Progettazione e Controllo di Mani Robotiche

The application of dexterous robotic hands out of research laboratories has been limited by the intrinsic complexity that these devices present. This is directly reflected as an economically unreasonable cost and a low overall reliability. Within the research reported in this thesis it is shown how the problem of complexity in the design of robotic hands can be tackled, taking advantage of modern technologies (i.e. rapid prototyping), leading to innovative concepts for the design of the mechanical structure, the actuation and sensory systems. The solutions adopted drastically reduce the prototyping and production costs and increase the reliability, reducing the number of parts required and averaging their single reliability factors. In order to get guidelines for the design process, the problem of robotic grasp and manipulation by a dual arm/hand system has been reviewed. In this way, the requirements that should be fulfilled at hardware level to guarantee successful execution of the task has been highlighted. The contribution of this research from the manipulation planning side focuses on the redundancy resolution that arise in the execution of the task in a dexterous arm/hand system. In literature the problem of coordination of arm and hand during manipulation of an object has been widely analyzed in theory but often experimentally demonstrated in simplified robotic setup. Our aim is to cover the lack in the study of this topic and experimentally evaluate it in a complex system as a anthropomorphic arm hand system

Study of Human Muscle Structure and Function with Velocity Encoded Phase Contrast and Diffusion Tensor Magnetic Resonance Imaging Techniques

The disproportionate loss of muscle force with aging and disuse atrophy compared to the loss of muscle mass is not yet completely understood. In addition to well-established neural and contractile determinants of force loss, remodeling of the extracellular matrix (ECM) has been recently shown in animal models to be another important contributor. In-vivo human studies exploring the structural remodeling of the ECM and its functional consequences are lacking due to the paucity of appropriate imaging techniques. This study focuses on the development and application of advanced Magnetic Resonance Imaging (MRI) methods to elucidate the mechanisms of loss of force with aging and disuse atrophy with the focus on ECM. Functional changes are investigated by strain and strain rate tensor mapping of muscle under different contraction paradigms using Velocity Encoded Phase-Contrast MRI. Methodological advances include improvements in hardware and software control of the dynamic studies. To overcome the limitation of long scan times, compressed sensing MR acquisition and reconstruction framework to reduce scan times to under a minute were developed. A multi-step automated analysis pipeline to extract 3D strain/strain rate tensors from the velocity images was implemented to process the large dynamic volumes. Strain indices reflecting the material properties of the ECM were shown to correlate with force loss leading to a hypothesis that shear strain may serve as a surrogate marker for lateral transmission of force. Diffusion tensor imaging has been applied previously to study skeletal muscle fiber architecture. The resolution of the images precludes direct inferences to be made about the microstructure. To address this limitation, bicompartmental and Random Permeable Barrier models of diffusion were applied to the diffusion data obtained with spin-echo and custom-developed stimulated echo echo-planar-imaging sequences respectively. Model derived parameters (fiber diameter, wall permeability) obtained from fitting time-dependent diffusion data were in physiologically reasonable range, with potential for tracking age related changes in muscle microstructure. The developed imaging and modeling techniques were applied to a cohort of young/senior subjects and to longitudinal tracking of disuse atrophy induced by Unilateral Limb Suspension. These studies may potentially provide the causal link between age- and disuse-related structural remodeling and its functional consequences

Trabecular bone patterning across the human hand

Hand bone morphology is regularly used to link particular hominin species with behaviors relevant to cognitive/technological progress. Debates about the functional significance of differing hominin hand bone morphologies tend to rely on establishing phylogenetic relationships and/or inferring behavior from epigenetic variation arising from mechanical loading and adaptive bone modeling. Most research focuses on variation in cortical bone structure, but additional information about hand function may be provided through the analysis of internal trabecular structure. While primate hand bone trabecular structure is known to vary in ways that are consistent with expected joint loading differences during manipulation and locomotion, no study exists that has documented this variation across the numerous bones of the hand. We quantify the trabecular structure in 22 bones of the human hand (early/extant modern Homo sapiens) and compare structural variation between two groups associated with post-agricultural/industrial (post-Neolithic) and foraging/hunter-gatherer (forager) subsistence strategies. We (1) establish trabecular bone volume fraction (BV/TV), modulus (E), degree of anisotropy (DA), mean trabecular thickness (Tb.Th) and spacing (Tb.Sp); (2) visualize the average distribution of site-specific BV/TV for each bone; and (3) examine if the variation in trabecular structure is consistent with expected joint loading differences among the regions of the hand and between the groups. Results indicate similar distributions of trabecular bone in both groups, with those of the forager sample presenting higher BV/TV, E, and lower DA, suggesting greater and more variable loading during manipulation. We find indications of higher loading along the ulnar side of the forager sample hand, with high site-specific BV/TV distributions among the carpals that are suggestive of high loading while the wrist moves through the ‘dart-thrower's’ motion. These results support the use of trabecular structure to infer behavior and have direct implications for refining our understanding of human hand evolution and fossil hominin hand use

Arthrokinematics of the Distal Radioulnar Joint in the Normal Wrist and Following Distal Radius Malunion

Contact patterns in the distal radioulnar joint (DRUJ) are not well understood for normal anatomy or with distal radius deformity. This thesis presents three studies which investigate the arthrokinematics of the DRUJ for these conditions. The first study compared casting and Tekscan, two standard methods for contact measurement, with a novel technique of proximity mapping termed Inter-cartilage Distance (ICD). The relative benefits, limitations and role for ICD in DRUJ contact assessment were examined and discussed. The second study used ICD to characterize contact patterns in the native DRUJ. Contact was found to be maximal in 10 degrees of supination and the contact centroid moved volar and proximal with supination. The third and final study evaluated the effect of dorsal angulation deformity on DRUJ arthrokinematics. The contact centroid moved volarly, while simulated TFCC rupture reduced DRUJ contact area and caused the centroid position to become more variable in its pathway

