Analysis of Physical Characteristic Differences in Sit-to-Stand Motions Using Gaussian Process Dynamical Model

Abstract

Sit-to-stand motion is one of the most crucial activities in daily life because its difficulty can significantly impact the quality of life. Since this action involves various physical characteristics such as muscle strength of the trunk and lower limbs, joint mobility, and sense of balance, its measurement data may contain a great deal of information to evaluate the qualitative deterioration of the locomotor system that may increase the risk of falls and other problems. In this study, we analyze sit-to-stand motion data using the Gaussian Process Dynamical Model (GPDM) to identify which aspects of body movements show differences depending on the acting person’s physical characteristics, aiming at a computational method to evaluate the functional level of one’s locomotor system. The GPDM generates low-dimensional latent variable models to summarize sit-to-stand motions under different physical constraints imposed by a geriatric simulation kit. The model’s output shows that the difference in the left-right balance of the ease of body movement affected the lateral shift of the center of the body mass during the postural change from the start of the standing up to the completion of the buttocks release phase.