Optical Enhancement of Exoskeleton-Based Estimation of Glenohumeral Angles

In Robot-Assisted Rehabilitation (RAR) the accurate estimation of the patient limb joint angles is critical for assessing therapy efficacy. In RAR, the use of classic motion capture systems (MOCAPs) (e.g., optical and electromagnetic) to estimate the Glenohumeral (GH) joint angles is hindered by the exoskeleton body, which causes occlusions and magnetic disturbances. Moreover, the exoskeleton posture does not accurately reflect limb posture, as their kinematic models differ. To address the said limitations in posture estimation, we propose installing the cameras of an optical marker-based MOCAP in the rehabilitation exoskeleton. Then, the GH joint angles are estimated by combining the estimated marker poses and exoskeleton Forward Kinematics. Such hybrid system prevents problems related to marker occlusions, reduced camera detection volume, and imprecise joint angle estimation due to the kinematic mismatch of the patient and exoskeleton models. This paper presents the formulation, simulation, and accuracy quantification of the proposed method with simulated human movements. In addition, a sensitivity analysis of the method accuracy to marker position estimation errors, due to system calibration errors and marker drifts, has been carried out. The results show that, even with significant errors in the marker position estimation, method accuracy is adequate for RAR.

Appraisal of open software for finite element simulation of 2D metal sheet laser cut.

FEA simulation of thermal metal cutting is central to interactive design and manufacturing. It is therefore relevant to assess the applicability of FEA open software to simulate 2D heat transfer in metal sheet laser cuts. Application of open source code (e.g. FreeFem++, FEniCS, MOOSE) makes possible additional scenarios (e.g. parallel, CUDA, etc.), with lower costs. However, a precise assessment is required on the scenarios in which open software can be a sound alternative to a commercial one. This article contributes in this regard, by presenting a comparison of the aforementioned freeware FEM software for the simulation of heat transfer in thin (i.e. 2D) sheets, subject to a gliding laser point source. We use the commercial ABAQUS software as the reference to compare such open software. A convective linear thin sheet heat transfer model, with and without material removal is used. This article does not intend a full design of computer experiments. Our partial assessment shows that the thin sheet approximation turns to be adequate in terms of the relative error for linear alumina sheets. Under mesh resolutions better than 10e−5 m , the open and reference software temperature differ in at most 1 % of the temperature prediction. Ongoing work includes adaptive re-meshing, nonlinearities, sheet stress analysis and Mach (also called ‘relativistic’) effects.

Graph-based structural analysis of planar mechanisms.

Kinematic structure of planar mechanisms addresses the study of attributes determined exclusively by the joining pattern among the links forming a mechanism. The system group classification is central to the kinematic structure and consists of determining a sequence of kinematically and statically independent-simple chains which represent a modular basis for the kinematics and force analysis of the mechanism. This article presents a novel graph-based algorithm for structural analysis of planar mechanisms with closed-loop kinematic structure which determines a sequence of modules (Assur groups) representing the topology of the mechanism. The computational complexity analysis and proof of correctness of the implemented algorithm are provided. A case study is presented to illustrate the results of the devised method.

Upper Limb Posture Estimation in Robotic and Virtual Reality-based Rehabilitation.

New motor rehabilitation therapies include virtual reality (VR) and robotic technologies. In limb rehabilitation, limb posture is required to (1) provide a limb realistic representation in VR games and (2) assess the patient improvement. When exoskeleton devices are used in the therapy, the measurements of their joint angles cannot be directly used to represent the posture of the patient limb, since the human and exoskeleton kinematic models differ. In response to this shortcoming, we propose a method to estimate the posture of the human limb attached to the exoskeleton. We use the exoskeleton joint angles measurements and the constraints of the exoskeleton on the limb to estimate the human limb joints angles. This paper presents (a) the mathematical formulation and solution to the problem, (b) the implementation of the proposed solution on a commercial exoskeleton system for the upper limb rehabilitation, (c) its integration into a rehabilitation VR game platform, and (d) the quantitative assessment of the method during elbow and wrist analytic training. Results show that this method properly estimates the limb posture to (i) animate avatars that represent the patient in VR games and (ii) obtain kinematic data for the patient assessment during elbow and wrist analytic rehabilitation.

Buenas noches... ¡soy un milagro!, después de la tempestad : la última copa 7

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Los alcohólicos recuperados lo saben, los mejores días están por llegar, gracias, no bebo, contra el zarpazo de la leona : la última copa 8

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Dicen los médicos especialistas : no es asunto de plata, sino de honorarios justos, el fondo del asunto

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Donde comen tres sí comen cuatro y sobrevivir es lo primero, usted qué opina "ella me mando pollo" : derribemos el muro

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Elecciones 92 : anzuelos y animales políticos

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Plataforma de información financiera como herramienta de apoyo para la gestión y toma de decisiones en las Pymes

Las pymes se encuentran envueltas en problemas derivados en distorsiones del sistema empresarial, que incide en la mortalidad de las mismas: la falta de criterios para la toma de decisiones asertivas, lo cual tiene un impacto directo también en la economía en general, y contribuye al aumento del desempleo, la desaceleración económica y, finalmente, a la reducción de la calidad de vida de la sociedad -- El objetivo general de esta investigación consiste en proponer una plataforma de información financiera integral que se constituya en una herramienta de análisis para las pymes en Medellín, Colombia -- Para resolverlo, se desarrollan los siguientes objetivos específicos: 1. Diagnosticar la gestión empresarial en la toma de decisiones -- 2. Describir la información financiera necesaria para la toma de decisiones empresariales -- 3. Indicar los aspectos constitutivos de una plataforma financiera para la gestión empresarial -- Para mitigar esta problemática, la implementación del sistema de información financiero propuesto contribuye al entorno competitivo de las pymes, lo cual permite automatizar procesos, estabilidad laboral y empresarial, reducción de costos, accesibilidad a nuevas tecnologías y crear las bases para la toma de decisiones, con la finalidad de mejorar la competitividad de las micro, pequeñas y medianas empresas

Filas de rosas, policías y jurados : le cumplimos al país : Registrador

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La odisea de encontrar colegio : tres luchas : entre lo legal y lo ilegal

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Un sueño se cumple en Salsipuedes

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Maltrato a niñas y adolescentes : la mujer rompe el silencio

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Prospects and Opportunities. New Technology Trends yield new opportunities for Libraries and Information Centers

A number of important trends currently impact libraries. Academic libraries face the fundamental shift of collections toward ever increasing proportions of electronic content; public libraries continue to see vigorous interest in print materials, now supplemented by demand to provide e-books for lending. Breeding will explore these and other trends and describe some of the technologies available and emerging to help libraries meet the challenges involved in this context.