An automatic adjustable backrest for a posture coordination of a seated patient on a wheelchair

For reducing a risk of pressure sore caused by long period sitting on a wheelchair, a patient is required to depressurize buttocks by changing the posture suitably. Thus, we have been developed an automatic depressurization motion assistance system for a seated patient on a wheelchair. In our previous work, we developed a sitting surface coordination system which can lift or incline and assists a depressurization motion of a patient. However, in some cases, it is difficult to change his posture suitably for patients who do not have enough physical strength in their upper body using our proposed device. Therefore, in this paper, we propose a novel posture coordination assistance system for a wheelchair user. Our system consists of the adjustable sitting surface and novel proposed adjustable backrest. These two devices coordinate the sitting posture of the patient automatically. Our key ideas are two topics. One topic is mechanical design of the adjustable backrest for practical use. We realize small mechanism which enables easy implementation to a general wheelchair without special reconstruction. The other topic is a natural posture coordination scheme using the sitting surface and the backrest. We analyze buttocks depressurization operation by a nursing specialist and drive our proposed devices for realizing it. The performance of our system is verified by experiments using our prototype.