The Robotic Socket: A Robotic Design and Biomimetic Application of an Auto-Adjusting Prosthetic Socket Prototype for Above-Knee Amputees

Abstract

Comfort in prosthetic sockets remains a significant challenge for many amputees, particularly for above-knee amputees bearing substantial weight on their soft tissue [1], [2]. The predominant source of discomfort often originates from swelling of the residual limb, a factor traditional prosthetic sockets fail to accommodate [3]. While Osseointegration surgery, a unique method to connect prosthetics and residual limbs while removing the socket, is recognized as a superior solution for enhancing comfort and quality of life, its accessibility remains limited [4]. Hence, the motivation for this study is to explore the development of an automatically actuating and adjustable socket. This research aims to design and develop a prosthetic limb socket offering enhanced comfort, flexibility, and user control i.e. a robotic socket (RS). A comprehensive literature review was conducted to assess existing interactive sockets and sensory systems, focusing on their performance and specifications. The methodology employed in this study (Phase 1) involved the design and testing of small-scale circuits which will later (Phase 2) evolve into a more complex and up-scaled system. The prototype developed in this study features a plastic bottle equipped with a pressure valve, simulating residual limb swelling by modulating the internal pressure. A 3D-printed button and locking wire serve as a rigid socket, preventing unchecked bottle expansion. A motor integrated into the system modulates hoop tension on the conceptual socket, ensuring user-specific pressure regulation. The system was developed using a Raspberry Pi to manage motor fluctuations based on user-defined set points and bottle pressure readings. Preliminary testing demonstrated promising results, with the motor effectively adjusting the cable tension in response to the pressure sensor’s readings. The use of a plastic bottle in the prototype makes this design cost-effective and accessible.