casos, se ha postulado la posibilidad de que la acción muscular ha compensado el fallo de función ligamentosa, evitando de esta manera que se produzca una inestabilidad articular. Para valorar la influencia que tienen los músculos periarticulares en la posición y orientación de los huesos del carpo cuando los ligamentos primarios fallan, hemos realizado un estudio con veinte antebrazos de cadáver criopreservados, que previamente no presentaban ninguna lesión ligamentosa ni ósea que pudiera alterar el resultado del estudio. Simulamos la contracción muscular mediante la carga axial de los músculos motores directos de la muñeca (FCR, FCU, APL, ECRL y ECU), de manera proporcional al área de sección fisiológica y actividad electromiográfica de cada músculo, antes y después de crear una inestabilidad escafolunar en diez antebrazos, y una inestabilidad lunopiramidal en otros diez. El movimiento que presentan los huesos del carpo se registra a través de un dispositivo de rastreo en las tres direcciones del espacio, mediante unos sensores colocados en escafoides, piramidal y hueso grande; comparamos situaciones similares de carga muscular, antes y después de cada inestabilidad con el test de Wilcoxon. En los casos con inestabilidad escafolunar, observamos que la acción de los músculos supinadores de la fila distal (ECRL y APL) no altera significativamente el movimiento de los huesos del carpo después de producir la disociación. El FCU, aunque es un supinador tiene un efecto negativo sobre esta articulación, ya que produce rotaciones opuestas en el escafoides y el piramidal aumentando la disociación. La contracción aislada del ECU, produce una pronación de la fila proximal y distal, que desestabiliza al escafoides en los tres planos del espacio, produciendo la típica subluxación rotatoria del escafoides. El FCR, aunque es un pronador de la fila distal y del piramidal, produce una supinación en el escafoides, con lo que provoca un acercamiento dorsal de la pareja piramidal-semilunar al escafoides, relajando la articulación, por lo que su efecto es beneficioso para este tipo de inestabilidad. En cuanto a la inestabilidad lunopiramidal, el efecto de los músculos supinadores de forma aislada (APL, ECRL y FCU) aumenta la flexión del piramidal y produce una supinación de la pareja escafoides-semilunar provocando una incongruencia articular y el típico resalte de esta inestabilidad. En cambio, el efecto aislado del ECU, produce cambios en la movilidad de los huesos del carpo que benefician a la articulación lunopiramidal, manteniéndola reducida. Por lo tanto, podemos concluir que ante una inestabilidad escafolunar dinámica, la fisioterapia de la mano debería basarse en la inhibición del ECU y del FCU y en el entrenamiento propioceptivo del ECRL, APL y FCR; en cambio, cuando existe una inestabilidad lunopiramidal hay que potenciar la contracción isométrica del ECU, e inhibir la acción de los músculos supinadores (APL, ECRL y FCU). Por otra parte, la manera de ferulizar la muñeca sería forzando una supinación intracarpiana y una desviación cubital de la muñeca en los casos con lesión aguda parcial del ligamento escafolunar, y mediante una pronación intracarpiana en los casos con lesión aguda parcial del ligamento lunopiramidal. / Twenty cadaveric forearms were tested using a wrist testing apparatus designed to investigate the mechanisms of muscle stabilization of the wrist. In ten specimens we created a scapholunate ligament disruption, while another ten we did a lunotriquetral dissociation. The specimens were set in a jig allowing the distal row to migrate proximally and rotate around the axis of pronosupination. Five wrist motor tendons (FCR, FCU, ECU, ECRL and APL) were loaded with specific weights. Reactive rotations of the scaphoid, triquetrum and capitate were measured by an electromagnetic motion tracking device before and after sectioning specific carpal ligaments. We compared similar situations of load before and after creating the dissociation with the Wilcoxon test. With scapholunate dissociation the action of supinator muscles (ECRL and APL) do not alter the movement of the carpal bones; the FCU has a negative effect on the scapholunate joint, as it produces opposite rotations between the scaphoid and lunate that increase the instability. Individual loading of ECU induces a pronation of the distal and proximal row, that destabilizes the scaphoid in the three space planes, producing the typical rotary subluxation of the scaphoid. The FCR has a supination effect on the scaphoid while it pronates the triquetrum and the distal row, this keeps the scapholunate joint closed. With the disruption of the lunotriquetral ligaments, individual loading of the supinator muscles (APL, ECRL and FCU), increases significantly the amount of flexion and supination exhibited by the triquetrum, this produces a joint incongruity that determines the presence of the typical lunotriquetral clunking. However, the ECU protects against carpal collapse, keeping the joint reduced. In conclusion, we can suppose that hand therapy in dynamic scapholunar dissociations should aim at proprioceptionally training the ECRL, APL and FCR muscles and an inhibition of ECU and FCU; while in dynamic lunotriquetral dissociations we must emphasize isometric contraction of the ECU and inhibit the action of the supinator muscles. Anyway, splinting of the wrist should be with intracarpal supination and wrist ulnar deviation in case of partial injury of scapholunate ligament, and with intracarpal pronation in case of partial injury of lunotriquetral ligament.

