This article presents a methodology for the design of rehabilitation devices that considers factors involved in a clinical environment. This methodology integrates different disciplines that work together. The methodology is composed by 3 phases and 13 stages with specific tasks, the first phase includes the clinical context considering the requirements of the patient and therapist during the rehabilitation, the second phase is focused in engineering based on the philosophy of digital twin, and in the third phase is evaluated the device. This article explains the characteristics of the methodology and how it was applied in the design of an exoskeleton for passive rehabilitation of the upper limb.
Atypical walking in the months and years after stroke constrain community reintegration and reduce mobility, health, and quality of life. The ReWalk ReStore™ is a soft robotic exosuit designed to assist the propulsion and ground clearance subtasks of post-stroke walking by actively assisting paretic ankle plantarflexion and dorsiflexion. Previous proof-of-concept evaluations of the technology demonstrated improved gait mechanics and energetics and faster and farther walking in users with post-stroke hemiparesis. We sought to determine the safety, reliability, and feasibility of using the ReStore™ during post-stroke rehabilitation.
A multi-site clinical trial (NCT03499210) was conducted in preparation for an application to the United States Food and Drug Administration (FDA). The study included 44 users with post-stroke hemiparesis who completed up to 5 days of training with the ReStore™ on the treadmill and over ground. In addition to primary and secondary endpoints of safety and device reliability across all training activities, an exploratory evaluation of the effect of multiple exposures to using the device on users’ maximum walking speeds with and without the device was conducted prior to and following the five training visits.
All 44 study participants completed safety and reliability evaluations. Thirty-six study participants completed all five training days. No device-related falls or serious adverse events were reported. A low rate of device malfunctions was reported by clinician-operators. Regardless of their reliance on ancillary assistive devices, after only 5 days of walking practice with the device, study participants increased both their device-assisted (Δ: 0.10 ± 0.03 m/s) and unassisted (Δ: 0.07 ± 0.03 m/s) maximum walking speeds (P’s < 0.05).
When used under the direction of a licensed physical therapist, the ReStore™ soft exosuit is safe and reliable for use during post-stroke gait rehabilitation to provide targeted assistance of both paretic ankle plantarflexion and dorsiflexion during treadmill and overground walking.
Bipedal locomotion is characterized by alternating periods of single and double limb support, with ground clearance by the swing limb and propulsion by the trailing stance limb serving as crucial walking subtasks [1, 2]. Healthy individuals are able to generate an ankle dorsiflexion moment during each limb’s swing phase to lift the foot and facilitate ground clearance. They are also able to generate an ankle plantarflexion moment during each limb’s late stance phase to produce the propulsive force required to advance the limb and body . In contrast, post-stroke hemiparesis results in impaired paretic dorsiflexion and plantarflexion that, in turn, hinders ground clearance and propulsion [4,5,6,7,8] and, ultimately, necessitates compensatory walking strategies [9, 10] that make walking more effortful and unstable [11,12,13,14].
The ReWalk ReStore™ is a soft robotic exosuit designed to augment the paretic ankle’s ability to produce both dorsiflexor and plantarflexor moments during walking. In early proof-of-concept studies conducted with a research version of the device [15, 16], exosuits were shown to facilitate immediate increases in swing phase paretic ankle dorsiflexion by an average 5 degrees , the propulsion force generated by the paretic limb by an average 10% , and the positive center of mass (COM) power generated by the paretic limb during late stance phase by an average 22% . Together, these improvements in paretic limb function resulted in reduced propulsion asymmetry by 20%  and the asymmetry in positive COM power generated during late stance phase by 39% . Also observed were immediate reductions in hip hiking and circumduction compensations of over 20% , reductions in the energy cost of walking by an average 10% [17, 18], faster overground walking speeds by a median 0.14 m/s, and farther walking distances during the 6-min walk test by a median 32m .
Building on this foundational biomechanical, physiological, and clinical research, the objective of this multi-site clinical trial was to evaluate safety, feasibility, and reliability of using exosuits during post-stroke rehabilitation in preparation for a commercial clinical application to the United States Food and Drug Administration (FDA). In contrast to previous laboratory-based research that studied the immediate effects of exosuit prototypes on clinical, biomechanical, and physiological outcomes, this translational research sought to determine the safety of clinicians and patients with post-stroke hemiparesis using the commercially-adapted ReStore™ in clinical settings, the feasibility of clinician operators applying the ReStore™ during both treadmill and over ground gait training activities, and the reliability of the technology across multiple training visits. In addition to outcomes of safety, feasibility, and device reliability, an exploratory evaluation of the impact that multiple training visits with the device have on users’ maximum walking speeds, both with and without the device, was also included.
