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The Cybathlon promotes the development of assistive technology for people with physical disabilities


Abstract and Figures

Background The Cybathlon is a new kind of championship, where people with physical disabilities compete against each other at tasks of daily life, with the aid of advanced assistive devices including robotic technologies. The first championship will take place at the Swiss Arena Kloten, Zurich, on 8 October 2016. The idea Six disciplines are part of the competition comprising races with powered leg prostheses, powered arm prostheses, functional electrical stimulation driven bikes, powered wheelchairs, powered exoskeletons and brain-computer interfaces. This commentary describes the six disciplines and explains the current technological deficiencies that have to be addressed by the competing teams. These deficiencies at present often lead to disappointment or even rejection of some of the related technologies in daily applications. Conclusion The Cybathlon aims to promote the development of useful technologies that facilitate the lives of people with disabilities. In the long run, the developed devices should become affordable and functional for all relevant activities in daily life.
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C O M M E N T A R Y Open Access
The Cybathlon promotes the development
of assistive technology for people with
physical disabilities
Robert Riener
Background: The Cybathlon is a new kind of championship, where people with physical disabilities compete
against each other at tasks of daily life, with the aid of advanced assistive devices including robotic technologies.
The first championship will take place at the Swiss Arena Kloten, Zurich, on 8 October 2016.
The idea: Six disciplines are part of the competition comprising races with powered leg prostheses, powered arm
prostheses, functional electrical stimulation driven bikes, powered wheelchairs, powered exoskeletons and
brain-computer interfaces. This commentary describes the six disciplines and explains the current technological
deficiencies that have to be addressed by the competing teams. These deficiencies at present often lead to
disappointment or even rejection of some of the related technologies in daily applications.
Conclusion: The Cybathlon aims to promote the development of useful technologies that facilitate the lives of
people with disabilities. In the long run, the developed devices should become affordable and functional for all
relevant activities in daily life.
Keywords: Competition, Championship, Prostheses, Exoskeletons, Functional electrical stimulation, Wheelchairs,
Brain computer interfaces
Millions of people worldwide rely on orthotic, pros-
thetic, wheelchairs and other assistive devices to improve
their qualities of life. In the US there live more than 1.6
million people with limb amputations [1] and the World
Health Organization estimates the number of wheelchair
users to about 65 million people worldwide [2]. Unfortu-
nately, current assistive technology does not address
their needs in an ideal fashion. For instance, wheelchairs
cannot climb stairs, arm prostheses do not enable versa-
tile hand functions, and power supplies of many orthotic
and prosthetic devices are limited. There is a need to
further push the development of assistive devices by
pooling the efforts of engineers and clinicians to develop
improved technologies, together with the feedback and
experiences of the users of the technologies.
The Cybathlon is a new kind of championship with
the aim of promoting the development of useful tech-
nologies. In contrast with the Paralympics, where para-
thletes aim to achieve maximum performance, at the
Cybathlon, people with physical disabilities compete
against each other at tasks of daily life, with the aid of
advanced assistive devices including robotic technolo-
gies. Most current assistive devices lack satisfactory func-
tion; people with disabilities are often disappointed, and
thus do not use and accept the technology. Rejection can
be due to a lack of communication between developers,
people with disabilities, therapists and clinicians, which
leads to a disregard of user needs and requirements. Other
reasons could be that the health status, level of lesion or
financial situation of the potential user are so severe that
she or he is unable to use the available technologies. Fur-
thermore, barriers in public environments make the use of
assistive technologies often very cumbersome or even
Six disciplines are part of the competition, addressing
people with either limb paralysis or limb amputations.
Sensory-Motor Systems Lab, ETH Zurich, Tannenstrasse 1, 8092 Zurich,
Spinal Cord Injury Center, University Hospital Bagrist, University of Zurich,
Zurich, Switzerland
© 2016 The Author(s). Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (, which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver
( applies to the data made available in this article, unless otherwise stated.
Riener Journal of NeuroEngineering and Rehabilitation (2016) 13:49
DOI 10.1186/s12984-016-0157-2
The six disciplines comprise races with powered leg pros-
theses, powered arm prostheses, functional electrical
stimulation (FES) driven bikes, powered wheelchairs and
powered exoskeletons (Fig. 1). The sixth discipline is a
racing game with virtual avatars that are controlled by
brain-computer interfaces (BCI). The functional and assist-
ive devices used can be prototypes developed by research
labs or companies, or commercially available products. The
competitors are called pilots, as they have to control a de-
vice that enhances their mobility. The teams each consist of
a pilot together with scientists and technology providers,
making the Cybathlon also a competition between compan-
ies and research laboratories. As a result there are two
awards for each winning team in each discipline: a medal
for the person who is controlling the device and a cup for
the provider of the device (i.e. the company or the lab).
