Use Of Exoskeletons Research Articles

Lower Limb Exoskeleton - Energy Optimization of Bipedal Walking With Energy Recycling - Modeling and Simulation

Humans tend to use more energy to walk compared to other limb-based locomotion animals. This higher energy usage is due to “heel strikes” and “negative work” during human gait. Passive walkers elevate this phenomenon by utilizing elastic joints that absorb/reuse some of the negative work. The objective of this study is to absorb energy at one phase of the gait cycle, store it, and then release it at a later phase through the use of a lower limb exoskeleton. Knee geometry is one important factor in energy efficiency during gait. Animals with reversed knees compared to humans (backward knee), such as ostriches, exhibit improved energy efficiency. As part of this study, new energy optimization strategies were developed utilizing collision-based ground reaction forces and a discrete lagrangian. The minimal cost of transport (CoT) gait patterns were calculated with both forward-knee and backward-knee human-exoskeleton models. Simulation results show that wearing a backward-knee exoskeleton can reduce the CoT by 15% of while carrying external loads ranging from 20 to 60 kg. In addition, when the exoskeleton utilized energy recycling, the CoT was shown to be further reduced to 35%. These simulation results suggested that the optimal design for an exoskeleton aimed at utilizing energy recycling principles should incorporate backward-knee configurations much like those found in energy-efficient biped/quadruped animals.

Evaluation of a Passive Upper Limb Exoskeleton in Healthcare Workers during a Surgical Instrument Cleaning Task.

(1) Background: Healthcare workers are highly affected by work-related musculoskeletal disorders, particularly in the lower back, neck and shoulders, as their occupational tasks expose them to biomechanical constraints. One solution to prevent these musculoskeletal disorders may be the use of a passive exoskeleton as it aims to reduce muscle solicitation. However, few studies have been carried out directly in this field to assess the impact of the use of a passive upper limb exoskeleton on this population. (2) Methods: Seven healthcare workers, equipped with electromyographic sensors, performed a tool cleaning task with and without a passive upper limb exoskeleton (Hapo MS, Ergosanté Technologie, France). Six muscles of the upper limbs were analysed, i.e., anterior deltoid, biceps brachii, pectoralis major, latissimus dorsi, triceps brachii and longissimus thoracis. A subjective analysis of the usability of the equipment, the perception of effort and discomfort, was also carried out using the System Usability Scale and the Borg scale. (3) Results: The longissimus thoracis was the most used muscle during this task. We observed a significant decrease in the muscular solicitation of the anterior deltoid and latissimus dorsi when wearing the exoskeleton. Other muscles were not significantly impacted by the device. (4) Conclusions: the passive exoskeleton used in this study allowed the reduction in muscular load on the anterior deltoid and latissimus dorsi without negative effects on other muscles. Other field studies with exoskeletons are now necessary, particularly in hospitals, to increase our knowledge and improve the acceptability of this system for the prevention of musculoskeletal disorders.

Evaluation of the FLEXotendon glove-III through a human subject case study.

Cervical spinal cord injury (SCI) can significantly impair an individual's hand functionality due to the disruption of nerve signals from the brain to the upper extremity. Robotic assistive hand exoskeletons have been proposed as a potential technology to facilitate improved patient rehabilitation outcomes, but few exoskeleton studies utilize standardized hand function tests and questionnaires to produce quantitative data regarding exoskeleton performance. This work presents the human subject case study evaluation of the FLEXotendon Glove-III, a 5 degree-of-freedom voice-controlled, tendon-driven soft robotic assistive hand exoskeleton for individuals with SCI. The exoskeleton system was evaluated in a case study with two individuals with SCI through two standardized hand function tests namely, the Jebsen-Taylor Hand Function Test and the Toronto Rehabilitation Institute Hand Function Test and three questionnaires (Capabilities of Upper Extremities Questionnaire, Orthotics Prosthetics Users Survey, Quebec User Evaluation of Satisfaction with Assistive Technology). Minor design changes were made to the exoskeleton: integrated fingertip force sensors to sense excessive grasp force, a quick connect system to expedite the exoskeleton glove swapping process between users, compact tendon tension sensors to measure tendon force for admittance control, and a redesigned smartphone app to encompass all aspects of exoskeleton use.