The ReStore™ is indicated for use by individuals with post-stroke hemiparesis undergoing stroke rehabilitation under the supervision of a licensed physical therapist. To assess the safety, device reliability, and clinical feasibility of using the ReStore™ during post-stroke gait rehabilitation, a multi-site trial was conducted. The trial included five clinical sites and 44 users with post-stroke hemiparesis. The study was approved by the Institutional Review Boards of Boston University, Spaulding Rehabilitation Hospital, The Shirley Ryan AbilityLab, TIRR Memorial Hermann Hospital, Kessler Rehabilitation Hospital, and Moss Rehabilitation Hospital. Written informed consent was secured for all participants.
Study inclusion and exclusion criteria
Study participant eligibility requirements consisted of: (i) one-sided ischemic or hemorrhagic stroke, (ii) > 2 weeks post-stroke, (iii) age > 18 years, (iv) height between 4′8″ and 6′7″, (v) weight < 264lbs, (vi) medical clearance, (vii) ability to ambulate at least 5 ft without an AFO and with no more than minimal contact assistance, (viii) ability to follow a 3-step command, (ix) ability to fit suit components, (x) no greater than 5 degrees of ankle plantar flexion contracture, and (xi) Modified Ashworth Scale for tone at 3 or less for ankle dorsiflexor and plantarflexor muscles. Exclusion criteria included: (i) severe aphasia limiting ability to express needs or discomfort verbally or non-verbally, (ii) serious co-morbidities that interfere with ability to participate, (iii) significant Peripheral Artery Disease, (iv) colostomy bag, (v) current pregnancy, (vi) uncontrolled hypertension, (vii) participation in any other clinical trial, (viii) open wounds or broken skin at device locations requiring medical management, (ix) urethane allergies, (x) and current DVT.
After screening and enrollment, study participants completed up to two walking evaluations and five device exposure visits. Each exposure visit consisted of up to 20 min of overground walking practice and 20 min of treadmill walking practice while receiving assistance from the device. The visit schedule consisted of a minimum of two visits per week, with the expectation of no more than 4 weeks between the pretraining and posttraining evaluations. Actual activities and durations were dependent on each study participant’s abilities as determined by the treating physical therapist as per their usual practices. The target level for plantarflexion assistance during all active walking with the ReStore™ was 25% of the user’s bodyweight [17, 19]. The target level for dorsiflexion assistance was the minimum needed for adequate ground clearance and heel strike, as determined visually by the physical therapist.
The exosuit consists of motors worn at the waist that generate mechanical forces that are transmitted by cables to attachment points located proximally on a functional textile worn around the calf and distally on a shoe insole (Fig. 1). The overall weight of the exosuit is approximately 5kgs, with the vast majority of the weight located proximally in the actuation pack worn at the waist. Each functional textile contains a detachable liner that can be washed. For users who require medio-lateral ankle support in addition to ankle plantarflexion and dorsiflexion assistance, an optional textile component that prevents ankle inversion without restricting dorsiflexion and plantarflexion can also be used. Inertial sensors that attach to a patient’s shoes measure gait events and automate the independent timing of the active ankle plantarflexion and dorsiflexion assistance provided by the ReStore™ as previously described . Load cell sensors located at the end of each cable are used to monitor the interaction between user and exosuit and ensure that the target level of assistance is achieved [16, 17]. A hand-held device with a graphical interface allows clinicians to monitor patients’ performance and select and progress, in real-time, the assistance parameters (Fig. 2).
