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Background: Ankle-foot orthoses (AFOs) are extensively used as a primary management method to assist ambulation of children with Cerebral Palsy (CP). However, there are certain barriers that hinder their prescription as well as their use as a mobility device in all kinds of daily-life activities. This exploratory research attempts to further understand the existing limitations of current AFOs to promote a better personalization of new design solutions. Methods: Stakeholders’ (professionals in CP and end-users with CP) perspectives on AFO technology were collected by two online surveys. Respondents evaluated the limitations of current assistive solutions and assessment methods, provided their expectations for a new AFO design, and analyzed the importance of different design features and metrics to enrich the gait performance of these patients in daily-life. Quantitative responses were rated and compared with respect to their perceived importance. Qualitative responses were classified into themes by using content analysis. Results: 130 survey responses from ten countries were analyzed, 94 from professionals and 36 from end-users with CP. The most highly rated design features by both stakeholder groups were the comfort and the ease of putting on and taking off the assistive device. In general, professionals preferred new features to enrich the independence of the patient by improving gait at functional levels. End-users also considered their social acceptance and participation. Health care professionals reported a lack of confidence concerning decision-making about AFO prescription. To some degree, this may be due to the reported inconsistent understanding of the type of assistance required for each pathological gait. Thus, they indicated that more information about patients’ day-to-day walking performance would be beneficial to assess patients’ capabilities. Conclusion: This study emphasizes the importance of developing new approaches to assess and treat CP gait in da

Introduction: Tuning the control parameters is one of the main challenges in robotic gait therapy. Control strategies that vary the control parameters based on the user’s performance are still scarce and do not exploit the potential of using spatiotemporal metrics. The goal of this study was to validate the feasibility of using shank-worn Inertial Measurement Units (IMUs) for clinical gait analysis after stroke and evaluate their preliminary applicability in designing an automatic and adaptive controller for a knee exoskeleton (ABLE-KS). Methods: First, we estimated the temporal (i.e., stride time, stance, and swing duration) and spatial (i.e., stride length, maximum vertical displacement, foot clearance, and circumduction) metrics in six post-stroke participants while walking on a treadmill and overground and compared these estimates with data from an optical motion tracking system. Next, we analyzed the relationships between the IMU-estimated metrics and an exoskeleton control parameter related to the peak knee flexion torque. Finally, we trained two machine learning algorithms, i.e., linear regression and neural network, to model the relationship between the exoskeleton torque and maximum vertical displacement, which was the metric that showed the strongest correlations with the data from the optical system [r = 0.84; ICC(A,1) = 0.73; ICC(C,1) = 0.81] and peak knee flexion torque (r = 0.957). Results: Offline validation of both neural network and linear regression models showed good predictions (R2 = 0.70–0.80; MAE = 0.48–0.58 Nm) of the peak torque based on the maximum vertical displacement metric for the participants with better gait function, i.e., gait speed > 0.7 m/s. For the participants with worse gait function, both models failed to provide good predictions (R2 = 0.00–0.19; MAE = 1.15–1.29 Nm) of the peak torque despite having a moderate-to-strong correlation between the spatiotemporal metric and control parameter. Discussion: Our preliminary results indi, Peer Reviewed, Postprint (published version)

