Title: Modelling friction at the mechanical interface between the human and the exoskeleton

Authors: Divyaksh Subhash Chander; Maria Pia Cavatorta

Addresses: Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca Degli Abruzzi, 24, 10129 Torino, Italy ' Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca Degli Abruzzi, 24, 10129 Torino, Italy

Abstract: In virtual assessments of exoskeletons, often, friction is not modelled even though the actual interface consists of straps or moulded surfaces, where friction could play a significant role. In this work, the human-exoskeleton interaction during the use of a passive lower limb exoskeleton is modelled in three test cases through two different interface models. In particular, a model introducing friction at the human-exoskeleton interface is compared with a more conventional model that uses a kinematic joint to simulate the interface forces. Both the models show a good match between the empirical and predicted distribution of body weight between the subject and the exoskeleton. However, the results also show different trends of the moment required at the assisted joint by the different interface models, highlighting the importance of a realistic interface model to investigate the effectiveness of the exoskeleton in virtual assessments.

Keywords: musculoskeletal model; industrial exoskeleton; virtual assessment; human-exoskeleton interaction; passive exoskeleton; interface forces; biomechanics; exoskeleton effectiveness; friction modelling; lower limb exoskeleton.

DOI: 10.1504/IJHFMS.2019.105434

International Journal of Human Factors Modelling and Simulation, 2019 Vol.7 No.2, pp.119 - 136

Received: 29 Jul 2019
Accepted: 13 Nov 2019
Published online: 28 Feb 2020 *

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