We present a study of high-resolution long-slit spectra of the Narrow-Line Regions (NLRs) of NGC 4151 (a Seyfert 1 galaxy) and NGC 1068 (a Seyfert 2 galaxy) obtained with the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope (HST). The spectra were retrieved from the Multimission Archive at Space Telescope (MAST) and were obtained from five and seven orbits of HST time resulting in five and seven parallel slit configurations at position angles of 52 degrees and 38 degrees for NGC 4151 and NGC 1068 respectively. The spectra have a spatial resolution of 0.2 arcsecond across and 0.1 arcsecond along each slit. Observations of [O III] emission from the NLRs were made using the medium resolution G430M grating aboard HST. The spectral resolving power of the grating, R~9000, resulted in the detection of multiple kinematic components of the [O III] emission line gas along each slit. Radial velocities of the components were measured using a Gaussian fitting procedure. Biconical outflow models were generated to match the data and for comparison to previous models done with lower dispersion observations. The general trend is an increase in radial velocity roughly proportional to distance from the nucleus, followed by a linear decrease after roughly 100 pc. This is similar to that seen in other Seyfert galaxies, indicating common acceleration and deceleration mechanisms. The full-width at half-maximum (FWHM) of the emission lines reaches a maximum of 1000 km/s near the nucleus, and generally decreases with increasing distance to about 100 km/s in the extended narrow-line region (ENLR), starting at about 400 pc from the nucleus. In addition to the bright emission knots, which generally fit our model, there are faint high velocity clouds that do not fit the biconical outflow pattern of our kinematic model. A comparison of our observations with high-resolution radio maps shows that the kinematics of the faint NLR clouds may be affected by the radio lobes that comprise the inner jet. However, the bright NLR clouds show a smooth transition across the radio knots in radial velocity and velocity dispersion plots and remain essentially undisturbed in their vicinity, indicating that the radio jet is not the principal driving force on the outflowing NLR clouds. A dynamical model was developed for NGC 1068; it includes forces of radiation pressure, gravity, and drag due an ambient medium, simultaneously acting on the NLR clouds. The velocity profile from this model was too steep to fit the data, which show a more slowly increasing velocity profile. Gravity alone was not able to slow down the clouds but with the drag forces included, the clouds could slow down, reaching systemic velocities at distances that depend on the column densities of the NLR gas and density of the intercloud medium. A biconical model using the geometric parameters from our kinematic fit, and the velocity law from the dynamic fit, was used to match the data. The resulting dynamic model represented a poor fit to the data, indicating the need for additional dynamical considerations.

The main purpose of this study was to develop a three-tier test for assessing tenthgrade students&rsquo / difficulties about kinematics graphs. In a three-tier test, first tier is classical multiple-choice question, the second tier is also classical multiple-choice question but presents reasons for answers given to the first tier and the third tier asks existence of confidence about the first two tiers. To develop a three-tier test, Turkish translation of the Test of Understanding Graphs in Kinematics (TUG-K) developed by Beichner (1994) was used. One more essay type question of asking students&rsquo / reasons of their answers and blank alternatives to write any suggestion different from choices were added to the each item of Turkish translation of this test translated by Delialioglu (2003). Finally, Kinematics Graphs Test Requesting Reasoning (KGTRR) was developed and administered to 253 students. To determine the distracters of the second-tiers of the Kinematics Graphs Three-Tier Test (KGTTT), answers on each item in KGTRR were categorized according to similarities in their meanings. Considering the frequency of these categories, the KGTTT was developed and administered to 495 students. Both quantitative and qualitative methods were used to determine the validity of the KGTTT. A positive correlation coefficient was calculated between student scores for the first two tiers and confidence levels for the third tiers. Also, percentages of false positives and false negatives were estimated. Cronbach alpha reliability coefficients of correct answers and difficulties of the students for all three tiers together were calculated as 0.84 and 0.69, respectively.

