Análisis de las consecuencias de asociar un elemento elástico a una ortesis activa de rodilla

Este trabajo presenta las consecuencias de incorporar un elemento elástico al actuador de una ortesis activa de rodilla. Para ello, se realiza el análisis dinámico de un modelo biomecánico con distintos diseños para el sistema de actuación de la ortesis de rodilla integrada. Con la finalidad de estudiar las ventajas y desventajas debidas a su incorporación, se determina la dinámica de cada diseño y se realiza una comparación sobre los parámetros relevantes en el ámbito. El estudio se enmarca en un proyecto en el que se ha desarrollado un prototipo de una ortesis activa de rodilla y tobillo con control de apoyo (Stance-Control Knee-Ankle-Foot Orthosis) para asistir la marcha de lesionados medulares incompletos. Para la realización de los diseños del sistemas de actuación es necesario conocer las especificaciones mecánicas, que son los esfuerzos articulares que realiza una persona sana al caminar, y el rango de trabajo en el que se suelen emplear los elementos elásticos. Para ello, después de realizar una búsqueda bibliográfica sobre el estado del arte de ensayos en distintos tipos de dispositivos ortésicos, se realiza un estudio de la marcha humana a partir de la captura en el Laboratorio de Biomecánica de ETSEIB (Escola Tècnica Superior d’Enginyeria Industrial de Barcelona) realizada por Arroyo basándose en el modelo similar al de Sistiaga. El trabajo incluye una breve explicación teórica sobre la biomecánica de la marcha humana y los cálculos utilizados durante el proyecto. Además, comprende parte del proceso requerido en cualquier estudio biomecánico: el análisis cinemático inverso del sistema a partir de los datos de la captura del movimiento con el que se obtienen los ángulos que orientan los distintos sólidos que conforman el sistema, y el análisis dinámico inverso con el que se obtiene el torsor muscular necesario en cada articulación que permite la cinemática impuesta. Una vez obtenidos los datos que definen el movimiento de la ortesis, se trata de efectuar un estudio preliminar de comparación entre distintos diseños encontrados en la literatura científica (implementación de modelos en el software MATLAB). Para poder cumplir con el plazo previsto se han realizado simplificaciones tanto en los cálculos de los distintos diseños de ortesis como en el modelo de la pierna. Sin embargo, a partir del modelo propuesto, se pueden realizar estudios de sensibilidad de distintos parámetros, que con modelos más complejos supondrían un alto coste computacional. Precisamente por ese motivo, no se ha escogido un diseño concreto (ni un valor concreto de k), unicamamente se han analizado las mejoras que ofrece la incorporación del elemento elástico

Neuroscientific and soft-robotic principles for a new generation of natural bionic limbs.

Compensating for losing the fine and coordinated functions of human upper extremities with prostheses is a medical, technological, psychological, and social challenge. Even though existing artificial limbs promise to restore some of those missing capabilities, there is still a wide gap between what available commercial devices offer and what users demand. While most commercial prostheses present rigid mechanical structures, emerging trends in the design of robotic hands are moving towards the introduction of soft technologies, capable to adapt their behavior according to changes in their configuration, in the environment, or according to external circumstances. Although this promising approach is inspired by nature and could be innovative for prosthetic applications, there is scant literature concerning its benefits for the end-users. The first contribution of this thesis is the evaluation of diverse stiffness levels and variable stiffness controllers in able-bodied subjects to understand the role of stiffness in humans. Then, I investigate the role and the benefits of soft robotic technologies in the field of prosthetics. Specifically, in collaboration with Usl Toscana NordOvest (Italy), I studied its effect on functionality, embodiment, and user-perception through different clinical assessment tools on unilateral and bilateral individuals with limb loss. The results of those studies, which agree with some of the intuitions found in the literature and our experience in Cybathlon, highlight important occasions for improvement. Some of these are studied further in my thesis, which develops more advanced biomechanics and algorithms for the creation of a new generation of prostheses. To implement those insights into practical solutions, my thesis focuses on the dual aspects of softness and synergies in human motor control. Postural synergies are considered guiding and simplifying the design, whereas muscular and neuronal synergies led to improvements in the intuitiveness and functionality of myoelectric control. One important class of improvements concerns advances in the mechanics of the hand and the wrist, where dexterity should be provided to users while preserving simplicity and usability. Here, I introduce novel solutions that leverage the principles of under-actuation, aiming to reduce compensatory movements. My work presents insights regarding the introduction of an articulated palm to increase the contribution of all hand parts in grasping, the use of dynamic synergies in prostheses, and multisynergistic hands for the continuous exploration of grasping patterns and in-hand manipulation. For the wrist, I propose a compact 3 DoF myoelectric semi-passive wrist capable of locking in different positions and able to adapt its mechanical impedance, from compliant to rigid, to favor natural body postures. Finally, my work explores different control strategies to introduce adaptability regulation in the human-robot interface and improve the sharing of intelligence toward natural methods. I explored the effect of voluntary and involuntary impedance control of prostheses in performing Activities of Daily Living and social interactions. Then, in collaboration with Prof. Dario Farina at Imperial College London, I proposed alternative myoelectric control strategies based on the functional organization of motor units and neuronal synergistic organization information, especially useful for multisynergistic hands

