Development of a Motorized Dynamic Load Matching Socket Prosthetic

Lower limb amputees comprise the majority of the 2.1 million Americans living with limb loss. This population faces a myriad of challenges concerning current socket based lower limb prostheses, which have an inherent conflict between stability and comfort. Tighter fitting devices provide better stability while causing the user discomfort and pressure sores on the skin. Looser fitting devices provide comfort but lack stability and cause skin abrasions from friction between the socket and the skin, oftentimes resulting in serious infections. Our goal was to design and test a proof of concept prototype; a motorized autonomously adjusting prosthetic socket that provides lower limb amputees a customizable fit that matches the user's current activity level.

Our design utilizes a network of sensors to determine the current user “mode” based on predefined angular velocity thresholds of the limb. As the user’s activity level increases or decreases, a system of cables embedded in the prosthetic socket are tightened or loosened by a DC motor, providing a fit that matches the user's demand. Our adaptive design provides stability for the user while reducing excessive force on the limb. In addition, our adaptive design will ultimately reduce skin irritation by a minimum of 30 percent, eliminate the unintentional vertical displacement of the limb in the socket (pistoning), and improve user comfort for all-day wear. To date, the team has largely completed our initial goal of a proof of concept by establishing values for angular velocity thresholds for different user “modes” and developing a system that responds to changes in user activity by tightening and loosening a system of cables utilizing a DC motor.