main-content

2022 | Book

# Wearable Robotics: Challenges and Trends

## Proceedings of the 5th International Symposium on Wearable Robotics, WeRob2020, and of WearRAcon Europe 2020, October 13–16, 2020

Editors: Dr. Juan C. Moreno, Jawad Masood, Urs Schneider, Christophe Maufroy, Prof. Jose L. Pons

Publisher:

Book Series: Biosystems & Biorobotics

Part of:

insite
SEARCH

This book reports on advanced topics in the areas of wearable robotics research and practice. It focuses on new technologies, including neural interfaces, soft wearable robots, sensors and actuators technologies, discussing industrially and medically-relevant issues, as well as legal and ethical aspects. It covers exemplary case studies highlighting challenges related to the implementation of wearable robots for different purposes, and describing advanced solutions. Based on the 5th International Symposium on Wearable Robotics, WeRob2020, and on WearRacon Europe 2020, which were both held online on October 13-16, 2020, the book addresses a large audience of academics and professionals working in for the government, in the industry, and in medical centers, as well as end-users alike. By merging together engineering, medical, ethical and industrial perspectives, it offers a multidisciplinary, timely snapshot of the field of wearable technologies.

#### What Should We Expect from Passive Exoskeletons?

##### The Hidden Potential of Energetically Passive Exoskeletons

Bicycles have successfully augmented top human movement speed despite supplying no external power or increasing human limb force. This raises the question on what are the fundamental requirements for moving faster, when increasing force or supplying external power are not necessary to moving faster. This presentation will communicate our recent efforts to develop analytical models to study the fundamental physics of human locomotion, and the development of energetically passive devices that maximize top running speed given the limited force and power of human limbs. We take inspiration from the bicycle, which uses pedals to allow the legs to supply energy continuously instead of intermittently in running.

Amanda Sutrisno, David J. Braun
##### Effect of a Back-Assist Exosuit on Logistics Worker Perceptions, Acceptance, and Muscle Activity

A workplace study was conducted to evaluate user perceptions, acceptance, and muscle activity amongst logistics workers wearing an unmotorized, dual-mode, back-assist exosuit prototype. Eleven workers performed a lifting/lowering task with versus without the exosuit, while back muscle activity was recorded. They then used the exosuit while performing their actual work tasks in a distribution center before completing a questionnaire about their user experience. Worker perceptions of the exosuit were overwhelmingly positive: 100% felt the exosuit could be useful and fit into their daily job without interfering, >90% felt assisted and that the exosuit made lifting easier, and >80% felt it was comfortable and that they were free to move naturally while wearing the exosuit. Finally, the majority of workers showed reduced back muscle activity while wearing the exosuit during lifting/lowering, consistent with results from prior lab studies. Worker feedback on this prototype was then used to inform design of the HeroWear Apex exosuit.

Matthew B. Yandell, Anna E. Wolfe, Matthew C. Marino, Mark P. Harris, Karl E. Zelik
##### A Design Tool for Passive Wrist Support

A design tool for passive wrist support using compliant spatial beams as gravity balancer is presented. The aim of this assistive device is to reduce required effort for pronation-supination and flexion-extension by 70% to help patients with muscular weakness keeping their hand’s posture and doing daily tasks, while the forearm is rested. To reach this goal, a setup with three connection points to the user’s hand, and two optimized spatial beams as elastic gravity compensators, are developed. The overall shape and cross-sectional dimensions of the compliant beams are attained using an optimization technique. The objective is reaching a desired endpoint kinetostatic behaviour which is determined based on the hand’s weight and available muscular forces. A design case is presented to show the ability of the method, and the final errors from the desired behaviour are clarified. In the end, possible further applications of the design tool are discussed.

Ali Amoozandeh Nobaveh, Giuseppe Radaelli, Just L. Herder
##### The Key Elements in the Design of Passive Assistive Devices

Nowadays, enhancing the physical abilities of able-bodied humans attracted the researchers’ attention besides the development of assistive devices for people with mobility disorders. As a result, the interest in designing of cheap and soft wearable exoskeletons called exosuits is distinctly growing. Careful investigation of the biological musculoskeletal systems reveals three essential features simplifying gait control. The first property is the embedded compliance in the muscle-tendon-complex (MTC). Force-velocity or damper-like muscle behavior is the second feature. The last useful feature is in the biological morphological design of multi-articular muscles. These properties can be implemented in passive, assistive devices in isolation or combination. In this paper, we summarize a few studies on passive lower limb assistive devices that benefit from these two design concepts. We elaborate more on the outcomes of a recent study on a lower limb exosuit design with two biarticular elastic elements that combine the two aforementioned mechanisms in a single device.

Maziar A. Sharbafi
##### Novel Designs for Passive Elastic Lower Limb Exoskeletons

Engineers and scientists have long tried to build powered robotic lower limb exoskeletons without success (at least commercially). A major limitation has been the need for large amounts of mechanical power from the actuators. Simply put, human muscles are amazing motors. The size and mass of robotic actuators that can match human muscle limit exoskeleton hardware designs. An alternative to heavy motors that engineers have relied on throughout history has been power amplification from passive elastic mechanisms. We review examples of successful passive elastic systems that have been previously used by humans and discuss how elastic mechanisms can be incorporated into lower limb exoskeletons for assisting human locomotion.

Daniel P. Ferris, W. Sebastian Barrutia
##### Passive Compliance in Legged Systems and Assistive Devices

At the Cybathlon 2016 the performance of active and passive assistive devices for legged locomotion was compared. In the category of legged prostheses, surprisingly passive devices outperformed active ones regarding their performance in challenging tasks. Also the performance of active exoskeletons clearly demonstrated the still limited mobility performance in assisting the users.

Andre Seyfarth
##### Spring Like Passive Elastic Exoskeletons May Improve Stability and Safety of Locomotion in Uneven Terrain

Passive elastic exoskeletons have been shown to reduce the energetic costs of steady-state locomotion. However, it is unclear how they affect the stability of unsteady movements, such as locomoting in uneven terrain. To answer this question, we developed a mathematic model of a human hopping with an ankle exoskeleton on a platform that can arbitrarily change its height. Although passive elastic exoskeletons cannot generate or dissipate energy, we found that hopping with a passive elastic exoskeleton results in faster and safer recovery from unexpected changes in ground height. Our results suggest that lightweight passive ankle exoskeletons have potential to move beyond the lab and improve locomotor stability in real-world natural terrain environments.

Laksh Kumar Punith, James Williamson, Taylor J. M. Dick, Gregory S. Sawicki

#### Balance Recovery Support Using Wearable Robotic Devices

##### Ankle-Exoskeleton Control for Assisting in Balance Recovery After Unexpected Disturbances During Walking

In the last two decades, lower-limb exoskeletons have been developed to assist human standing and locomotion. One of the ongoing challenges is still balance support. Here we present a control strategy for an ankle-exoskeleton to assist balance recovery after unexpected disturbances during walking. We evaluated the controller in two healthy participants wearing the ankles of the Symbitron exoskeleton while receiving forward pushes at the pelvis during walking. Providing low and medium assistance resulted in improvement of balance recovery (decreased center of mass movement in the direction of the perturbation) and reduction of muscle activity, respect to trials with no assistance. These effects saturated with high levels of assistance. The results are promising, but the controller should be improved to use human’s real-time response as a feedback to trigger the support.

C. Bayón, W. F. Rampeltshammer, A. Q. L. Keemink, H. van der Kooij, E. H. F. van Asseldonk
##### Coupling an Active Pelvis Orthosis with Different Prosthetic Knees While Transfemoral Amputees Manage a Slippage: A Pilot Study

This pilot study aimed at testing the hypothesis that the effectiveness of an Active Pelvis Orthosis (APO)—mediated strategy to counteract the fall risk in transfemoral amputees (TFAs) can depend on the adopted prosthetic knee. Two TFAs with good and similar functional capabilities (k-level = 3) were asked to manage unexpected slipping like perturbations: the first used a hydraulic knee; the second a microprocessor-controlled knee. Results revealed that the APO-mediated strategy against the fall risk was more effective in the second participant. Accordingly, the adopted prosthetic knee seems to significantly condition the overall balance response despite the balance recovery is supposed to be mainly driven by the APO assistance. Therefore, the prosthetic knee should be considered a confounding factor for these types of experiments and its relevance deserves further investigations.

Monaco Vito, Aprigliano Federica, Arnetoli Gabriele, Doronzio Stefano, Giffone Antonella, Vitiello Nicola, Micera Silvestro
##### Self-induced Gyroscopic Torques in Lower Extremities During Gait: A Pilot Study

To affect functional relevant task-space gait parameters such as foot placement or progression angle, conventional lower-limb robotic gait rehabilitation devices require active control and synchronization of their actuators. As an alternative, we propose the use of gyroscopic actuators, portable actuators that have the ability to generate torques that are caused by and therefore intrinsically synchronized with the swing motion of the legs. Here we investigate the kinematic and kinetic effects at hip-joint level of self-induced gyroscopic torques of a shank-worn gyroscopic actuator. Preliminary results show the wearer’s swing leg motion can induce gyroscopic effects that significantly alter the kinematics of the hip-joint ( $$p < 0.05$$ p < 0.05 ) for both tested conditions in hip-joint endo/exo rotation and ab/ad-duction.

Saher Jabeen, Bram Sterke, Heike Vallery, Daniel Lemus
##### Comparison of Balance Recovery Among Current Control Strategies for Robotic Leg Prostheses

Over the past two decades, a number of control strategies have been developed for powered transfemoral prostheses. These strategies have in common that they help restore gait in amputee locomotion. However, it remains unclear how well they support balance recovery after disturbances. Here, we first present a comparison of balance recovery performance among current controls for powered transfemoral when their users are subjected to unexpected ground slips. While some controls perform better than others in this comparison, they all suffer from a limited awareness of both the environment and the user’s intent, which inevitably leads to catastrophic failures and eventual falls. We then introduce our current efforts toward more interactive prosthesis controls that continuously adapt to changes in the environment and user intent. In initial work, we find that such continuous adaptations substantially improve gait robustness, encouraging a more aggressive research agenda toward real-time reactive leg prosthesis controls.

Nitish Thatte, Hartmut Geyer
##### Reflex-Model with Additional COM Feedback Describes the Ankle Strategy in Perturbed Walking

Here we evaluate if a neuromechanical model, controlled by reflexes, can describe the reactive control of balance in response to anterior-posterior directed perturbations during walking. We optimized the parameters of the reflex model to track the measured joint moments in unperturbed and perturbed walking. We showed that an additional feedback loop, based on COM feedback, is needed to describe the response of the ankle muscles during perturbed walking.

Maarten Afschrift, Friedl De Groote
##### Optimising Balance Margin in Lower Limb Exoskeleton to Assist User-Driven Gait Stability

When exoskeletons are driven in open loop with predetermined trajectories, the onus is placed on the user to maintain balance through their crutches. This work uses simulation of a human-exoskeleton model to explore the idea that such trajectories could be optimised to give the user the ‘best chance’ to maintain their balance in the presence of perturbations. The method evaluates a reward function under different gait trajectories and initial poses. It is concluded that such an optimisation method could increase the set of perturbations which a user can counter without adding significant complexity or expense to the exoskeleton.

