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

Cutting the cylinder into squares: The square form factor

In this article we present a method for constructing two-point functions in the spirit of the hexagon proposal, which leads us to propose a "square form factor". Since cutting the square gives us two squares, we can write a consistency condition that heavily constrains such form factors. In particular, we are able to use this constraint to reconstruct the Gaudin through the forest expansion of the determinant appearing in its definition. We also use this procedure to compute the norm of off-shell Bethe states for some simple cases.Comment: 34 pages, 10 figure

Inverse kinematics for upper limb compound movement estimation in exoskeleton-assisted rehabilitation

Robot-Assisted Rehabilitation (RAR) is relevant for treating patients affected by nervous system injuries (e.g., stroke and spinal cord injury) -- The accurate estimation of the joint angles of the patient limbs in RAR is critical to assess the patient improvement -- The economical prevalent method to estimate the patient posture in Exoskeleton-based RAR is to approximate the limb joint angles with the ones of the Exoskeleton -- This approximation is rough since their kinematic structures differ -- Motion capture systems (MOCAPs) can improve the estimations, at the expenses of a considerable overload of the therapy setup -- Alternatively, the Extended Inverse Kinematics Posture Estimation (EIKPE) computational method models the limb and Exoskeleton as differing parallel kinematic chains -- EIKPE has been tested with single DOFmovements of the wrist and elbow joints -- This paper presents the assessment of EIKPEwith elbow-shoulder compoundmovements (i.e., object prehension) -- Ground-truth for estimation assessment is obtained from an optical MOCAP (not intended for the treatment stage) -- The assessment shows EIKPE rendering a good numerical approximation of the actual posture during the compoundmovement execution, especially for the shoulder joint angles -- This work opens the horizon for clinical studies with patient groups, Exoskeleton models, and movements types -

Análisis biomecánico para confirmar el diagnóstico en neurorrehabilitación

[ES] En los pacientes con lesión medular cervical (LMC) se ve comprometida en mayor o menor medida la fuerza de las extremidades superiores, lo que se traduce en dependencia para las AVDs. Si la lesión es incompleta, puede preservarse la capacidad de marcha. En este contexto, resulta difícil realizar un diagnóstico clínico correcto y los equipos de fotogrametría constituyen una herramienta de gran valor para objetivar las secuelas motoras. El objetivo es presentar la metodología biomecánica de miembros superiores e inferiores aplicada a un caso de estudio. Se trata de un paciente varón de 61 años que padeció una LMC incompleta de etiología traumática que, previamente, había sufrido un TCE. Mediante fotogrametría se analizaron los recorridos articulares de la cadera, rodilla y tobillo durante los ciclos de la marcha y del hombro, codo y muñeca, así como una serie de índices cinemáticos descriptores del movimiento del miembro superior. Se obtuvo un patrón de marcha muy simétrico en ambos miembros inferiores. Sin embargo, la funcionalidad global y los índices de destreza en ambos miembros superiores presentaron una marcada asimetría entre ellos. Las herramientas biomecánicas evidencian aspectos del control motor no fácilmente visibles con los tests clínicos y que perfeccionan el diagnóstico de los casos complejos.[EN] In cervical spinal cord injured (SCI) patients, upper limbs strength is affected to a greater or lesser extent, producing dependence on the execution of ADLs. If the lesion is incomplete, the gait ability can be preserved. In this context, it is difficult to make a correct clinical diagnosis and the photogrammetry equipments constitute a tool of great value to determine with objectivity motor sequelae. The objective is to present the biomechanics methodology of upper and lower limbs applied to a case study. It is a 61- year-old male patient who suffered an incomplete SCI of traumatic etiology that had previously suffered a traumatic brain injury. Through photogrammetry, the range of motion of the hip, knee and ankle joints were analyzed during the cycles of the gait and the shoulder, elbow and wrist joints, as well as a series of kinematic indices describing the ability and dexterity of the upper limb movement. A very symmetrical gait pattern was obtained in both lower limbs. However, overall functionality and skill indices in both upper limbs present a high asymmetry between them. Biomechanical tools demonstrate aspects of motor control not easily visible with clinical tests and perfect diagnosis of complex casesDe Los Reyes Guzmán, A.; López-Dolado, E.; Pérez-Rizo, E.; Lozano-Berrio, V.; Gil-Agudo, A.; Del Ama Espinosa, A. (2019). Análisis biomecánico para confirmar el diagnóstico en neurorrehabilitación. En 11º Simposio CEA de Bioingeniería. Editorial Universitat Politècnica de València. 49-63. https://doi.org/10.4995/CEABioIng.2019.10045OCS496

Conceptual design of a functional electrical stimulation cycling platform as a rehabilitation therapy for spinal cord injury or stroke

Stroke and spinal cord injuries (SCI) are leading causes of disability worldwide, involving problems in mobility, balance and coordination, among others. While aerobic exercise is associated with a greater plasticity in the motor cortex of healthy individuals, its effect on neuroplasticity after suffer- ing a stroke or a SCI is still unknown. Besides, there is no methodology to promote both cardiovascular and neuroplastic recovery in patients suffering from neurological injuries. Up to now, it has been demonstrated that physical exercise is a therapeutic intervention in many rehabilitation programs that, apart from providing clear benefits related to the phys- ical conditioning, functionality, mood and cardiovascular health, it could also promote neuroplasticity. The literature suggests that stronger neuroplastic responses are elicited in mid-to-high intensity training programs, but the lack of homogeneity in the dose-response and the non-uniform eval- uations of the neuroplasticity seem to be a limitation to gen- eralise the obtained results. The combination of functional electrical stimulation (FES) with the benefits of cardiovas- cular exercise makes cycling assisted by FES a promising approach to target both the aerobic capacity and the neu- romotor function. The objective of this project is to prove that aerobic exercise during personalized FES-cycling could contribute to enhance the process of neuroplasticity, and to maintain locomotor and cardiovascular function in patients with stroke or spinal cord injury.This work is partially developed within the Research Network FUSION “Red Tem´atica Sobre Fusi´on de Tec- nolog´ıas Rob´oticas y Estimulaci´on El´ectrica Neuro- muscular para Neurorrehabilitaci´on de Trastornos del Movimiento”, grant by Agencia Estatal de Investigaci´on (RED2022-134319-T)

