Personal Lifting Pedestal for Above Knee Amputees

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Personal Lifting Pedestal for Above Knee Amputees

Senior Designers: Megan Chamlee, Rakesh Lala, Saso Klesnik

Client Coordinators:  Mr. Harlan Dutton; Alan Eberhardt, PhD, Department of Biomedical Engineering


The problem statement was to design a user controlled personal lift pedestal (PLP) for an average-sized male (160lb) lower limb, above knee amputee.  The device was to raise the user from a sitting position to a standing height of 5 ft. 7 in – a required rise of 15.9 in.  Other design constraints for the PLP consisted of ease of entry/exit, user friendly controls, safety, and stability.

In the final design, the frame was composed of carbon steel due to its impact resistance, strength-to-weight advantage, and weldability.  The dimensions of the frame were 30x26x30 in., consisting of two 26 in. hollow bars and two 30” hollow bars along the top and bottom; each 2×1 in. in cross section.  The side bars were four telescoping hollow rods (outer diameter = 1 in.)  The frame is open in front which allows for easy entry into the PLP.

Two actuators are used as the lifting mechanism, selected because they had telescoping casings that resist bending moments, and because they offered the appropriate stroke length and  thrust.  The actuators are controlled simultaneously using a remote with a memory function and height display. A chair harness was chosen for the hanging seat since it had a seat board that provided built-in suspension support and a harness for restraint.  The user climbs into the chair and fastens himself in using the harness when the pedestal is in the lowest position (Fig. 4, left).  Using push button controls, the user actuates the system to rise to a standing height (Fig. 4, right). Preliminary calculations were performed to ensure the stability of the PLP.  The completed device was tested in various positions using a 160lb male and determined to be safe and functional.  The cost of materials and machining was $1315.64.  This effort represents phase 1 of a two phase project to develop a motorized PLP for use in a work environment, which will ultimately permit the user to move throughout a room and raise and lower himself to perform various tasks that require the user to reach standing heights, such as placing books on high shelves.

30 - lifting pedestal for AKA

Figure 30.  The personal lift pedestal for lower limb amputees.  (Left). In the lowered position, the user lifts himself into a seated position.  (Right). In it upper most position, the user is elevated to standing height.