Xiruo Cheng, Justin Fong, Ying Tan, Denny Oetomo

#### Active Life with Prosthesis

##### Control of Servomotor Rotation in a Myoelectric Upper-Limb Prosthesis Using a 16-Channel sEMG Sensor System

The characteristics to consider during the development of myoelectric prostheses are the cultural, socio-economic and climatic conditions in which they are used. The weather condition affects in particular the recording of muscular activation for the prosthesis control. The aim of this study was the development of an easy to use myoelectric control system that can be used for the myoelectric control of opening and closing of the hand through electrodes that are not inside the prosthesis socket. Two time-domain features and Channel Selection were used to identify the specific channels corresponding to the biceps and triceps muscles. Eleven healthy subjects were tested. Channel selection was correct in 80% of all trials ensuring that the myoelectric sensor system can be used in any position outside of the prosthesis socket. This study provides an essential step towards the development of a mechanism for grip control in a myoelectric-controlled prosthetic hand.

Elisa Romero Avila, Elmar Junker, Catherine Disselhorst-Klug
##### Compliant Control of a Transfemoral Prosthesis Combining Predictive Learning and Primitive-Based Reference Trajectories

This paper reports the development of a novel compliant controller for a transfemoral prosthesis that combines a feed-forward prediction torque component with a feedback error correction. The controller architecture aims to track primitive-based reference trajectories by the prosthetic joints. It relies on Locally Weighted Projection Regression, a function approximator that acts as an inverse internal model of the prosthesis. The proposed strategy is validated in a simulation environment.

Sophie Heins, Renaud Ronsse
##### Design and Testing of a Fully-Integrated Electro-Hydrostatic Actuator for Powered Knee Prostheses

Electro-hydrostatic actuation represents a well-suited alternative in prosthetic and robotic applications to electro-mechanical actuation. In this regard, its favorable controllability and intrinsic back-drivability are key enabling features. This work offers a specific design methodology to obtain a highly-integrated and back-drivable electro-hydrostatic unit for a powered knee prosthesis to be used both in active and regenerative modes. The designed actuator was manufactured, assembled and tested in position tracking and admittance control, where promising performance was attained.

Federico Tessari, Renato Galluzzi, Nicola Amati, Andrea Tonoli, Matteo Laffranchi, Lorenzo De Michieli
##### Controlling Upper-Limb Prostheses with Body Compensations

With their advanced mechatronics, myoelectric upper-limb prostheses now have many motion possibilities. Yet, the latter are not fully employed because of the inconvenient control and prostheses wearers often use their device as a rigid tool while achieving hand positioning and orientation with compensatory movements. In this paper, we propose to take advantage of this natural human behaviour to control prosthesis motions: the user is in charge of the end-effector while the device’s role is to correct the human posture when necessary. We here apply this concept to control a prosthetic wrist pronosupination. A Rolyan clothespin test performed by two transradial amputees shows that the proposed control is as efficient as myoelectric control while requiring no learning.

Mathilde Legrand, Nathanaël Jarrassé, Charlotte Marchand, Florian Richer, Amélie Touillet, Noël Martinet, Jean Paysant, Guillaume Morel
##### HandMECH—Mechanical Hand Prosthesis: Conceptual Design of a Two Degrees-of-Freedom Compliant Wrist

A compliant wrist joint is important for positioning the hand in different positions to perform various daily tasks. It is also important that the wrist is able to achieve sufficient range of motion (RoM). The RoM is determined by classifying the daily activities and the most critical applications. This study presents kinematical, structural and kinetic analyses of the conceptual design of a wrist joint in mechanical hand prosthesis: HandMECH. Kinematic and kinetic analyses are carried out to determine the design parameters of the wrist to handle daily activities. Structural analyses is performed to evaluate the stress distributed over the critical part of the wrist and show that the design with a mass of 50 g satisfies the applied boundary condition.

Ahmed A. I. Elsayed, Ramazan Unal
##### HandMECH—Mechanical Hand Prosthesis: Conceptual Design of the Hand Compartment

In this study, conceptual design of the hand compartment of a body-powered hand prosthesis, HandMECH, is presented. HandMECH is a body-powered prosthesis and the hand compartment is designed according to human finger size and range of motion (RoM). Moreover, the design is governed by the daily activities performed by hand. In this regard, three types of grasp that are mostly used are identified. The thumb is designed with three degrees of freedom (DoF), i.e., translation and rotation, the index finger with three rotational DoF, and the other three fingers that generally move together are designed as combined and having one rotational DoF. In order to give the human finger flexibility, the fingers are designed to be made of flexible material and the other parts are of ABS material with the consideration of 3D printer for prototyping. CAD model is presented as an outcome of this study.

Baris Baysal, Ramazan Unal

#### Legislation, Safety and Performance: Regulatory Aspects in Wearable Robots

##### CO-GUIDING: Ergonomic Analysis of a Hand Guidance System for Car Door Assembly

Hand Guidance is a type of Human-Robot Collaboration with high interest in the manufacturing industry. In this paper, we present an ergonomic analysis of an assisted hand guidance operation of car door assembly that can also be applied to the wearable robots. A simulated scenario and an experimental specific safety protocol are created. Two subjects perform a work cycle. Biomechanical data from the subjects and mechanical data from the robots are collected. We follow guidelines of UNE-EN 1005–3:2002, UNE-EN 1005–5:2007 and UNE-EN ISO 8996:2005 to execute risk assessment procedures. We consider the cycle time, applied force (push/pull), external load, muscle load, and workstation adaptability as key risk analysis measures. The results show the external load is acceptable by the subjects; the applied forces on the subjects do not exceed the followed norms; arm muscles activities (load) remains within acceptable ranges, and subject one shows better task adaptability.

Erika Triviño-Tonato, Jawad Masood, Ruben P. Cibeira, Angel Dacal-Nieto
##### ATEX Certification for ALDAK Exoskeleton in Petrochemical Industry

Most certification processes require the complex and tedious analysis of multiple normative and references to understand and apply the appropriate methods to get the desired mark. This work intends to ease the way for ATEX certification of exoskeletons, especially relevant for mining and petrochemical industries. GOGOA’s ALDAK exoskeleton aims to become the first ATEX certified exoskeleton and this work reviews the process and steps to follow.

Ane Intxaurburu, Iñaki Díaz, Juan Martín, Xabier Justo
##### Acceptance of Exoskeletons: Questionnaire Survey

The introduction of exoskeletons in companies, like any new technology, is a major change. In this context the specific question of the acceptance of these devices by workers is addressed. To this end, a questionnaire was specifically developed and administered to current and former exoskeleton users. The results presented provide information on the quality of the operator-exoskeleton interaction, and identify blocking and/or facilitating points for the use of these devices.

Liên Wioland, J. Jean-Jacques, Atain-Kouadio, Latifa Debay, Hugo Bréard
##### Perceived Exertion During Robot-Assisted Gait After Stroke

The present study investigated the level of perceived exertion during robot-assisted walking in non-ambulatory stroke survivors. In addition, we studied the relationship between the user’s subjective level of perceived exertion and objective measures of exertion (i.e. oxygen consumption and heart rate). Our results suggest that stroke survivors perceive fully assisted Lokomat walking as extremely light to very light and fully assisted Ekso GT walking as very light to somewhat hard. Weak positive correlations were found between subjective and objective measures of exertion.

Nina Lefeber, Emma De Keersmaecker, Eric Kerckhofs, Eva Swinnen
##### Testing Safety of Lower Limbs Exoskeletons: Current Regulatory Gaps

Exoskeletons are a growing technology that is increasingly being studied and researched in various application domains. However, new technologies must fit into current regulations, which update more slowly than market needs. This paper analyses the main regulations and standards in which exoskeletons can fit, underlining the gaps and barriers that still exist and may hinder the smooth introduction of exoskeleton technology in the market.

Stefano Massardi, David Pinto-Fernandez, Jan F.Veneman, Diego Torricelli

#### The Testing of Industrial Exoskeletons

##### Evaluation of Two Upper-Limb Exoskeletons for Ceiling Welding in the Naval Industry

Shipbuilding entails demanding operator tasks in several scenarios, like workshops, blocks or even ships under construction. This work focuses on ceiling welding, a usual task in the two latter scenarios, for which two commercial upper-limb exoskeletons were evaluated. Tests were conducted with two expert operators wearing the exoskeletons in a motion analysis lab equipped with an optical motion capture system, force plates and electromyographic sensors. Heart rate was also measured, videos were recorded and a questionnaire was filled by each operator. Muscular activity, kinematics, driving torques, metabolic cost, donning/doffing and execution times, were compared for both operators without and with the two exoskeletons in three assistance levels. It is concluded that improvement is achieved with both exos in most indicators although the total time to perform the task is not always reduced.

Francisco Mouzo, Florian Michaud, Urbano Lugris, Jawad Masood, Javier Cuadrado
##### Preliminary Study of an Exoskeleton Index for Ergonomic Assessment in the Workplace

Work-related low-back disorders represent the most common and costly musculoskeletal problems, so, recently, industrial exoskeletons have been developed to prevent injury by reducing the load on the back. Their effects are described by a growing body of literature, but is not captured by any standard risk index used in ergonomic practice. This study aims to suggest a method to quantify how the effect of a back-support exoskeleton might be accounted in the NIOSH Lifting Index. Twelve subjects participated in the study and we recorded the surface electromyographic signals of the erector spinae longissimus. Subjects held four different loads in a static position for 10 s without the exoskeleton and wearing it. A substantial reduction in the median of the muscle activity when wearing the exoskeleton was observed. We suggest that this reduction could be reflected in a multiplicative factor that directly affects the NIOSH Lifting Index.

Giorgia Chini, Christian Di Natali, Stefano Toxiri, Francesco Draicchio, Luigi Monica, Darwin G. Caldwell, Jesús Ortiz
##### Effect of a New Passive Shoulder Exoskeleton on the Full Body Musculoskeletal Load During Overhead Work

Objective to investigate the effect of a passive shoulder exoskeleton on full body musculoskeletal loading during a wiring and lifting task above shoulder height. Methods: Three participants performed a wiring and lifting task with 10 kg above shoulder height with and without âssive shoulder exoskeleton. OpenSim was used to calculate kinematics, kinetics, muscle forces and joint contact forces at the shoulder and L5. Results: Kinematics did not change during the lifting task but kinematics did change for two out of the three participants during the wiring task while wearing the exoskeleton. Moreover, joint moments and muscle forces in the shoulder were decreased. In addition, compression forces at L5 were decreased but shear forces were increased while wearing the exoskeleton during both tasks. Conclusion: Considering that this is preliminary data, this exoskeleton could decrease the risk of developing work-related shoulder disorders in specific tasks.