A rehearsal was organized in July 2015 to test race
tracks, scoring system and logistics and to generate foot-
age for advertisement. The premiere will take place at
the Swiss Arena, in Kloten, Zurich, on 8 October 2016.
More information can be found on the Cybathlon web-
The six disciplines and the challenges in their fields
Pilots with above knee amputations will use actuated
prosthetic devices and compete along an obstacle course
containing ramps, stairs, doors, soft-cushioned seats, bar-
riers etc. Most of the commercially available leg prosthesis
technologies are passive ballistic devices, which are easy to
control but make uphill walking and stair ascent challen-
ging. In persons with intact legs, especially the knee joint
requires much higher capability of joint power generation
during ascent than during level walking [3]. Consequently,
users of passive prostheses, including microprocessor-
controlled dissipative knee prostheses, have to use hand
rails and/or perform an asymmetric non-physiological gait
to compensate for the missing power generation in the
knee (see for example [4] among many other studies).
Powered leg prostheses can induce the missing power and
in this way solve these deficiencies; however, the control
of such devices is not trivial when interfacing them with
the users motion intention [5]. Additionally, state-of-the-
art batteries are either too heavy or lack sufficient capacity
to provide power throughout an entire day. The teams at
the Cybathlon will showcase new technologies that might
overcome current deficiencies.
At the Cybathlon, pilots with amputations of the lower
arm or above will use actuated prosthetic hands and arms
to complete various household and food preparation tasks
(Fig. 2). The dexterity and versatility of currently available
prosthetic hand devices is usually limited with respect to
the number of grasps and tasks that can be successfully
performed. Therefore, persons with unilateral amputations
use their intact arm to perform most daily tasks. Bimanual
tasks, which require a high load transfer (e.g., carrying a
heavy box) or particular fine motor skills (e.g., opening a
small jar of jam) are challenging, because they cannot be
solved with most state-of-the-art upper arm prostheses.
Consequently, up to 60 % of people with upper-limb am-
putation fitted for conventional upper-limb prosthetic de-
vice fail to use it regularly or reject it altogether [6, 7]. The
high rejection rate of upper limb prostheses has been
attributed to poor training, late fitting, limited usefulness
especially for the users with more proximal amputations,
and various other factors. Significantly lower rates of re-
jection can be seen for more advanced, i.e. body-powered
(26 %) and electric (23 %) devices [8].
Four out of the six disciplines of the Cybathlon ad-
dress people with limb paralysis of varying degrees after
lesions such as spinal cord injury: Pilots with complete
paraplegia will compete in a bike race, where FES de-
vices assist them in performing pedaling movements.
FES technology has been used for movement restoration
for decades, but has not achieved satisfactory perform-
ance due to limitations in setup-time, movement con-
trollability, muscle force magnitude, muscle selectivity
and fatigue resistance [9, 10]. Most promising stimula-
tion systems are implanted, as they yield better selectiv-
ity and higher force output than non-invasive systems
[9, 11]. However, there are drawbacks with respect to in-
vasiveness, risk of infections and costs. Because of these
deficiencies, current FES technology has not been
Fig. 1 Arena with four parallel race tracks designed for the exoskeleton competition. The pilots start at the left and have to overcome six obstacles
with increasing difficulty level
Riener Journal of NeuroEngineering and Rehabilitation (2016) 13:49 Page 2 of 4
accepted by physicians and patients for daily clinical
routine [12].
In both the powered wheelchair race and the powered
exoskeleton race, pilots with paralysis will master obstacle
courses with ramps, stairs, bends, doors and uneven ter-
rain (Fig. 1). More and more companies offer advanced
and powerful solutions for wheelchairs. However, control
technology does not provide adequate mobility and com-
fort for many electrically powered wheelchair users, espe-
cially under adverse driving conditions [13]. Wheelchair
accessibility in public buildings is still limited despite the
enforcement of existing laws and regulations [14]. Most
outdoor devices are too bulky and not agile enough for in-
door use, whereas commercial indoor wheelchairs are not
capable of overcoming uneven terrain or steps. So called
intelligent or smart wheelchairs have been available for de-
cades, but have not yet been adopted by a large portion of
the population [15, 16]. An alternative to wheelchairs are
exoskeletal devices that assist people with paraplegic le-
sions during gait in the upright position [17, 18]. However,
battery power is limited to a few hours of operation and
the devices are still very bulky and heavy. Most of the
commercially available multi-joint exoskeletons have
weights in the range of 2128 kg, with the device REX
reaching a weight of almost 40 kg [17, 19]. Furthermore,
current commercial systems have a limited number of de-
grees of freedom and reduced ranges of movements pre-
venting the devices from gait on inclined surfaces or
stairs. Thus, exoskeletal devices are not yet a realistic al-
ternative for lightweight, energy efficient, and often fold-
able manual wheelchairs.