Despite limited scientific evidence, there is an increasing interest in soft robotic gloves to optimize hand- and finger-related functional abilities following a neurological event. This review maps evidence on the effects and effectiveness of soft robotic gloves for hand rehabilitation and, whenever possible, patients’ satisfaction. A systematized search of the literature was conducted using keywords structured around three areas: technology attributes, anatomy, and rehabilitation. A total of 272 titles, abstracts, and keywords were initially retrieved, and data were extracted out of 13 articles. Six articles investigated the effects of wearing a soft robotic glove and eight studied the effect or effectiveness of an intervention with it. Some statistically significant and meaningful beneficial effects were confirmed with the 29 outcome measures used. Finally, 11 articles also confirmed users’ satisfaction with regard to the soft robotic glove, while some articles also noticed an increased engagement in the rehabilitation program with this technology. Despite the heterogeneity across studies, soft robotic gloves stand out as a safe and promising technology to improve hand- and finger-related dexterity and functional performance. However, strengthened evidence of the effects or effectiveness of such devices is needed before their transition from laboratory to clinical practice.
The hand and fingers are essential organs to perform a multitude of functional tasks in daily life, particularly to grasp and handle objects. In fact, the movements performed with the hand to grasp and handle objects, which can solicit up to 19 articulations driven by 29 muscles,1 can be grouped into two broad categories: power and precision grasps. Power grasping requires an individual performing gross motor tasks to generate large forces to firmly hold an object. In contrast, precision grasping requires an individual performing fine motor tasks to generate multiple levels of force to hold an object. The power grasps can be further characterized into cylindrical, spherical, or hook grasps whereas the precision grasps can be further categorized into pinch, tripodal, or lumbrical grasps (Figure 1).2 Whenever sensorimotor impairments of the hand and fingers develop as a result of a neurological event (e.g. stroke, spinal cord injury, Parkinson’s disease),3 the ability to grasp becomes jeopardized to various extents and may negatively impact functional abilities, as well as social participation and life satisfaction.4
Figure 1. Different types of power and precision grasps.
Despite intensive neurorehabilitation efforts, the likelihood of regaining optimal hand and finger-related functional abilities remains low following a neurological event. For examples, three months after a stroke, only 12% of survivors say they have no problem at all whereas 38% report major difficulties with hand and finger-related functional abilities,5,6 while 75% of individuals with a spinal cord injury at the cervical vertebral level (i.e. tetraplegia), who were asked which function they would most like to have restored, chose upper extremity function,7 with improvement in hand function being their highest-ranked goal.8 Therefore, it is no surprise that one of the most commonly expressed goals of individuals who have sustained a neurological event (i.e. stoke, tetraplegia) and rehabilitation professionals is to engage in neurorehabilitation interventions that can reduce hand and finger sensorimotor impairments, thus improving related functional abilities that are crucial for optimal social participation and life satisfaction.
Rehabilitation strategies designed to maximize hand and finger-related functional abilities are predominantly founded on activity-based therapy, integrating the principles of neuroplasticity.9 Such an approach requires these individuals to engage in meaningful hand- and finger-specific exercises that they must repeat intensively on a daily basis.10,11 In fact, to expect beneficial neuroplastic adaptations, animal studies focusing on gait suggest that up to 1000 to 2000 steps must be taken daily, whereas human studies focusing on grasping in stroke survivors suggest that at least 100 repetitions need to be completed daily.12 Although the evidence suggests the need, adhering to these principles13 remains challenging in clinical practice, especially given various time and productivity constraints. Indeed, it is common to observe in clinical practice that exercise programs are performed individually with direct supervision by a rehabilitation professional, which leads to productivity issues and limits the possibility of implementing interventions at high intensity.14,15 In fact, evidence suggests that the number of repetitions observed for upper extremity work in stroke survivors undergoing neurorehabilitation typically ranges between 12 and 60 repetitions per session, which is far below the number required to expect neuroplastic adaptations.16,17 In addition, recovery may be limited by lack of treatment time, due to the elevated demand for neurorehabilitation services and increased therapists’ workload, especially in publicly funded healthcare environments.18 As a result, individuals with sensorimotor deficits undergoing intensive functional rehabilitation may not achieve the full potential of their hand and fingers sensorimotor and related functional recovery and may reach a ‘recovery plateau’ earlier than expected during the rehabilitation process.