A. van der Have, S. Van Rossom, M. Rossini, I. Jonkers
##### The Experience of Plasterers Towards Using an Arm Support Exoskeleton

Positive effects of arm support exoskeletons in reducing the shoulder load, have been reported mainly from laboratory studies. However, for exoskeletons to provide worker support in practice, they need to be accepted as well. Therefore, it is necessary to obtain insight into the user experience and attitude towards exoskeleton use, in relevant working fields. Eleven plasterers were recruited to perform their activities while wearing an arm support exoskeleton. Before the experiment, participants were asked for which activities they could use support, and which body regions they wished to be supported. After working with the exoskeleton, they reported their experience and will to use the exoskeleton during daily work. Overall, the user experience of the plasterers was positive, and all reported they would probably, or even definitely, use the exoskeleton for a selection of activities, mainly overhead work, but not during the whole day. Together with earlier findings on reduced muscle activity, exoskeleton use in certain tasks seems promising.

Aijse W. de Vries, Michiel P. de Looze, Frank Krause
##### Biomechanical Evaluation of the Effect of Three Trunk Support Exoskeletons on Spine Loading During Lifting

To evaluate the biomechanical effect of exoskeletons during lifting, three studies were performed to compare spine compression during lifting without and with three exoskeletons (Laevo, Robo-Mate, SPEXOR). In these studies, participants (11, 10 and 10, respectively) lifted boxes (10, 15 and 10 kg, respectively) from ankle height. Spine compression reductions ranged from minor changes in the first exoskeleton to 17% and 14% reductions in the second and third exoskeleton, respectively. Lumbar flexion was increased by the first exoskeleton while it was reduced by the second and unaffected by the third. Effects of exoskeletons on spine compression were affected by support moments, reductions in lifting speed and subtle changes in lifting style. Modifications of design and control could help to improve the timing and magnitude of support of exoskeletons during lifting.

Idsart Kingma, Axel S. Koopman, Michiel P. de Looze, Jaap H. van Dieën
##### Can HDEMG-Based Low Back Muscle Fatigue Estimates Be Used in Exoskeleton Control During Prolonged Trunk Bending? A Pilot Study

The effectiveness of exoskeletons could be enhanced by incorporating low back muscle fatigue estimates in their control. The aim of the present study was to evaluate whether low back muscle fatigue can be estimated using the spectral content of trunk extensor muscle high-density EMG (HDEMG) by considering the motor unit action potential conduction velocity (MUAP CV) as a reference. The HDEMG-based MUAP CV was estimated for multiple sites on the lower back consistently throughout a 30 degrees lumbar flexion endurance trial. Significant linear relationships were observed between MUAP CV and spectral content. However, MUAP CV and spectral changes over time did not show the expected decrease, probably due to additional recruitment of motor units or alternating activity of synergistic muscles. The anatomical information about the sites that allow MUAP CV estimation can be valuable for future low back muscle fatigue estimations.

Niels P. Brouwer, Ali Tabasi, Alejandro Moya-Esteban, Massimo Sartori, Wietse van Dijk, Idsart Kingma, Jaap H. van Dieën
##### Back-Support Exoskeleton Control Using User’s Torso Acceleration and Velocity to Assist Manual Material Handling

This work analyzes the use of users’ dynamics to define the assistance of a back-support exoskeleton for assisting manual material handling. Exploiting the acceleration and velocity of the user’s torso on the sagittal plane allows to distinguish between lifting and lowering phases and accordingly adapt the assistance. Theoretical and practical issues of strategy implementation are discussed.

Maria Lazzaroni, Ali Tabasi, Stefano Toxiri, Darwin G. Caldwell, Idsart Kingma, Elena De Momi, Jesús Ortiz
##### Subjective Assessment of Occupational Exoskeletons: Feasibility Study for a Custom Survey for Braces

Occupational exoskeletons are emerging as a viable solution to mitigate the effect of poor ergonomic work tasks. However, there is still a lack of understanding of which are the key factors to improve the low acceptance rate, from a subjective point of view. Effectively translating users’ feedback in requirements is of paramount importance to raise adoption of exoskeletons. To this end, we present and evaluate a tailored set of constructs and questions to collect subjective ratings of braces, that are the physical interface between users and exoskeletons and play a key role in acceptance rate.

M. Sposito, D. G. Caldwell, E. De Momi, J. Ortiz

#### Evidenced-Based Indications/Contraindications for and Potential Benefits of Exoskeletal-Assisted Walking in Persons with Spinal Cord Injury

##### Alteration of Push-Off Mechanics During Walking with Different Prototype Designs of a Soft Exoskeleton in People with Incomplete Spinal Cord Injury—A Case Series

The push-off is a key factor determining the walking capability. People with impaired function due to incomplete spinal cord injury (iSCI) have altered biomechanics and are, therefore, at a disadvantage during activities of daily living such as walking. XoSoft is a prototype soft exoskeleton designed to assist during walking. Different generations of XoSoft followed different strategies of tailoring the garment (custom-made vs. one-size fits all). This may result in altered effects on the mechanics of walking. In this study, we assessed two generations of XoSoft with three people with iSCI and focused on the push-off mechanics (ankle kinematics & kinetics) during level walking. The results showed that XoSoft was able to support the gait, but systematic differences between prototype generations were not found. Consequently, a more general approach for the garment design may be feasible.

Eveline S. Graf, Christoph M. Bauer, Carole Pauli, Markus Wirz
##### The Effect of Exoskeletal-Assisted Walking on Bowel and Bladder Function: Results from a Randomized Trial

A three center randomized controlled crossover clinical trial of exoskeletal-assisted walking (EAW) compared to usual activity (UA) in people with chronic spinal cord injury (SCI) was performed. As secondary outcome measures, the effect of this intervention on bowel and bladder function was assessed using the 10Q Bowel function Survey, the Bristol Stool Form Scale (BFS) and the bowel and bladder components of the Spinal Cord Injury Quality of Life (SCI-QOL) instrument. Fifty subjects were completed the study, with bowel and bladder data available for 49. The amount of time needed for the bowel program on average was reduced in 24% of the participants after EAW. There was a trend toward normalization of stool form noted. There were no significant effects in patient reported outcomes for bowel or bladder function on the SCI-QOL components, although time since injury may have played a role.

Peter H. Gorman, Gail F. Forrest, Pierre K. Asselin, William Scott, Stephen Kornfeld, Eunkyoung Hong, Ann M. Spungen
##### Smartwear with Artificial Intelligence (AI) in Assessing Workload in View of Ergonomics

Myontec’s wearable technology is designed to decrease work based musculoskeletal disorders (MSDs), reduce accidents and sick leaves. Smartwear with embedded muscle activation level (EMG), upper arm elevation and trunk bending, together with wrist watch measuring heart rate apps are used to execute the measurements wirelessly. This smartwear based solution takes biosignal measurements to workplaces and gives results fast and accurate, thus being a cost-effective method for assessing exoskeletons, product design and research.

Pekka Tolvanen, Riitta Simonen, Janne Pylväs
##### Comparison of ReWalk® and Ekso® Powered Exoskeletons for Stepping and Speed During Training Sessions

Design attributes specific to the powered exoskeletons contribute to differences in walking performance. As part of a large multicenter trial that used two powered exoskeletons, the design attributes that contribute to the differences in average number of steps per session and walking speed were explored.

Pierre K. Asselin, Gail F. Forrest, Stephen Kornfeld, Eunkyoung Hong, Peter H. Gorman, Ann M. Spungen
##### Indications and Contraindications for Exoskeletal-Assisted Walking in Persons with Spinal Cord Injury

Adopting appropriate eligibility criteria for research and clinical programs in which powered exoskeletal-assisted walking devices are used remains a challenge to avoid risk of injury and to encourage the successful use of these devices. Reducing the risk of fracture is a primary concern when establishing eligibility criteria. Evidence from a three-site clinical trial supports the use of screening criteria for bone mineral density at the knee to permit safe use of exoskeletal devices.

Ann M. Spungen, Peter H. Gorman, Gail F. Forrest, Pierre K. Asselin, Stephen Kornfeld, Eunkyoung Hong, William A. Bauman
##### The Impact of Exoskeletal-Assisted Walking on the Immune System of Individuals with Chronic Spinal Cord Injury (SCI)

Persons with chronic spinal cord injury (SCI) are at increased risk for stroke and cardiovascular disease (CVD). Systemic inflammation is commonly observed in persons with SCI and is inversely correlated with mobility. In the general population, light-moderate intensity exercise such as walking reduces risk of stroke, CVD and reduces systemic inflammation. Powered exoskeletons for persons with SCI offer a means to provide physical activity through overground ambulation. It is currently unclear if, and to what extent, exoskeletal-assisted walking (EAW) leads to health benefits associated with walking. A pilot case series was performed to determine if EAW impacts whole blood gene expression in persons with chronic SCI.

Anthony A. Arcese, Ann M. Spungen, Ona Bloom
##### Exoskeleton Controller and Design Considerations: Effect on Training Response for Persons with Spinal Cord Injury

The objective of this research was to identify variables (demographic, device, neurological, clinical, and training session dose) that were associated with results of the ten-minute walk test (10MWT) for individuals with a spinal cord injury (SCI) who participated in a large randomized crossover clinical trial of exoskeletal walking. Fifty individuals were randomized into Group AB or BA (A = exoskeleton intervention arm, B = control arm). A generalized linear mixed model was applied to model 10MWT and found that a training dose of 36 sessions and gender were the most significant. These variables were more significant than neurological level of injury or completeness of injury. Understanding the effects of exoskeleton/human interface for different devices is crucial for identifying suitable candidates to use the device and developing effective/efficient clinical training protocols for community ambulation, rehabilitation, and recovery post-SCI.

Gail F. Forrest, Peter H. Gorman, Arvind Ramanujam, Pierre K. Asselin, Steven Knezevic, Sandra Wojciehowski, Ann M. Spungen

#### Neuromechanical Modelling and Control for Wearable Robots: Enhancing Movement After Neuromuscular Injuries

##### Neuromusculoskeletal Model-Based Controller for Voluntary and Continuous Assistance in a Broad Range of Locomotion Tasks

Neuromusculoskeletal modeling driven by electromyograms (EMG) has shown the ability to predict joint torque for a wide variety of movements. Taking advantage of this, we connected a real-time version of an EMG-driven model to a bilateral ankle exoskeleton to continuously assist during a wide repertory of locomotion tasks. The advantage is that the user controls the exoskeleton voluntarily, i.e. as a direct function of own muscle force. As a result, the developed framework can seamlessly assist in different tasks as well as transitions between tasks without having to change any parameters or using an additional algorithm to switch between states. Results on three participants show that an exoskeleton controlled via this framework reduces EMGs during locomotion tasks with various speeds and/or inclinations. This is the first step toward creating controller allowing to assist in tasks independent manner.

