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

Occupational Exoskeletons: Understanding the Impact on Workers and Suggesting Guidelines for Practitioners and Future Research Needs

This paper examines occupational exoskeletons and their effects on workers. The study includes a thorough evaluation of the current literature on occupational exoskeletons, with an emphasis on the impact of these devices on workers’ health and the safety, performance and users’ subjective perceptions. The aim of the study was to gain knowledge of how exoskeletons affect the workers and to identify practical suggestions for practitioners. The findings of the study suggest that exoskeletons can have both positive and negative effects on workers. Some users claimed enhanced comfort and decreased fatigue, whilst others reported discomfort and suffering. The study highlights the importance of considering the individual needs and preferences of workers when selecting and implementing exoskeletons in the workplace, with a focus on health, safety, performance and user acceptance. Based on the findings, the paper presents suggestions for employers and practitioners to ensure the effective and safe use of exoskeletons in occupational settings. These recommendations cover areas such as the assessment of workplace requirements, the selection and fit of exoskeletons, the optimization of design and ergonomics and the evaluation of performance. The paper concludes by highlighting the need for further research in this area, particularly in the areas of long-term use

Sensor-Based Task Ergonomics Feedback for a Passive Low-Back Exoskeleton

Low-back exoskeletons are a wide-spreading technology tackling low-back pain, the leading work-related musculoskeletal disorder in many work sectors. Currently, spring-based (i.e., passive) exoskeletons are the mostly adopted in the industry, being cheaper and generally less complex and more intuitive to use. We introduce a system of interconnected wireless sensing units to provide online ergonomics feedback to the wearer. We integrate the system into our passive low-back exoskeleton and evaluate its usability with healthy volunteers and potential end users. In this way, we provide the exoskeleton with a tool aimed both at monitoring the interaction of the system with the user, providing them with an ergonomics feedback during task execution. The sensor system can also be integrated with a custom-developed Unity3D application which can be used to interface with Augmented- or Virtual-Reality applications with higher potential for improved user feedback, ergonomics training, and offline ergonomics evaluation of the workplace. We believe that providing ergonomics feedback to exoskeleton users in the industrial sector could help further reduce the drastic impact of low-back pain and prevent its onset

Neuromechanics and Augmentation of Muscle-Tendon Actuators in Unsteady Cyclic Tasks

Legged animals navigate complex environments with incredible stability, agility and economy despite having significant neuromechanical constraints like large delays and highly compliant actuators. They do so partly by tuning the mechanics of their actuators (i.e. muscle-tendon units) to act in a context-dependent manner. This raises several questions, three of which are discussed in this thesis. (A) to what extent can you purely rely on the mechanics of your actuators? In particular, can muscle-tendon units reject perturbations like uneven terrain without changing neural control? (B) how does stability, agility and economy vary with changing muscle-tendon properties individually and how do they tradeoff? and (C) if morphology affects movement performance in animals, can we augment human function across multiple objective functions (namely stability agility and economy) simultaneously by augmenting the morphology of muscle-tendon units with passive wearable robots. To answer these questions in a causal, controllable and generative manner, we developed a framework where a single muscle-tendon unit is interacting with a mass in gravity through a lever arm in closed loop to generate cyclic movement with variable terrain (both in simulation and in-vitro closed-loop experiments), variable morphology (in simulation) and variable nervous system control (in simulation). Through our work, we show that (A) muscle-tendon units can rapidly stabilize a hopping body when faced with a sudden change in ground height despite zero change in neural control, (B) series elastic tendons variably influence stability, agility and economy of movement such that animals need to trade off stability, agility and economy when tuning their muscle-tendon properties and (C) passive elastic exoskeletons are able to simultaneously augment stability, agility and economy despite being 'spring-like' and unable to do net work themselves by shifting the mechanics of underlying muscle-tendon units. Through our research, : (1) we gain fundamental neuromechanical understanding of how animals enable stable, agile and economic movement by tuning their actuators and (2) we generate a template for the design of a new generation of bioinspired robotic actuators to enable legged and wearable robots to navigate the world in all its richness and complexity.Ph.D

A Review of Lower Limb Exoskeletons

In general, exoskeletons are defined as wearable robotic mechanisms for providing mobility. In the last six decades, many research work have been achieved to enhance the performance of exoskeletons thus developing them to nearly commercialized products. In this paper, a review is made for the lower limb exoskeleton concerning history, classification, selection and development, also a discussion for the most important aspects of comparison between different designs is presented. Further, some concluding remarks are withdrawn which could be useful for future work. Keywords: Exoskeletons, Lower extremity exoskeleton, Wearable robot

Modeling of a Non-Rigid Passive Exoskeleton-Mathematical Description and Musculoskeletal Simulations