Passive exoskeletons alter low back load transfer mechanism

Previous studies that tested passive back-support exoskeletons focused only on active low-back tissue. Therefore, this study examines the effect from a passive back-support exoskeleton by investigating changes in the load transfer mechanism between active and passive tissue in the low back. Twelve healthy male participants performed a full range of trunk flexion–extension movements under three conditions—FREE (no exoskeleton), the backX, or the CoreBot exoskeleton—while holding 0 kg, 4 kg, and 8 kg loads. Body kinematics and electromyography were recorded. Results showed that the average muscle activity of the lumbar erector spinae (LES) was significantly reduced while wearing the exoskeletons, with a 5.9%MVC reduction with the backX and a 3.3%MVC reduction with the CoreBot. Earlier occurrence of the flexion-relaxation phenomenon induced by the trunk extension moment of exoskeletons played an important role in reducing LES muscle activity because the LES returned to a relaxed state earlier (EMG-Off: a 3.1° reduction with the backX, and a 1.8° reduction with the CoreBot; EMG-On: a 2.3° reduction with the backX, and a 1.4° reduction with the CoreBot). In addition, the maximum lumbar flexion angle (a 2.2° reduction with the backX and a 1.5° reduction with the CoreBot) showed significant decreases compared to the FREE condition, indicating that exoskeleton use can prevent low-back passive tissue from being fully activated. These results suggested the overall effects of passive back-support exoskeletons in reducing loads on both active and passive tissue in the low back.

Effects of back-support exoskeletons with different functional mechanisms on trunk muscle activity and kinematics.

Musculoskeletal disorders constitute the leading work-related health issue. Mechanical loading of the lower back contributes as a major risk factor and is prevalent in many tasks performed in logistics. The study aimed to compare acute effects of exoskeletons with different functional mechanisms in a logistic task. Twelve young, healthy individuals participated in the study. Five exoskeletons with different functional mechanisms were tested in a logistic task, consisting of lifting, carrying, and lowering a 13kg box. By using electromyography (EMG), mean muscle activities of four muscles in the trunk were analyzed. Additionally, kinematics by task completion time and range of motion (RoM) of the major joints and segments were investigated. A main effect was found for Musculus erector spinae, Musculus multifidus, and Musculus latissimus dorsi showing differences in muscle activity reductions between exoskeletons. Reduction in ES mean activity compared to baseline was primarily during lifting from ground level. The exoskeletons SoftExo Lift and Cray X also showed ES mean reduction during lowering the box. Prolonged task duration during the lifting phase was found for the exoskeletons BionicBack, SoftExo Lift, and Japet.W. Japet.W showed a trend in reducing hip RoM during that phase. SoftExo Lift caused a reduction in trunk flexion during the lifting phase. A stronger trunk inclination was only found during lifting from the table for the SoftExo Lift and the Cray X. In conclusion, muscle activity reductions by exoskeleton use should not be assessed without taking their designed force paths into account to correctly interpret the effects for long-term injury prevention.

Engineering design strategies for force augmentation exoskeletons: A general review

In the industrial and military sector, work activities are required transporting or supporting heavy loads manually, affecting this the human spinal column due to the weight of the loads or the repetition of this labor. In this regard, the use of force-enhancing exoskeletons is a potential solution to this issue. Therefore, this article summarizes the state of the art in relevant contributions to structural design, control systems, actuators, and performance metrics to evaluate the proper functioning of exoskeletons used for load support and transfer. This is essential to address current and new open problems in these applications, and this includes reducing the metabolic cost and enhancing the loading force in exoskeletons, in which challenges such as structural design and kinetic interactions between the human and the robot are presented. The systematic review of the strategies found in the literature helps addressing these challenges in an orderly way. The proposal of some alternative solutions could help to solving some of the challenges mentioned above, as well as further research to improve the design of these devices is necessary.

