**5. Conclusion**

A new approach of estimation of the anthropometric inertia parameters and model of the passive viscoelasticity of the knee joint has been presented. Fuzzy model has been used to model the passive viscoelasticity and could be an effective tool for the modeling of uncertain nonlinear systems without represents using complicated mathematical model. The anthropometric inertia parameters of the lower limb such as foot mass, shank mass, moment of inertia about COM and positions of COM along the segmental length of the lower limb have been optimized between the given ranges to obtain the accurate value of the equations of motion. These optimizations have been performed simultaneously using GA with the objective to minimize the error between prediction model and the experimental data. Each person has a unique composition of muscle tissue in their body therefore this passive properties are not generally applicable.