Guillaume Durandau, Wolfgang Rampeltshammer, Herman van der Kooij, Massimo Sartori
##### Energy Cost of Transport in Overground Walking of a Transfemoral Amputee Following One Month of Robot-Mediated Training

Transfemoral amputees (TFAs) require higher energy expenditure than able-bodied individuals during walking. In this study we examined the effects on one TFA of training for a month with a portable bilateral hip exoskeleton on (i) energy cost of transport (CoT) and (ii) distance covered during a 6-minute walking test (6mWT), assessed without (NoExo) and with (Exo) the exoskeleton. Results showed that in NoExo the CoT was reduced by 13.4% after the training, while the 6mWT distance increased by 20.3%. However, the CoT increased in Exo compared to NoExo both before (24.8%) and after (11.8%) the training. These results provide initial evidence that robot-mediated training should deserve further exploration as a tool for improving walking efficiency of TFAs. Future research will investigate customized tuning procedures more in depth to maximize the beneficial effects of this approach.

C. B. Sanz-Morère, E. Martini, G. Arnetoli, S. Doronzio, A. Giffone, B. Meoni, A. Parri, R. Conti, F. Giovacchini, Þ. Friðriksson, D. Romo, R. Molino-Lova, S. Crea, N. Vitiello
##### Physical Therapy and Outdoor Assistance with the Myosuit: Preliminary Results

Soft robotic suits are good candidates both for supporting physical therapy in clinical environments and for improving mobility in outdoor settings. Here, we investigate both modes of use using the Myosuit, a lightweight robotic suit for the lower limbs: (1) we show that it can be safely used to support a supervised physical therapy program, and (2) present a single-case study on the immediate effects that Myosuit assistance can have in an outdoor setting. Eight participants with diverse walking impairments completed a five-sessions Myosuit-assisted training program, showing an average improvement in walking performance that is encouraging for the design of a future controlled study. When walking on a sloped mountain path, one participant with incomplete spinal cord injury showed a 30% increase in walking speed and 9% reduction in cost of transport when assisted by the Myosuit, compared to when not wearing the device.

Michele Xiloyannis, Florian L. Haufe, Jaime E. Duarte, Kai Schmidt, Peter Wolf, Robert Riener
##### Predictive Simulation of Sit-to-Stand Movements

The development of technology that can assist people during movements such as sit to stand can benefit from simulations that can estimate the effect of different assistance patterns. These simulations need to be based on frameworks that can replicate the neuromechanical features of non-pathological sit-to-stand movements. In this study, we present a framework for predictive simulations of sit to stand that can be used to synthesize physiological data in the absence of experimental ones. Here we reproduce sit-to-stand movements on a model with 9 degrees of freedom and 52 actuators by optimizing the parameters of a feedback controller that accounts for the position, velocity and acceleration of the pelvis and torso, under the constraints dictated by a specifically designed cost function. We obtained a simulation that could replicate the kinematics and muscular activation observed in previous studies.

David Munoz, Leonardo Gizzi, Cristiano De Marchis, Giacomo Severini
##### SimBionics: Neuromechanical Simulation and Sensory Feedback for the Control of Bionic Legs

Lower limb prosthetic technology has greatly advanced in the last decade, but there are still many challenges that need to be tackled to allow amputees to walk efficiently and safely on many different terrain conditions. Neuro-mechanical modelling and online simulations combined with somatosensory feedback, has the potential to address this challenge. By virtually reconstructing the missing limb together with the associated somatosensory feedback, this approach could enable amputees to potentially perceive the bionic legs as extensions of their bodies. A prosthesis equipped with such biologically inspired closed-loop control could duplicate the mechanics of walking far more accurately than conventional solutions. The project SimBionics aims to explore these opportunities and advance the state-of-the-art in lower limb prosthesis control.

Jose Gonzalez-Vargas, Massimo Sartori, Strahinja Dosen, Herman van der Kooij, Johan Rietman
##### Pseudo-online Muscle Onset Detection Algorithm with Threshold Auto-Adjustment for Lower Limb Exoskeleton Control

Spinal cord injury (SCI) is one of the main disabling injuries affecting people worldwide. The use of a wearable robot in rehabilitation reduces physical exhaustion during training. Moreover, developing novel control paradigms that allow the wearable system to move in a more intuitively way, resembling patients’ intention, may enhance rehabilitation outcomes. In this paper, we present an algorithm that automatically detects users’ onset and offset of lower limb muscle’s contraction using electromyography (EMG) signals. The users’ intention was detected through a single threshold algorithm. The algorithm auto-adjusts the threshold according to individual EMG characteristics. The algorithm was tested with EMG data from seven healthy subjects performing ankle and knee flexion/extension movements and correctly detected the intention of movement in approximately 96% of cases in an average time of 147.15 ms. To conclude, this algorithm can potentially be explored in future approaches to enable real-time triggering and control of a wearable exoskeleton to be used in the rehabilitation setting.

J. Marvin Fernández García, Camila R. Carvalho, Filipe O. Barroso, Juan C. Moreno
##### Benefits and Potential of a Neuromuscular Controller for Exoskeleton-Assisted Walking

Controlling wearable exoskeletons to interact with people suffering from locomotion disabilities due to lesions of the central nervous system is a complex challenge since it entails fulfillment of many concurrent objectives: versatility in different applications (assistance and rehabilitation), user-specific adaptation to residual motor functions, compliance with different gait features (e.g. personal walking patterns and especially speed changes), smoothness of human-robot interaction, natural and intuitive exoskeleton control, acceptability and usability of the worn system. A novel bio-inspired modular controller for lower limb exoskeletons was developed by the Authors, which delivers assistive joint torques by using a reflex-based neuromuscular model. This paper presents an overview of previous and ongoing findings in testing this controller with the aim to highlight its benefits and potential in complying with user needs and with different applications.

N. L. Tagliamonte, A. R. Wu, I. Pisotta, F. Tamburella, M. Masciullo, M. Arquilla, E. H. F. van Asseldonk, H. van der Kooij, F. Dzeladini, A. J. Ijspeert, M. Molinari
##### CANopen Robot Controller (CORC): An Open Software Stack for Human Robot Interaction Development

Interest in the investigation of novel software and control algorithms for wearable robotics is growing. However, entry into this field requires a significant investment in a testing platform. This work introduces CANopen Robot Controller (CORC)—an open source software stack designed to accelerate the development of robot software and control algorithms—justifying its choice of platform, describing its overall structure, and demonstrating its viability on two distinct platforms.

Justin Fong, Emek Barış Küçüktabak, Vincent Crocher, Ying Tan, Kevin M. Lynch, Jose L. Pons, Denny Oetomo

#### Toward Efficient Human-Exoskeleton Symbiosis

##### Direct Collocation-Based Optimal Controller for Multi-modal Assistance: Simulation Study

Multi-modal assistive system is a hybrid system that aims to provide assistance-as-needed for paretic subjects. The hybrid system combines human muscle efforts, stimulated by a Functional Electric Stimulator (FES) and an lower-limb active exoskeleton. With optimal sharing of the two activation inputs, a hybrid system could overcome several challenges, such as human force due to FES-induced muscular fatigue. In this paper, a novel optimal controller, based on an efficient (3.9 ms to predict a time windows of 40 ms) closed-loop direct collocation approach is proposed to predict the control allocation between FES and exoskeleton. Simulation results, performed with dynamically varying desired trajectory, show that the proposed controller adapts the control input with respect to muscular fatigue.

Anh T. Nguyen, Vincent Bonnet, Samer Mohammed
##### A Semi-active Upper-Body Exoskeleton for Motion Assistance

This paper describes a semi-active assistive exoskeleton for upper-body motion assistance. The exoskeleton combines a passive shoulder exoskeleton and an active elbow joint unit, which can achieve both passive gravity compensation and also active assistance to carrying and sit-to-stand motion. The design, sensing and control are introduced, with preliminary test results performed.

Shaoping Bai, Muhammad R. Islam, Karl Hansen, Jacob Nørgaard, Chin-Yin Chen, Guilin Yang
##### Ultrasound-Based Sensing and Control of Functional Electrical Stimulation for Ankle Joint Dorsiflexion: Preliminary Study

Functional electrical stimulation (FES) is a potential technique for reanimating paralyzed muscles post neurological injury/disease. Several technical challenges, including the difficulty in measuring FES-induced muscle activation and muscle fatigue, and compensating for the electromechanical delay (EMD) during muscle force generation, inhibit its satisfactory control performance. In this paper, an ultrasound (US) imaging approach is proposed to observe muscle activation and fatigue levels during FES-elicited ankle dorsiflexors. Due to the low sampling rate of the US imaging-derived signal, a sampled-data observer (SDO) is designed to continuously estimate the muscle activation and fatigue based on their continuous dynamics. The SDO is combined with a delay compensation term to address the ankle dorsiflexion trajectory tracking problem with a known input delay. Experimental results on an able-bodied participant show the effectiveness of the proposed control method, and the superior tracking performance compared to a traditional control method, where the muscle activation and fatigue are computed from an off-line identified model.

Qiang Zhang, Ashwin Iyer, Nitin Sharma
##### Towards Crutch-Free 3-D Walking Support with the Lower Body Exoskeleton Co-Ex: Self-balancing Squatting Experiments

In this paper, we succinctly present the hardware properties and capabilities of the lower body exoskeleton Co-Ex, which was developed to attain self-balancing and crutch-free walking support for those experiencing ambulatory difficulties in general. To provide full 3-D walking support while containing the number of required actuators, it includes 4 active joints per leg. Custom-built series elastic actuators enable the torque sensing and controllability at each joint, enhancing the robot’s physical interaction capabilities. While limiting the number of active joints minimizes the weight and energy requirements, the underactuated leg configuration increased the computational load. The preliminary squatting experiments revealed that Co-Ex may provide crutch-free 3-D movement support.

Sinan Coruk, Ahmed Fahmy Soliman, Oguzhan Dalgic, Mehmet C. Yildirim, Deniz Ugur, Barkan Ugurlu
##### Ankle Dorsiflexion Assistance Using Adaptive Functional Electrical Stimulation and Actuated Ankle Foot Orthosis

This work presents the development of a hybrid control strategy to assist ankle joint dorsiflexion movements during walking. An actuated ankle foot orthosis (AAFO) is used in conjunction with Adaptive Functional Electrical Stimulation (AFES) of the peroneal nerve at the Tibialis Anterior (TA) muscle level. The purpose is to provide sufficient ankle dorsiflexion during the swing phase to compensate for foot-drop in paretic patients. The degree of ankle dorsiflexion is indexed with respect to the knee flexion through an adaptive FES paradigm.

Carlos Canchola-Hernandez, Hala Rifai, Yacine Amirat, Samer Mohammed

#### Soft Wearable Robots for Health and Industry

##### Feasibility and Effectiveness of a Soft Exoskeleton for Pediatric Rehabilitation

Exoskeletons have the potential to improve outcomes for rehabilitation clients. For these devices to be effective, rehabilitation professionals and end users must be involved throughout the design process, so the devices meet the broad needs of users. In this article, we present a model to guide the design of rehabilitation devices. This model is user-centered and focuses on users’ functional, expressive, aesthetic, and accessibility needs (FEA2) for devices. We then summarize the results of the first studies evaluating the feasibility and effectiveness of the Playskin Lift™ soft exoskeleton for pediatric populations utilized for intervention in the natural environment. The exoskeleton was feasible for daily use by families in the natural environment. For infants and toddlers with physical disabilities, the exoskeleton assisted reaching and play performance within a single session when it was worn and improved independent reaching function and play activity after months of daily intervention with the exoskeleton.