A framework for the systematic selection of occupational exoskeletons

The use of occupational exoskeletons (OE) promises improved ergonomics, empowerment of users and prevention of musculoskeletal disorders. However, selecting an OE for a specific application is difficult, the process is complex and a holistic approach that will guide decision-makers in companies is missing. The goal of this paper is to describe a framework that will assist the selection of an OE for a given use case. Based on a systematic literature review existing implementation plans for OE are identified and 99 relevant criteria collected. As the criteria are described in different level of abstractions, a categorisation is proposed, that include human and task-centred dimensions (Task & Workplace, User, Human-Machine-Interface) as well as macro-economic dimensions based on the PEST framework (Political, Economic, Socio-cultural, Technological). The derived framework with its criteria and dimension can be implemented in existing selection processes and provides a key step for increasing the market penetration of OE.

EXOSKELETONS - ROBOTIC SUITS IMPROVING WORK IN LOGISTICS

Logistics, in the future, will be a decisive factor in the competitive struggle between organizations, economic regions and countries for value creation. The level of competence in logistics primarily determines success in this struggle. For modern companies, supply, production and distribution issues are becoming more and more relevant. It is possible to improve this process by strengthening logistic integration and coordinated interaction with external partners and between different departments within the company. Today, with the high development of technologies, it has become possible to automate not only production processes but also the movements of a person who, for one reason or another, cannot perform usual functions, in particular, to restore or replace partially or completely human limbs. This article deals with the issue of reducing logistics workers' workload. We are talking about the development of a robotic platform, namely exoskeletons, which are designed to supplement lost functions, increase human muscle strength and expand their physical capabilities, which will significantly increase the degree of worker efficiency. This article aims to optimize and facilitate workers' work by explaining the use of exoskeletons in supply and distribution logistics.

Field study on the use and acceptance of an arm support exoskeleton in plastering

Exoskeleton use in day-to-day plastering may face several challenges. Not all plasterer’s tasks comprise of movements that will be supported by the exoskeleton and might even be hindered. Furthermore, use in practice might be jeopardised by time pressure, colleagues being negative, discomfort, or any other hindrance of the exoskeleton. We set up a field study, in which 39 plasterers were equipped with an exoskeleton for six weeks, to study exoskeleton usage. Moreover, we studied workload and fatigue, behaviour, productivity and quality, advantages and disadvantages, and acceptance. Exoskeleton use was dependent on the task performed but did not change over the course of the six weeks. For three tasks, higher exoskeleton use was associated with lower perceived loads, although differences were small. Advantages outweighed disadvantages for the majority of our population. This study shows that a majority of plasterers will wear the exoskeleton and is enthusiastic about the load reducing effect. Practitioner summary: For exoskeletons to make an impact on the health and well-being of workers, they need to be applicable in real work situations and accepted by the users. This study shows that 65% of the plasterers in this study want to use the exoskeleton in the future, for specific tasks.

Fractional proportional derivative-based active disturbance rejection control of knee exoskeleton device for rehabilitation care

The use of rehabilitation exoskeleton by physiotherapists in their daily practice is becoming more common. In this study, the active disturbance rejection controller (ADRC) is proposed to ensure high performance of trajectory tracking for asstitve exoskeleton at the level of knee-joint. The controlled medical robot has to mimic the actual physical training and application for knee-rehabilitation. Two versions of ADRC is presented to control the rehabilitation system. One version is based on conventional ADRC, while the other version is based on fractional proportional-derivative PD-ADRC. A comparison study in performance has been conducted between two versions of ADRCs in terms of robustness against disturbances. According to numerical simulations, the results showed that the fractional PD-based ADRC ouptperforms the ADRC in terms of robustness characteritics based on the index root mean square error (RMSE).

Design procedure for orthogonal steel exoskeleton structures for seismic strengthening

The steel exoskeleton systems are widespread structures applied on the external perimeter of an existing building designed to absorb the horizontal actions providing at the same time useful support for energy efficiency upgrading and architectural restyling. The growing interest in the use of exoskeletons is due to the possibility of creating an integrated retrofit (structural, energetic, formal and functional), combining “structural safety” with the concepts of “deep renovation”. Among many solutions present in the literature, in the present work, the steel exoskeletons placed orthogonally to the facade of the existing building have been analysed; this structural typology has the advantage to allow rapid retrofit execution without interfering with the activities carried out within the existing structure. In this framework, the aim of the present work is the introduction of a detailed step-by-step design procedure for steel exoskeletons systems adopted for seismic retrofit of existing buildings looking also at the accessibility and operability aspects. Each step of the procedure was individually explained and it was applied for the design of a strengthening intervention on a real single-storey steel industrial building. The existing building is located in Nusco (Av, Italy) which is classified as in medium–high seismic intensity area which corresponds a peak ground acceleration (ag) equal to 0.238 g. Non-linear analyses were conducted to assess the existing structure’s performance as well as to verify the effectiveness of the strengthening solutions designed. The use of the exoskeleton systems allows to strongly increase both the elastic stiffness and the resistance of the investigated industrial building without interrupting its product activity.