In the BCI race, pilots with paralysis of all four limbs
will control a virtual avatar in a racing game displayed
on a computer screen. The best pilots will be able to dis-
tinguish three different commands to overcome three
different kinds of virtual obstacles and, thus, will be
rewarded by a temporal advantage in the game. A wrong
command or a command with too long latency will be
penalized by decelerating the avatar on its track. BCI
technology is becoming more and more popular, how-
ever most systems only function accurately in a lab en-
vironment [20]. The time needed for device setup,
comfort, cosmetic aspects, function and reliability are
still not satisfactory and have prevented broad use and
acceptance outside labs [21].
The Cybathlon will provide a platform that encourages
exchange between people with disabilities or physical
weaknesses, the research and development world, fund-
ing agencies, and the general public. In this way, the
Cybathlon aims to promote the development of useful
technologies that facilitate the daily lives of people with
disabilities or physical weaknesses and provide the basis
for more independence. In the long run, the developed
devices should become affordable and functional for all
relevant activities in daily life.
Cybathlon can also be considered as a complement to
the Olympic or Paralympic games. In contrast to the
Paralympic games, it allows the use of any kind of tech-
nical aids, thus also enabling people with more severe
disabilities to participate in a competition. The goal is
not to be the fastest and the strongest among the partic-
ipants, rather the goal is to be the most skilled pilot who
utilizes advanced technologies in ways that allow the
challenges of everyday life to be overcome with ease.
Fig. 2 Pilot with a powered arm prosthesis performing a daily living task. Picture was taken at the Cybathlon rehearsal in July 2015 by Alessandro
Della Bella, ETH Zurich. The pilot on this image as consented to the publication of this image
Riener Journal of NeuroEngineering and Rehabilitation (2016) 13:49 Page 3 of 4
BCI, Brain-Computer Interface; FES, Functional Electrical Stimulation; US,
United States
Special thanks go to Roland Auberger Verena Klamroth-Maganska, Domen
Novak, Anna Pagel, Serge Pfeifer, Kai Schmidt, Linda Seward, Roland Sigrist,
Peter Wolf, Dario Wyss for their contributions to this manuscript, including
organization of references and proof-reading.
This work is funded by ETH Zurich, Switzerland, and the Swiss National Science
Foundation (SNSF) National Competence Center in Research (NCCR) in Robotics.
Availability of data and materials
Not applicable.
Authors contribution
RR is the inventor, initiator and chief organizer of the Cybathlon. He has
drafted the manuscript.
Competing interests
Cybathlon is a non-profit, charitable event. The author is initiator of the
Cybathlon and member of the organizing board. The author confirms that
there are no further competing interests.
Ethics approval and consent to participate
The individual in Fig. 2 consented to the publication of this image.
Received: 4 April 2016 Accepted: 23 May 2016
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Riener Journal of NeuroEngineering and Rehabilitation (2016) 13:49 Page 4 of 4
... Based on these observations and assumptions, CYBATHLON was founded at ETH Zurich in 2013. CYBATHLON aims at driving user-centered development of assistive technologies for people with disabilities by providing a benchmarking platform in an out-of-laboratory setting (3,4). As such, CYBATHLON organizes international competitions in which people with disabilities (called pilots) compete against each other with the help of their assistive technology in tasks representing their actual daily-life challenges. ...
... The criteria serve to (a) guarantee a level playing field among the participants and (b) ensure that participation is safe for the pilot from a medical and technical perspective. Teams can apply existing, adapted, or completely novel approaches or technologies (prototypes) (3). A detailed description of the medical and technology eligibility criteria is included in the 2021-2024 rule book (5). ...
... In summary, CYBATHLON offers the unique opportunity to encourage user-centered design in a challenging context and to increase the number of studies and scientific contributions in the field of assistive technology, ranging from innovative solutions to the assessment of novel features (3). In the last few years, CYBATHLON has become a key event to promote diversity and social inclusion with a general audience and a showcase to highlight innovative interdisciplinary research and promising future directions. ...
Approximately 1.1. billion people worldwide live with some form of disability, and assistive technology has the potential to increase their overall quality of life. However, the end users' perspective and needs are often not sufficiently considered during the development of this technology, leading to frustration and nonuse of existing devices. Since its first competition in 2016, CYBATHLON has aimed to drive innovation in the field of assistive technology by motivating teams to involve end users more actively in the development process and to tailor novel devices to their actual daily-life needs. Competition tasks therefore represent unsolved daily-life challenges for people with disabilities and serve the purpose of benchmarking the latest developments from research laboratories and companies from around the world. This review describes each of the competition disciplines, their contributions to assistive technology, and remaining challenges in the user-centered development of this technology.
... This work proposes a "quantitative" analysis and review of new trends and current challenges in upper limb prostheses. As a representation of the state-of-the-art, we selected the participants of Cybathlon Powered Arm Prostheses Race [10], an international competition that addresses unresolved challenges encountered in everyday life, with the primary objective of establishing a benchmark for the latest advancements in research laboratories and companies worldwide. There, upper-limb prosthetic technologies must support users to complete 6 tasks based on Activities of Daily Living (ADL). ...