Análisis de las consecuencias de asociar un elemento elástico a una ortesis activa de rodilla

Este trabajo presenta las consecuencias de incorporar un elemento elástico al actuador de una ortesis activa de rodilla. Para ello, se realiza el análisis dinámico de un modelo biomecánico con distintos diseños para el sistema de actuación de la ortesis de rodilla integrada. Con la finalidad de estudiar las ventajas y desventajas debidas a su incorporación, se determina la dinámica de cada diseño y se realiza una comparación sobre los parámetros relevantes en el ámbito. El estudio se enmarca en un proyecto en el que se ha desarrollado un prototipo de una ortesis activa de rodilla y tobillo con control de apoyo (Stance-Control Knee-Ankle-Foot Orthosis) para asistir la marcha de lesionados medulares incompletos. Para la realización de los diseños del sistemas de actuación es necesario conocer las especificaciones mecánicas, que son los esfuerzos articulares que realiza una persona sana al caminar, y el rango de trabajo en el que se suelen emplear los elementos elásticos. Para ello, después de realizar una búsqueda bibliográfica sobre el estado del arte de ensayos en distintos tipos de dispositivos ortésicos, se realiza un estudio de la marcha humana a partir de la captura en el Laboratorio de Biomecánica de ETSEIB (Escola Tècnica Superior d’Enginyeria Industrial de Barcelona) realizada por Arroyo basándose en el modelo similar al de Sistiaga. El trabajo incluye una breve explicación teórica sobre la biomecánica de la marcha humana y los cálculos utilizados durante el proyecto. Además, comprende parte del proceso requerido en cualquier estudio biomecánico: el análisis cinemático inverso del sistema a partir de los datos de la captura del movimiento con el que se obtienen los ángulos que orientan los distintos sólidos que conforman el sistema, y el análisis dinámico inverso con el que se obtiene el torsor muscular necesario en cada articulación que permite la cinemática impuesta. Una vez obtenidos los datos que definen el movimiento de la ortesis, se trata de efectuar un estudio preliminar de comparación entre distintos diseños encontrados en la literatura científica (implementación de modelos en el software MATLAB). Para poder cumplir con el plazo previsto se han realizado simplificaciones tanto en los cálculos de los distintos diseños de ortesis como en el modelo de la pierna. Sin embargo, a partir del modelo propuesto, se pueden realizar estudios de sensibilidad de distintos parámetros, que con modelos más complejos supondrían un alto coste computacional. Precisamente por ese motivo, no se ha escogido un diseño concreto (ni un valor concreto de k), unicamamente se han analizado las mejoras que ofrece la incorporación del elemento elástico

Comparison between rigid and soft poly-articulated prosthetic hands in non-expert myo-electric users shows advantages of soft robotics

