Shoe-Type Postural Stabilization Training System with Vibration Stimulation

Takeshi Tsuruga, Tomohiro Nomura, Norio Kato

Fall prevention, Postural control, Vibration stimulation, Sensor-actuator insole

In this study, we propose a shoe-based training system for preventing falls in elderly populations and evaluate the performance of its core component, namely the sensor-actuator insole, which is a low-cost, portable device that incorporates vibration motors and pressure sensors. To investigate the perceptual characteristics of vibration stimuli applied to a plantar surface, we examine combinations of various insole materials, which vary in thickness and hardness, and applied voltages to the vibration motors. The proposed system enables balance training by inducing center of pressure (COP) displacement through targeted vibration stimuli. To estimate the COP from pressure sensor outputs, individual calibration equations are derived using multiple regression analysis based on data collected from a force plate. In the verification experiment, for subjects instructed to lean in the direction of the presented vibration stimuli, COP coordinates estimated from the sensor-actuator insole are compared to those measured by the force plate. The results show that the mean COP estimation error using the regression model is 4.2 mm (standard deviation = 2.5 mm), indicating generally good accuracy using simple, low-cost sensors. A negative correlation (r = –0.58) is found between foot length and estimation error, suggesting that subject-specific characteristics may influence measurement precision. With further refinements, such as adjustments for individual differences, the proposed system has potential as a practical tool for supporting fall prevention in elderly populations.

https://doi.org/10.31871/IJNTR.11.6.3