Comparing walking with knee-ankle-foot orthoses and a knee-powered exoskeleton after spinal cord injury: a randomized, crossover clinical trial

Recovering the ability to stand and walk independently can have numerous health benefits for people with spinal cord injury (SCI). Wearable exoskeletons are being considered as a promising alternative to conventional knee-ankle-foot orthoses (KAFOs) for gait training and assisting functional mobility. However, comparisons between these two types of devices in terms of gait biomechanics and energetics have been limited. Through a randomized, crossover clinical trial, this study compared the use of a knee-powered lower limb exoskeleton (the ABLE Exoskeleton) against passive orthoses, which are the current standard of care for verticalization and gait ambulation outside the clinical setting in people with SCI. Ten patients with SCI completed a 10-session gait training program with each device followed by user satisfaction questionnaires. Walking with the ABLE Exoskeleton improved gait kinematics compared to the KAFOs, providing a more physiological gait pattern with less compensatory movements (38% reduction of circumduction, 25% increase of step length, 29% improvement in weight shifting). However, participants did not exhibit significantly better results in walking performance for the standard clinical tests (Timed Up and Go, 10-m Walk Test, and 6-min Walk Test), nor significant reductions in energy consumption. These results suggest that providing powered assistance only on the knee joints is not enough to significantly reduce the energy consumption required by people with SCI to walk compared to passive orthoses. Active assistance on the hip or ankle joints seems necessary to achieve this outcome.

A novel approach to quantify the assistive torque profiles generated by passive back-support exoskeletons

Industrial exoskeletons are a promising ergonomic intervention to reduce the risk of work-related musculoskeletal disorders by providing external physical support to workers. Passive exoskeletons, having no power supplies, are of particular interest given their predominance in the commercial market. Understanding the mechanical behavior of the torque generation mechanisms embedded in passive exoskeletons is, however, essential to determine the efficacy of these devices in reducing physical loads (e.g., in manual material handling tasks). We introduce a novel approach using a computerized dynamometer to quantify the assistive torque profiles of two passive back-support exoskeletons (BSEs) at different support settings and in both static and dynamic conditions. The feasibility of this approach was examined using both human subjects and a mannequin. Clear differences in assistive torque magnitudes were evident between the two BSEs, and both devices generated more assistive torques during trunk/hip flexion than extension. Assistive torques obtained from human subjects were often within similar ranges as those from the mannequin, though values were more comparable over a narrow range of flexion/extension angles due to practical limitations with the dynamometer and human subjects. Characterizing exoskeleton assistive torque profiles can help in better understanding how to select a torque profile for given task requirements and user anthropometry, and aid in predicting the potential impacts of exoskeleton use by incorporating measured torque profiles in a musculoskeletal modeling system. Future work is recommended to assess this approach for other occupational exoskeletons.

A framework for clinical utilization of robotic exoskeletons in rehabilitation

Exoskeletons are externally worn motorized devices that assist with sit-to-stand and walking in individuals with motor and functional impairments. The Food & Drug Administration (FDA) has approved several of these technologies for clinical use however, there is limited evidence to guide optimal utilization in every day clinical practice. With the diversity of technologies & equipment available, it presents a challenge for clinicians to decide which device to use, when to initiate, how to implement these technologies with different patient presentations, and when to wean off the devices. Thus, we present a clinical utilization framework specific to exoskeletons with four aims.These aims are to assist with clinical decision making of when exoskeleton use is clinically indicated, identification of which device is most appropriate based on patient deficits and device characteristics, providing guidance on dosage parameters within a plan of care and guidance for reflection following utilization. This framework streamlines how clinicians can approach implementation through the synthesis of published evidence with appropriate clinical assessment & device selection to reflection for success and understanding of these innovative & complex technologies.