To overcome this challenge, the last decade has seen substantial progress in the development of soft robotic gloves that can facilitate hand and finger movements when performing activities of daily living (ADL) and instrumental activities (iADL) that require grasping objects.19 Moreover, these soft robotic gloves are predicted to be a promising adjunct neurorehabilitation intervention to potentiate the effects of conventional rehabilitation interventions and are now about to be introduced into clinical practice; their effects, however, remain uncertain due to a paucity of evidence. In this context, the present review aims to map, for the first time, the evidence of the effects of the soft robotic glove on the performance of hand- and finger-related functional activities (i.e. with vs. without the technology) and on hand and finger sensorimotor and related functional abilities (i.e. before vs. after an intervention using the technology), among individuals with hand and finger sensorimotor impairments and related disabilities and, whenever investigated, patients’ satisfaction related to the use of the soft robotic glove. Specifically, this review seeks to address the following objectives: (1) determine the effects of rehabilitation interventions using soft robotic gloves; and (2) determine the acceptability and the perceived usefulness of this technology.[…]
The purpose of this paper is to design and develop a new robotic device for the rehabilitation of the upper limbs. The authors are focusing on a new symmetrical robot which can be used to rehabilitate the right upper limb and the left upper limb. The robotic arm can be automatically extended or reduced depending on the measurements of the patient’s arm. The main idea is to integrate electrical stimulation into motor rehabilitation by robot. The goal is to provide automatic electrical stimulation based on muscle status during the rehabilitation process.
The developed robotic arm can be automatically extended or reduced depending on the measurements of the patient’s arm. The system merges two rehabilitation strategies: motor rehabilitation and electrical stimulation. The goal is to take the advantages of both approaches. Electrical stimulation is often used for building muscle through endurance, resistance and strength exercises. However, in the proposed approach the electrical stimulation is used for recovery, relaxation and pain relief. In addition, the device includes an electromyography (EMG) muscle sensor that records muscle activity in real time. The control architecture provides the ability to automatically activate the appropriate stimulation mode based on the acquired EMG signal. The system software provides two modes for stimulation activation: the manual preset mode and the EMG driven mode. The program ensures traceability and provides the ability to issue a patient status monitoring report.
The developed robotic device is symmetrical and reconfigurable. The presented rehabilitation system includes a muscle stimulator associated with the robot to improve the quality of the rehabilitation process. The integration of neuromuscular electrical stimulation into the physical rehabilitation process offers effective rehabilitation sessions for neuromuscular recovery of the upper limb. A laboratory-made stimulator is developed to generate three modes of stimulation: pain relief, massage and relaxation. Through the control software interface, the physiotherapist can set the exercise movement parameters, define the stimulation mode and record the patient training in real time.
There are certain constraints when applying the proposed method, such as the sensitivity of the acquired EMG signals. This involves the use of professional equipment and mainly the implementation of sophisticated algorithms for signal extraction.
Functional electrical stimulation and robot-based motor rehabilitation are the most important technologies applied in post-stroke rehabilitation. The main objective of integrating robots into the rehabilitation process is to compensate for the functions lost in people with physical disabilities. The stimulation technique can be used for recovery, relaxation and drainage and pain relief. In this context, the idea is to integrate electrical stimulation into motor rehabilitation based on a robot to obtain the advantages of the two approaches to further improve the rehabilitation process. The introduction of this type of robot also makes it possible to develop new exciting assistance devices.
The proposed design is symmetrical, reconfigurable and light, covering all the joints of the upper limbs and their movements. In addition, the developed platform is inexpensive and a portable solution based on open source hardware platforms which opens the way to more extensions and developments. Electrical stimulation is often used to improve motor function and restore loss of function. However, the main objective behind the proposed stimulation in this paper is to recover after effort. The novelty of the proposed solution is to integrate the electrical stimulation powered by EMG in robotic rehabilitation.
The purpose of this research is to review upper
limb exoskeleton for industrial and rehabilitation
application from other researchers such as control system,
mechanical design, load transmission methods, and control
strategies. They mainly used the upper limb exoskeleton in
the field of rehabilitation and power-assist. Electromyogram
or EMG and Force sensor are used for measuring the user
motion. Moreover, the load transmission methods have a lot
of impact in term of speed and torque such as DC motor
with gearbox, DC motor with driving wire, servo motor, and
more. In this works, we study the various technique before
design and develop the upper limb exoskeleton for
supporting who is a disability of upper limb motion, to be
more precise, low-cost, lightweight material, modern control
algorithm, and capability upper limb motion.