The basic planar cam mechanisms and link mechanisms are widely used in industrial automatic machines. In determining the design method and design procedure for the cam-link mechanism, the basic kinematic synthesis and motion curve generation method require effective design procedure and optimization method to determine the kinematic structure of the mechanism and its kinematic performance clearly. In order to determine the result of the multi-objective optimization problem for the cam-link mechanism, the genetic algorithm is defined as the problem solver and begins this dissertation. By considering the influences of the parameters in the evolving procedure and by defining the conditions of the parameters and variables properly, the best solutions of the multi-objective optimization problem can then be solved successfully. By comparing the curves for the motion synthesis of the cam-link mechanism, the existing motion functions with their kinematic characteristics used in cam mechanisms are introduced and the rational B-spline motion function is proposed. By using the genetic algorithm to approximate the motion curves that is combined with trigonometric functions, the flexibility of the rational B-spline is demonstrated. Furthermore, to minimize different kinematic characteristics of the single-objective minimization problems, these problems are also searched by using rational B-splines with genetic algorithm for having better results. For synthesizing different structures of cam-link mechanisms, first of all is to derive the kinematics of the two planar link mechanisms and four planar cam mechanisms and then the genetic algorithm is used here to find out the minimal cam dimension with the limits of the motion curves, the pressure angles, and the radius of curvatures. Then, the kinematic synthesis problem of the function generation slider-crank mechanisms as the slider starts at the toggle position is discussed. Through the analysis finds out that when using the traditional motion functions with acceleration continuity to synthesize the slider motion, the angular acceleration of the crank cannot be continuous. To achieve the acceleration continuity of the crank motion, the curve that contains the fourth derivatives of the displacement with respect to time are set to be zeros can fulfill the continuity requirement. Then using the structural synthesis design procedure, by following the input and output relations of the link mechanisms and cam mechanisms with design constraints to select the proper structures of the mechanisms. To apply the cam-link mechanism in real application, a machine containing a slider-crank mechanism as toggle mechanism is introduced. Through the design constraints of space and motion limits to find out the possible mechanism structure and define the dimensions and then analyze the kinematics and kinetostatics of the machine. By using the genetic algorithm to solve the multi-objective optimization problem, the parameters of the rational B-spline are adjusted to have optimal kinematics and minimal kinetostatics to reduce the contact stress and to improve the fatigue life of the cam follower. Due to the existing problem of the slider-crank mechanism that contains discontinuous acceleration at the toggle position, to prove the correctness of the theoretical results, the experimental tests are measured and verified with the theoretical results in high similarity. The results show that when the slider motion curves begin at the toggle position with boundary motion constraints up to fourth or more than fourth derivatives of the displacement with respect to time that are set to be zeros, the angular accelerations of the cranks are continuous. In summary, this dissertation provides suggestions of the kinematic characteristics for the designer to design cam-link mechanisms that contain a slider-crank mechanism as the toggle mechanism and design methods for the synthesis, analysis and experimental test of the simple function generation cam-link mechanism.

This thesis develops a finite element based dynamic modeling method for design and analysis of compliant mechanisms which transfer input force, displacement and energy through elastic deformations. Most published analyses have largely based on quasi-static and lump-parameter models neglecting the effects of damping, torsion, complex geometry, and nonlinearity of deformable contacts. For applications such as handling of objects by the robotic hands with multiple high-damped compliant fingers, there is a need for a dynamic model capable of analyzing the flexible multibody system. This research begins with the formulation of the explicit dynamic finite element method (FEM) which takes into account the effects of damping, complex geometry and contact nonlinearity. The numerical stability is considered by evaluating the critical time step in terms of material properties and mesh quality. A general framework incorporating explicit dynamic FEM, topology optimization, modal analysis, and damping identification has been developed. Unlike previous studies commonly focusing on geometry optimization, this research considers both geometric and operating parameters for evaluation where the dynamic performance and trajectory of the multibody motion are particularly interested. The dynamic response and contact behavior of the rotating fingers acting on the fixed and moving objects are validated by comparing against published experimental results. The effectiveness of the dynamic modeling method, which relaxes the quasi-static assumption, has been demonstrated in the analyses of developing an automated transfer system involved grasping and handling objects by the compliant robotic hands. This FEM based dynamic model offers a more realistic simulation and a better understanding of the multibody motion for improving future design. It is expected that the method presented here can be applied to a spectrum of engineering applications where flexible multibody dynamics plays a significant role.

Title from PDF of title page. / Document formatted into pages; contains 89 pages. / Thesis (M.S.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: The ability of an organism to modulate its feeding behavior is an important focus of feeding ecology studies. Modulation is the ability to distinctly and consistently alter a behavior to accommodate different stimuli. The goal of this study was to examine the ability of the nurse shark Ginglymostoma cirratum to modulate its food capture behavior with different sizes and types of food items. This was carried out through kinematic and electromyographic analysis. Eight sub-adult specimens of G. cirratum were filmed feeding on two different food types (squid and fish) and sizes (gape size and larger than gape size). Filming consisted of high-speed videography utilizing a low-light digital video system. Kinematic variables related to lower jaw movement, mouth width, and head angle were measured from video footage. Up to twelve muscles in each of six specimens were implanted with bipolar electrodes to measure the onset and duration of motor activity. / ABSTRACT: There were no significant differences between food sizes and any of the kinematic variables. Only two muscles showed significant differences in onset time based on food size. In regards to food types, squid bites were significantly faster than fish bites, but when examined proportionately to bite duration only the time to jaw closure remained significantly different. The motor pattern of G. cirratum demonstrates an anterior to posterior sequence, which corresponds to the anterior to posterior kinematic sequence. Little cranial elevation is present during feeding sequences and is not thought to contribute significantly to feeding. Ginglymostoma cirratum is a stereotyped, inertial suction feeder. There is little evidence that there is modulation in feeding behavior based on food size or food type. If modulation does exist in the feeding behavior, it is more likely to occur after prey capture while the prey is being processed and manipulated prior to transport. / ABSTRACT: Initial observations suggested that a novel behavior termed 'spit-suck manipulation' is utilized for larger prey items. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