Michele A. Lobo, Bai Li
##### FleXo—Modular Flexible Back-Support Passive Exoskeleton

This paper presents a back-support exoskeleton concept, which mimics the biological structure of the human back. The design is based on a novel modular flexible mechanism, that allows a complete freedom of movement and a good level of comfort. The assistive forces are transmitted perpendicularly to the body, improving the benefits of the system, and distributed efficiently through the body thanks to a smart routing system. The current implementation, called FleXo, uses passive actuation based on an elastic band.

Jesús Ortiz, Jorge Fernández, Tommaso Poliero, Luigi Monica, Sara Anastasi, Francesco Draicchio, Darwin G. Caldwell
##### A Model-Based Control Strategy for Upper Limb Exosuits

Increase the symbiosis between the human and the machine, is the major open challenge in wearable robotics research. Limitations are not only in hardware but also on the control side which is often limited in its bandwidth lacking to match frequency ranges of biomechanics, but also in detecting and interpreting human intention. In this work we propose a control framework for an upper limb exosuit which works using an EMG model based myoprocessor module. Results suggest that using biosignal in the control loop for wearable robotics improves reliability and interaction between the device and its pilot.

N. Lotti, F. Missiroli, M. Xiloyannis, L. Masia
##### Pneumatic Control System for Exoskeleton Joint Actuation

The aim of the work is to present the design and construction of a pneumatic system for actuation of an exoskeleton for upper limbs, suitable for rehabilitation and training. Testing and adjustment of control system of the prototype as well as experimentation of the functionality of the exoskeleton and evaluation of joint actuation have been performed.

Pavel Venev, Ivanka Veneva, Dimitar Chakarov
##### PowerGrasp: Development Aspects for Arm Support Systems

Exoskeletons can support workers on physically demanding tasks, but in industry they lack of acceptance. This contribution gives an insight into design aspects for upper body exoskeletons, especially how active exoskeletons for industrial applications differ from military and medical use-cases. To overcome typical rigid exoskeleton problems, we suggest the use of modular soft-exosuit support systems and therefore checked different types of soft actuation principles for their eligibility for the use on upper body joints. Most promising approach is using two-layered actuators sting of robust fabric with embedded rubber tubes as pressure chambers. By inflating the tubes, it is possible to vary the stiffness of the chambers, which can be effectively used to generate assisting forces and moments at human joints (shoulder, elbow, wrist, finger).

Jean-Paul Goppold, Jan Kuschan, Henning Schmidt, Jörg Krüger
##### Mobile Unilateral Hip Flexion Exosuit Assistance for Overground Walking in Individuals Post-Stroke: A Case Series

Stroke is a leading medical issue that can impact the person’s ability to walk effectively. There is limited research into the design and biomechanical response for exosuits that assist more proximal joints such as the hip. For this case series, three subjects with chronic stroke participated in a single-session study to evaluate hip flexion exosuit assistance in overground walking. We iteratively tuned the unilateral hip flexion assistance profiles in overground gait. Compared to the initial unpowered baseline, walking speed at the end of tuning and with the device powered increased for 2 of 3 individuals and on average by 0.16 m s $$^{-1}$$ - 1 . We then compared powered versus unpowered overground walking during a 5 min evaluation period. Circumduction was reduced by 9 $$\pm 1$$ ± 1 mm and cost of transport was reduced by 8.6 $$\pm 1.7$$ ± 1.7 % for the 3 participants.

Richard W. Nuckols, Franchino Porciuncula, Chih-Kang Chang, Teresa C. Baker, Dorothy Orzel, Asa Eckert-Erdheim, David Perry, Terry Ellis, Louis Awad, Conor J. Walsh
##### The SoftPro Wearable System for Grasp Compensation in Stroke Patients

This extended abstract presents a wearable system for assistance that is a combination of different technologies including sensing, haptics, orthotics and robotics. The result is a device that, by compensating for force deficiencies, helps lifting the forearm and thanks to a robotic supernumerary finger improves the grasping ability of an impaired hand. A pilot study involving three post-stroke patients was conducted to test the effectiveness of the device to assist in performing activities of daily living (ADLs), confirming its usefulness.

L. Franco, M. Tschiersky, G. Wolterink, F. Barontini, M. Poggiani, M. Catalano, G. Grioli, M. Bianchi, A. Bicchi, S. Rossi, D. Prattichizzo, G. Salvietti
##### Towards a Fabric-Based Soft Hand Exoskeleton for Various Grasp Taxonomies

This paper describes a functional evaluation test of a fabric-based hand exoskeleton for various grasp taxonomies. We conducted an adapted version of the Jebsen Taylor Hand Function Test (JTHFT) with a healthy subject. The evaluation investigates a comparison of the times it takes the user to perform the task with and without the device, establishing a range of actions with a delay of 2.0–6.0 s maximum. This preliminary study aims to understand the implications of future clinical studies with post-stroke patients for rehabilitation.

Andrea Peñas, Juan C. Maldonado-Mejía, Orion Ramos, Marcela Múnera, Patricio Barria, Mehran Moazen, Helge Wurdemann, Carlos A. Cifuentes

#### Musculoskeletal Modelling to Evaluate and Optimize Performance of Wearable Robotic Devices

##### Predictive Gait Simulations of Human Energy Optimization

We previously demonstrated that humans can continuously adapt their gait to optimize energetic cost in real-time when wearing a lower-limb exoskeleton. Here, we aim to recreate this paradigm using predictive gait simulations to further investigate how the nervous system performs this optimization and how energy costs change locally. To match the real-world experiment, we modeled a knee-worn exoskeleton that applied resistive torques that were either proportional or inversely proportional to step frequency—decreasing or increasing the energy optimal step frequency, respectively. We solved simulations with and without the knee exoskeleton and with fixed and free step frequency. We were able to replicate the experiment, finding higher and lower optimal step frequencies than in the natural walking under each respective condition. Our simulated resistive torques and optimized objective function resembled the measured experimental resistive torque and metabolic energy landscape. Muscle metabolic power changed for individual muscles spanning all three joints and revealed distinct coordination strategies consistent with each exoskeleton controller condition.

Anne D. Koelewijn, Jessica C. Selinger
##### Reconstruction of Hip Moments Through Constrained Shape Primitives

Among the various control laws developed for lower-limb wearable robotics, several intend to replicate leg joint moments observed in healthy humans. While this can be achieved by different means, inspiration can be gained from the so-called motor primitives, i.e. a small set of fundamental signals used by the nervous system to recruit numerous motor pools in a task-specific way. Here we report a methodology for the extraction of constrained-shape primitives. Stimulations of two antagonist hip muscles are initially retrieved from a database composed of different locomotion tasks. A first guess of the primitives parameters is then performed in order to reconstitute these stimulations. Finally these parameters are optimized with the aim of retrieving the original database moments. Our findings suggest that a small number of symmetric Gaussian-like periodic primitives may reconstruct these hip moments with a level of fidelity that would be sufficient for providing a task-specific user support.

Henri Laloyaux, Renaud Ronsse
##### Simulated Exoskeletons with Coupled Degrees-of-Freedom Reduce the Metabolic Cost of Walking

Exoskeletons that assist multiple joints could reduce the metabolic cost of walking beyond reductions achieved with single-joint devices. However, assisting many degrees-of-freedom can require multiple actuators with complicated controllers and long experiment times to tune these controllers. Coupled assistance, where the same control signal is applied to multiple joints, may help simplify exoskeleton design but has not been tested extensively. In this study, we used direct collocation optimal control and a lower-limb musculoskeletal model to simulate five different exoskeleton control strategies to assist multiple joints during walking. We simulated strategies where the torque provided at each joint was controlled independently or coupled between joints. We found that coupled assistance was able to provide similar savings in whole-body metabolic power consumption compared to independent assistance. Our results may help device designers create exoskeletons that achieve good metabolic savings while requiring fewer actuators and less experimental testing to create effective assistance strategies.

Nicholas A. Bianco, Patrick W. Franks, Jennifer L. Hicks, Scott L. Delp
##### Model-Based Biomechanics for Conceptual Exoskeleton Support Estimation Applied for a Lifting Task

The aim of this study was to analyse biomechanics in lifting tasks and evaluate an exoskeleton concept using musculoskeletal model-based analysis. Three male participants lifted a box of 21 kg from waist level to 1.46 m height. Movement was recorded with motion capture and simulated with individual musculoskeletal models. The effect of an exoskeleton concept supporting the upper arm and/or forearm with external torque around the shoulder was examined for one subject. Muscle activity was reduced for arm flexors and shoulder muscles. Glenohumeral and elbow joint forces were also decreased by the support concept.

Elena Gneiting, Jonas Schiebl, Mark Tröster, Verena Kopp, Christophe Maufroy, Urs Schneider
##### Calibrating an EMG-Driven Muscle Model and a Regression Model to Estimate Moments Generated Actively by Back Muscles for Controlling an Actuated Exoskeleton with Limited Data

Estimation of low-back load can be used to determine the assistance to be provided by an actuated back-support exoskeleton. To this end, an EMG-driven muscle model and a regression model can be implemented. The goal of the regression model is to reduce the number of required sensors for load estimation. Both models need to be calibrated. This study aims to find the impacts of limiting calibration data on low-back loading estimation through these models.

Ali Tabasi, Maria Lazzaroni, Niels P. Brouwer, Idsart Kingma, Wietse van Dijk, Michiel P. de Looze, Stefano Toxiri, Jesús Ortiz, Jaap H. van Dieën
##### Effect of Mono- Versus Bi-Articular Ankle Foot Orthosis on Muscular Performance of the Lower Leg

Ankle foot orthoses (AFOs) are used to assist impaired gait. In this study, we investigated the effects of a mono- and a bi-articular AFO with different stiffness on the muscles’ performance in the lower extremities. The effects of both AFOs on the activation level and power of gastrocnemius, soleus and tibialis anterior muscles together with knee extensors and flexors were simulated in Opensim. The muscular performances were compared between the case without orthosis and the case with mono- and bi-articular AFO with different stiffness values (5, 10, 15, 20 and 25 kN/m). The simulations showed that increasing the stiffness of both AFOs led to reductions (up to 70%) of the activation levels of soleus and gastrocnemius in comparison to the case without orthosis. The overall stronger effects caused by the bi-articular configuration led us to investigate its effects on the knee extensors and flexors. Indeed, bi-articular AFO led to strong activation of the knee extensor muscles, suggesting a power interaction between upper and lower leg. Therefore, an intelligent design of mono- and bi-articular AFO with soft springs (<10 kN/m) may potentially allow to balance muscle activation and power consumption of the respective muscles of the leg. Experiments with customized patient-specific AFOs and with different human subjects walking at different speeds will be required to validate these conclusions.