... Although the main metric used for the Cybathlon competition is based on the time to complete the race, we aim to analyze the performance of each team using a standard clinical assessment. Earlier studies on Cybathlon offer valuable perspectives on the influential role of this event in advancing the field of assistive technology and research impact [10,11]. Additionally, regarding the Powered Arm Prostheses Race, the preparatory activities associated with the Cybathlon competition have promoted a human-centered design approach [12,13] and have facilitated an effective test bench for assessing system performance in realworld settings [14]. ...
Full-text available
Although recent technological developments in the field of bionic upper limb prostheses, their rejection rate remains excessively high. The reasons are diverse (e.g. lack of functionality, control complexity, and comfortability) and most of these are reported only through self-rated questionnaires. Indeed, there is no quantitative evaluation of the extent to which a novel prosthetic solution can effectively address users' needs compared to other technologies. This manuscript discusses the challenges and limitations of current upper limb prosthetic devices and evaluates their functionality through a standard functional assessment, the Assessment of Capacity for Myoelectric Control (ACMC). To include a good representation of technologies, the authors collect information from participants in the Cybathlon Powered Arm Prostheses Race 2016 and 2020. The article analyzes 7 hour and 41 min of video footage to evaluate the performance of different prosthetic devices in various tasks inspired by activities of daily living (ADL). The results show that commercially-available rigid hands perform well in dexterous grasping, while body-powered solutions are more reliable and convenient for competitive environments. The article also highlights the importance of wrist design and control modality for successful execution of ADL. Moreover, we discuss the limitations of the evaluation methodology and suggest improvements for future assessments. With regard to future development, this work highlights the need for research in intuitive control of multiple degrees of freedom, adaptive solutions, and the integration of sensory feedback.
... Because the users can access an external viewing angle and their own natural viewpoint, they may be able to move differently. Such sports could use technology in a way that is similar to e-Sports [31] or Cybathlon [32]. ...
Full-text available
Most sports-assisting technologies have been developed to improve performances only in individual sports such as skiing, batting, and swimming. In team sports, it is important to perceive one's position relative to others. Few studies have focused on team sports, which not only require the motor ability of individual players, but also their perceptual abilities. This pilot study aimed to evaluate the effectiveness of a visual feedback system to improve players' spatial perception relative to others. The visual feedback system was composed of a flying drone that transmitted an image to the participant's smart glasses. The participant was able to see his/her own relative position in real time using the glasses with and without the system. Nine participants tried to position themselves on an imaginary line between two experimenters 30 m away from each other, which simulated the situation of a baseball cutoff man. The results showed that the error in distance between the participants' positions and the line decreased significantly when using the system compared to when not using it. Furthermore, there was also a reduction in positioning error in subsequent trials after participants performed the task using the system, compared to before they used the system. In conclusion, the real-time feedback system from a bird's-eye view has the potential to improve accuracy in spatial perception.
... Since the 1990s, many research results on wheelchair-type stair climbing robots have been achieved and a variety of commercial wheelchairs and prototypes have been developed [23]. Many examples of wheelchair-type stairs have been demonstrated at Cybathlon [24]. Cybathlon is a non-profit project of ETH Zurich (Zurich, Germany) who acts as a platform that challenges teams from all over the world to develop assistive technologies suitable for everyday use with and for people with disabilities. ...
Full-text available
Stair climbing is one of the most challenging tasks for vehicles, especially when transporting people and heavy loads. Although many solutions have been proposed and demonstrated in practice, it is necessary to further improve their climbing ability and safety. This paper presents a systematic review of the scientific and engineering stair climbing literature, providing brief descriptions of the mechanism and method of operation and highlighting the advantages and disadvantages of different types of climbing platform. To quantitatively evaluate the system performance, various metrics are presented that consider allowable payload, maximum climbing speed, maximum crossable slope, transport ability and their combinations. Using these metrics, it is possible to compare vehicles with different locomotion modes and properties, allowing researchers and practitioners to gain in-depth knowledge of stair-climbing vehicles and choose the best category for transporting people and heavy loads up a flight of stairs.
... Although invented in the 1980s [8], over the last decade, FES cycling has seen an upsurge in interest, in large part due to international sporting events such as the Cybathlon [9,10] and Lyon Cyberdays [11]. This is reflected in the increase in the number of articles published on the topic of FES cycling since 2016: 101 articles in the year 2022, which is more than double the number of articles published any year prior to the Lyon Cyberdays and the first Cybathlon in 2016. ...
