Design and evaluation of the gait rehabilitation robot LOPES

The goal of the work presented in this thesis was to realize a robotic device that is able provide suitable gait training to stroke patients.\ud It is believed that motor training in general, but specifically for stroke patients should be intensive and task-specific in order to reach optimal outcome. Meanwhile, the training of severe stroke patients has proven to be physically very demanding to therapists. For this reason it is believed that robotic aids can be useful alternative for physical therapists to provide gait training. In this research we supposed a training setting in which a therapist is in control of the training, while the robot carries out the physical labor in guiding, assisting and correcting the patient

Centroidal Momentum Analysis for Defining a Stability Index for Human-Exoskeleton Interactive Walking : Perturbation Detection in Human Gait

Recently, exoskeletons have been in the spotlight as many studies demonstrated the effectiveness of the exoskeletons as a means that enables to not only resolve long-standing issues such as increase of societal burden for the care of ageing populations but also augments productivity in several fields, such as rehabilitation and industrial fields. In particular, lower limb exoskeletons have attracted the medical field, especially related to the ageing society due to its impact on augmentation and recovery of walking capability which is one of the core determinants of independent daily living. For practical use of the lower limb exoskeletons in real environments, however, there are still several issues to be resolved. One of them is how to manage balance of human walking supported by the exoskeleton, in other words, how to monitor walking stability of a system combined with human and exoskeleton and maintain (or recover) the system balance when the user meets unpredicted disturbances, and thus to avoid falls. The former is a rationale of the study and this paper deals with a ‘stability index’, referred to as a kind of measure to monitor the actual (in)stability state during walking. The proposed stability index is based on the Centroidal Momentum (CM) that consists of linear and angular momenta at the Center of Mass (CoM). CM is a fundamental parameter used to describe physical motion of a system in classical mechanics, and it has been studied widely in biomechanics and bipedal robot fields over the last decade as it, specifically angular momentum-based analysis, offers important clues on how humans maintain balance during walking as well as facilitates postural balance control of humanoid robots in standing. As an extension of this context, in our previous work, we analyzed CM behavior during human walking under perturbations, specifically lateral perturbations applied to the pelvis. As a continuation of the study, in this paper, we examine whether CM could be used as the stability index to detect the perturbations as well as an initial loss of balance. In other words, a perturbation detection method on the basis of calculation of CM while waking is presented. In the method, variation of CM patterns between unperturbed and perturbed walking plays a crucial role in detecting perturbations. The method has been evaluated with experimental data of human walking and results show that the method is capable of detecting moderate and strong perturbations determined by combination of diverse durations and magnitudes of disturbance force. Average detection time obtained was about 334 msec. This study was carried out in the context of the EU FP7 project BALANCE that aims at supporting the function of maintaining postural balance directly through a leg exoskeleton. For this purpose CM-based stability index to be developed and related findings will be extended to the exoskeleton cooperating with a human and assessed on performance inEuropean Commission FP

Design and Evaluation of the LOPES Exoskeleton Robot for Interactive Gait Rehabilitation

This paper introduces a newly developed gait rehabilitation device. The device, called LOPES, combines a freely translatable and 2-D-actuated pelvis segment with a leg exoskeleton containing three actuated rotational joints: two at the hip and one at the knee. The joints are impedance controlled to allow bidirectional mechanical interaction between the robot and the training subject. Evaluation measurements show that the device allows both a "pa- tient-in-charge" and "robot-in-charge" mode, in which the robot is controlled either to follow or to guide a patient, respectively. Electromyography (EMG) measurements (one subject) on eight important leg muscles, show that free walking in the device strongly resembles free treadmill walking; an indication that the device can offer task-specific gait training. The possibilities and limitations to using the device as gait measurement tool are also shown at the moment position measurements are not accurate enough for inverse-dynamical gait analysis

Benchmarking Bipedal Locomotion: A Unified Scheme for Humanoids, Wearable Robots, and Humans

In the field of robotics, there is a growing awareness of the importance of benchmarking [1], [2]. Benchmarking not only allows the assessment and comparison of the performance of different technologies but also defines and supports the standardization and regulation processes during their introduction to the market. Its importance has been recently emphasized by the adoption of the technology readiness levels (TRLs) in the Horizon 2020 information and communication technologies by the European Union as an important guideline to assess when a technology can shift from one TRL to the other. The objective of this article is to define the basis of a benchmarking scheme for the assessment of bipedal locomotion that could be applied and shared across different research communities.European Commission Seventh Framework Program, and COS

Stimulation Discomfort Comparison of Asynchronous and Synchronous Methods with Multi-Field Surface Electrodes

