Development of Automatic Immediate Fitting Socket (AIFS) system for artificial leg socket modeling using fuzzy set control

The Automatic Immediate Fitting Socket (AIFS) system was developed to reduce the time consumption for making an artificial leg. The AIFS is composed of an outer shell, a particle containing bag and three air bags. The rigidity of the AIFS can be controlled by the application of negative pressure between the outer shell and the particle bag. The three air bags are used for adjusting the shape of the socket. A fuzzy set theory was utilized for the real-time automatic control of the socket shape based on the subjective evaluation by amputee. Two experiments were conducted for evaluation of this system. One was for measurement of contact pressures between the surface of the stump and the socket during walking. This result revealed that the pressure distribution function of the AFIS was more uniform than conventional artificial legs. Another experiment was conducted for evaluation of a shape-modelling function. The shape-modelling performance was evaluated by measuring the cross-section area ratio of the stump calf to the stump end. This ratio with AIFS was about 1.5 times as large as the conventional artificial leg. This result showed that AIFS system provides a suitable shape for walking. The entire AIFS modeling process including test walking was completed in. 40 minutes, which is significantly shorter than the time for the conventional modeling process.