Kinematic analysis and design of surface wave distributed actuators with application to a powered bed for bedridden patients

A surface wave distributed actuation method and its potential for transporting bedridden patients is explored. First, the basic principle of surface wave distributed actuation is presented, followed by kinematic modeling and analysis. Based on the analysis, modifications to natural wave transport are made to enhance transport efficiency and human comfort. Further kinematic analysis reveals that an object can be transferred by a simplified actuator architecture that makes the concept amenable to hardware realization. Two proof-of-concept prototypes are designed, built, and tested. The first is a powered water bed consisting of a water vat, a flexible mat placed on the water surface, and an exciter creating surface waves at resonant frequencies. The other is a powered mechanical bed having an array of coordinated active nodes that generate psuedo-continuum surface waves. Experiments demonstrate the surface wave actuation concept and verify the analytical results.