Full-text available
Background: Functional electrical stimulation (FES) cycling has seen an upsurge in interest over the last decade. The present study describes the novel instrumented cycling ergometer platform designed to assess the efficiency of electrical stimulation strategies. The capabilities of the platform are showcased in an example determining the adequate stimulation patterns for reproducing a cycling movement of the paralyzed legs of a spinal cord injury (SCI) subject. Methods: Two procedures have been followed to determine the stimulation patterns: (1) using the EMG recordings of the able-bodied subject; (2) using the recordings of the forces produced by the SCI subject's stimulated muscles. Results: the stimulation pattern derived from the SCI subject's force output was found to produce 14% more power than the EMG-derived stimulation pattern. Conclusions: the cycling platform proved useful for determining and assessing stimulation patterns, and it can be used to further investigate advanced stimulation strategies.
... Subsequently, the robotics community has an increasing interest in scientifically assessing and comparing the performance of exoskeletons by making a standard 9 Currently, the main way to compare exoskeletons is to hold competitions such as Cybathlon 11 . The main disadvantage of competitions is that scores are usually based on very simple indicators, such as task completion or completion time, which are difficult to reflect multiple aspects of exoskeleton power-assisted effectiveness. ...
Full-text available
Wearable robots have been growing exponentially during the past years and it is crucial to quantify the performance effectiveness and to convert them into practical benchmarks. Although there exist some common metrics such as metabolic cost, many other characteristics still needs to be presented and demonstrated. In this study, we developed an integrated evaluation (IE) approach of wearable exoskeletons of lower limb focusing on human performance augmentation. We proposed a novel classification of trial tasks closely related to exoskeleton functions, which were divided into three categories, namely, basic trial at the preliminary phase, semi-reality trial at the intermediate phase, and reality trial at the advanced phase. In the present study, the IE approach has been exercised with a subject who wore an active power-assisted knee (APAK) exoskeleton with three types of trial tasks, including walking on a treadmill at a certain angle, walking up and down on three-step stairs, and ascending in 11-storey stairs. Three wearable conditions were carried out in each trial task, i.e. with unpowered exoskeleton, with powered exoskeleton, and without the exoskeleton. Nine performance indicators (PIs) for evaluating performance effectiveness were adopted basing on three aspects of goal-level, task-based kinematics, and human–robot interactions. Results indicated that compared with other conditions, the powered APAK exoskeleton make generally lesser heart rate (HR), Metabolic equivalent (METs), biceps femoris (BF) and rectus femoris (RF) muscles activation of the subject at the preliminary phase and intermediate phase, however, with minimal performance augmentation at advanced phase, suggesting that the APAK exoskeleton is not suitable for marketing and should be further improved. In the future, continuous iterative optimization for the IE approach may help the robot community to attain a comprehensive benchmarking methodology for robot-assisted locomotion more efficiently.
... Despite body-powered prostheses showing very limited innovations and improvements in the last century, users prefer this solution not only for its low weight and cost but also for its high reliability and control simplicity. The latter aspects were highlighted during the CYBATHLON Powered Arm Prosthetic Race [6], where body-powered prostheses outperformed more sophisticated solutions. ...
Full-text available
Background Among commercially-available upper-limb prostheses, the two most often used solutions are simple hook-style grippers and poly-articulated hands, which present a higher number of articulations and show a closer resemblance to biological limbs. In their majority, the former type of prostheses is body-powered, while the second type is controlled by myoelectric signals. Body-powered grippers are easy to control and allow a simple form of force feedback, frequently appreciated by users. However, they present limited versatility. Poly-articulated hands afford a wide range of grasp and manipulation types, but require enough residual muscle activation for dexterous control. Several factors, e.g. level of limb loss, personal preferences, cost, current occupation, and hobbies can influence the preference for one option over the other, and is always a result of the trade-off between system performance and users’ needs. Methods The SoftHand Pro (SHP) is an artificial hand platform that has 19 independent joints (degrees-of-freedom), but is controlled by a single input. The design of this prosthesis is inspired by the concept of postural synergies in motor control and implemented with soft-robotic technologies. Their combination provides increased robustness, safe interaction and the execution of diverse grasps. The potential of the SHP is fully unleashed when users learn how to exploit its features and create an intimate relationship between the technical aspects of the prosthesis design and its control by the user. Results The great versatility of the SoftHand Pro (a reasearch protpotype) permitted its adaptation to the user requirements. This was experienced by the SoftHand Pro Team during the preparation for different CYBATHLON events (from 2016 to 2020). The mixed power and dexterous hand operations required by each task of the race is inspired by everyday tasks. Our prosthesis was driven by different pilots, with different habits and backgrounds. Consequently, the hand control modality was customized according to the user’s preferences. Furthermore, the CYBATHLON tasks had some variations in this period, promoting the continuous development of our technology with a user-centered approach. In this paper, we describe the participation and preparation of the SoftHand Pro Team from 2016 to 2020 with three pilots and two different activation modalities, hybrid body-controlled and myoelectric control. Conclusions We introduced our pilots, the implementation of the two control modalities, and describe the successful participation in all CYBATHLON events. This work proves the versatility of the system towards the user’s preferences and the changes in the race requirements. Finally, we discussed how the CYBATHLON experience and the training in the real-world scenario have driven the evolution of our system and gave us remarkable insights for future perspectives.
