Feasibility of a depth camera-based center of mass feedback system for closed-loop functional electrical stimulation...

Individuals with incomplete spinal cord injury are at an increased risk of falls due to impaired balance control. Our group previously developed a closed-loop visual feedback balance training (VFBT) system combined with functional electrical stimulation (FES) therapy to provide standing balance therapy (FES + VFBT system). However, its clinical use has been limited by the reliance on force plates, which are costly and not widely available. The purpose of this study was to develop and evaluate a clinically accessible FES + VFBT system that uses a depth camera in place of a force plate to provide center of mass (COM) feedback. Ten neurologically intact participants (6 males, 4 female) completed three sets of four balance exercises. The COM estimates from the depth camera-based system showed very good correlation with the force plate-based system (r_AP>0.85;r_ML>0.7) and low root mean squared error, RMSE, (RMSE_AP<0.009 m; RMSE_ML<0.017 m). The stimulation profiles derived from the COM estimates from the depth camera-based system also closely matched those from the force plate system (RMSE<1.8 mA). These results demonstrate that the proposed depth camera-based FES + VFBT system performs comparably to the original system, offering a more accessible solution for balance therapy in clinical settings.