Soft Pneumatic System for Interface Pressure Regulation and Automated Hands-Free Donning in Robotic Prostheses

Abstract

This paper discusses the design and preliminary evaluation of a soft pneumatic socket (SPS) with real-time pressure regulation and an automated underactuated donning mechanism (UDM). The ability to modulate the pressure at the human-socket interface of a prosthesis or wearable device to accommodate user's activities has the potential to make the user more comfortable. Furthermore, a hands-free, underactuated donning mechanism designed to reliably and safely don the socket onto the user may increase the convenience of prostheses and wearable devices. The pneumatic socket and donning mechanism are evaluated on synthetic forearm model designed to closely match the mechanical properties of the human forearm. The pneumatic socket was tested to determine the maximum loads it can withstand before slipping and the displacement of the socket after loading. The donning mechanism was able to successfully don the socket on to the replica forearm with a 100% success rate for the 30 trials that were tested. Both devices were also tested to determine the pressures they impart on the user. The highest pressures the socket can impart on the user is 4psi and the maximum pressure the donning mechanism imparts on the user is 0.83psi. These pressures were found to be lower than the reported pressures that cause pain and tissue damage.