A First Design of the Inertially Correct Testbed Arm Platform for Testing of Wearable Devices

Wearable systems for rehabilitation and assistive applications presents significant challenges related to personalization to individual size and shapes of the users' limbs, which can often turn design into a slow and challenging trial and error process. Additionally, because of the limited amount of body shapes and sizes that can be tested in research settings, wearable systems risk being ill-suited when it comes to adapting to individual users, and can be perceived as difficult or uncomfortable to interact with. In this paper we propose to address this challenge through the design of simple and relatively lowcost physical simulators. In this first iteration we offer a proof of concept of this approach with the Inertially Correct Arm, a physical prototype that is designed to have the shape and inertia properties consistent with anthropometric data on the average arm for male population and is intended as a tool to aid development of a soft arm-swing exosuit. In addition to the inertia properties, we tested a few different configurations for damping obtained through deformable pads compressed between plates at fixed distances, and compared the results of free swinging from a 90 degree shoulder elevation from the ICT with results from human participants, as quantified by dynamic time warping distances. Our results show that the system follows human data more closely when a higher level of joint resistance is present.