[Resumen] La propulsión que ejerce el tobillo es esencial para la ejecuci´on de una marcha humana eficiente. En los últimos años, se han venido aplicando diversos principios de funcionamiento a las ortesis de tobillo y pie (AFO), con el fin de mejorar el trabajo de los músculos flexores plantares y lograr así una propulsión adecuada durante la marcha. Es difícil comparar la ejecución y eficacia de los diferentes diseños debido a que los investigadores no siguen un conjunto estandarizado de criterios y procedimientos comunes. Esto lleva a la realización de una amplia gama de pruebas, con variaciones en factores importantes como la velocidad de marcha y la asistencia proporcionada, lo que afecta en gran medida a la cinemática y la cinética de los usuarios. Este trabajo está enfocado a comprender las posibilidades y los potenciales beneficios de dos importantes principios de diseño para asistir la propulsión del tobillo con una AFO no actuada. Para ello, presentamos y evaluamos dos prototipos de AFO con resorte paralelo al tendón de Aquiles, basados en: (i) un resorte de compresión lineal, y (ii) una transmisión no lineal y personalizada de leva con resorte de ballesta. Se presentan los efectos de ambas AFOs para un estudio de caso con un usuario sano usando ambos prototipos a dos velocidades de marcha bajo las mismas condiciones experimentales. Se encontraron grandes reducciones en la actividad muscular cuando el usuario recibió asistencia, y la cinemática del tobillo estuvo influenciada por los diferentes principios de dicha asistencia. Este estudio de caso fue pensado como un primer intento para proporcionar información sobre cómo dos principios prometedores pueden asistir de forma pasiva la propulsión de tobillo durante la marcha., [Abstract] Ankle propulsion is essential for efficient human walking. In recent years, several working principles have been investigated and applied to ankle-foot orthoses (AFOs) to enhance the work of the plantarflexor muscles and achieve proper propulsion during gait. Comparing the performance and effectiveness of different designs is difficult because researchers do not have a standardized set of criteria and procedures to follow. This leads to a wide range of tests being conducted, with variations in important factors such as walking speed and assistance provided, which greatly affect users’ kinematics and kinetics. In this work, we try to better understand the possibilities and potential benefits of two of the most important design principles for supporting ankle propulsion with unpowered AFOs. To do so, we present and evaluate two AFO prototypes with springs parallel to the Achilles tendon based on: (i) a linear compression spring, and (ii) a customized leaf spring-cam transmission with a nonlinear ankle torque–angle curve. The effects of both AFOs are reported for a case study with one healthy user using both prototypes at two walking speeds under the same experimental conditions. Large reductions in muscular activity were found when the user received assistance, and ankle kinematics were influenced by the different assistance principles. This case study was intended as a first attempt to provide insights on how two promising principles can passively support push-off during gait.

BACKGROUND: In the last two decades, lower-limb exoskeletons have been developed to assist human standing and locomotion. One of the ongoing challenges is the cooperation between the exoskeleton balance support and the wearer control. Here we present a cooperative ankle-exoskeleton control strategy to assist in balance recovery after unexpected disturbances during walking, which is inspired on human balance responses. METHODS: We evaluated the novel controller in ten able-bodied participants wearing the ankle modules of the Symbitron exoskeleton. During walking, participants received unexpected forward pushes with different timing and magnitude at the pelvis level, while being supported (Exo-Assistance) or not (Exo-NoAssistance) by the robotic assistance provided by the controller. The effectiveness of the assistive strategy was assessed in terms of (1) controller performance (Detection Delay, Joint Angles, and Exerted Ankle Torques), (2) analysis of effort (integral of normalized Muscle Activity after perturbation onset); and (3) Analysis of center of mass COM kinematics (relative maximum COM Motion, Recovery Time and Margin of Stability) and spatio-temporal parameters (Step Length and Swing Time). RESULTS: In general, the results show that when the controller was active, it was able to reduce participants' effort while keeping similar ability to counteract and withstand the balance disturbances. Significant reductions were found for soleus and gastrocnemius medialis activity of the stance leg when comparing Exo-Assistance and Exo-NoAssistance walking conditions. CONCLUSIONS: The proposed controller was able to cooperate with the able-bodied participants in counteracting perturbations, contributing to the state-of-the-art of bio-inspired cooperative ankle exoskeleton controllers for supporting dynamic balance. In the future, this control strategy may be used in exoskeletons to support and improve balance control in users with motor disabilities., Biomechatronics & Human-Machine Control

[Resumen] Avances recientes en el control de exoesqueletos se están centrando en mejorar la asistencia de equilibrio y disminuir la dependencia de las muletas. Sin embargo, métodos apropiados para cuantificar la estabilidad de estos exoesqueletos (y de sus usuarios) aún son escasos. Una evaluación del equilibrio cuantitativa es fundamental para enriquecer el desempeño de los exoesqueletos y su interacción con los seres humanos. En este trabajo presentamos el sistema BenchBalance, una soluci ón para realizar evaluaciones comparativas y reproducibles de equilibrio en exoesqueletos y sus usuarios. Al integrar dos elementos clave (perturbador manual y prenda inteligente), BenchBalance es una herramienta portátil y de bajo coste que proporciona una evaluación cuantitativa relacionada con la reacción y la capacidad de los exoesqueletos portátiles y sus usuarios para responder a perturbaciones externas controladas., [Abstract] Recent advances on the control of exoskeletons are being centered on improving balance support and decreasing the reliance on crutches. However, appropriate methods to quantify the stability of these exoskeletons (and and their users) are still under development. A reliable and reproducible balance assessment is critical to enrich exoskeletons’ performances and their interaction with human beings. In this work we present the BenchBalance system, a benchmarking solution to conduct reproducible balance assessments of exoskeleton and users. Integrating two key elements (manual perturbator and smart garment), BenchBalance is a portable and low-cost tool that provides a quantitative assessment related to the reaction and capacity of wearable exoskeletons and their users to respond to controlled external perturbations.

