OCCUPATIONAL APPLICATIONS Many new occupational back-support exoskeletons have been developed in the past few years both as research prototypes and as commercial products. These devices are intended to reduce the risk of lowerback pain and injury for workers in various possible application sectors, including assembly in automotive and aerospace, logistics, construction, healthcare, and agriculture. This article describes the technologies adopted for back-support exoskeletons and discusses their advantages and drawbacks. Such an overview is intended to promote a common understanding and to encourage discussion among different stakeholders such as developers, ergonomics practitioners, customers, and workers. TECHNICAL ABSTRACT Background: The large prevalence and risk of occupational lower-back pain and injury associated with manual material handling activities has raised interest in novel technical solutions. Wearable back-support exoskeletons promise to improve ergonomics by reducing the loading on the lumbar spine. Purpose: Since many new prototypes and products are being developed, this article presents an up-to-date overview of the different technologies. By discussing the corresponding advantages and drawbacks, the objective is to promote awareness and communication among developers, ergonomics practitioners, customers, and factory workers. Methods: The state-of-the-art is presented with a focus on three technological aspects: (i) the actuators generating assistive forces/torques, with a main distinction between passive and active devices; (ii) the structures and physical attachments that transfer those forces/torques to the user, with structures being soft, rigid, or a combination of the two; and (iii) the control strategies employed (i.e., how devices adjust assistive forces/torques to accommodate different activities and parameters). Discussion: The choice of actuation technology may determine the applicability of a device to different scenarios. Passive exoskeletons appear more suitable for tasks requiring relatively light assistance and little dynamic movements. By contrast, heavier and more dynamic tasks will justify the use of more complex active exoskeletons. While onboard battery power is increasingly present on active exoskeletons, the tradeoff between power autonomy and additional battery mass will probably depend on the

SummaryWearable devices are fast evolving to address mobility and autonomy needs of elderly people who would benefit from physical assistance. Recent developments in soft robotics provide important opportunities to develop soft exoskeletons (also called exosuits) to enable both physical assistance and improved usability and acceptance for users. The XoSoft EU project has developed a modular soft lower limb exoskeleton to assist people with low mobility impairments. In this paper, we present the design of a soft modular lower limb exoskeleton to improve person’s mobility, contributing to independence and enhancing quality of life. The novelty of this work is the integration of quasi-passive elements in a soft exoskeleton. The exoskeleton provides mechanical assistance for subjects with low mobility impairments reducing energy requirements between 10% and 20%. Investigation of different control strategies based on gait segmentation and actuation elements is presented. A first hip–knee unilateral prototype is described, developed, and its performance assessed on a post-stroke patient for straight walking. The study presents an analysis of the human–exoskeleton energy patterns by way of the task-based biological power generation. The resultant assistance, in terms of power, was 10.9% ± 2.2% for hip actuation and 9.3% ± 3.5% for knee actuation. The control strategy improved the gait and postural patterns by increasing joint angles and foot clearance at specific phases of the walking cycle.

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Physical interfaces with the body are one of the key enabling component to promote user acceptance, comfort and force transmission efficiency. A structured design workflow is needed for any application-driven product, such as industrial exoskeleton. In this paper, we review objective and subjective evaluation metrics that can be applied to physical interfaces. These indexes are analyzed to create an ordered list of requirements to guide future body attachment design. Pressure magnitude, duration, distribution, direction and time to don and doff are relevant objective indexes related to interfaces. While pain, comfort and ease of operation are subjective indexes. We propose that collecting a suitable set of metrics will lay the foundation for an effective design guideline for industrial exoskeletons.

Exoskeletons are wearable devices intended to physically assist one or multiple human joints in executing certain activities. From a mechanical point of view, they are kinematic structures arranged in parallel to the biological joints. In order to allow the users to move while assisted, it is crucial to avoid mobility restrictions introduced by the exoskeleton’s kinematics. Passive degrees of freedom and other self-alignment mechanisms are a common option to avoid any restrictions. However, the literature lacks a systematic method to account for large inter- and intra-subject variability in designing and assessing kinematic chains. To this end, we introduce a model-based method to assess the kinematics of exoskeletons by representing restrictions in mobility as disturbances and undesired forces at the anchor points. The method makes use of robotic kinematic tools and generates useful insights to support the design process. Though an application on a back-support exoskeleton designed for lifting tasks is illustrated, the method can describe any type of rigid exoskeleton. A qualitative pilot trial is conducted to assess the kinematic model that proved to predict kinematic configurations associated to rising undesired forces recorded at the anchor points, that give rise to mobility restrictions and discomfort on the users.