Mahdy Eslamy, Florian Mackes, Arndt F. Schilling
##### Ultrasound Imaging of Plantarflexor Muscles During Robotic Ankle Assisted Walking: Effects on Muscle Tendon Dynamics and Application Towards Improved Exoskeleton and Exosuit Control

Ankle exosuits/exoskeletons can improve gait but the assistance needs to be tuned to the individual. We suspect that ankle assistance can affect underlying muscle-tendon dynamics and should be accounted for in the control design. We highlight two complementary studies that begin to address these issues. First, we use ultrasound imaging to directly measure the effect of ankle exoskeleton rotational stiffness on soleus contractile dynamics. With increasing stiffness, the soleus operating length and muscle economy increased in early stance, but this was offset by increased shortening velocity and reduced muscle economy in late stance. Second, we demonstrate an approach to rapidly estimate muscle contractile state and its application in prescribing assistance profiles. These results provide evidence for the importance of muscle dynamics and how it can be used to inform design of wearable devices.

Richard W. Nuckols, Sangjun Lee, Krithika Swaminathan, Conor J. Walsh, Robert D. Howe, Gregory S. Sawicki
##### Simulation Platform for Dynamic Modeling of Lower Limb Rehabilitation Exoskeletons: Exo-H3 Case Study

A flexible simulation platform for human gait with exoskeletons is presented to support the analysis of the human-robot interaction and performance assessment of control strategies design, e.g., assist-as-needed. The platform includes the dynamic modeling of the lower limb’s exoskeleton-human with six degrees of freedom in sagittal plane, actuated by servomotors, where the movement equations are explicitly obtained through the Euler-Lagrange approach. The full model is hybrid and it contains four sub-models that are switched between themselves according to the gait cycle phases; also, it comprises the joint actuators dynamics and the low level control system, this modeling was assembled in Simulink-Matlab. It is shown that the proposed platform is a useful tool for assistance control strategies in the gait rehabilitation. Furthermore, simulation results for the Exo-H3 exoskeleton show the successful tracking of angular trajectories, the level of human participation, and the realistic torques.

Sergey González-Mejía, José M. Ramírez-Scarpetta, Juan C. Moreno, José L. Pons
##### Understanding Technology-Induced Compensation: Effects of a Wrist-Constrained Robotic Hand Orthosis on Grasping Kinematics

Robotic hand orthoses have the potential of supporting grasp function of people with sensorimotor impairments. To achieve lightweight and simple solutions, most devices focus on supporting only a subset of the functional abilities of the hand. This study investigates the effect of such a design trade-off in a wrist-constrained robotic hand orthosis and its effects on upper limb kinematics and grasping abilities of seven able-bodied subjects. Using wearable, inertial sensors on hand, arm, and shoulder we quantified how a reduction of degrees of freedom affected movement strategies in eleven grasping tasks. This analysis helps to understand how simplified design solutions may affect movement patterns of the target end-users, depending on their residual level of functionality. Also, this further highlights the issue of usability-related design trade-offs between compact and lightweight solutions, and more complex multi-degree of freedom devices.

Jan T. Meyer, Charlotte Werner, Sarah Hermann, László Demkó, Olivier Lambercy, Roger Gassert
##### The Effects of Vestibular Stimulation to Enhance Rehabilitation and Enable Robotic Exoskeleton Training for Persons with CP

Reduction of spasticity in persons with cerebral palsy is possible using the application of non-invasive mechanical vestibular stimulation (VS) to the otoliths (in the inner ear). In this study we examined the effects of providing a single session of VS (15 min of a 3-in. of vertical oscillation) to a 35-year old male with spasticity due to CP. This investigation shows promising results of VS application as an intervention that could magnify the effectiveness of conventionally prescribed rehabilitation training/exercises, and can even unlock newly established rehabilitation options (e.g. gait training using robotic exoskeleton).

Ghaith J. Androwis, Peter A. Michael, Richard A. Foulds

#### Digitalization and Artificial Intelligence Applied to Wearable Technologies and Ergonomics

##### A New Terrain Recognition Approach for Predictive Control of Assistive Devices Using Depth Vision

Vision based systems for terrain detection play important roles in mobile robotics, and recently such systems emerged for locomotion assistance of disabled people. For instance, they can be used as wearable devices to assist blind people or to guide prosthesis or exoskeleton controller to retrieve gait patterns being adapted to the executed task (overground walking, stairs, slopes, etc.). In this paper, we present a computer vision-based algorithm achieving the detection of flat ground, steps, and ramps using a depth camera. Starting from point cloud data collected by the camera, it classifies the environment as a function of extracted features. We further provide a pilot validation in an indoor environment containing a rich set of different types of terrains, even with partial occlusion, and observed that the overall system accuracy is above 94 $$\%$$ % . The paper further shows that our system needs less computational resources than recently published concurrent approaches, owing to the original transformation method we developed.

Ali H. A. Al-dabbagh, Renaud Ronsse
##### Simulation-Based Optimization Methodology for Designing a Workspace with an Exoskeleton

We present a preliminary concept of simulation-based optimization methodology framework for designing workspace with exoskeleton. The framework consists of three main elements human (ergonomic performance), workspace (industrial tasks, sub-tasks, environment, safety) and exoskeleton (assistance levels, robustness, workspace, imposed constraints), mathematical models and interactions that can converge to an optimal solution i.e. workspace design recommendations. We select the changing the drill bit in for the vertical drilling machine as an industrial task. The human and workspace mathematical modelling is performed using the Jack software and Process Simulate software. In future, we will focus on developing exoskeleton mathematical model and establish mathematical interaction between human model and the exoskeleton model.

Zohar Potash, Jawad Masood, Raziel Riemer
##### Optimizing Active Spinal Exoskeletons to Minimize Low Back Loads

The design and control of exoskeletons is not a straight forward task and presents a lot of challenges. Especially in cases of preventing biomechanical damages, for example low back loads, exoskeletons should be able to provide the necessary amount of support without hindering or hurting the user in any way. To this extend, this study exploits optimal control to evaluate cost functions that minimize (a) cumulative low back loads, (b) peak low back loads and (c) a combination of the previous, while constraining contact (interaction) forces between human and exoskeleton. The results are compared to a kinematic reconstruction from a human without exoskeleton performing the same task of lifting a 10 kg box. Cost function (c) performs the best in terms of achieving an equilibrium between minimizing cumulative and peak lumbar torques—subject to the actuator’s torque and speed limit—reducing the peak torque by 48%.

Giorgos D. Marinou, Katja D. Mombaur
##### LSTM and CNN Based IMU Sensor Fusion Approach for Human Pose Identification in Manual Handling Activities

In recent years, human pose estimation has become a very important research topic in the context of control engines, and exoskeletons. In this paper, we propose a Long Short-Term Memory (LSTM) and Convolutional Neural Networks (CNN) based Hybrid Deep Neural network, aimed to estimate human pose while handling of loads. The proposed model is capable to identify three such activities, i.e. load lifting from the ground, load shifting, and uplifting of the load. For this purpose, a inertial sensor unit (IMU)-based system was developed to collect the raw data. Next, to obtain more robust and accurate results, Kalman filtering has been used as a fusion technique. Rigorous fine-tuning and simulations show that the model obtained from the Kalman filtering achieves better results as compared to the raw data. Our proposed model can classify the target activities with a test accuracy of 86%.

Enrique Bances, Adnan Mushtaq Ali Karol, Urs Schneider
##### Visual Feedback Strategy Based on Serious Games for Therapy with T-FLEX Ankle Exoskeleton

Therapies with repetitive exercises can result in a lack of interest and motivation of the patient. Therefore, the inclusion of feedback strategies, such as serious games, evidences a significant improvement in those aspects. This paper presents the development and a preliminary validation with a healthy subject of a visual and interactive interface based on serious games for the rehabilitation of patients with ankle dysfunctions. The results show a high level of adaptation of the user to the interface and positive perception in this application.

Angie Pino, Daniel Gomez-Vargas, Marcela Múnera, Carlos A. Cifuentes
##### The Utilization Effects of Powered Wearable Orthotics in Improving Upper Extremity Function in Persons with SCI: A Case Study

Persons with upper extremity (UE) impairments due to spinal cord injury (SCI) have limited capacity to move or perform basic activities of daily living (ADL). Such movement limitations significantly reduce a patient’s quality of life (QOL) and level of independence. Restoration of UE motor function in people with SCI remains a high priority in rehabilitation and in the field of assistive technology. UE myoelectric powered wearable orthoses (UE-MPWO) specifically designed to restore wrist/hand movements may help fill the gap by increasing strength of the participating muscles, range of motion (ROM) of the joints, and ability to perform daily tasks involving using wrist/hand in persons with SCI. The goal of this study was to evaluate the effects of the UE-MPWO (MyoPro) in ameliorating wrist/hand/UE movement capability, and increasing ADL and QOL in people with SCI.

Ghaith J. Androwis, Steven Kirshblum, Guang Yue

#### Exoskeletons in Industry 4.0: Open Challenges and Perspectives

##### Using a Spring-Loaded Upper-Limb Exoskeleton in Cleaning Tasks: A Preliminary Study

In the next few years, exoskeletons for workers’ support are expected to be key players in the global industrial market. Interventional studies to explore the exoskeletons’ effectiveness in real and realistic simulated scenarios have to be carried out in the wide variety of use cases. This work introduces a preliminary comprehensive assessment of a spring-loaded upper-limb exoskeleton, carried out using both instrumental and perception-related metrics in a realistically simulated job activity. Results show that the MATE exoskeleton significantly alleviates the strain in the shoulder and reduces the perceived effort in the investigated task. Questionnaires indicated well-above-threshold usability and acceptability indices. Short-term evidence of strain reduction induced by the use of exoskeletal vests paves the way for systematic assessment across different use-cases.

I. Pacifico, F. Aprigliano, A. Parri, G. Cannillo, I. Melandri, F. S. Violante, F. Molteni, F. Giovacchini, N. Vitiello, S. Crea
##### Methods for User Activity Recognition in Exoskeletons

Exoskeleton technology is making its way into the industry as an assistance tool to prevent workers from suffering musculoskeletal disorders. However, current control algorithms do not yet allow for a natural human-robot collaboration interface. A key issue to develop efficient exoskeleton controllers resides in the user’s activity recognition. This work describes several exoskeleton sensorization options and Machine Learning methods tested on GOGOA’s ALDAK active exoskeleton to identify user activity type.

Iñaki Díaz, Juan Martín, Xabier Justo, Carlos Fernández, Jorge Juan Gil
##### A Topology-Optimization-Based Design Methodology for Wearable Robots: Implementation and Application

Robotic-based human assistance is increasingly spreading both in clinical practice and in the industrial sector. The use of wearable robots, such as exoskeletons, is considered one of the most promising applications since it allows for merging human flexibility and creativity with machine endurance. Such devices shall be comfortable and lightweight to be as transparent as possible to the user’s perception. At the same time, they shall also be stiff enough to drive body parts while bearing the exchanged forces efficiently. The gold standard methodology to achieve such results is the topology optimization, which, even if used mainly in structural optimization, is still relatively new to wearable robots. In this paper, the authors propose a topology-optimization-based design strategy suitable to be applied, if adapted case by case, to a generic design of a wearable system. The presented test case, used as a benchmark to assess the optimization-based design process, focuses on a hand exoskeleton made of aluminum alloy, resorting to an additive manufacturing process.