Recent advances in the control of overground exoskeletons are being centered on improving balance support and decreasing the reliance on crutches. However, appropriate methods to quantify the stability of these exoskeletons (and their users) are still under development. A reliable and reproducible balance assessment is critical to enrich exoskeletons’ performance and their interaction with humans. In this work, we present the BenchBalance system, which is a benchmarking solution to conduct reproducible balance assessments of exoskeletons and their users. Integrating two key elements, i.e., a hand-held perturbator and a smart garment, BenchBalance is a portable and low-cost system that provides a quantitative assessment related to the reaction and capacity of wearable exoskeletons and their users to respond to controlled external perturbations. A software interface is used to guide the experimenter throughout a predefined protocol of measurable perturbations, taking into account antero-posterior and mediolateral responses. In total, the protocol is composed of sixteen perturbation conditions, which vary in magnitude and location while still controlling their orientation. The data acquired by the interface are classified and saved for a subsequent analysis based on synthetic metrics. In this paper, we present a proof of principle of the BenchBalance system with a healthy user in two scenarios: subject not wearing and subject wearing the H2 lower-limb exoskeleton. After a brief training period, the experimenter was able to provide the manual perturbations of the protocol in a consistent and reproducible way. The balance metrics defined within the BenchBalance framework were able to detect differences in performance depending on the perturbation magnitude, location, and the presence or not of the exoskeleton. The BenchBalance system will be integrated at EUROBENCH facilities to benchmark the balance capabilities of wearable exoskeletons and their users.

The main objective of this doctoral thesis is to provide a novel robotic solution for gait rehabilitation of pediatric population with CP and related disorders. The approach that the proposed robotic device expects to offer is different from those existing so far, providing new ideas not only about the design and control of the device, but also about clinical intervention protocols. The methodology used to reach this objective was based on a detailed study about the application of robotic trainers developed in the last years for CP rehabilitation. This research identified the main limitations and challenges of current robotic therapies, which served as the base to design and develop a novel robotic platform in the framework of this thesis: CPWalker. CPWalker is composed by two main parts: a smart walker and an exoskeleton with 6 degrees of freedom. Through them, it is possible to provide user's partial body weight support in parallel with guided joint motion and over-ground displacement. CPWalker trainer promotes the progression of patients with CP into the rehabilitation treatment, increasing the level of intensity and frequency of the exercises as well as enhancing the motivation and tailoring the therapy to each user. To do so, innovative control strategies were used, which may be individually selected per joint giving a high versatility for the treatment's design. The developed robotic platform was evaluated both technically and in clinical environments with pediatric patients. The results show the potential of the novel robotic platform to serve as a rehabilitation tool, also providing preliminary support for future clinical implementations not only in CPWalker, but also in other existing robotic gait trainers. [EN], El objetivo principal de esta tesis doctoral es ofrecer una novedosa soluci on rob otica para la rehabilitación de la marcha de pacientes pediátricos con PC y desórdenes similares. El enfoque que se pretende dar con el dispositivo robótico propuesto en la tesis es distinto al que existe hasta el momento, aportando nuevas ideas no sólo sobre el diseño y el control del dispositivo, sino también sobre los protocolos de intervención clínica. La metodología utilizada para alcanzar este objetivo se basó en un estudio detallado sobre la aplicación de entrenadores robóticos de rehabilitación elaborados en los últimos años. Con esta investigación se identi ficaron las principales limitaciones y desafíos de las terapias robóticas actuales, los cuales sirvieron para sentar las bases del diseño y desarrollo de una nueva plataforma robótica englobada en el marco de trabajo de esta tesis: CPWalker. CPWalker está compuesto por dos partes principales: un andador inteligente y un exoesqueleto con 6 grados de libertad. A través de ellas, es posible proporcionar soporte parcial de peso del usuario al mismo tiempo que se realiza un movimiento guiado de las articulaciones con desplazamiento en entornos reales. El entrenador robótico CPWalker promueve la progresión de pacientes con PC dentro del tratamiento de rehabilitación, incrementando el nivel de intensidad y frecuencia de los ejercicios, al mismo tiempo que aumenta la motivación del usuario y adapta la terapia a las posibilidades de cada paciente. Para ello, utiliza estrategias de control innovadoras, las cuales pueden ser seleccionadas de forma individual para cada articulación, dando así una alta versatilidad en la definición de los tratamientos. La plataforma robótica desarrollada fue evaluada tanto técnica como clínicamente con pacientes pediátricos. Los resultados muestran el potencial del dispositivo como herramienta de rehabilitación, proporcionando también soporte preliminar para futuras implementaciones clínicas, no solo e