This paper presents designs for Multistable Shape-Shifting Surfaces (MSSS) by introducing bistability into the Shape-Shifting Surface (SSS). SSSs are defined as surfaces that retain their effectiveness as a physical barrier while undergoing changes in shape. The addition of bistability to the SSS gives the surface multiple distinct positions in which it remains when shifted to, i.e. by designing bistability into a single SSS link, the SSS unit cell can change into multiple shapes, and stabilize within the resulting shape, while maintaining integrity against various forms of external assaults normal to its surface. Planar stable configurations of the unit cell include, expanded, compressed, sheared, half-compressed, and partially-compressed, resulting in the planar shapes of a large square, small square, rhombus, rectangle, and trapezoid respectively. Tiling methods were introduced which gave the ability to produce out-of-plane assemblies using planar MSSS unit cells. A five-walled rigid storage container prototype was produced that allowed for numerous stable positions and volumes. Applications for MSSSs can include size-changing vehicle beds, expandable laptop screens, deformable walls, and volume-changing rigid-storage containers. Analysis of the MSSS was done using pseudo-rigid-Body Models (PRBMs) and Finite Element Analysis (FEA) which ensured bistable characteristics before prototypes were fabricated.

Chronic neck pain is a widespread problem that causes individual suffering as well as large costs for the society. The knowledge about the pathophysiology is poor and therefore specific diagnosis and causal treatment are rare. Important knowledge for characterization of the disorders has been gained from research on sensorimotor functions in people with neck pain. Moreover, rehabilitation regimes including sensorimotor exercises indicate promising results. The main objectives of this thesis were to extend the knowledge on sensorimotor dysfunctions in chronic neck pain, and to develop a new exercise method for improving sensorimotor functions of the neck. The studies focused on aspects of postural control and movements of the arm and neck. These are vital functions for many activities of daily living. People with chronic (>3 months) neck pain were compared to healthy controls (CON). Neck pain related to trauma was referred to as whiplash associated disorders (WAD), while neck pain without association to trauma was referred to as non-specific (NS). Arm-functioning was assessed in a pointing task. WAD and NS had reduced pointing precision compared to CON. The reduced precision was associated with self-rated difficulties performing neck movements, physical functioning, and in WAD, also pain and balance disturbances. Postural control was assessed in quiet standing on a force platform without vision. The center of pressure signal was decomposed into it’s slow and fast components. WAD and NS were compared to CON. The results revealed an effect of age on the magnitude of the fast sway component, but no effect of group. The magnitude of the slow component was elevated in both WAD and NS. This increase was associated with self-rated balance disturbance, arm-functioning, difficulties to run and sensory alterations in WAD, while in NS, the increase in the slow sway component was associated with concurrent low back pain. Neck movements were assessed in a cervical axial rotation test with maximal speed. In total 8 variables representing basic kinematics, including variables reflecting movement smoothness and conjunct motions were calculated. NS were compared to CON. Linear discriminant modelling indicated Peak Speed and conjunct motions as significant classification variables that together had a sensitivity of 76.3% and specificity of 77.6%. Retest reliability was good for Peak Speed but poor for the measure of conjunct motions. Peak Speed was slower in NS compared to CON, and even slower in a sub-group of NS with concurrent low back pain. Reduced Peak Speed was associated with self-rated difficulties performing neck movements, car driving, running, sleeping disturbances and pain. The clinical applicability of a novel method for neck coordination exercise was assessed in a pilot study on persons with NS. The results supported the applicability and indicated positive effects of the exercise: reduced postural sway in quiet standing and increased smoothness in cervical rotations. Indications on improvement in self-rated disability and fear of movement were seen at six months follow up. In conclusion, sensorimotor functions can be altered in chronic neck pain, particularly in neck disorders with concurrent low back pain and WAD. The discriminative ability and clinical validity displayed in pointing precision, postural sway and cervical axial rotation speed imply that such tests can be valuable tools in the assessment of chronic neck pain patients, and for selecting and evaluating treatment interventions. Indications of improvements seen in the pilot-study support a future RCT.