Controlling safety and health challenges intrinsic in exoskeleton use in construction

Construction practitioners have started exploring the use of exoskeletons within operations to combat the high rate of work-related musculoskeletal disorders, declining productivity, and worker attrition. In attempting to adopt exoskeletons, the ensuing human-robot interaction (HRI) can lead to the emergence of novel safety risks or the increment of existing safety risks as a result of hazards peculiar to the task-technology execution. These risks, if ignored, can worsen construction worker safety performance. This paper presents research aimed at developing insights needed to control safety risks associated with exoskeleton (wearable robot) use across three construction tasks – bricklaying, drywall installation, and concrete grinding and polishing. To achieve this aim, the Delphi method, which relied on inferential and descriptive statistics such as mean analysis and consensus evaluation, was employed to (1) quantify wearable robot safety risks for selected construction tasks, and (2) identify effective and feasible safety risk mitigation strategies using the study results. Findings from the present study include 10 critical safety and health risks associated with exoskeletons and 12 key safety risk mitigation strategies. This research contributes to knowledge by characterizing the safety risks and mitigation strategies associated with HRI and providing valuable insights that could be used by researchers to advance construction worker safety and health research. Through increased awareness of HRI safety risk and mitigation strategies, practitioners can prioritize safety resources and improve worker safety and productivity.

Influence of a passive back support exoskeleton on simulated patient bed bathing: results of an exploratory study

Low-back pain is a major concern among healthcare workers. One cause is the frequent adoption of repetitive forward bent postures in their daily activities. Occupational exoskeletons have the potential to assist workers in such situations. However, their efficacy is largely task-dependent, and their biomechanical benefit in the healthcare sector has rarely been evaluated. The present study investigates the effects of a passive back support exoskeleton in a simulated patient bed bathing task. Nine participants performed the task on a medical manikin, with and without the exoskeleton. Results show that working with the exoskeleton induced a significantly larger trunk forward flexion, by 13 deg in average. Due to this postural change, using the exoskeleton did not affect substantially the muscular and cardiovascular demands nor the perceived effort. These results illustrate that postural changes induced by exoskeleton use, whether voluntary or not, should be considered carefully since they may cancel out biomechanical benefits expected from the assistance. Practitioner summary: Low-back pain is a major concern among nurses, associated with bent postures. We observed that using a passive back-support exoskeleton during the typical patient bed bathing activity results in a larger trunk flexion, without changing muscular, cardiovascular or perceived physical effort.

Immediate effects of the honda walking assist on spatiotemporal gait characteristics in individuals after stroke

The use of unconstrained lower limb exoskeletons has become a promising approach to assist individuals with gait impairments. The Honda Walking Assist (HWA) is a hip-assistive exoskeleton functioning as a gait trainer and has been shown to improve several gait related outcomes after training. Studies investigating its immediate effects on spatiotemporal gait parameters other than walking speed in stroke survivors are lacking. The aim of this study was to investigate immediate differences in spatiotemporal gait parameters of stroke survivors between normal overground walking, walking with an unpowered, non-assisting HWA and walking with an optimally assisting HWA. Five ischemic stroke survivors (mean time since stroke 115 ​± ​213.6 days) walked 3 times 5 ​m in each condition. Differences in 14 spatiotemporal gait parameters between all 3 conditions were registered and reported in a descriptive manner. With optimal assistance, 4 patients walked faster (0.057–0.095 ​m/s) with longer strides of the paretic (0.055–0.069 ​m) and non-paretic (0.053–0.077 ​m) leg compared to normal walking. Compared to unpowered walking, all patients walked faster (0.020–0.063 ​m/s) in the optimal assist condition, with longer strides of the paretic (0.036–0.072 ​m) and non-paretic leg (0.045–0.082 ​m). During unpowered walking, gait velocity remained unchanged in 2 patients, increased (0.012–0.051 ​m/s) in 2 patients and decreased (−0.022 ​m/s) in 1 patient compared to normal walking. Changes in paretic stride lengths ranged from −0.066 to 0.029 ​m. The optimal individualized motor assistance provided by the HWA induces small, positive changes in gait parameters. This indicates that this light-weight hip-assistive exoskeleton can be of value in rehabilitation setting, where multiple training sessions with the device are possible.

