Spine-Inspired Continuum Soft Exoskeleton for Stoop Lifting Assistance

Abstract

Back injuries are the most prevalent work-related musculoskeletal disorders and represent a major cause of disability. Although innovations in wearable robots aim to alleviate this hazard, the majority of existing exoskeletons are obtrusive because the rigid linkage design limits natural movement, thus causing ergonomic risk. Moreover, these existing systems are typically only suitable for one type of movement assistance, not ubiquitous for a wide variety of activities. To fill in this gap, this paper presents a new wearable robot design approach continuum soft exoskeleton. This spineinspired wearable robot is unobtrusive and assists both squat and stoops while not impeding walking motion. To tackle the challenge of the unique anatomy of spine that is inappropriate to be simplified as a single degree of freedom joint, our robot is conformal to human anatomy and it can reduce multiple types of forces along the human spine such as the spinae muscle force, shear, and compression force of the lumbar vertebrae. We derived kinematics and kinetics models of this mechanism and established an analytical biomechanics model of human-robot interaction. Quantitative analysis of disc compression force, disc shear force and muscle force was performed in simulation. We further developed a virtual impedance control strategy to deliver force control and compensate hysteresis of Bowden cable transmission. The feasibility of the prototype was experimentally tested on three healthy subjects. The root mean square error of force tracking is 6. 63 N (3.3 % of the 200N peak force) and it demonstrated that it can actively control the stiffness to the desired value. This continuum soft exoskeleton represents a feasible solution with the potential to reduce back pain for multiple activities and multiple forces along the human spine.

Design and preliminary evaluation of a flexible exoskeleton to assist with lifting

“…One review reported seven passive back exoskeletons (de Looze et al, 2016), and several designs have been published since then (Lamers et al, 2017;Baltrusch et al, 2020). Similarly, there have been many active back exoskeletons; some recent examples include Huysamen et al (2018), Ko et al (2018), Toxiri et al (2018), Yang et al (2019).…”

Challenges and solutions for application and wider adoption of wearable robots

“…In contrast to stiff devices, soft exoskeletons (also called exosuits) deliver mechanical power to the user using anchors that are typically made of clothing textiles and powered by cable-driven actuation (Awad et al, 2017;Schmidt et al, 2017;Li et al, 2018;Di Natali et al, 2019;Kim et al, 2019a,b;Xiloyannis et al, 2019;Yang et al, 2019;Goršič et al, 2021; Figure 3). Furthermore, soft exoskeletons are typically ergonomic, lightweight, and often designed following bioinspired techniques to better reproduce human physiological movements (Lessard et al, 2018;Figure 3b).…”

A review of soft wearable robots that provide active assistance: Trends, common actuation methods, fabrication, and applications

“…This is especially critical for factory or industrial workers, or other individuals who do repetitive heavy lifting (Babicˇet al 2017;Lamers et al 2018). Several soft systems utilize passive methods of actuation such as pretensioned elastic bands or pulley systems that help support the back at opportune moments for injury (Cho et al 2017;Yang et al 2019). The benefit of actuation that uses tension in-line with the spine is the ability to store and release energy during lifting with the flexion and extension of the trunk.…”