Development of automatic immediate fitting socket system for artificial leg socket modeling using fuzzy control

Abstract

Automatic immediate fitting socket (AIFS) system was developed to shorten the long length of time for making an artificial leg, by applying powder technology. AIFS is constructed of an outer shell, a particle containing bag, which the rigidity can be controlled by the application of negative air pressure and three airbags between the outer shell and the particle bag to adjust the shape by controlling the compression. A fuzzy controller was applied for the real-time automatic control of the shape based on the subjective evaluation of the amputee. The surface contact pressure was evaluated during AIFS walking as well as the walking with the conventional socket. The peak pressure at the tibia end was 30 kPa in AIFS walking while 90 kPa with conventional socket. The pressure distribution among medial condyle, fibula head and tibia end was more uniform with AIFS. The shape modeling performance was evaluated by measuring the circumferences of four amputees' stumps. The modeling error was 6%. The shape modeling including test walking was completed in 10 minutes in all four amputees and practical shapes were obtained.