Modeling of friction using spectral analysis

Usually friction is considered to be a velocity-dependent phenomenon. As a result, most of the available friction models describe friction only as a function of velocity. However, there is also positional dependency which is routinely ignored. Experiments reported in this paper confirm previously published findings of others that friction is position dependent, and that this dependency should not be ignored. Therefore, it is necessary to develop models that describe friction as a function of both position and velocity. Furthermore, available models of nonlinear friction are usually developed by investigating simple cases, such as sliding of two flat surfaces or rolling of a perfectly rounded body on a flat surface. These models do not accurately describe friction generated by mechanisms that have numerous sliding and rolling parts. In this paper, a new spectral-based modeling technique capable of describing nonlinear friction as a function of position and velocity is proposed. This technique identifies the specific contribution to the overall friction of every moving part of the mechanism.