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Session: Poster session 2 (Odd numbers)
Session starts: Friday 27 January, 10:00
Presentation starts: 10:00

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Alexandre Ratschat (Delft University of Technology; Erasmus University Medical Center)
Gerard Ribbers (Erasmus University Medical Center)
Laura Marchal-Crespo (Delft University of Technology; Erasmus University Medical Center)

Abstract:
Neuroscientific evidence suggests that people after stroke should engage in task-specific, high-intensity training to maximize their recovery [1]. Additionally, somatosensory information plays a fundamental role in generating skillful movements [2]. Current rehabilitation robots do provide high-intensity training, however only for non-functional movements and with limited simulation of somatosensory information [3]. As part of the HyperRehab project, we aim to simulate realistic tangible virtual objects to effectively train activities of daily living using an upper-limb exoskeleton and immersive virtual reality. Here, we focus on the users’ perception of simulated objects in combination with robotic assistive strategies like arm weight support. We plan to assess the weight perception for four conditions: (1) Lifting real weight, (2) lifting weight simulated by an upper-limb exoskeleton, (3) lifting real weight with arm weight support from an exoskeleton, and (4) lifting weight simulated and arm weight supported by an exoskeleton. This study will be performed with 24 healthy participants. Using a two-alternative forced choice and an up-down transformed response method we will determine the just notable difference (JND) of weight perception for the four conditions while monitoring the muscular activation using Electromyography. We expect the JND for the real weight conditions to be lower than the JND of the simulated weight conditions since the robot currently has no capabilities to render tactile stimuli related to weight perception. For the assistive arm weight support conditions the assistance and weight simulation signals are rendered by the same actuators of the robot, potentially leading to hampered weight discriminability, i.e. higher JNDs. Finally, we will analyze how muscle activation differs per condition and whether this correlates with the perception of weight differences. The results of this study will help us to improve our understanding of tangible virtual object perception in upper-limb rehabilitation. Based on our findings, we will propose guidelines to enable realistic perception of tangible virtual objects, leading to improved transfer from training in the clinics to daily life and ultimately improving the quality of life of people after stroke.