ScholarWorks@성균관대학교

초록

Dynamic arm supports (DAS) help individuals with impaired upper limb function perform activities of daily living. However, most existing systems lack accurate gravity compensation based on user posture, and few studies have explored design methods to reduce required torque. In this study, we propose a novel end-effector-type active DAS (A-DAS) system using a spring joint mechanism driven by a deflected twisted string actuator. The design was optimized for maximum transmission ratio, compactness, and safety. We implemented an assistive force control strategy providing precise assistance based on the user's body weight and desired assistance level. To validate the system, we conducted a simulated eating task with 12 healthy participants. Results showed that the A-DAS provided superior control accuracy (0.48 versus 13.57 mm root-mean-squared error) compared to conventional passive systems. This led to significantly improved muscle activation patterns, showing both reduced activation range ($\kappa$) in the anterior deltoid (33.2% versus 60.9% reference voluntary contraction) and more stable activity (coefficient of variation) in the biceps (32.0% versus 49.0%). Future research will focus on expanding clinical applications to wider patient populations, including those with tremors.

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