Notwithstanding the advancement of modern bionic hands and the large variety of prosthetic hands in the market, commercial devices still present limited acceptance and percentage of daily use. While commercial prostheses present rigid mechanical structures, emerging trends in the design of robotic hands are moving towards soft technologies. Although this approach is inspired by nature and could be promising for prosthetic applications, there is scant literature concerning its benefits for end-users and in real-life scenarios. In this work, we evaluate and assess the role and the benefits of soft robotic technologies in the field of prosthetics. We propose a thorough comparison between rigid and soft characteristics of two poly-articulated hands in 5 non-expert myo-electric prosthesis users in pre- and post-therapeutic training conditions. The protocol includes two standard functional assessments, three surveys for user-perception, and three customized tests to evaluate the sense of embodiment. Results highlight that rigid hands provide a more precise grasp, while soft properties show higher functionalities thanks to their adaptability to different requirements, intuitive use and more natural execution of activities of daily living. This comprehensive evaluation suggests that softness could also promote a quick integration of the system in non-expert users

Functional assessment of current upper limb prostheses: An integrated clinical and technological perspective

Although recent technological developments in the field of bionic upper limb prostheses, their rejection rate remains excessively high. The reasons are diverse (e.g. lack of functionality, control complexity, and comfortability) and most of these are reported only through self-rated questionnaires. Indeed, there is no quantitative evaluation of the extent to which a novel prosthetic solution can effectively address users’ needs compared to other technologies. This manuscript discusses the challenges and limitations of current upper limb prosthetic devices and evaluates their functionality through a standard functional assessment, the Assessment of Capacity for Myoelectric Control (ACMC). To include a good representation of technologies, the authors collect information from participants in the Cybathlon Powered Arm Prostheses Race 2016 and 2020. The article analyzes 7 hour and 41 min of video footage to evaluate the performance of different prosthetic devices in various tasks inspired by activities of daily living (ADL). The results show that commercially-available rigid hands perform well in dexterous grasping, while body-powered solutions are more reliable and convenient for competitive environments. The article also highlights the importance of wrist design and control modality for successful execution of ADL. Moreover, we discuss the limitations of the evaluation methodology and suggest improvements for future assessments. With regard to future development, this work highlights the need for research in intuitive control of multiple degrees of freedom, adaptive solutions, and the integration of sensory feedback

How the CYBATHLON Competition Has Advanced Assistive Technologies

Approximately 1.1. billion people worldwide live with some form of disability, and assistive technology has the potential to increase their overall quality of life. However, the end users' perspective and needs are often not sufficiently considered during the development of this technology, leading to frustration and nonuse of existing devices. Since its first competition in 2016, CYBATHLON has aimed to drive innovation in the field of assistive technology by motivating teams to involve end users more actively in the development process and to tailor novel devices to their actual daily-life needs. Competition tasks therefore represent unsolved daily-life challenges for people with disabilities and serve the purpose of benchmarking the latest developments from research laboratories and companies from around the world. This review describes each of the competition disciplines, their contributions to assistive technology, and remaining challenges in the user-centered development of this technology.ISSN:2573-514

Semimechanistic models to relate noxious stimulation, movement, and pupillary dilation responses in the presence of opioids.

Intraoperative targeting of the analgesic effect still lacks an optimal solution. Opioids are currently the main drug used to achieve antinociception, and although underdosing can lead to an increased stress response, overdose can also lead to undesirable adverse effects. To better understand how to achieve the optimal analgesic effect of opioids, we studied the influence of remifentanil on the pupillary reflex dilation (PRD) and its relationship with the reflex movement response to a standardized noxious stimulus. The main objective was to generate population pharmacodynamic models relating remifentanil predicted concentrations to movement and to pupillary dilation during general anesthesia. A total of 78 patients undergoing gynecological surgery under general anesthesia were recruited for the study. PRD and movement response to a tetanic stimulus were measured multiple times before and after surgery. We used nonlinear mixed effects modeling to generate a population pharmacodynamic model to describe both the time profiles of PRD and movement responses to noxious stimulation. Our model demonstrated that movement and PRD are equally depressed by remifentanil. Using the developed model, we changed the intensity of stimulation and simulated remifentanil predicted concentrations maximizing the probability of absence of movement response. An estimated effect site concentration of 2 ng/ml of remifentanil was found to inhibit movement to a tetanic stimulation with a probability of 81%