BACKGROUND: The use of robotic trainers has increased with the aim of improving gait function in patients with limitations. Nevertheless, there is an absence of studies that deeply describe detailed guidelines of how to correctly implement robot-based treatments for gait rehabilitation. This contribution proposes an accurate robot-based training program for gait rehabilitation of pediatric population with Cerebral Palsy (CP). METHODS: The program is focused on the achievement of some specifications defined by the International Classification of Functioning, Disability and Health framework, Children and Youth version (ICF-CY). It is framed on 16 non-consecutive sessions where motor control, strength and power exercises of lower limbs are performed in parallel with a postural control strategy. A clinical evaluation with four pediatric patients with CP using the CPWalker robotic platform is presented. RESULTS: The preliminary evaluation with patients with CP shows improvements in several aspects as strength (74.03±40.20%), mean velocity (21.46±33.79%), step length (17.95±20.45%) or gait performance (e.g. 18.88±14.31% in Gross Motor Function Measure-88 items, E and D dimensions). CONCLUSIONS: The improvements achieved in the short term show the importance of working strength and power functions meanwhile over-ground training with postural control. This research could serve as preliminary support for future clinical implementations in any robotic device. TRIAL REGISTRATION: The study was carried out with the number R-0032/12 from Local Ethical Committee of the Hospital Infantil Niño Jesús. Public trial registration: ISRCTN18254257. Registered 23 March 2017, retrospectively registered.

Background: Recently developed controllers for robot-assisted gait training allow for the adjustment of assistance for specific subtasks (i.e. specific joints and intervals of the gait cycle that are related to common impairments after stroke). However, not much is known about possible interactions between subtasks and a better understanding of this can help to optimize (manual or automatic) assistance tuning in the future. In this study, we assessed the effect of separately assisting three commonly impaired subtasks after stroke: foot clearance (FC, knee flexion/extension during swing), stability during stance (SS, knee flexion/extension during stance) and weight shift (WS, lateral pelvis movement). For each of the assisted subtasks, we determined the influence on the performance of the respective subtask, and possible effects on other subtasks of walking and spatiotemporal gait parameters. Methods: The robotic assistance for the FC, SS and WS subtasks was assessed in nine mildly impaired chronic stroke survivors while walking in the LOPES II gait trainer. Seven trials were performed for each participant in a randomized order: six trials in which either 20% or 80% of assistance was provided for each of the selected subtasks, and one baseline trial where the participant did not receive subtask-specific assistance. The influence of the assistance on performances (errors compared to reference trajectories) for the assisted subtasks and other subtasks of walking as well as spatiotemporal parameters (step length, width and height, swing and stance time) was analyzed. Results: Performances for the impaired subtasks (FC, SS and WS) improved significantly when assistance was applied for the respective subtask. Although WS performance improved when assisting this subtask, participants were not shifting their weight well towards the paretic leg. On a group level, not many effects on other subtasks and spatiotemporal parameters were found. Still, performance for the leadin, Biomechatronics & Human-Machine Control

Background: In clinical practice, therapists choose the amount of assistance for robot-assisted training. This can result in outcomes that are influenced by subjective decisions and tuning of training parameters can be time-consuming. Therefore, various algorithms to automatically tune the assistance have been developed. However, the assistance applied by these algorithms has not been directly compared to manually-tuned assistance yet. In this study, we focused on subtask-based assistance and compared automatically-tuned (AT) robotic assistance with manually-tuned (MT) robotic assistance. Methods: Ten people with neurological disorders (six stroke, four spinal cord injury) walked in the LOPES II gait trainer with AT and MT assistance. In both cases, assistance was adjusted separately for various subtasks of walking (in this study defined as control of: weight shift, lateral foot placement, trailing and leading limb angle, prepositioning, stability during stance, foot clearance). For the MT approach, robotic assistance was tuned by an experienced therapist and for the AT approach an algorithm that adjusted the assistance based on performances for the different subtasks was used. Time needed to tune the assistance, assistance levels and deviations from reference trajectories were compared between both approaches. In addition, participants evaluated safety, comfort, effect and amount of assistance for the AT and MT approach. Results: For the AT algorithm, stable assistance levels were reached quicker than for the MT approach. Considerable differences in the assistance per subtask provided by the two approaches were found. The amount of assistance was more often higher for the MT approach than for the AT approach. Despite this, the largest deviations from the reference trajectories were found for the MT algorithm. Participants did not clearly prefer one approach over the other regarding safety, comfort, effect and amount of assistance. Conclusion: Automatic tuning ha, Biomechatronics & Human-Machine Control