A practical method for friction identification in hydraulic actuators

Friction in hydraulic actuators can be described using nonlinear, velocity dependent models. In this paper, the friction is described by an exponential Stribeck friction model. An iterative algorithm is presented to identify the friction model parameters. The method fits two lines on the experimental data relating steady-state velocities to actuator pressure differentials. The parameters of the fitted lines are obtained using an iterative optimization technique. Based on the obtained parameters, the original nonlinear friction model parameters are completely reconstructed. The proposed method is validated by building a simulation model for a valve-controlled hydraulic system in which the friction is modeled based on the method described here. The proposed method can be used in practical situations, whereby fast and reliable identification of major parameters of the friction in hydraulic actuators is needed with easy to obtained pressure measurements.