Evaluation of a spring-loaded upper-limb exoskeleton in cleaning activities

In the past few years, companies have started considering the adoption of upper-limb occupational exoskeletons as a solution to reduce the health and cost issues associated with work-related shoulder overuse injuries. Most of the previous research studies have evaluated the efficacy of these devices in laboratories by measuring the reduction in muscle exertion resulting from device use in stereotyped tasks and controlled conditions. However, to date, uncertainties exist about generalizing laboratory results to more realistic conditions of use. The current study aims to investigate the in-field efficacy (through electromyography and perceived exertion), usability, and acceptance of a commercial spring-loaded upper-limb exoskeleton in cleaning job activities. The operators were required to maintain prolonged overhead postures while holding and moving a pole equipped with tools for window and ceiling cleaning. Compared to the normal working condition, the exoskeleton significantly reduced the total shoulder muscle activity (∼17%), the activity of the anterior deltoid (∼26%), medial deltoid (∼28%), and upper trapezius (∼24%). With the exoskeleton, the operators perceived reduced global effort (∼17%) as well as a reduced local effort in the shoulder (∼18%), arm (∼22%), upper back (∼14%), and lower back (∼16%). The beneficial effect of the exoskeleton and its suitability in cleaning settings are corroborated by the acceptance and usability scores assigned by operators, which averaged ∼5.5 out of 7 points. To the authors' knowledge, this study is the first to present an experience of exoskeleton use in cleaning contexts. The outcomes of this research invite further studies to test occupational exoskeletons in various realistic applications to foster scientific-grounded ergonomic evaluations and encourage the informed adoption of the technology.

Using passive or active back-support exoskeletons during a repetitive lifting task: influence on cardiorespiratory parameters

The objective of this laboratory study was to assess the cardiorespiratory consequences related to the use of different back-support exoskeletons during a repetitive lifting task. Fourteen women and thirteen men performed a dynamic stoop lifting task involving full flexion/extension of the trunk in the sagittal plane. This task was repeated for 5min with a 10kg load to handle. Four conditions were tested: with a passive exoskeleton (P-EXO), with two active exoskeletons (A-EXO1 and A-EXO2), as well as without exoskeleton (FREE). The oxygen consumption rate and cardiac costs were measured continuously. Results showed a significantly lower (p < 0.05) oxygen consumption rate for all exoskeletons as compared to FREE (12.6 ± 2.2ml/kg/min). The values were also significantly lower (p < 0.001) for A-EXO1 (9.1 ± 1.8ml/kg/min) compared to A-EXO2 (11.0 ± 1.8ml/kg/min) and P-EXO (11.8 ± 2.4ml/kg/min). Compared to FREE (59.7 ± 12.9bpm), the cardiac cost was significantly reduced (p < 0.001) only for A-EXO1 (45.1 ± 11.5bpm). Several factors can explain these differences on the cardiorespiratory parameters observed between exoskeletons: the technology used (passive vs active), the torque provided by the assistive device, the weight of the system, but also the level of anthropomorphism (related to the number of joints used by the exoskeleton). Our results also highlighted the lack of interaction between the exoskeleton and sex. Thereby, the three back-support exoskeletons tested appeared to reduce the overall physical workload associated with a repetitive lifting task both for men and women.

Feasibility of using depth cameras for evaluating human - exoskeleton interaction

With the increased use of exoskeletons in a variety of fields such as industry, military, and health care, there is a need for measurement standards to understand the effects of exoskeletons on human motion. Optical tracking systems (OTS) provide high accuracy human motion tracking, but are expensive, require markers, and constrain the tests to a specified area where the cameras can provide sufficient coverage. This study describes the feasibility of using lower cost, portable, markerless depth camera systems for measuring human and exoskeleton 3-dimensional (3D) joint positions and angles. A human performing a variety of industrial tasks while wearing three different exoskeletons was tracked by both an OTS with modified skeletal models and a depth camera body tracking system. A comparison of the acquired data was then used to facilitate discussions regarding the potential use of depth cameras for exoskeleton evaluation.