Detecting the Intention of Sit-to-Stand by Analyzing Reaction Forces on the Foot with Pareto Optimum

This study introduces a novel method for detecting a user's sit-to-stand (STS) intention, focusing on minimizing sensor usage for ease of application in everyday settings. Our approach involves applying an external stimulus to the user's toes when they are likely to stand and analyzing the resulting reaction forces on the foot. In the subject experiments, we optimized thresholds using the Pareto optimum to differentiate STS motions from other similar movements, targeting both correct detection and an earlier detection timing before the user's buttocks leave the seat. Each participant performed five offline tests to establish appropriate thresholds, followed by fifteen online tests to evaluate both the correct ratio and timing of the detection. The results demonstrated a high correct ratio and the successful detection of STS intention approximately 500 ms before the users' buttocks left the seat, demonstrating the potential effectiveness of the proposed method in daily applications.