1. A filtering process, comprising the steps of: (a) computing a model relevant information for a time update and a measurement update in a model selection; and (b) providing, from said model selection, an initial condition of a system estimate for a system model computation in said time update, an initial condition of a covariance error matrix for a derivative system model computation in said time update, a system model for said system model computation in said time update, a derivative system model for said derivative system model computation in said time update, a measurement model for a measurement model computation in said measurement update, and a derivative measurement model for a derivative measurement model computation in said measurement update.