Dynamic resistance training device for evaluation of tongue motor function

Abstract

In this study, we propose a device for isotonic training of tongue-pushing movements. This device realizes dynamic constant external force resistance training by applying a constant load by a DC geared motor to the tongue during the tongue up-and-down movement. This has a back-drive capability by using a series elastic actuator (SEA) with elasticity in the transmission shaft, and the force can be controlled without using a torque sensor. In addition, vibration is damped by impedance control to ensure a safe response for the tongue movement. The tongue muscle ability of five healthy subjects was evaluated using the proposed device. Subjects with higher maximal isometric contraction rates also had higher rates of upward and downward movement at light loads (1.5 N), but subjects who were able to quickly vocalize /ta/ syllables at oral diadochokinesis (OD) rates tended to have less tongue movement when using this device. From the experimental results, it was found that this device can measure motor agility under constant loading, and the index obtained under light loading correlates with the maximum tongue pressure during isometric contraction and negatively correlates with the OD rate results.