In rehabilitation of patients who have lost their ability to move independently due to the paralysis of lower limbs, using exoskeletons is a perspective direction. In recent years a great number of robotic devices improving walking of people with lower paraparesis have been developed. However, their comparison is hindered since there are no standardized approaches to the assessment of their efficiency and safety. In this review, general principles of evaluating external robotic devices have been presented, and methods of determining safety and convenience of exoskeleton usage have been analyzed. Assessment of qualitative and quantitative parameters of exoskeleton-assisted walking has also been considered. The characteristic of the questionnaires, standard tests and biochemical investigations, which are used in approbation of exoskeletal devices in people with paraplegia has been presented. Possible ways of evaluating energy expenditure when moving in exoskeletons are shown. The need of elaborating a unified evaluation strategy of walking in exoskeletons has been substantiated.
Introduction. Bioengineering devices, enhancing functional capabilities of patients with pathology of the musculoskeletal apparatus, include, among others, exoskeletons, which are special constructions that are put on a man in the form of an external frame, reproduce the biomechanics of his movements, improve muscular power, and reduce metabolic expenditure for walking [1–7]. In rehabilitation medicine, the development of exoskeletons for patients who have lost the ability to ambulate due to paralyzation of the lower limbs, is the most grounded and perspective [8–15]. A sufficient number of models of robotic orthoses and exoskeletons enabling patients with lower paraplegia and paraparesis to stand up and sit down, walk along an even surface and ascend stairs [16–27]. Creation and improvement of such systems require assessment of their efficiency and safety. Nevertheless there are not so many publications on this topic. The majority of these works touch upon more simple robotic devices compared to skeletons [28–31] often using different metrical sets [32–34]. Assessing the efficiency of a new robotic device with functional electrostimulation for patients with lower limb paraparesis, Goldfarb et al. analyzed an average walking speed, heart rate (HR), arterial pressure (AP), gas exchange, variability of the angles in the pelvic and knee joints [30, 35]. An average walking speed and HR normalized relative to the walking speed served as criteria of evaluation of orthoses for people with paraplegia in the works of Nene, Harvey, Winchester et al. [36–39]. Ohta et al. assessed a robotic orthosis designed for patients with vertebral-cerebrospinal trauma (VCST) using walking speed, step length, amplitude of vertical and lateral displacement of the head in walking . In some cases, in addition to the walking speed, the authors took into consideration the maximal distance the patient could travel without rest using the device [40–42], or the kinematics of motions in the knee or pelvic joints . Kobetic et al. studied the efficiency of a robotic orthosis intended for restoration of the capacity of persons with paraparesis to standing, walking and ascending stairs by analyzing the kinematics of motions in the knee joint . A short analysis of biomechanical parameters was presented also in the work of Jung et al.: the investigators performed a comparative analysis of gaits of patients with spinal cord traumas using robotic devices and without their assistance . In order to evaluate the efficiency of using exoskeletons for rehabilitation of stroke patients Fan et al. analyzed indices of surface electromyogram . Quantitative characteristic of the efficiency of an active lower limb exoskeleton in the work of Neuhaus et al. was given on the basis of walking speed, and an extent of efforts expended on the exoskeleton control was evaluated by registration of the HR, respiration rate, color of the skin; the authors assessed also the stability of standing (ability of the patient to catch a ball), and cognitive efforts (ability to maintain a visual contact) . Apart from walking, of patient’s capacity to sit down and stand up in the exoskeleton was estimated in some cases; for this purpose angles in the pelvic and knee joints , as well as pressure of the arms on the wheel-chair handles during these maneuvers were used [20, 21].
On the whole, it should be noted that a generally accepted methodology of exoskeleton assessment has not been worked out so far [47–50]. But the analysis of the literature showed, that a great deal of investigations are devoted to the elaboration of the general principles of approbation of novel robotic device, exoskeletons for lower limbs in particular. Approbation of exoskeletons usually includes testing of the walk in the exoskeleton and determination of such indices as energy expenditure, safety, convenience and simplicity of using the external device [24, 51]. These approaches to approbation are valid for all types of lower limb exoskeletons, making it possible to compare different variants of exoskeleton devices [52, 53].[…]
The development of upper limb and lower extremity robotic exoskeletons has emerged as a way to improve the quality of life as well as act as a primary rehabilitation device for individuals suffering from stroke or spinal cord injury. This paper contains extractions from the database of robotic exoskeleton for human upper limb rehabilitation and prime factors behind the burden of stroke. Various studies on stroke-induced deficiency from different countries were included in the review. The data were extracted from both clinical tests and surveys. Though there have been splendid advancements in this field, they still present enormous challenges. This paper provides the current developments, progress and research challenges in exoskeleton technology along with future research directions associated with the field of exoskeletons and orthosis. Robot-assisted training (RT) was found to be more effective than conventional training (CT) sessions. The present research articles in this field have many weaknesses as they do not cover the systematic review including the clinical studies and various surveys that lay a foundation for the requirement of robotic assistive devices. This review paper also discusses various exoskeleton devices that have been clinically evaluated.
