Theoretical and Experimental Investigation of Friction in Hydraulic Actuators

This paper deals with the experimental verification of friction models used in the estimation of frictional forces in a hydraulic actuator. The friction force is calculated with the measured readings of pressure in the cylinder chambers and the acceleration of the piston. In order to predict friction forces in the hydraulic actuator, mathematical models, namely LuGre model and modified LuGre model, are extensively used. These models are simulated to predict the friction forces in the test actuator. The physical test setup and the simulation models are commanded with identical velocity inputs, and the results in each test case are compared. The experiment results show that the modified LuGre model with dimensionless fluid film thickness parameter predicts the friction forces in hydraulic actuator with a good accuracy when compared with the other models.