Estimation and Minimization of Body Load during Sit-to-Stand Movement for Rehabilitation

Abstract

Equipment developed for rehabilitation commonly carries patients in reference movements that are generally based on natural movements of healthy people. This type of movement may not place the lowest load on a patient's body. We propose a selecting process of an index value that quantifies the body load during sit-to-stand (STS) movement to evaluate natural movements of a person and to calculate an optimized movement about a specific part of the body for individualized rehabilitation. The computation starts by collecting kinematic and kinetic data, estimating the forces and moments, and then extracting an index value of the movement that quantifies the body load. The index value strongly correlates with the chair height, and decreasing the value of this index by changing the movement during STS transfer could reduce the impact on the body, which is the same amount of load as that placed on the body while standing up from a higher chair height. A modified STS movement that can minimize the body load is finally computed. The results of this study could be used to help users see how much force and moment are placed on the ankle, knee, and hip joints, and provide a personalized optimum movement for rehabilitation with reduced body load on patients.