Background: As a result of stroke, patients have problems with locomotion and transfers, which lead to frequent falls. Recovery after stroke is a major goal of rehabilitation, but it is difficult to choose which treatment method is most beneficial for stroke survivors. Recently, powered robotic exoskeletons are used in treatment to maximize the neural recovery of patients after stroke, but there are no studies evaluating the changes in balance among patients rehabilitated with an exoskeleton.
Purpose: The aim of this study was to evaluate the effects of Ekso GT exoskeleton-assisted gait training on balance, load distribution, and functional status of patients after ischemic stroke.
Methods: The outcomes are based on 44 patients aged 55–85 years after ischemic stroke who were previously randomly assigned into two groups: experimental (with Ekso GT rehabilitation) and control (with classical rehabilitation). At baseline and after 4 weeks of treatment, the patients were evaluated on balance, load distribution, and functional status using, respectively a stabilometric platform, the Barthel Index, and the Rivermead Mobility Index.
Results: In the experimental group, balance improved regarding the variables describing sway area as ellipse major and minor axes. In the control group, improvement was noted in sway velocity. After the therapy, total load distribution on feet in both groups showed a small and insignificant tendency toward reduction in the amount of uninvolved limb loading. In the control group, significant load transfer from the backfoot to the forefoot was noted. Both forms of rehabilitation caused significant changes in functional status.
Conclusions: Both training with the use of the Ekso GT exoskeleton and classical physiotherapy lead to functional improvement of patients after ischemic stroke. However, in the experimental group, improvement was observed in a larger number of categories, which may suggest potentially greater impact of treatment with the exoskeleton on functional status. Also, both forms of rehabilitation caused significant changes in balance, but we have noted some trends indicating that treatment with exoskeleton may be more beneficial for some patients. The load transfer from the backfoot to the forefoot observed in the control group was an unfavorable phenomenon. We suggest that the Ekso GT exoskeleton may be a promising tool in the rehabilitation of patients after stroke.
Stroke is the third leading cause of death worldwide and is the most common cause of disability among adults (1, 2). As a result of stroke, patients have problems with locomotion and transfers, which lead to frequent falls. People with hemiparesis have uneven distribution of body mass between the sides of the body, causing balance and coordination disorders, deep and superficial sensation, increased muscle tone, and fear of falling (2, 3). Patients have problems with lack of normal postural muscle tone, and proper reciprocal innervation as well as normal, automatic movement patterns and balance reactions (4). Some studies have reported that balance alterations significantly limit the physical activity of stroke patients, which may be the reason for deconditioning of patients in the chronic phase and reduction in their gait possibilities as well as other activities of daily living (5). That is why gait rehabilitation and also balance therapy are very important in improving the quality of everyday and social life of those patients (6).
Gait training may improve not only strength, endurance, and coordination of the lower limbs but also the entire body of the patient, influencing general fitness and endurance, balance, normalization of muscle tone, and functional improvement (7). The Barthel Index (BI) and Rivermead Mobility Index (RMI) tests are considered to be proper criteria for assessing a patient’s functional state after stroke and good indicators of the effectiveness of the applied therapy (8, 9).
Recovery after stroke is a major goal of rehabilitation, but it is difficult to choose which treatment method is most beneficial for stroke survivors. Recently, powered robotic exoskeletons are used in treatment to maximize the neural recovery of patients after stroke (10, 11). However, in a review paper, Louie and Eng (12) have reported that only four different types of powered exoskeletons have been studied among a small number of stroke patients, and the published data were controversial. Moreover, in the available literature, there are no studies evaluating the changes in balance among patients rehabilitated with an exoskeleton. Most authors have reported various aspects of walking, and only a few papers have presented data concerning changes in balance. Additionally, most of the studies used subjective tools such as the Berg Balance Scale (13, 14). There is a lack of studies in which changes in balance and load distribution due to rehabilitation with the exoskeleton would be examined using an objective tool—stabilometric platform; therefore, this study undertakes this task for the first time.