There is a growing application of passive exoskeletons in the industrial sector with the purpose to reduce the incidence of work-related musculoskeletal disorders (MSDs). Nowadays, while many passive shoulder exoskeletons have been developed to support overhead tasks, they present limitations in supporting tasks such as load lifting and carrying. Further developments are therefore needed to have a wider application of these devices in the industrial sector. This paper presents a modelling procedure of a passive non-rigid exoskeleton for shoulder support that can be used to evaluate the device in its development phase. The modelling began with the definition of the equations to describe the exoskeleton kinematics and dynamics to obtain the support force profile provided by the device over the shoulder flexion angle. A musculoskeletal simulation software was then used to evaluate the effect of the device on the human body. The computed support force profile is in agreement with the purpose of the device, with the maximal support force obtained for a shoulder flexion angle of 85–90°. The maximum support force value had the same magnitude as the one reported by the device user manual (3.5 kg). In particular, for a determined exoskeleton configuration, the maximum support force value computed was 34.3 N, equal to the reported by the manufacturer. The subsequent musculoskeletal simulation showed the ability of the device to reduce the muscular activation of agonist muscles such as the anterior deltoid (−36.01%) compared to the case when the exoskeleton is not used. The musculoskeletal results showed a positive effect of the device on the joint reaction forces at the glenohumeral joint with a reduction up to 41.91%. Overall the methodology and the mathematical model proposed can be used to further develop these devices, making them suitable for a wider range of tasks

Development and Biomechanical Analysis toward a Mechanically Passive Wearable Shoulder Exoskeleton

Shoulder disability is a prevalent health issue associated with various orthopedic and neurological conditions, like rotator cuff tear and peripheral nerve injury. Many individuals with shoulder disability experience mild to moderate impairment and struggle with elevating the shoulder or holding the arm against gravity. To address this clinical need, I have focused my research on developing wearable passive exoskeletons that provide continuous at-home movement assistance. Through a combination of experiments and computational tools, I aim to optimize the design of these exoskeletons. In pursuit of this goal, I have designed, fabricated, and preliminarily evaluated a wearable, passive, cam-driven shoulder exoskeleton prototype. Notably, the exoskeleton features a modular spring-cam-wheel module, allowing customizable assistive force to compensate for different proportions of the shoulder elevation moment due to gravity. The results of my research demonstrated that this exoskeleton, providing modest one-fourth gravity moment compensation at the shoulder, can effectively reduce muscle activity, including deltoid and rotator cuff muscles. One crucial aspect of passive shoulder exoskeleton design is determining the optimal anti-gravity assistance level. I have addressed this challenge using computational tools and found that an assistance level within the range of 20-30% of the maximum gravity torque at the shoulder joint yields superior performance for specific shoulder functional tasks. When facing a new task dynamic, such as wearing a passive shoulder exoskeleton, the human neuro-musculoskeletal system adapts and modulates limb impedance at the end-limb (i.e., hand) to enhance task stability. I have presented development and validation of a realistic neuromusculoskeletal model of the upper limb that can predict stiffness modulation and motor adaptation in response to newly introduced environments and force fields. Future studies will explore the model\u27s applicability in predicting stiffness modulation for 3D movements in novel environments, such as passive assistive devices\u27 force fields

Investigation into the applicability of a passive upper-limb exoskeleton in automotive industry

The fourth industrial revolution faces the technological challenge of human-robot cooperation in manufacturing process. Aim of this study was to investigate the effectiveness and user’s acceptance of a passive exoskeleton for upper limbs. Three different tests, involving static and dynamic tasks, were performed by 29 automotive operators without and with the exoskeleton. Main aspects and results of the testing campaign are presented in the paper. Potential issues associated to the introduction of these auxiliary devices in the automotive industry are briefly addressed, together with the open questions on how to assess the biomechanical workload risk, especially in the design phase

Feasibility Study of a Passive Pneumatic Exoskeleton for Upper Limbs Based on a McKibben Artificial Muscle

Exoskeletons are wearable structures or systems designed to enhance human movement and to improve the wearer’s strength or agility, providing auxiliary support aimed at reducing efforts on muscles and joints of the human body. The aim of this work is to discuss on the feasibility of a new passive upper limb exoskeleton, based on the use of pneumatic artificial muscles, and characterized by extreme lightness, cheapness, and ease of use. A broad overview of the state of the art on current exoskeletons is introduced. Then the concept of the new device is presented, and different transmission architectures between pneumatic muscle and limb are discussed. The study demonstrates the potential effectiveness of such a device for supporting an operator in heavy work condition

Modeling and Design of a Spring-loaded, Cable-driven, Wearable Exoskeleton for the Upper Extremity

An approach to the design of wearable exoskeletons on the basis of simulation of the exoskeleton and a human body model is proposed in this paper. The new approach, addressing the problem of physical human-exoskeleton interactions, models and simulates the mechanics of both the exoskeleton and the human body, which allows designers to effectively analyze and evaluate an exoskeleton design for their function in concert with the human body. A simulation platform is developed by integrating a biomechanical model of the human body and the exoskeleton. With the proposed approach, an exoskeleton is designed for assisting patients with neuromuscular injuries. Results of the analysis and optimization are included