Student Designed Projects - Rotational Mobility System for Bed-Ridden Patients

A new system designed by mechanical engineering students at FSU would make it easier for people suffering from debilitating injuries or diseases to perform an important basic function—independently rolling from side to side in bed.

Seniors Andrew Limbaugh, Shawn Miller, Adam McCoy, David Diehl, and Phil Wagner spent the spring semester working on a system that could be permanently mounted to a bed and extending a few inches from each side, intended to have minimal impact on space availability near the bed. It is centered around a powered device that raises the handrails, supplying tension to a strengthened bed sheet underlying the patient. This strengthened sheet is routed over rollers which are integral to the handrails of the bed, giving it a ‘u’ shape with the patient in the bottom of the ‘u.’ The rollers are padded so that when in the lowered position, it is not uncomfortable for the patient. The opposite ends of the sheet are attached to two individual spools located underneath the bed, which act as the prime movers.

The process of rolling an individual over begins with the use of a corded remote located near the head of the bed. The patient chooses the desired roll direction on the control panel to initiate the automated rolling sequence. First, the handrail assemblies on the sides of the bed are raised to the optimal operating position. This ensures correct tension in the sheet and slightly lifts the patient off the mattress, lowering resistance to the rotational motion. Once lifted to the proper position, the spools turn causing the strengthened sheet to travel over the various rollers and under the patient, supplying the necessary rolling motion. Once the desired angle of roll has been completed, the rollers are then gently lowered back to their original position and the spools remove any excess slack from the strengthened sheet.

Prior to developing the actual design, the students first had to set a budget and a pertinent Gantt chart. They then conducted a generalized survey, supplemented with interviews of individuals that would benefit from such a device, to determine the desired characteristics. This was followed by the detailed design stage. As the various subsystem designs were completed, the students purchased materials and assembled them. Assembly began with a 1/4-scaled version of the system. Once that model was completed, the students tested and refined their design and made any necessary changes. The system was then recreated in a full scale to be used on a regular size bed.