Design and Implementation of Innovative Robotic Devices Using Twisted String Actuation (TSA) System

The twisted string actuation system is particularly suitable for very compact, low-cost and light-weight robotic devices, like artificial limbs and exoskeletons, since it allows the implementation of powerful tendon-based driving systems, based on small-size DC motors characterized by high speed, low torque and very limited inertia. The following activities has been done using the Twisted String Actuation System: - The basic properties of the twisted string actuation system. - An ongoing work for verifying the behavior of a twisted string actuator in contact with a sliding surface or guided through a sheath. - The implementation of a variable stiffness joint actuated by a couple of twisted string actuators in antagonistic configuration. - The design and the implementation of a force sensor based on a commercial optoelectronic component called light fork and characterized by the simple construction process. - A twisted string actuation module with an integrated force sensor based on optoelectronic components. - The preliminary experimental study toward the implementation of an arm rehabilitation device based on a twisted string actuation module. - A 6 DoF cable-driven haptic interface for applications in various robotic scenarios. - A wearable hand haptic interface driven by a couple of twisted string actuators

Quantification of knee extensor muscle forces: a multimodality approach

Given the growing interest of using musculoskeletal (MSK) models in a large number of clinical applications for quantifying the internal loading of the human MSK system, verification and validation of the model’s predictions, especially at the knee joint, have remained as one of the biggest challenges in the use of the models as clinical tools. This thesis proposes a methodology for more accurate quantification of knee extensor forces by exploring different experimental and modelling techniques that can be used to enhance the process of verification and validation of the knee joint model within the MSK models for transforming the models to a viable clinical tool. In this methodology, an experimental protocol was developed for simultaneous measurement of the knee joint motion, torques, external forces and muscular activation during an isolated knee extension exercise. This experimental protocol was tested on a cohort of 11 male subjects and the measurements were used to quantify knee extensor forces using two different MSK models representing a simplified model of the knee extensor mechanism and a previously-developed three-dimensional MSK model of the lower limb. The quantified knee extensor forces from the MSK models were then compared to evaluate the performance of the models for quantifying knee extensor forces. The MSK models were also used to investigate the sensitivity of the calculated knee extensor forces to key modelling parameters of the knee including the method of quantifying the knee centre of rotation and the effect of joint translation during motion. In addition, the feasibility of an emerging ultrasound-based imaging technique (shear wave elastography) for direct quantification of the physiologically-relevant musculotendon forces was investigated. The results in this thesis showed that a simplified model of the knee can be reliably used during a controlled planar activity as a computationally-fast and effective tool for hierarchical verification of the knee joint model in optimisation-based large-scale MSK models to provide more confidence in the outputs of the models. Furthermore, the calculation of knee extensor muscle forces has been found to be sensitive to knee joint translation (moving centre of rotation of the knee), highlighting the importance of this modelling parameter for quantifying physiologically-realistic knee muscle forces in the MSK models. It was also demonstrated how the movement of the knee axis of rotation during motion can be used as an intuitive tool for understanding the functional anatomy of the knee joint. Moreover, the findings in this thesis indicated that the shear wave elastography technique can be potentially used as a novel method for direct quantification of the physiologically-relevant musculotendon forces for independent validation of the predictions of musculotendon forces from the MSK models.Open Acces

An Ontology-Based Expert System for the Systematic Design of Humanoid Robots

Die Entwicklung humanoider Roboter ist eine zeitaufwendige, komplexe und herausfordernde Aufgabe. Daher stellt diese Thesis einen neuen, systematischen Ansatz vor, der es erlaubt, Expertenwissen zum Entwurf humanoider Roboter zu konservieren, um damit zukünftige Entwicklungen zu unterstützen. Der Ansatz kann in drei aufeinanderfolgende Schritte unterteilt werden. Im ersten Schritt wird Wissen zum Entwurf humanoider Roboter durch die Entwicklung von Roboterkomponenten und die Analyse verwandter Arbeiten gewonnen. Dieses Wissen wird im zweiten Schritt formalisiert und in Form einer ontologischen Wissensbasis gespeichert. Im letzten Schritt wird diese Wissensbasis von einem Expertensystem verwendet, um Lösungsvorschläge zum Entwurf von Roboterkomponenten auf Grundlage von Benutzeranforderungen zu generieren. Der Ansatz wird anhand von Fallstudien zu Komponenten des humanoiden Roboters ARMAR-6 evaluiert: Sensor-Aktor-Controller-Einheiten für Robotergelenke und Roboterhände

Injury and Skeletal Biomechanics

This book covers many aspects of Injury and Skeletal Biomechanics. As the title represents, the aspects of force, motion, kinetics, kinematics, deformation, stress and strain are examined in a range of topics such as human muscles and skeleton, gait, injury and risk assessment under given situations. Topics range from image processing to articular cartilage biomechanical behavior, gait behavior under different scenarios, and training, to musculoskeletal and injury biomechanics modeling and risk assessment to motion preservation. This book, together with "Human Musculoskeletal Biomechanics", is available for free download to students and instructors who may find it suitable to develop new graduate level courses and undergraduate teaching in biomechanics