The aim of this study was to evaluate the effectiveness of rehabilitation with Ekso GT exoskeleton in patients after ischemic stroke and to compare this type of therapy with the classical model of rehabilitation. The novelty of this study was the verification of the robot-assisted gait training effects on balance, load distribution, and functional status of stroke patients.[…]
In this paper, we propose and demonstrate the functionality of a novel exoskeleton which provides variable resistance training for human hands. It is intended for people who suffer from diminished hand strength and low dexterity due to non-severe forms of neuropathy or other ailments. A new variable-stiffness mechanism is designed based on the concept of aligning three different sized springs to produce four different levels of stiffness, for variable kinesthetic feedback during an exercise. Moreover, the design incorporates an interactive computer game and a flexible sensor-based glove that motivates the patients to use the exoskeleton. The patients can exercise their hands by playing the game and see their progress recorded from the glove for further motivation. Thus the rehabilitation training will be consistent and the patients will re-learn proper hand function through neuroplasticity. The developed exoskeleton is intrinsically safe when compared with active exoskeleton systems since the applied compliance provides only passive resistance. The design is also comparatively lighter than literature designs and commercial platforms.
Since the early 2000s, researchers have been trying to develop lower-limb exoskeletons that augment human mobility by reducing the metabolic cost of walking and running versus without a device. In 2013, researchers finally broke this ‘metabolic cost barrier’. We analyzed the literature through December 2019, and identified 23 studies that demonstrate exoskeleton designs that improved human walking and running economy beyond capable without a device. Here, we reviewed these studies and highlighted key innovations and techniques that enabled these devices to surpass the metabolic cost barrier and steadily improve user walking and running economy from 2013 to nearly 2020. These studies include, physiologically-informed targeting of lower-limb joints; use of off-board actuators to rapidly prototype exoskeleton controllers; mechatronic designs of both active and passive systems; and a renewed focus on human-exoskeleton interface design. Lastly, we highlight emerging trends that we anticipate will further augment wearable-device performance and pose the next grand challenges facing exoskeleton technology for augmenting human mobility.
Exoskeletons to augment human walking and running economy: previous predictions and recent milestones
The day that people move about their communities with the assistance of wearable exoskeletons is fast approaching. A decade ago, Ferris predicted that this day would happen by 2024  and Herr foresaw a future where people using exoskeletons to move on natural terrain would be more common than them driving automobiles on concrete roads . Impressively, Ferris and Herr put forth these visions prior to the field achieving the sought-after goal of developing an exoskeleton that breaks the ‘metabolic cost barrier’. That is, a wearable assistive device that alters user limb-joint dynamics, often with the intention of reducing user metabolic cost during natural level-ground walking and running compared to not using a device. When the goal is to reduce effort, metabolic cost is the gold-standard for assessing lower-limb exoskeleton performance since it is an easily attainable, objective measure of effort, and relates closely to overall performance within a given gait mode [3, 4]. For example, reducing ‘exoskeleton’ mass improves user running economy, and in turn running performance . Further, enhanced walking performance is often related to improved walking economy  and quality of life [5, 6]. To augment human walking and running performance, researchers seriously began attempting to break the metabolic cost barrier using exoskeletons in the first decade of this century, shortly after the launch of DARPA’s Exoskeletons for Human Performance Augmentation program [7,8,9,10].
It was not until 2013 that an exoskeleton broke the metabolic cost barrier . In that year, Malcolm and colleagues  were the first to break the barrier when they developed a tethered active ankle exoskeleton that reduced their participants’ metabolic cost during walking (improved walking economy) by 6% (Fig. 1). In the following 2 years, both autonomous active  and passive  ankle exoskeletons emerged that also improved human walking economy (Fig. 1). Shortly after those milestones, Lee and colleagues  broke running’s metabolic cost barrier using a tethered active hip exoskeleton that improved participants’ running economy by 5% (Fig. 1). Since then, researchers have also developed autonomous active [15, 16] and passive [17, 18] exoskeletons that improve human running economy (Fig. 1).
Fig, 1 Milestones illustrating the advancement of exoskeleton technology. Tethered (blue) and autonomous (red) exoskeletons assisting at the ankle (circle), knee (triangle), and hip (square) joint to improve healthy, natural walking (left) and running (right) economy versus using no device are shown