Valoración de la Experiencia del Usuario en Entornos Virtuales de Rehabilitación de Miembros Superiores

Las aplicaciones de Realidad Virtual están en auge en el contexto de la rehabilitación de patologías neurológicas y es necesario abordar estudios para conocer el nivel de aceptación de los usuarios, en este caso pacientes con Lesión Medular. Se ha desarrollado un cuestionario exhaustivo formado por 40 preguntas para recoger el nivel de satisfacción y aceptación del usuario comparando la aplicación virtual del Box and Block en su versión inmersiva y no inmersiva. En el estudio participaron 6 sujetos sanos y 6 pacientes con LME. Se obtuvieron diferencias entre ambos entornos virtuales y la ausencia de efectos adversos relacionados con la RV se convierte en un factor fundamental para su aplicación en terapias de rehabilitación.Proyectos PID2020-117361RB-C21 y PID2020-117361RB-C22 financiados por MCIN/AEI/10.13039/501100011033

Cinemática del movimiento del miembro superior durante una tarea funcional realizada en entorno virtual y entorno físico real en población sana y con lesión medular cervical

Hay un interés creciente en nuevas terapias por medio de tecnología, como la Realidad Virtual (RV). La RV ofrece un gran potencial para mejorar la función motora de miembro superior (MS) en paciente neurológicos. No obstante, se desconoce acerca de las características de los patrones de movimiento ejecutados en entornos virtuales en contexto rehabilitador. Por ello, este estudio analiza las características cinemáticas de los movimientos de MS durante la ejecución de una tarea funcional, el test clínico Box and Block (BBT), en pacientes con lesión medular (LM) cervical y en población sana en entornos virtuales inmersivos (3D), no inmersivos (2D) y en el entorno físico real. El análisis principal se centra en comparar la cinemática de los pacientes con la de los sujetos sanos para conocer la funcionalidad global del MS durante la ejecución del BBT en los tres entornos de experimentación. Para ello se estudian medidas relativas al desempeño de la tarea y medidas relativas al patrón de movimiento. Finalmente, existen diferencias entre los patrones cinemáticos ejecutados en el BBT de entorno real y los de RV. En ambas poblaciones existen diferencias en los rangos de movimiento (ROM) articular de codo y muñeca. En pacientes con LM, además, varían el ROM de hombro y el desplazamiento de tronco. En ambos grupos, la velocidad y suavidad disminuyen en entornos de RV respecto al entorno físico real. La longitud de trayectoria aumenta en sanos en el entorno de RV 3D, mientras que, en el caso de pacientes con LM, disminuye.Proyecto REHAB-IMMERSIVE PID2020-117361RB-C22 financiado por MCIN/AEI/10.13039/501100011033

Quantitative assessment based on kinematic measures of functional impairments during upper extremity movements: a review

Quantitative measures of human movement quality are important for discriminating healthy and pathological conditions and for expressing the outcomes and clinically important changes in subjects' functional state. However the most frequently used instruments for the upper extremity functional assessment are clinical scales, that previously have been standardized and validated, but have a high subjective component depending on the observer who scores the test. But they are not enough to assess motor strategies used during movements, and their use in combination with other more objective measures is necessary. The objective of the present review is to provide an overview on objective metrics found in literature with the aim of quantifying the upper extremity performance during functional tasks, regardless of the equipment or system used for registering kinematic data

Kinematic analysis of the daily activity of drinking from a glass in a population with cervical spinal cord injury

Background Three-dimensional kinematic analysis equipment is a valuable instrument for studying the execution of movement during functional activities of the upper limbs. The aim of this study was to analyze the kinematic differences in the execution of a daily activity such as drinking from a glass between two groups of patients with tetraplegia and a control group. Methods A total of 24 people were separated into three groups for analysis: 8 subjects with metameric level C6 tetraplegia, 8 subjects with metameric level C7 tetraplegia and 8 control subjects (CG). A set of active markers that emit infrared light were positioned on the upper limb. Two scanning units were used to record the sessions. The activity of drinking from a glass was broken down into a series of clearly identifiable phases to facilitate analysis. Movement times, velocities, and the joint angles of the shoulder, elbow and wrist in the three spatial planes were the variables analyzed. Results The most relevant differences between the three groups were in the wrist. Wrist palmar flexion during the back transport phase was greater in the patients with C6 and C7 tetraplegia than in the CG, whereas the highest wrist dorsal flexion values were in forward transport in the subjects with C6 or C7 tetraplegia, who required complete activation of the tenodesis effect to complete grasping. Conclusions A detailed description was made of the three-dimensional kinematic analysis of the task of drinking from a glass in healthy subjects and in two groups of patients with tetraplegia. This was a useful application of kinematic analysis of upper limb movement in a clinical setting. Better knowledge of the execution of this movement in each of these groups allows therapeutic recommendations to be specifically adapted to the functional deficit present. This information can be useful in designing wearable robots to compensate the performance of AVD, such as drinking, in people with cervical SCI