'Wearability'? WHAT FUCKING CRAPOLA RESEARCH IS THAT? Do you not understand that survivors want recovery results? Testing using only two survivors is another failure point.
Characterization and wearability evaluation of a fully portable wrist exoskeleton for unsupervised training after stroke
Journal of NeuroEngineering and Rehabilitation volume 17, Article number: 132 (2020)
Abstract
Background
Chronic hand and wrist impairment are frequently present following stroke and severely limit independence in everyday life. The wrist orientates and stabilizes the hand before and during grasping, and is therefore of critical importance in activities of daily living (ADL). To improve rehabilitation outcomes, classical therapy could be supplemented by novel therapies that can be applied in unsupervised settings. This would enable more distributed practice and could potentially increase overall training dose. Robotic technology offers new possibilities to address this challenge, but it is critical that devices for independent training are easy and appealing to use. Here, we present the development, characterization and wearability evaluation of a fully portable exoskeleton for active wrist extension/flexion support in stroke rehabilitation.
Methods
First we defined the requirements, and based on these, constructed the exoskeleton. We then characterized the device with standardized haptic and human-robot interaction metrics. The exoskeleton is composed of two modules placed on the forearm/hand and the upper arm. These modules weigh 238 g and 224 g, respectively. The forearm module actively supports wrist extension and flexion with a torque up to 3.7 Nm and an angular velocity up to 530 deg/s over a range of 154∘. The upper arm module includes the control electronics and battery, which can power the device for about 125 min in normal use. Special emphasis was put on independent donning and doffing of the device, which was tested via a wearability evaluation in 15 healthy participants and 2 stroke survivors using both qualitative and quantitative methods.
Results
All participants were able to independently don and doff the device after only 4 practice trials. For healthy participants the donning and doffing process took 61 ±15 s and 24 ±6 s, respectively. The two stroke survivors donned and doffed the exoskeleton in 54 s/22 s and 113 s/32 s, respectively. Usability questionnaires revealed that despite minor difficulties, all participants were positive regarding the device.
Conclusions
This study describes an actuated wrist exoskeleton which weighs less than 500 g, and which is easy and fast to don and doff with one hand. Our design has put special emphasis on the donning aspect of robotic devices which constitutes the first barrier a user will face in unsupervised settings. The proposed device is a first and intermediate step towards wearable rehabilitation technologies that can be used independently by the patient and in unsupervised settings.
Background
Stroke affects approximately 795’000 people each year in the US alone and is one of the leading causes of long-term adult disability and dependency [1]. Traditional stroke rehabilitation options for outpatients include therapist-based treatments with hands-on physical and occupational therapy in rehabilitation centres. The treatment lasts several weeks and is composed of periodic blocked practice, but overall training time remains low compared to the time the patient is inactive at home [2, 3]. Moreover, stroke patients are discharged at an increasingly early stage [4, 5] requiring new approaches for rehabilitation training in unsupervised settings. These novel approaches must be effective [6, 7], and empower patients to self-initiate rehabilitation training that will enable more distributed sessions. This is particularly important since, in the future, more rehabilitation resources will be moved to community settings and patient homes to complement conventional therapy [8–11].
Upper extremity hemiparesis is a common weakness following stroke and heavily impairs ADL [12]. Adequate wrist function is critical for orientating and stabilising the hand [13], but the recovery process of this specific joint is still not well understood in stroke survivors [14]. It has been shown that the probability of recovering distal functions (e.g. the wrist) are closely linked with the acute state of proximal functions (shoulder or elbow) [15]. In the same vein, distal training can lead to positive effects at the shoulder and elbow [16–18]. While the hand has received a lot of attention from the research community, there remains a need to provide wrist function training.
Robot-assisted therapy for stroke patients is a promising approach [19, 20] and proven advantages include: 1) increasing dose and intensity of training [21–23], 2) allowing quantitative measurements to assess performance and recovery of the patient more precisely than conventional rehabilitation training [24], and 3) engaging the patient in a motivating and stimulating environment [25, 26]. However, a robot-mediated therapy administered in unsupervised settings implies several technical, clinical and social challenges: first of all, the technology must be safe to be deployed in such a context, its footprint acceptable to the patient, relatives and caregivers, and it should adhere to conventional therapy principles to administer appropriate treatment to the user. Moreover, the device must be adaptable to the individual and designed such that patients can use it independently and in various environmental settings [27–29].
A myriad of devices have targeted training of the whole arm, and also more specifically the hand and fingers [19, 20, 30], while relatively few wearable exoskeletons have focused on the wrist [31–35]. Unlike stationary rehabilitation devices [36–38], a fully wearable exoskeleton offers the possibility to use (i.e. to train) the paretic limb during functional everyday tasks [7, 39, 40] where higher training dose could more conveniently be achieved. Exoskeletons interact at the level of individual joints and enable joint specific kinematic assessments [41, 42]. Moreover, it has been shown that training isolated individual joint movements facilitates learning complex multi-joint movements [43, 44]. Practically, this means that through the “part-whole transfer paradigm” simple low degree of freedom (DoF) robotic devices could facilitate the training of more complex movements. In an unsupervised training context, simplicity is paramount [45], therefore, simple wearable technologies might provide an interesting add-on to a conventional therapy where complex movements are trained.
We have previously presented a first prototype version of the eWrist [46]. Here we present further developments which focussed on improving portability, independence of use and adaptability in view of unsupervised use of the system. The eWrist is a fully wearable single DoF sEMG-based force controlled wrist exoskeleton that actively supports extension and flexion. We put special emphasis on the attachment mechanisms that facilitate the donning and doffing of the device so that a hemiparetic patient could mount the device independently with a single hand. Among the vast amount of published work on rehabilitation devices for in-home therapy, few have addressed the fixation issue, which constitutes the first barrier a user would have to overcome in order to use the device independently [47, 48]. Currently the eWrist is intended to be used as a training device rather than as an assistive exoskeleton during ADL. However, our long term design goal is to fuse training and assistance with the aim of increasing movement of the affected arm in daily life via technology that modulates assistance in order to improve upper arm function. This requires an exoskeleton that is fully wearable, easy to use, and especially simple to don and doff. The eWrist is our first wearable prototype that is capable of assisting wrist flexion and extension, the latter being particularly relevant for post stroke recovery [49].
Here we briefly describe the previous eWrist version, we then outline requirements for a fully wearable wrist exoskeleton and present an advanced eWrist device where we focussed on wearability improvements. We first characterize the current implementation based on standardized haptic and human-robot interaction metrics for rehabilitation devices. Secondly, we present the results of a wearability study which evaluates the donning/doffing procedure in healthy and stroke participants. Finally, limitations of the current work and potential future use of the eWrist are discussed.
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