Functional Electrical Stimulation (FES) is a technique that artificially stimulates motor nerves in order to restore motor/sensory functions for assistive and therapeutic applications. Recently, multi-field surface electrodes for transcutaneous electrical stimulation have been suggested to overcome problems of single channel surface stimulation. This study compares sensation perceived by 15 healthy subjects on upper limb when two different stimulation methods are applied by means of multi-field electrodes. Asynchronous and synchronous stimulation methods are compared for four different cases: activation of two neighbor fields, three neighbor fields, two distant fields and three distant fields. Two descriptors rated from 1 to 5 are used to describe discomfort: superficial discomfort and deep discomfort. Results expressed no differences in superficial discomfort for any case, but showed significant differences in deep discomfort for distant field activations. In these cases, synchronous stimulation resulted in higher perceived deep discomfort than asynchronous stimulation and affected its efficacy

Re-defining wearable robots: a multidisciplinary approach towards a unified terminology

Effective communication is especially important in the wearable robots (WRs) community, which encloses a great variety of devices across different application domains, e.g., healthcare, occupational, and consumer. In this paper we present a vocabulary of terms with the aim to create a common understanding of terms and concepts among the different fields of expertise relevant in the WRs community. Our goal is to develop shared documentation that could serve as a reference to facilitate the use of accepted definitions in the field. The presented vocabulary is the result of different focus group discussions among experts in the field. The resulting document was then validated by presenting it to the WR community through an online survey. The results of the survey highlight a strong agreement in terms of acceptance of the vocabulary, its usefulness, and applicability of the proposed definitions as well as an overall appreciation for its purpose and target. This work represents a pilot study providing unique material for the WR community, encouraging the use of shared agreed definitions. The reported version of the vocabulary has been made available as a live document in a github repository, for public commenting and further improvements

Clinical validation of a novel postural support device for hospitalized sub-acute post stroke wheelchair users

Purpose: We present a novel wheelchair posture support device (WPSD) and its clinical validation. The device was developed in order to assure correct sitting posture and to reduce the time spent by caregivers for re-positioning of hospitalized, wheelchair-bound, post-acute stroke patients. Method: The device was validated with 16 subjects during a period of 5 days in which use of the device was compared with regular care practice. Results: The device was used for the five consecutive days in 69% of patients, while for 6% it was not suitable; 25% did not complete the 5 days for reasons unrelated to the device. Caregivers needed to re-position the patients that used the device for the full 5 days (n=11) on an average 52% less often when using the device, as compared to regular practice. Furthermore, the device was rated as usable and functional by the caregivers while significantly reducing perception of trunk and shoulder pain in patients during its use. Conclusions: The newly designed WPSD is a valuable system for the improvement of medical assistance to wheelchair-bound post-stroke patients by reducing pain and number of re-positioning manoeuvres. The WPSD might be applicable to any group of patients who need posture control in either wheelchair or common chair with arms support.The FIK initiative; funding the development of the Varstiff material technology. Fundaci on Bot ın’s ‘‘Mind the Gap’’ program co-funding the design process of the WPSD. Spherium Biomed co-funding the study with the WPSD

Relevance of hazards in exoskeleton applications:a survey-based enquiry

Exoskeletons are becoming the reference technology for assistance and augmentation of human motor functions in a wide range of application domains. Unfortunately, the exponential growth of this sector has not been accompanied by a rigorous risk assessment (RA) process, which is necessary to identify the major aspects concerning the safety and impact of this new technology on humans. This situation may seriously hamper the market uptake of new products. This paper presents the results of a survey that was circulated to understand how hazards are considered by exoskeleton users, from research and industry perspectives. Our analysis aimed to identify the perceived occurrence and the impact of a sample of generic hazards, as well as to collect suggestions and general opinions from the respondents that can serve as a reference for more targeted RA. Our results identified a list of relevant hazards for exoskeletons. Among them, misalignments and unintended device motion were perceived as key aspects for exoskeletons’ safety. This survey aims to represent a first attempt in recording overall feedback from the community and contribute to future RAs and the identification of better mitigation strategies in the field.</p

Relevance of hazards in exoskeleton applications: a survey-based enquiry

Exoskeletons are becoming the reference technology for assistance and augmentation of human motor functions in a wide range of application domains. Unfortunately, the exponential growth of this sector has not been accompanied by a rigorous risk assessment (RA) process, which is necessary to identify the major aspects concerning the safety and impact of this new technology on humans. This situation may seriously hamper the market uptake of new products. This paper presents the results of a survey that was circulated to understand how hazards are considered by exoskeleton users, from research and industry perspectives. Our analysis aimed to identify the perceived occurrence and the impact of a sample of generic hazards, as well as to collect suggestions and general opinions from the respondents that can serve as a reference for more targeted RA. Our results identified a list of relevant hazards for exoskeletons. Among them, misalignments and unintended device motion were perceived as key aspects for exoskeletons' safety. This survey aims to represent a first attempt in recording overall feedback from the community and contribute to future RAs and the identification of better mitigation strategies in the field