A Depressurization Motion Assistance for a Seated Wheelchair User Using Pressure Distribution Estimation

For reducing the risk of pressure sore caused by long period sitting on a wheelchair, we have developed a depressurization motion assistance system which is low cost and suitable for practical use. Our developing system consists of a seating cushion which the patient sits on and four air cells which can lift or incline the seating cushion. Each air cell is actuated by small air compressor, which can drive using batteries on the wheelchair respectively, and each compressor has a pressure sensor on its body. In this paper, we develop the depressurization assistance control scheme based on the pressure distribution estimation. For realizing the pressure distribution estimation during the depressurization motion, we analyze the hip depressurization operation by the nursing specialists and from analytical results, our system uses the center of pressure as an index value. Using the estimated results, our system controls the inclination of its seating cushion for increasing the depressurization performance. With our proposed system, the patient can depressurize on his sacral part without special operation. The performance of our system is verified by experiments using our prototype.