The marionette bed: automated rolling and repositioning of bedridden patients

A design for rolling and repositioning a bedridden patient is presented. A pair of actuated rollers are attached to both sides of the bedsheet in order to lift and manipulate the patient body, like a marionette. The patient is gently supported on a hammock-like active bedsheet, creating virtually no shear forces on the patient body. Therefore, the patient can safely and easily be maneuvered with minimal physical assistance! by the caregiver. This prevents development of painful bedsores and of pneumonia. In the paper, functional requirements and design issues are addressed, followed by the basic design concept, mechanism, and control strategy. A prototype is built and initial experiments demonstrate that a human body is rolled and manipulated by the marionette device, providing proof of concept. A simple kinematic model is built to create trajectories for generation of desired body motion. Extended functionalities including bed-to-chair and bed-to-bed transfers, are described at the end.