Natural surface waves, created by periodic circular motion of material particles, can transfer a long object placed upon the crests of the waves in an arbitrary direction within the horizontal plane. Inspired by this natural behavior, a surface wave distributed actuation method and its potential for transporting bedridden patients is explored in this paper. 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. Finally, design trade-offs and guidelines for developing a feasible and practical surface wave bed are discussed based on the prototyping and experiments.

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.

Bedridden patients and elastic bodies are transported by a novel ball transfer mechanism about their support surface. A series of spherical balls are constrained in their position in the support surface, but are allowed to rotate freely in three dimensions. A series of 'bed bugs' are coordinated to provide flexible support and tangential motion patterns of the human patient. This ball drive actuation allows a bedridden patient to move freely while lying upon the bed. First, the design concept is explained, then a description of the important parameters and performance measures is made. Interactions between the soft tissue and the bed surface with a ball transfer mechanism are addressed, and technical requirements for transporting humans and elastic bodies will be obtained. A proof-of-concept prototype has been designed and will be tested to verify model results and the manipulation concept.

Bedridden patients and elastic bodies are transported by generating surface waves on an active bed. Surface waves are shown to be a viable transport mechanism for large-scale, elastic bodies given certain conditions and constraints on the design. Surface wave actuation allows a bedridden patient to move freely while lying comfortably upon the bed. The motion of each node on the bed surface is coordinated such that it follows a circular trajectory with a certain phase lag from adjacent nodes. Basic properties of surface waves are presented. Based on these properties a new, concept, the extender, is added to the design to take advantage to the inherent rotational component of surface wave points. Kinematic analysis is performed to characterize the actuation concept. Sensitivity of design parameters on critical human transport issues is presented. Transport speed and efficiency are analyzed as well. A proof-of-concept prototype is designed, built and tested. It is demonstrated that a human is moved along the bed surface while lying on the bed.

A hybrid wheelchair/bed system for bedridden persons is developed and tested. A powered wheelchair can be docked to a bed portion and reconfigured to a flat stationary bed so that the bedridden person does not have to change seating when transferring between the chair and bed. Moreover the wheelchair can also be docked to a toilet directly and automatically. A holonomic omnidirectional vehicle with a ball wheel mechanism is used for the wheelchair. The high maneuverability and holonomic nature of the vehicle allow the chair to be docked easily and precisely against a fixture. The wheelchair is equipped with teleconferencing facility so that the bedridden patient may communicate face-to-face with a distal caregiver, friends and relatives. This paper describes the basic concept of the reconfigurable holonomic omnidirectional mobile bed with unified seating (RHOMBUS). Issues on the mechanical design of the vehicle, chair, and bed are addressed, followed by control issues. A force-guided docking control method using force sensors embedded in the bumper of the vehicle is developed. A prototype system is designed and tested.