Wheelchair seating evaluation system ∼ Introduction of system functions ∼

In this study, a system for evaluating the wheelchair seating posture is introduced. The system consists of three subsystems: a seating posture changing system, a seating posture analysis system, and a propulsion analysis system. The seating posture changing system uses pneumatically controlled airbags installed in the wheelchair seat to change the posture of the patient and aims to generate a good posture heuristically. The seating posture analysis system uses seat sensors, video cameras, and whose analysis software to measure and analyze the current posture by seat sensors. One of the features of the analysis system is that the shape of the spine is estimated virtually, as the shape is one of the best indicators of a patient's posture. From the current seating posture, the propulsion analysis system estimates the posture, driving force, and muscular forces necessary to propel the wheelchair. Basic hardware and software for the pneumatically controlled functions have been developed for the posture changing system, and the displacements of the human body were measured by a 3D motion analysis system when four airbags were filled with air independently. A method to estimate the spinal shape by the finite element method (FEM) using beam elements has been developed for the seating posture analysis system. This method has a fast processing time and takes external forces into consideration. A method that can estimate the position of the neutral axis of the spine from markers placed on body surfaces was also developed. For the propulsion analysis system, propulsion motion and muscular forces of a subject in the wheelchair with a seat cushion or a back seat cushion were analyzed. Future work includes the development of the remaining functions, such as the overlay display function of the video camera images and sensor data, and the integration of the entire system.