Document Type
Restricted Campus Only
Publication Date
4-22-2025
Abstract
The global environment has progressively adapted to better accommodate individuals with mobility impairments, driven primarily by governmental regulations mandating increased accessibility in public spaces. In contrast, private residences often lacked such adaptations, leaving individuals responsible for procuring and implementing solutions tailored to their specific needs. While various assistive products were available, the high associated costs frequently discouraged their adoption, fostering the user’s feelings of being a burden and delaying access to potentially life-enhancing solutions. To address this issue, Dr. Enright sponsored the development of a lift bed, which functioned as a standard bed while also enabling low effort transitions to mobility aids like walkers or wheelchairs. The objectives of the project were to create a lift bed that would bring the user from a horizontal sleeping position to a semi standing one, specified as to allow them to be easily transferred to a wheelchair. This transition to the vertical must not take longer than 45 seconds, with the bed not occupying more floor space than a standard twin bed, with an overall low run production cost of under $1000.
To achieve this, the final design incorporated three key subsystems: the linear actuators, the frame, and a set of movable handrails to provide user support.
An A-Frame base supports the pivoting portion of the bed via central axle. The moving portion of the bed is then divided into three different parts; the head, middle, and foot sections. The middle section can only pivot about the central axle, while the head and foot sections rotate freely about the middle section. This allows the head and foot sections to be moved into the orientation preferred by the user throughout the whole tilting motion. The middle section is hard mounted to a central “spine”, which is what the central axle runs through.
Three different linear actuators are mounted to the rotating portion. One rotates the entire bed about the central axle, and the other two move the head and foot sections respectively to achieve a semi sitting position. The actuators responsible for moving the head and foot sections are mounted to the central spine so that they rotate with the bed, while the actuator dictating the overall tilt of the bed is secured to the A-Frame. The idea of a semi sitting position was introduced to a member of the target user demographic and received positive feedback due to the consistent support it would provide.
Live testing focused on the functionality of the bed as an assembly. Cursory evaluation of the functionality of the linear actuators was conducted, however due to the quality of sourcing, the team believed it to be reasonable to accept the listed forces exerted. Additionally, the result of primary interest was how quickly the segments could be moved, not how quickly the actuators themselves traveled. The fully assembled bed was tested for its range of motion, the speed at which each segment could be rotated, and its serviceability.
The primary purpose of the bed is to rotate the user from a horizontal lying position up into a supported, semi vertical position from which they can be transferred into a wheelchair. The first test involved measuring the realized range of motion of each segment. An iPhone was used to measure the starting and ending angles for each segment. The head segment achieved an average maximum travel of 48.5 degrees relative to the middle segment, far exceeding the stipulated 30 degrees. Similarly, the foot segment rotated to -39 degrees from the horizontal, another accepted result. The foot segment’s travel was limited by hitting the supporting spine underneath. The middle section, and thus the entire bed, was able to rotate up to 46 degrees relative to the sleeping position, hitting the target travel. The
A-Frame of the prototype has since been modified to allow for an even greater tilt angle, with this then informing the final design, should the sponsor desire it.
Speed testing of the bed was also performed. The head, middle, and foot were able to go through their complete range of motion in an average of 42.4, 18.6, and 22.4 seconds respectively. The head segment, by far the slowest segment, still falls within the 45 second goal for total rotation from the horizontal.
The prototype was evaluated to be a success in its critical objectives of bringing the user up to the desired angle 45 degrees within 45 seconds, with an overall evaluated cost of under $1,000. As a refined version of the prototype, the final design successfully fulfills the project objectives.
Repository Citation
Chia, Daniel; Curtis, Rachel; Jung, Max; and Kapellusch, Jaxson, "Final Project Report: Lift Bed for the Mobility Impaired" (2025). Engineering Senior Design Reports. 100.
https://digitalcommons.trinity.edu/engine_designreports/100
Comments
Dr. Michael Enright, Ph.D., P.E., Team Adviser, Team Sponsor