Lorenzo Bartalucci, Matteo Bianchi, Enrico Meli, Alessandro Ridolfi, Andrea Rindi, Nicola Secciani
##### Lifting and Carrying: Do We Need Back-Support Exoskeleton Versatility?

In recent years, back-support exoskeletons have shown potential to mitigate the ergonomic risk associated with lifting activities. In addition to lifting, carrying is known to represent a risk for the workers. In this work, we elaborate on the effects of an active back-support exoskeleton (XoTrunk) assisting with carrying activities, using the same control strategy adopted in lifting-assistance. The results show that for most of the users (7 out of 9) such assistance is hindering the leg movements. As a consequence, exoskeletons should embed task recognition capabilities in order to switch control strategies according to the performed task.

Tommaso Poliero, Maria Lazzaroni, Stefano Toxiri, Christian Di Natali, Darwin G. Caldwell, Jesús Ortiz
##### Exoskeletons Introduction in Industry. Methodologies and Experience of Centro Ricerche Fiat (CRF)

Exoskeletons and other technologies for aiding work need to be tested and selected before starting the implementation plan or further evaluation phases. Innovation in this field is highly dynamic and new products are frequently proposed at prototype level so discriminating phase is important. This paper aims to explain how FCA–CRF is approaching the evaluation of new products and the new technologies for aiding work. The evaluation is based on applicative cases and on testing procedures as well as on testing session results. The selection phase is important to define if exoskeleton or other technology under investigation fits the needs of workstation and tasks to be faced during work activity. In this way an objective performance evaluation of the exoskeleton matching the workplace needs can be operated. The applied testing procedure for this exoskeletons investigation demonstrated its usefulness at laboratory and pilot case level.

Massimo Di Pardo, Rossella Monferino, Francesca Gallo, Felice Tauro
##### Quantifying the Impact of a Lower Limb Exoskeleton on Whole-Body Manipulation Tasks. Methodological Approach and First Results

Yaiza Benito Molpeceres, Guillermo Asín-Prieto, Juan Carlos García Orden, Diego Torricelli
##### Assessment of Exoskeleton Related Changes in Kinematics and Muscle Activity

Work-related musculoskeletal disorders, reported at shoulder and low back regions, rank among the most serious health problems in industry. Owing to their ability in providing support to the shoulder and back regions during sustained and repetitive tasks, passive exoskeletons are expected to prevent work-related disorders. In this work, experimental protocols were conducted for the extraction of relevant information regarding the neuromuscular activation and kinematics during simulated working activities with passive exoskeletons. Our results support the notion these passive exoskeletons have the potential to alleviate muscular loading and therefore to prevent musculoskeletal disorders in the industrial sector.

Fabio V. dos Anjos, Taian M. Vieira, Giacinto L. Cerone, Talita P. Pinto, Marco Gazzoni

#### Exoskeletons for Military Applications

##### Exoskeletons for Military Logistics and Maintenance

Field studies were performed at various logistics and maintenance facilities of the German armed forces, with the aim to develop a set of design requirements for novel exoskeletons in military logistics applications. This led to an improved understanding of common logistics tasks and a list of design requirements including main and secondary activities, ranges of motion and environmental parameters. From these design requirements, designs and first prototypes were derived.

Mona Hichert, Markus Güttes, Ines Bäuerle, Nils Ziegenspeck, Nico Bölke, Jonas Schiebl
##### Aerial Porter Exoskeleton (APEX) for Lifting and Pushing

A hip exoskeleton was designed that can assist hip extension during squat lifting and pushing. The device incorporates a motor, ball screw in a compact lightweight package. The total weight of the system including the battery is 3.94 kg and the system can supply over 30 Nm of torque to each leg. The device assists lifting and pushing and is not engaged during walking, running or other tasks.

W. Brandon Martin, Alexander Boehler, Kevin W. Hollander, Darren Kinney, Joseph K. Hitt, Jay Kudva, Thomas G. Sugar
##### Exoskeletons for Unarmed Military Use: Requirements and Approaches to Support Human Movements Using an Example of Protection Against Unknown CBRN Dangers

Using individual protective equipment (IPE) while handling unknown chemical, biological, radiological and nuclear (CBRN) dangers can lead to high physical stress on the user. The use of exoskeletons may be a good approach to help relieving the user and may increase the overall wear time of the IPE. Due to the unique environment and equipment, this use case applies additional requirements on the exoskeletal functions, design and interaction with the IPE. By the example of disposal of unknown CBRN dangers, this contribution observes and analyses the different tasks in the field of handling unknown CBRN dangers and deduces requirements for the combination of the IPE and exoskeletons. The results recommend the use of exoskeletons combined with the IPE, especially the gas-tight protective suit and a few approaches to include exoskeletal systems in the security measures.

C. Linnenberg, J. Klabunde, K. Hagner, R. Weidner
##### Analysis of a Passive Ankle Exoskeleton for the Reduction of the Metabolic Costs During walking—A Preliminary Study

The present study has as main objective the design and development of a passive exoskeleton for the reduction of the metabolic costs during gait. The prototype was designed based on an existing concept, exploring specific issues related to ankle mobility, user’s ergonomics and structural customization. The evaluation of the exoskeleton performance was performed by 15 volunteers belonging to the Portuguese Army, based on the 6MWT. The exoskeleton was tested considering three force elements with different stiffnesses to assess the influence of this parameter in its performance. A qualitative analysis was also performed to assess the users’ perception during the trials. Results showed a reduction of the metabolic costs in 10 subjects, presenting an average value of 3%. Moreover, the results indicate that the selection of the force elements and the tuning of the spring-engaging mechanism plays a key role in the efficiency of the developed solution.

Luís P. Quinto, Pedro Pinheiro, Sérgio B. Gonçalves, Ivo F. Roupa, Miguel T. Silva
##### A Multivariate Analysis for Force Element Selection in Passive Ankle Exoskeletons

Exoskeletons performance is influenced by several factors such as ergonomics, actuation force or actuation timing. In particular, for passive exoskeletons, the force element specifications are crucial for its performance. This study aims to infer the existence of a relation between the stiffness of the force element installed on an ankle exoskeleton and the anthropometric parameters of its user. Multivariate statistical techniques were applied to analyse the relevance of the anthropometric data in the energy expenditure of 15 subjects, during the execution of the six-minute walk test using a passive ankle exoskeleton. Results suggest a multiple linear relation between the anthropometric data and the metabolic results obtained for each volunteer. In conclusion, the presented methodology enables the selection of the most appropriate spring for each user, without resorting to time-consuming laboratory or field tests.

Nuno A. Ribeiro, Luís P. Quinto, Sérgio B. Gonçalves, Ivo F. Roupa, Paula P. Simões, Miguel T. Silva

#### Application Industrial Exoskeletons

##### On the Design of Kalman Observers for Back-Support Exoskeletons

This paper presents the synthesis of a Kalman state observer for an industrial back-support exoskeleton. The design of a state observer always should be based on a model providing an adequate description of the system dynamics; however, when back-support exoskeletons are considered, the synthesis of a state observer becomes very challenging, since only nonlinear models may be adopted to reproduce the system dynamic response with adequate accuracy. In this work, the possibility of employing a Kalman state observer together with a suitable linear model is investigated. Simulated results illustrate the effectiveness of the proposed approach when it is applied to the synthesis of a state observer for a back-support exoskeleton.

Erfan Shojaei Barjuei, Darwin G. Caldwell, Jesús Ortiz
##### Subjective Perception of Shoulder Support Exoskeleton at Groupe PSA

The emerging Industrial Exoskeleton Technology (IET) adoption in industry requires an assessment of its long duration impact. We present the subjective assessment of the shoulder support exoskeleton (Levitate AIRFRAME) at Groupe PSA Vigo factory by setting-up evaluation phases in the assembly line under industrial conditions. These phases are the preliminary-term [28 workers, 14 h], short-term [8 workers 75 h] and the medium-term [11 workers, 240 h]. We continuously monitored the workers and gradually increased the usage time until full autonomy was achieved for full shift. We discovered that searching the initial static fit of the exoskeleton is a non-trivial task. In addition, we noted that the usability and reliability aspects which were absent in preliminary-term and short-term testing are influential in medium-term testing such as body temperature elevation and exoskeleton mechanical wear and tear. Finally, we observed the gradual decrease in the exoskeleton usage among workers contrary to our hypothesis.

Jawad Masood, Erika Triviño-Tonato, Maria Del Pilar Rivas-Gonzalez, Maria Del Mar Arias-Matilla, Ana Elvira Planas-Lara
##### MH-Forces, a Motion-Capture Based Method to Evaluate Workplace Ergonomics: Simulating Exoskeleton Effects

In this document, we explain the MoveHuman-Forces (MH-Forces) method, which aims to evaluate the ergonomics of a specific workplace. This method provides the level of risk to suffer an injury on each body joint. The risk calculation is based on a motion-capture measurement in the workplace. This method can be used for the assessment of existing workplaces and the validation of new ones. After introducing their foundations, we introduce how MH-Forces can be used to assess the inclusion of exoskeletons in workplaces.

Javier Marín, Juan de la Torre, José J. Marín
##### A Methodology to Assess the Effectiveness and the Acceptance of the Use of an Exoskeleton in a Company

The integration of new technologies in the workplace and, in particular, the use of exoskeletons, requires a precise analysis of the effects these devices have on the workers and their environment. This analysis will allow us to assess the advantages and effectiveness of the implementation. A structured and systematic methodology for the subjective and objective analysis of the use of exoskeletons in the field is presented in this work, as a result of years of experience working with different companies. The methodology is developed in four phases of work, from a preliminary needs analysis to the implementation of the exoskeleton in the workplace.

J. A. Tomás-Royo, M. Ducun-Lecumberri, A. E. Planas-Lara, M. Arias-Matilla
##### Objective Techniques to Measure the Effect of an Exoskeleton

Know in advance the effects of an exoskeleton on the worker’s body, before its implementation in the workplace, will give us valuable information to make decisions and optimize company resources. Three objective techniques (surface electromyography, 3D motion capture and dynamometry for the biomechanical analysis with the MH-Forces ergonomics assessment method) are used for this aim. Measurements results will show how the use of an exoskeleton while performing a task can modify the efforts, the muscular activity, the postures, the movements and the forces on the worker’s joints. These objective techniques can provide quantitative and reliable data to prevent potential exoskeleton users from suffering musculoskeletal disorders.

A. E. Planas-Lara, M. Ducun-Lecumberri, J. A. Tomás-Royo, Javier Marín, José J. Marín
##### Designing an Integrated Tool Set Framework for Industrial Exoskeletons

The main objective of industrial exoskeletons is to provide physical assistance to prevent musculoskeletal disorder in workers. A group of active exoskeletons are powered by electrical actuators, in this scenario different challenges appear when modulating the effective active assistance. This paper presents a digital tool set framework as a strategy to improve the industrial exoskeleton performance during testing sessions and real scenarios. The design considerations are based on the required visual interfaces of this framework. The proposed human-machine interface is composed by (i) the user-command interface, a wearable device for user settings input (ii) the monitor-system, a desktop visual interface, and (iii) the gain-system interface, a mobile parameter configuration manager. Case studies where the framework potentially can be implemented are presented; the framework is designed to be compatible with the industrial exoskeleton XoTrunk.

