A Comparison of Two Methods for Estimating the Parameters of the Nonlinear Friction Characteristics of a Vibration Damper for Diesel Engines

Usually, the characteristic of a vibration damper for a Diesel engine is described by a linear (viscous) friction term. Two methods for the estimation of the parameters of non-linear frictional terms such as "quadratic" friction and Coulomb friction. The first method by a Gauss-Newton minimization of a quadratic criterion uses sensitivity equations and a special approximation for the arising Dirac-Delta functions, the second method uses a Statistically Linearised Filter for simultaneous state and parameter estimation. Based on four different sets of measurement data, the two methods are compared, their relative strengths and drawbacks are demonstrated and practical aspects of parameter estimation are dealt with.