10 Fakultät Wirtschafts- und Sozialwissenschaften

Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/11

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    Upright posture control in changing gravity conditions
    (2021) Smirnov, Evgenii
    In order to be able to withstand and to take advantage of external forces and to be able to direct motor actions, living organisms developed ability to sense environmental impacts. For instance, proprioceptors and cutaneous receptors allow vertebrates to take into account, above all, gravitational influences. These receptors participate in planning and correcting posture, locomotion and other movements. In this thesis mechanisms of equilibrium control in changing gravity conditions were studied by means of literature analysis and analysis of data obtained in parabolic flight. This analysis revealed that standing balance in overloading is likely controlled in a manner resembling a single-link inverted pendulum. Such behavior could be beneficial to take advantage of passive body structures and to more actively involve foot receptors in balance regulation in challenging conditions. This adaptation also resembles typical postural responses in balance perturbation tasks. The latter were then studied in more detail. Further literature overview supported the suggestion that plantar foot receptors play an essential role in dynamic stability of upright posture. The obtained conclusions allowed to formulate possible mechanisms of sway and balance control and make suggestions on possible implementation of these mechanisms into the neuromusculoskeletal human model proposed by Walter, Gunther, Haeufle, and Schmitt (2021) in order to make equilibrium control of this model robuster.
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    Active exoskeleton reduces erector spinae muscle activity during lifting
    (2023) Walter, Tobias; Stutzig, Norman; Siebert, Tobias
    Musculoskeletal disorders (MSD) are a widespread problem, often regarding the lumbar region. Exoskeletons designed to support the lower back could be used in physically demanding professions with the intention of reducing the strain on the musculoskeletal system, e.g., by lowering task-related muscle activation. The present study aims to investigate the effect of an active exoskeleton on back muscle activity when lifting weights. Within the framework of the study, 14 subjects were asked to lift a 15 kg box with and without an active exoskeleton which allows the adjustment of different levels of support, while the activity of their M. erector spinae (MES) was measured using surface electromyography. Additionally, the subjects were asked about their overall rating of perceived exertion (RPE) during lifting under various conditions. Using the exoskeleton with the maximum level of support, the muscle activity was significantly lower than without exoskeleton. A significant correlation was found between the exoskeleton’s support level and the reduction of MES activity. The higher the support level, the lower the observed muscle activity. Furthermore, when lifting with the maximum level of support, RPE was found to be significantly lower than without exoskeleton too. A reduction in the MES activity indicates actual support for the movement task and might indicate lower compression forces in the lumbar region. It is concluded that the active exoskeleton supports people noticeably when lifting heavy weights. Exoskeletons seem to be a powerful tool for reducing load during physically demanding jobs and thus, their use might be helpful in lowering the risk of MSD.