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Brain-Computer Interfaces (BCI) is an exciting and emerging research area for researchers and scientists. It is a suitable combination of software and hardware to operate any device mentally. This review emphasizes the significant stages in the BCI domain, current problems, and state-of-the-art findings. This article also covers how current results can contribute to new knowledge about BCI, an overview of BCI from its early developments to recent advancements, BCI applications, challenges, and future directions. The authors pointed to unresolved issues and expressed how BCI is valuable for analyzing the human brain. Humans' dependence on machines has led humankind into a new future where BCI can play an essential role in improving this modern world.
The performances of sprinters and long jumpers with below the knee amputation (BKA) have improved continuously since the development of prostheses specifically for athletic movements. In the last years, a number of athletes with BKA have attempted to compete in non-amputee competitions. Due to the specific shape and material properties of the running-specific prosthesis (RSP), concerns exist that it may give athletes an advantage over non-amputee athletes. In this work, we investigate and compare sprinting and long jump movements of athletes with and without unilateral BKA using accurate computer models. In this context, the aim of the work is to describe similarities and differences between the athletes’ movements and to show that the employed model- and optimization-based computations are useful for this purpose. We created subject-specific multi-body models for five different athletes (four non-amputee athletes, one athlete with unilateral BKA) in order to be able to investigate the different movements. Depending on the research question, the models vary in the number of degrees of freedom (DOFs), from 16 DOFs for a two-dimensional model in the sagittal plane to 31 DOFs for a three-dimensional model. For the athlete with BKA, we created a three-segment model of the RSP with one rotational DOF in the sagittal plane. The respective motion is described by a sequence of several phases, which differ by the type of ground contact. Each of these phases is described by its own set of ordinary differential equations (ODEs) or differential algebraic equations (DAEs). We use multi-phase optimal control problems (OCPs) with discontinuities to generate sprint and long jump motions. Three different formulations of OCPs are adopted in this work. (1) We formulate a least squares OCP to reconstruct the dynamics of sprint and long jump motion capture recordings of the individual athletes. (2) For the generation of realistic motions, which can be used for prediction, we formulate a synthesis OCP; this optimizes an objective function consisting of a weighted combination of chosen optimization criteria. (3) Last, in the study of sprint movements, we use an inverse optimal control problem (IOCP): this consists of an inner loop, in which a synthesis OCP is solved, and an outer loop, which adjusts the weights of the individual optimization criteria such that the distance between the inner loop solution and a reference movement becomes minimal. We have successfully applied these three optimization problem formulations to the computation of two sprint steps of three athletes without and one athlete with unilateral transtibial amputation. Here, the movements of the non-amputee athletes differ from that of the amputee athlete in a large number of variables. In particular, the athletes use different actuation strategies for running with and without a RSP. We have observed lower torques in the amputee athlete in the leg affected by the amputation than in the non-amputee control group. In contrast, significantly larger torques occurred in the joints of the upper extremity in the amputee athlete. Furthermore, the comparison has shown that the asymmetry created by the RSP is reflected throughout the body and affects the entire movement. Using the OCPs for motion reconstruction (1) and synthesis (2), we have successfully computed the last three steps of the approach and the jump of a long jump for an athlete without and an athlete with unilateral amputation. In the reconstructed solutions, the amputee athlete achieves a greater jump distance compared to the non-amputee athlete, despite a slower approach velocity, because his take-off is more efficient. In the synthesis solutions, on the other hand, the non-amputee athlete achieves the greater jump distance because he generates a greater vertical force during the take-off and achieves a better ratio of gain of vertical to loss of horizontal velocity. Finally, we have presented our idea of a simulator tool to compare the amputee athlete with himself without amputation and have demonstrated it using the sprint and long jump movements. For this purpose, we have kept the model of the athlete with unilateral transtibial amputation from the previous studies and have created a non-amputee version of the same model by mirroring the biological leg. We have selected one objective function each for sprinting and for long jump and have solved the OCP for motion synthesis (2) for both model versions. Using the differences to the solutions based on the models of two real athletes, we have highlighted the importance of the simulator tool in the evaluation of advantages and disadvantages due to the use of the RSP.
