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Graduate, Undergraduate Category: Engineering, Health, Rehabilitation Degree Level: PhD,MSc Abstract ID# 430

Assessment of Ankle’s Motor Control Using Virtually Interfaced Rehabilitation Robotic System Mohsen

1 Nabian ,

,2 Farjadian ,

3 Hartman ,

Amir B. Amber John Constantinos Mavroidis1, 2, Maureen K. Holden2, 3

3 Corsino ,

Department of Mechanical and Industrial Engineering1, Bioengineering2, Department of Physical Therapy3, Northeastern University

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Millions of individuals are affected by neurological diseases and injuries that impact physical function Dysfunction of muscles around the ankle is a common residual impairment that affects balance and gait There is no robotic device on the market that reduces rehabilitation costs vi-RABT is a robotic device for retraining motor control at the ankle (Fig. 1) vi-RABT has 2 degree of freedom (DOF) actuation with angle and torque measurement mechanisms The robotic device is interfaced with a series of virtual reality (VR) games for retraining ankle function (Fig. 2) VR games performed with either force- or motioncontrol (Fig. 3) 5 healthy subjects recruited for pilot study to examine performance between 2 control mechanisms Early results indicate participants have better performance with motion-control than force-control in tasks with 2-DOF

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Subjects’ maximal force production was assessed for PF/DF (plantarflexion/dorsiflexion, IV/EV (inversion/eversion)(Table 1). Single-axis ROM was assessed for PF/DF, IV/EV (Table 1). Assessment findings were used to set parameters within the games; for example, the user may have to perform 80% of maximal dorsiflexion to reach a target. Subjects participated in 2 blocks of 30 trials each, for each of 3 VR games, under two conditions: Force-control and Positioncontrol: The first 2 games were the ‘Board’ game (Fig. 3 – left) played in single-DOF mode, then in 2-DOF mode. The 3rd game, ‘Maze” game (Fig. 3- Right), was played with 2-DOF only. For the Maze game, errors (wall collisions) were also counted.

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• Early results from the first five subjects are reported here. We compared time to acquire 30 targets using force vs. motion control in different game settings. • Subjects demonstrated a significantly better performance for motion control vs. strength control when performing in the two axis mode (Fig. 4 – Right). Error scores had a similar pattern. • Subjects did not show a significant difference for motion control vs. strength control when performing in the single axis mode (Fig. 4 – Left )

Strength Motion

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[1] V. L. Roger, et. al., “Executive summary: heart disease and stroke statistics--2012 update: a report from the American Heart Association,” Circulation, vol. 125, no. 1, pp. 188–197, Jan. 2012. [2] B. R. Waterman, B. D. Owens, S. Davey, M. A. Zacchilli, and P. J. Belmont Jr, “The epidemiology of ankle sprains in the United States,” J Bone Joint Surg Am, vol. 92, no. 13, pp. 2279–2284, Oct. 2010. [3] Y. Ding, M. Sivak, B. Weinberg, C. Mavroidis, and M. K. Holden, “NUVABAT: Northeastern university virtual ankle and balance trainer,” in Proc. of the 2010 IEEE Haptics Symposium, pp. 509–514, 2010.