O. A. Moreno, F. Draicchio, L. Monica, S. Anastasi, D. G. Caldwell, J. Ortiz

#### Benchmarking Wearable Robots

##### Wearable Robots Benchmarking: Comprehending and Considering User Experience

In real-world applications, wearable robots need to serve functional requirements, but also satisfy user demands. A systematic evaluation will require multidisciplinary benchmarking methods. Since user experience seems to be of distinct relevance, this paper analyzes how user experience influences wearable robots use and how it can be considered in benchmarking. Focus is set on potential metrics and how we could include them in human-centered benchmarking approaches.

Philipp Beckerle
##### Performance Indicators of Humanoid Posture Control and Balance Inspired by Human Experiments

Posture control and maintaining balance are fundamental elements of humanoid robot control and have a significant impact for the performance of robots. The evaluation of robotic performance, at the state of the art, is mostly evaluated at goal level, e.g. with robot competitions. While falling is a typical reason beyond the failure of the humanoid operation, the failure itself does not provide many details about the nature of the underlying problem that can be used to improve the control. In order to provide a more specific analysis of posture control and balance, this contribution presents a set of performance indicators, i.e. indexes that can be used to compare the performance of robots with the human control systems. The inspiration for the proposed tests and indicators comes from human experiments and particular emphasis is placed on human-robot comparison.

Vittorio Lippi, Thomas Mergner, Christoph Maurer, Thomas Seel
##### Lower-Limbs Exoskeletons Benchmark Exploiting a Stairs-Based Testbed: The STEPbySTEP Project

Wearable exoskeletons can be valuable assistive robots to physically support humans in a wide variety of daily living activities. However, there is a lack of standards for the devices benchmark and evaluation. The STEPbySTEP project is developing a modular and sensorized reconfigurable staircase testbed for lower-limb exoskeletons benchmarking to be included in the main EUROBENCH project testing facility. In addition, metrics for the benchmark and evaluation of different solutions are defined, including physical interaction metrics, ergonomics metrics, and human factors metrics.

Nicole Maugliani, Marco Caimmi, Matteo Malosio, Francesco Airoldi, Diego Borro, Daniel Rosquete, Ausejo Sergio, Davide Giusino, Federico Fraboni, Giuseppe Ranieri, Luca Pietrantoni, Loris Roveda
##### Towards a Unified Terminology for Benchmarking Bipedal Systems

In the European project EUROBENCH, we are developing a framework for benchmarking the performances of bipedal systems: from humans to humanoids through wearable robots. Fair benchmarking requires defining and sharing clear and complete protocols so that bipedal systems can be studied and compared within similar and reproducible conditions. Even if the experimental methods and system comparisons are common scientific tasks, the description of the experimental protocols that are followed are rarely complete enough to allow it to be replicated. We list, in this article, the information required to properly define a protocol (e.g. experiment objectives, testbeds, type of collected and processed data, performance indicators used to score and compare experiments). Agreeing on a common terminology for benchmarking concepts will ease the evaluation of new technologies and promote communication between the different stakeholders involved in the development and use of bipedal systems.

Anthony Remazeilles, Alfonso Dominguez, Pierre Barralon, Diego Torricelli
##### A Methodology for Benchmarking Force Control Algorithms

Force control is nowadays a mature technology, widespread in modern robotics systems and commercialized within several application domains. However, assessing the performance of a force-controlled system is not a trivial task because it may be strongly influenced by the environment dynamics. Exerting a force on a soft environment is different from exerting a force on a rigid environment. Indeed, the same force-controlled robot can have different force responses in different environments and a standardized and comprehensive method to assess the performance of a force-controlled system is not available yet. This paper, as part of the Forecast project, aims at filling this gap by proposing a benchmarking method able to define a comprehensive score for a given force-controlled system accounting for its sensitivity to environment uncertainties and variations. This paper describes such benchmarking methodology which allows to compare force control algorithms on a common ground and to determine the preferable control solutions in a specific application domain.

R. Vicario, A. Calanca, N. Murr, M. Meneghetti, E. Sartori, G. Zanni, P. Fiorini
##### Limitation of Ankle Mobility Challenges Gait Stability While Walking on Lateral Inclines

Exoskeletons often allow limited movement of the ankle joint. This could increase the chance of falling while walking, particularly on challenging surfaces, such as lateral inclines. In this study, the effect of a mobility limiting ankle brace on gait stability in the frontal plane was assessed, while participants walked on lateral inclines. The brace negatively affected gait stability when it was worn on the leg that was on the vertically lower side or ‘valley side’ of the lateral incline, which would indicate an increased risk of falling in that direction.

Maarten R. Prins, Nick Kluft, Wieke Philippart, Han Houdijk, Jaap H. van Dieën, Sjoerd M. Bruijn
##### A Workaround for Recruitment Issues in Preliminary WR Studies: Audio Feedback and Instrumented Crutches to Train Test Subjects

One of the main problems in studies involving exoskeletons for assisting gait of Spinal Cord Injury (SCI) users is recruitment of a suitable number of subjects, especially when age, gender, and pathologies are considered. Studies involving able-bodied subjects could instead rely on a considerable number of subjects, but the reliability of the results when transferred to real exoskeleton users is limited. This limitation could be partially solved using able-bodied subjects for preliminary tests. In this paper, we describe a first approach to train able-bodied subjects to behave as SCI subjects during walking. An audio feedback driven by a pair of instrumented crutches has been used to train healthy subjects during exoskeleton walking. To test the system, 22 able-bodied subjects have been analyzed during a straight walk with and without the audio feedback. Results show that the audio feedback induces a learning effect and a persistency effect in the participants.

Matteo Lancini, Simone Pasinetti, Marco Ghidelli, Pietro Padovani, David Pinto-Fernández, Antonio J. del-Ama, Diego Torricelli
##### 3D Relative Motion Assessment in Lower-Limb Exoskeletons: A Case of Study with AGoRA Exoskeleton

Different studies have been conducted to assess the performance of several features of exoskeletons. One of the most critical component is the physical interfaces which transfer the energy to the user. Nevertheless, they have been isolated within the assessment process. In this sense, this work presents a 3D relative motion methodology to evaluate a lower-limb exoskeleton’s physical interfaces. One male subject wore the AGoRA exoskeleton to apply the proposed methodology using an optoelectronic system. Kinematic results showed the 3D human-robot interaction (HRI) of the user’s thigh, identifying an undesired degree of freedom of 36.5 $$^{\circ }$$ ∘ among the gait cycle. Hence, the implications of this analysis provide a comprehensive indicator of physical interface’s performance.

Felipe Ballen-Moreno, Carlos A. Cifuentes, Thomas Provot, Maxime Bourgain, Marcela Múnera
##### Robotic Rehabilitation in Cerebral Palsy: A Case Report

Cerebral palsy includes several posture and movement disorders which produce limitations in functional activities such as gait. In recent years robotics have been used as a complement of the treatment of neurological pathologies. The exoskeleton Ekso bionics enables professionals to perform treatments to improve gait in patients with cerebral palsy. After 24 sessions many spatiotemporal and kinematic parameters were improved in one patient with cerebral palsy.

Beatriz Moral, Óscar Rodríguez, Elena García, Eduardo Rocón, Sergio Lerma
##### Test Method for Exoskeleton Locomotion on Irregular Terrains: Testbed Design and Construction

This work aims to define a benchmarking scenario for the evaluation of the performance of lower limb exoskeletons while walking on irregular terrains. We designed a modular testbed that can be easily configured to replicate a wide range of uneven terrains. The testbed, based on several design criteria such as modularity, reproducibility, robustness and low-cost, aims to be a concrete solution to researchers and developers to test their systems according to a standardized method. The long term goal is to provide means to demonstrate the ability of new exoskeletal systems to operate safely and reliably in realistic out-of-the-lab conditions.

A. Torres-Pardo, D. Pinto-Fernández, E. Belalcázar-Bolaños, J. L. Pons, J. C. Moreno, D. Torricelli

#### Small–Medium Enterprises in the Wearable Robotics Field: Tools and Opportunities to Create a Successful Company

##### Private/Public Funding Strategies for Interactive Robotics Companies

The aim of is paper is to provide a structured view of funding possibilities for companies in the field of interactive robotics. The paper presents a set of funding sources which are of interests for start-ups, spin-off and young companies working in the design and development of interactive robots, including wearable devices. This paper is divided into three chapters, covering private funding (types of existing funding sources, their specific target companies and requirements, and the reasons on how and why investors invest), public funding (mainly coming from European grants under several programs) and the conclusions.

Arantxa Rentería-Bilbao
##### RobotUnion Project: Accelerating Startups in Robotics

RobotUnion discovers, supports and funds 20 European scaleups confirmed by venture capital investors and global corporates of four market domains for robotics: manufacturing, agriculture, healthcare and civil infrastructure. 40 companies developing selected out of a pan-European deal flow of 300 scaleups through 2 Open Calls. The top 20 have joined an acceleration programme that helps them progress from TRL4 to TRL7 onwards. The programme provides them with technical and non-technical support services: researchers in residence, entrepreneurs in residence, vouchers to access to facilities and technical services, public and private funding.

Leire Martínez, Arantxa Rentería-Bilbao
##### Starting Up a Surgical Robotics Company: The Case of Kirubotics

This paper presents the steps followed by the Spanish start-up company Kirubotics, whose aim is to develop and market an innovative concept of surgical robot. It covers the phases of design, development of a functional protype, tests in laboratory, market research, analysis of regulatory requirements and contacts and agreements with future potential providers of components. In parallel, different types of funding sources have been achieved, while others are still being looked for. The process is still open. Preliminary results show that, as important as an innovative idea and a good technical team, it is to have enough economic backup at the right moment of the overall process.

Arantxa Renteria-Bilbao, Fernando Mateo, Leire Martínez
##### Redesigning Tax Incentives for Inclusive and Green Robotics in the European Union Reconstruction

With a view to help with the urgent socio-economic recovery after the COVID-19 pandemic, the goal of this paper is to show a possible path to promote, through tax incentives for Responsible Research and Innovation, sound uses of robots in this context. Its scope is in line with the current priorities in the European Union, which are in turn aligned with the United Nations 2030 Agenda on global Sustainable Development. Some proposals are made to address the needs of social returns in the form of inclusive and green robotics, based upon the results of a jurisprudential critical review (focused in the Spanish experience as a tool for comparative Law analysis), bearing in mind relevant previous judgments of the European Union Court of Justice in the field and a recent tool presented by the OECD.

María Amparo Grau Ruiz
Title
Wearable Robotics: Challenges and Trends
Editors
Dr. Juan C. Moreno