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Rehabilitation professionals have little information concerning lower limb exoskeletons for people with paraplegia. This study has four objectives: (1) Outline the characteristics of the exoskeletons' design and their usefulness evidence as assistive mobility devices in the community for the Rewalk™, Mina, Indego®, Ekso™ (previously known as the eLEGS™) and Rex®; (2) document functional mobility outcomes of using these exoskeletons; (3) document secondary skills and benefits achieved with these exoskeletons, safety, user satisfaction and applicability in the community; and (4) establish level of scientific evidence of the selected studies. A systematic review of the literature (January 2004 to April 2014) was done using the databases PubMed, CINAHL and Embase and groups of keywords associated with "exoskeleton", "lower limb" and "paraplegia". Seven articles were selected. Exoskeleton use is effective for walking in a laboratory but there are no training protocols to modify identified outcomes over the term usage (ReWalk™: 3 months, Mina: 2 months and Indego®: 1 session). Levels of evidence of selected papers are low. The applicability and effectiveness of lower limb exoskeletons as assistive devices in the community have not been demonstrated. More research is needed on walking performance with these exoskeletons compared to other mobility devices and other training contexts in the community. Implications for rehabilitation Characteristics of the exoskeletons' design and their usefulness evidence as assistive mobility devices in the community are addressed for the Rewalk™, Mina, Indego®, Ekso™ and Rex® ReWalk™, Indego® and Mina lower limb exoskeletons are effective for walking in a laboratory for individuals with complete lower-level SCI. The ReWalk™ has the best results for walking, with a maximum speed of 0.51 m/s after 45 sessions lasting 60 to 120 min; it is comparable to the average speed per day or per week in a manual wheelchair. The level of scientific evidence is low. Other studies are needed to provide more information about performance over the longer term when walking with an exoskeleton, compared to wheelchair mobility, the user's usual locomotion, the use of different exoskeletons or the training context in which the exoskeleton is used.
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Modern wearable robots are not yet intelligent enough to fully satisfy the demands of end-users, as they lack the sensor fusion algorithms needed to provide optimal assistance and react quickly to perturbations or changes in user intentions. Sensor fusion applications such as intention detection have been emphasized as a major challenge for both robotic orthoses and prostheses. In order to better examine the strengths and shortcomings of the field, this paper presents a review of existing sensor fusion methods for wearable robots, both stationary ones such as rehabilitation exoskeletons and portable ones such as active prostheses and full-body exoskeletons. Fusion methods are first presented as applied to individual sensing modalities (primarily electromyography, electroencephalography and mechanical sensors), and then four approaches to combining multiple modalities are presented. The strengths and weaknesses of the different methods are compared, and recommendations are made for future sensor fusion research.
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Different approaches are available to compensate gait in persons with spinal cord injury, including passive orthoses, functional electrical stimulation (FES), and robotic exoskeletons. However, several drawbacks arise from each specific approach. Orthotic gait is energy-demanding for the user and functionally ineffective. FES uses the muscles as natural actuators to generate gait, providing not only functional but also psychological benefits to the users. However, disadvantages are also related to the early appearance of muscle fatigue and the control of joint trajectories. Robotic exoskeletons that provide joint moment compensation or substitution to the body during walking have been developed in recent years. Significant advances have been achieved, but the technology itself is not mature yet because of many limitations related to both physical and cognitive interaction as well as portability and energy-management issues. Meanwhile, the combination of FES technology and exoskeletons has emerged as a promising approach to both gait compensation and rehabilitation, bringing together technologies, methods, and rehabilitation principles that can overcome the drawbacks of each individual approach. This article presents an overview of hybrid lower-limb exoskeletons, related technologies, and advances in actuation and control systems. Also, we highlight the functional assessment of individuals with spinal cord injury.
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A brain-computer interface (BCI) is a hardware and software communications system that permits cerebral activity alone to control computers or external devices. The immediate goal of BCI research is to provide communications capabilities to severely disabled people who are totally paralyzed or 'locked in' by neurological neuromuscular disorders, such as amyotrophic lateral sclerosis, brain stem stroke, or spinal cord injury. Here, we review the state-of-the-art of BCIs, looking at the different steps that form a standard BCI: signal acquisition, preprocessing or signal enhancement, feature extraction, classification and the control interface. We discuss their advantages, drawbacks, and latest advances, and we survey the numerous technologies reported in the scientific literature to design each step of a BCI. First, the review examines the neuroimaging modalities used in the signal acquisition step, each of which monitors a different functional brain activity such as electrical, magnetic or metabolic activity. Second, the review discusses different electrophysiological control signals that determine user intentions, which can be detected in brain activity. Third, the review includes some techniques used in the signal enhancement step to deal with the artifacts in the control signals and improve the performance. Fourth, the review studies some mathematic algorithms used in the feature extraction and classification steps which translate the information in the control signals into commands that operate a computer or other device. Finally, the review provides an overview of various BCI applications that control a range of devices.
