Wearable biofeedback improves human-robot compliance during ankle-foot exoskeleton-assisted gait training: a pre-post controlled study in healthy participants

Supplementary material available at: https://www.mdpi.com/1424-8220/20/20/5876/s1The adjunctive use of biofeedback systems with exoskeletons may accelerate post-stroke gait rehabilitation. Wearable patient-oriented human-robot interaction-based biofeedback is proposed to improve patient-exoskeleton compliance regarding the interaction torque’s direction (joint motion strategy) and magnitude (user participation strategy) through auditory and vibrotactile cues during assisted gait training, respectively. Parallel physiotherapist-oriented strategies are also proposed such that physiotherapists can follow in real-time a patient’s motor performance towards effective involvement during training. A preliminary pre-post controlled study was conducted with eight healthy participants to conclude about the biofeedback’s efficacy during gait training driven by an ankle-foot exoskeleton and guided by a technical person. For the study group, performance related to the interaction torque’s direction increased during (p-value = 0.07) and after (p-value = 0.07) joint motion training. Further, the performance regarding the interaction torque’s magnitude significantly increased during (p-value = 0.03) and after (p-value = 68.59 × 10−3) user participation training. The experimental group and a technical person reported promising usability of the biofeedback and highlighted the importance of the timely cues from physiotherapist-oriented strategies. Less significant improvements in patient–exoskeleton compliance were observed in the control group. The overall findings suggest that the proposed biofeedback was able to improve the participant-exoskeleton compliance by enhancing human-robot interaction; thus, it may be a powerful tool to accelerate post-stroke ankle-foot deformity recovery.INCT-EN -Instituto Nacional de Ciência e Tecnologia para Excitotoxicidade e Neuroproteção(UIDB/04436/2020

Haptic wearables as sensory replacement, sensory augmentation and trainer - a review

Sensory impairments decrease quality of life and can slow or hinder rehabilitation. Small, computationally powerful electronics have enabled the recent development of wearable systems aimed to improve function for individuals with sensory impairments. The purpose of this review is to synthesize current haptic wearable research for clinical applications involving sensory impairments. We define haptic wearables as untethered, ungrounded body worn devices that interact with skin directly or through clothing and can be used in natural environments outside a laboratory. Results of this review are categorized by degree of sensory impairment. Total impairment, such as in an amputee, blind, or deaf individual, involves haptics acting as sensory replacement; partial impairment, as is common in rehabilitation, involves haptics as sensory augmentation; and no impairment involves haptics as trainer. This review found that wearable haptic devices improved function for a variety of clinical applications including: rehabilitation, prosthetics, vestibular loss, osteoarthritis, vision loss and hearing loss. Future haptic wearables development should focus on clinical needs, intuitive and multimodal haptic displays, low energy demands, and biomechanical compliance for long-term usage

