Modeling and identification of lubricated polymer friction dynamics

A systematic approach is proposed to model the dynamics of lubricated polym er friction. It starts with the development of a physical model to describe the fundamental mechanisms of the friction. The physical model then serves as the basic structure for the development of a complex model able to capt ure a wider spectrum of the deterministic and stochastic dynamics of fricti on. To assess the accuracy of the complex model, two estimation algorithms are formulated to estimate the unknown parameter in the model and to test t he model against experimental data. One algorithm is based on the maximum l ikelihood principle to estimate the constant parameters for stationary fric tion dynamics, and the other based on the extended Kalman filter to estimat e the time-varying parameters for nonstationary friction dynamics. The mode l and the algorithms are all validated through experiments.