The rapid advancement of robotics technology in recent years has pushed the development of a distinctive field of robotic applications, namely robotic exoskeletons. Because of the aging population, more people are suffering from neurological disorders such as stroke, central nervous system disorder, and spinal cord injury. As manual therapy seems to be physically demanding for both the patient and therapist, robotic exoskeletons have been developed to increase the efficiency of rehabilitation therapy. Robotic exoskeletons are capable of providing more intensive patient training, better quantitative feedback, and improved functional outcomes for patients compared to manual therapy. This review emphasizes treadmill-based and over-ground exoskeletons for rehabilitation. Analyses of their mechanical designs, actuation systems, and integrated control strategies are given priority because the interactions between these components are crucial for the optimal performance of the rehabilitation robot. The review also discusses the limitations of current exoskeletons and technical challenges faced in exoskeleton development. A general perspective of the future development of more effective robot exoskeletons, specifically real-time biological synergy-based exoskeletons, could help promote brain plasticity among neurologically impaired patients and allow them to regain normal walking ability.
Brain-computer interfaces (BCIs) acquire brain signals, analyze them, and translate them into commands that are relayed to output devices that carry out desired actions. BCIs do not use normal neuromuscular output pathways. The main goal of BCI is to replace or restore useful function to people disabled by neuromuscular disorders such as amyotrophic lateral sclerosis, cerebral palsy, stroke, or spinal cord injury. From initial demonstrations of electroencephalography-based spelling and single-neuron-based device control, researchers have gone on to use electroencephalographic, intracortical, electrocorticographic, and other brain signals for increasingly complex control of cursors, robotic arms, prostheses, wheelchairs, and other devices. Brain-computer interfaces may also prove useful for rehabilitation after stroke and for other disorders. In the future, they might augment the performance of surgeons or other medical professionals. Brain-computer interface technology is the focus of a rapidly growing research and development enterprise that is greatly exciting scientists, engineers, clinicians, and the public in general. Its future achievements will depend on advances in 3 crucial areas. Brain-computer interfaces need signal-acquisition hardware that is convenient, portable, safe, and able to function in all environments. Brain-computer interface systems need to be validated in long-term studies of real-world use by people with severe disabilities, and effective and viable models for their widespread dissemination must be implemented. Finally, the day-to-day and moment-to-moment reliability of BCI performance must be improved so that it approaches the reliability of natural muscle-based function.
The aim of prosthetic devices is to mimic the function of biological systems. Numerous investigations have demonstrated significant asymmetries in unilateral amputee gait. The underlying interactions of prosthetic and intact leg are not widely discussed, so far. To get more insight into the functionality of asymmetries, we investigated temporal and kinetic parameters of walking transfemoral amputees wearing the computerized C-Leg and the non-computerized 3R80. Experiments were conducted on an instrumented treadmill at four different walking speeds (0.5, 0.8, 1.1, 1.4m/s) measuring vertical and horizontal ground reaction forces. Single support, double support and contact times, vertical and horizontal impulses as well as their asymmetry factors were calculated. Gait patterns were similar for both prosthetic knee joints, manifesting in (i) reduced stance times of the prosthetic leg, (ii) prolonged load transfer during double support from intact to prosthetic leg at lower speeds, (iii) reduced vertical and horizontal impulses of the prosthetic leg, (iv) net accelerating horizontal impulses during contact of the prosthetic leg, (v) missing impacts at touch-down of the prosthetic leg. Our results suggest that deficits of the prosthetic leg like missing active knee extension and ankle push-off are compensated by the intact leg. The altered touch-down configuration for the prosthetic leg enables it to provide forward propulsion while load bearing is largely shifted to the intact leg.
The purpose of this review was to examine the wheelchair accessibility in public buildings and discuss the role of professional in this practice area. Of the 85 originally identified publications from a search of major electronic bibliographic databases, 12 studies relating to wheelchair accessibility in public buildings were selected. The compliance rates with wheelchair accessibility in different areas were summarised. No study reported 100% wheelchair accessibility despite the enforcement of existing laws and regulations. Parking had the lowest compliance rate among all facilities in terms of accessibility, while entrances had the highest. A global review is needed of both new and old buildings regarding wheelchair accessibility. Professional in this practice area has an important role to play in advocating wheelchair accessibility and assisting wheelchair users to participate fully in all areas of the community.
Patterns of use of contemporary prostheses by 135 patients with major upper extremity amputations were evaluated by questionnaire. Eighty-four percent of the patients were male and 16% were female. Amputation levels represented were below elbow, 44%; above elbow, 40%; and shoulder disarticulations or forequarter amputations, 16%. The follow-up interval averaged 12 years (range, 1-67 years). One hundred and thirteen patients were fitted with either a myoelectric or body-powered prosthesis. The overall rejection rate was 38%. Thirty-nine of 42 in the below-elbow amputation group used the prosthesis and appeared to benefit the most. Eight of 141 in the wrist disarticulation group used the prosthesis: as did 9 of 21 in the above-elbow amputation group. In contrast, all bilateral amputees used their prostheses. Stiff shoulders and brachial plexus injury were both predictors for poor prosthetic usage.