Modeling of dynamic friction behaviors of hydraulic cylinders

This paper deals with modeling of dynamic friction behaviors of hydraulic cylinders. Using hydraulic cylinders with different packing materials and sizes, friction characteristics are experimentally investigated under different magnitudes of external load. It is shown that the dynamic friction characteristics are affected by the packing material of the cylinder and by the pressures in the cylinder chambers. Comparisons between dynamic friction characteristics measured and those predicted by the modified LuGre model show that the model cannot simulate the real hysteretic behaviors of the friction force-velocity curve in the fluid lubrication regime. The modified LuGre model is improved by replacing the usual fluid friction term, which is proportional to velocity, with a first-order lead dynamics. It is shown that the proposed model can give accurate simulation results in the fluid lubrication regime. (C) 2011 Elsevier Ltd. All rights reserved.