Development of a physiological knee motion simulator

Several kinds of knee motion simulator systems have been developed for the accurate analysis of knee biomechanics. Knee motion simulators, however, ar e not recognized For their practical use because of difficulties in design and control. Tn this study, a wire-driven knee simulator which generates ph ysiological knee motion has been developed. Physiological three-dimensional tibia motion against the femur can be generated by the simulator. Many cli nical studies have been performed to analyze the length displacement patter n of the anterior cruciate ligament (ACL) and the posterior cruciate ligame nt (PCL). We assume that the physiological knee motion can be realized if t he length displacement patterns of the ACL and PCL against the knee flexion angle are the same as the experimental data obtained from the literature. A fuzzy neural control policy, one of the most effective intelligent contro l policies, has been applied for control of the simulator. Applying the fuz zy neural control policy, human knowledge and experience can be reflected a nd adaptive/learning ability can be incorporated in the controller. On-line learning of the fuzzy neural controller is carried our to minimize a fuzzy controlled evaluation function using the back-propagation learning algorit hm. The effectiveness of the proposed simulator has been evaluated by exper iments using a model bone.