Biofeedback system to improve the human-orthosis interaction

Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Eletrónica Médica)Every year, 15 million people worldwide suffer a stroke. More than 80 % of stroke survivors present gait disabilities, limiting their motor independence and well-being. The patients may regain their motor independence with active orthoses. Biofeedback systems (BSs) may be used as an orthotic rehabilitation’s complementary tool to inform the user timely and objectively about their behaviour during gait. Thus, teaching the patients how to improve the human-orthosis interaction. Overall, this allows accelerating and increasing the effectiveness of the gait recovery. Nonetheless, there is a lack of BSs for orthotic gait rehabilitation, and no wearable solution is available. This dissertation aims the development of a wearable, stand-alone and modular BS to be integrated into SmartOs-ankle orthosis, following a user-centered design. The developed BS provides sensory, sonorous, and visual stimulation through vibrotactile motors, headphones, and a Red-Green-Blue Light-Emitting Diode, respectively. The BS includes a microcontroller to manage the activation of the stimuli according to the interaction torque and the reference trajectory of the SmartOs-ankle orthosis. The sensory and sonorous stimuli were chosen for developing user-oriented strategies to teach the user, as follows. When and how to perform the paretic and non-paretic foot-floor contact (foot-floor contact biofeedback); the direction of ankle rotation along the gait cycle (joint motion biofeedback); and, the necessary muscular strength along with the gait cycle (user participation biofeedback). The visual stimulus is used to help the therapist to follow the performance of the patients during the therapy and, consequently, help and motivate them – therapist-oriented strategies. From a validation with healthy subjects, the BS increased the user’s motor performance significantly when walking with an orthosis. The system was able to teach the users about the direction of ankle rotation and the necessary muscular strength along with the gait cycle, improving the human-orthosis interaction. Future work towards enhancing the foot-floor contact strategies and extending the BS validation with a large group of participants and longer training period.A cada ano, 15 milhões de pessoas, mundialmente, sofrem um acidente vascular cerebral (AVC). Mais de 80 % dos sobreviventes apresentam incapacidades de marcha, limitando a sua independência motora e bem-estar. Estes pacientes podem recuperar a sua independência motora através do uso de ortóteses ativas. Adicionalmente os sistemas de biofeedback (BSs) podem ser usados como uma ferramenta complementar da reabilitação assistida por ortótese, informando os usuários, oportunamente e objetivamente, acerca do seu comportamento durante a execução de uma tarefa, e ensinando-os a melhorar a sua interação com a ortótese; assim, acelerando e aumentando a eficácia da recuperação. Não obstante, existem poucos BSs desenvolvidos para a reabilitação assistida por ortóteses, os quais não são vestíveis. Esta dissertação tem como objetivo o desenvolvimento de um BS vestível, autónomo e modular para ser integrado na ortótese de tornozelo do sistema SmartOs, baseando-se numa visão centralizada no utilizador. O BS desenvolvido fornece estimulação sensorial, sonora e visual através de motores vibratórios, auscultadores e um díodo emissor de luz vermelha-verde-azul, respetivamente. O BS inclui um microcontrolador que gere a ativação dos estímulos de acordo com o torque de interação e trajetória de referência da ortótese do tornozelo. Os estímulos sensorial e sonoro foram escolhidos para ensinar o utilizador sobre: quando e como executar o contacto entre o pé, parético e não parético, e o solo; o sentido de rotação do tornozelo ao longo do ciclo da marcha; e a força muscular necessária ao longo do ciclo da marcha. O estímulo visual é usado para ajudar o terapeuta a seguir o desempenho dos pacientes ao longo da terapia, de forma que o terapeuta possa ajudá-los e motivá-los. A partir da validação com sujeitos saudáveis, verificou-se que o BS aumentou significativamente o desempenho motor do utilizador durante a marcha com a ortótese. O sistema mostrou-se capaz de ensinar os utilizadores sobre a direção e magnitude da força muscular necessária ao longo do ciclo da marcha, melhorando a interação entre o humano e a ortótese. O trabalho futuro envolve a melhoria das estratégias que visam o contacto entre o pé e o solo e a validação do sistema com mais participantes e treinos mais longos

Cerebral Palsy

Nowadays, cerebral palsy (CP) rehabilitation, along with medical and surgical interventions in children with CP, leads to better motor and postural control and can ensure ambulation and functional independence. In achieving these improvements, many modern practices may be used, such as comprehensive multidisciplinary assessment, clinical decision making, multilevel surgery, botulinum toxin applications, robotic ambulation applications, treadmill, and other walking aids to increase the quality and endurance of walking. Trainings are based on neurodevelopmental therapy, muscle training and strength applications, adaptive equipment and orthotics, communication, technological solves, and many others beyond the scope of this book. In the years of clinical and academic experiences, children with cerebral palsy have shown us that the world needs a book to give clinical knowledge to health professionals regarding these important issue. This book is an attempt to fulfill and to give “current steps” about CP. The book is intended for use by physicians, therapists, and allied health professionals who treat/rehabilitate children with CP. We focus on the recent concepts in the treatment of body and structure problems and describe the associated disability, providing suggestions for further reading. All authors presented the most frequently used and accepted treatment methods with scientifically proven efficacy and included references at the end of each chapter

Vibrotactile biofeedback devices in Parkinson’s disease: a narrative review

Parkinson’s disease (PD) is often associated with a vast list of gait-associated disabilities, for which there is still a limited pharmacological/surgical treatment efficacy. Therefore, alternative approaches have emerged as vibrotactile biofeedback systems (VBS). This review aims to focus on the technologies supporting VBS and identify their effects on improving gait-associated disabilities by verifying how VBS were applied and validated with end-users. It is expected to furnish guidance to researchers looking to enhance the effectiveness of future vibrotactile cueing systems. The use of vibrotactile cues has proved to be relevant and attractive, as positive results have been obtained in patients’ gait performance, suitability in any environment, and easy adherence. There seems to be a preference in developing VBS to mitigate freezing of gait, to improve balance, to overcome the risk of fall, and a prevalent use to apply miniaturized wearable actuators and sensors. Most studies implemented a biofeedback loop able to provide rescue strategies during or after the detection of a gait-associated disability. However, there is a need of more clinical evidence and inclusion of experimental sessions to evaluate if the biofeedback was effectively integrated into the patients’ motor system.This work was supported by FCT national funds, under the national support to R&D units grant, through the reference project UIDB/04436/2020 and UIDP/04436/2020, and under the Reference Scholarship under Grant SFRH/BD/136569/2018

Novel Bidirectional Body - Machine Interface to Control Upper Limb Prosthesis

Objective. The journey of a bionic prosthetic user is characterized by the opportunities and limitations involved in adopting a device (the prosthesis) that should enable activities of daily living (ADL). Within this context, experiencing a bionic hand as a functional (and, possibly, embodied) limb constitutes the premise for mitigating the risk of its abandonment through the continuous use of the device. To achieve such a result, different aspects must be considered for making the artificial limb an effective support for carrying out ADLs. Among them, intuitive and robust control is fundamental to improving amputees’ quality of life using upper limb prostheses. Still, as artificial proprioception is essential to perceive the prosthesis movement without constant visual attention, a good control framework may not be enough to restore practical functionality to the limb. To overcome this, bidirectional communication between the user and the prosthesis has been recently introduced and is a requirement of utmost importance in developing prosthetic hands. Indeed, closing the control loop between the user and a prosthesis by providing artificial sensory feedback is a fundamental step towards the complete restoration of the lost sensory-motor functions. Within my PhD work, I proposed the development of a more controllable and sensitive human-like hand prosthesis, i.e., the Hannes prosthetic hand, to improve its usability and effectiveness. Approach. To achieve the objectives of this thesis work, I developed a modular and scalable software and firmware architecture to control the Hannes prosthetic multi-Degree of Freedom (DoF) system and to fit all users’ needs (hand aperture, wrist rotation, and wrist flexion in different combinations). On top of this, I developed several Pattern Recognition (PR) algorithms to translate electromyographic (EMG) activity into complex movements. However, stability and repeatability were still unmet requirements in multi-DoF upper limb systems; hence, I started by investigating different strategies to produce a more robust control. To do this, EMG signals were collected from trans-radial amputees using an array of up to six sensors placed over the skin. Secondly, I developed a vibrotactile system to implement haptic feedback to restore proprioception and create a bidirectional connection between the user and the prosthesis. Similarly, I implemented an object stiffness detection to restore tactile sensation able to connect the user with the external word. This closed-loop control between EMG and vibration feedback is essential to implementing a Bidirectional Body - Machine Interface to impact amputees’ daily life strongly. For each of these three activities: (i) implementation of robust pattern recognition control algorithms, (ii) restoration of proprioception, and (iii) restoration of the feeling of the grasped object's stiffness, I performed a study where data from healthy subjects and amputees was collected, in order to demonstrate the efficacy and usability of my implementations. In each study, I evaluated both the algorithms and the subjects’ ability to use the prosthesis by means of the F1Score parameter (offline) and the Target Achievement Control test-TAC (online). With this test, I analyzed the error rate, path efficiency, and time efficiency in completing different tasks. Main results. Among the several tested methods for Pattern Recognition, the Non-Linear Logistic Regression (NLR) resulted to be the best algorithm in terms of F1Score (99%, robustness), whereas the minimum number of electrodes needed for its functioning was determined to be 4 in the conducted offline analyses. Further, I demonstrated that its low computational burden allowed its implementation and integration on a microcontroller running at a sampling frequency of 300Hz (efficiency). Finally, the online implementation allowed the subject to simultaneously control the Hannes prosthesis DoFs, in a bioinspired and human-like way. In addition, I performed further tests with the same NLR-based control by endowing it with closed-loop proprioceptive feedback. In this scenario, the results achieved during the TAC test obtained an error rate of 15% and a path efficiency of 60% in experiments where no sources of information were available (no visual and no audio feedback). Such results demonstrated an improvement in the controllability of the system with an impact on user experience. Significance. The obtained results confirmed the hypothesis of improving robustness and efficiency of a prosthetic control thanks to of the implemented closed-loop approach. The bidirectional communication between the user and the prosthesis is capable to restore the loss of sensory functionality, with promising implications on direct translation in the clinical practice

Down-Conditioning of Soleus Reflex Activity using Mechanical Stimuli and EMG Biofeedback

Spasticity is a common syndrome caused by various brain and neural injuries, which can severely impair walking ability and functional independence. To improve functional independence, conditioning protocols are available aimed at reducing spasticity by facilitating spinal neuroplasticity. This down-conditioning can be performed using different types of stimuli, electrical or mechanical, and reflex activity measures, EMG or impedance, used as biofeedback variable. Still, current results on effectiveness of these conditioning protocols are incomplete, making comparisons difficult. We aimed to show the within-session task- dependent and across-session long-term adaptation of a conditioning protocol based on mechanical stimuli and EMG biofeedback. However, in contrast to literature, preliminary results show that subjects were unable to successfully obtain task-dependent modulation of their soleus short-latency stretch reflex magnitude