Theoretical and Experimental Investigation of Friction in Hydraulic Actuators

Abstract

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.

Terminal Sliding Mode Force Control Based on Modified Fast Double-Power Reaching Law for Aerospace Electro-Hydraulic Load Simulator of Large Loads

“…To account for the internal and external disturbances that affect the mechanism of the loading simulator, a more accurate mathematical model, including nonlinear factors and uncertainties, advanced control algorithms (i.e., backstepping [12], sliding mode, neural network [13], iterative learning control [14]), and sensor faults and disturbances observation [15,16], is utilized for accurate tracking and nonlinear compensation. The backstepping adaptive control, combined with the modified LuGre friction model [17], is introduced into the force-tracking control of the loading simulator [18]. This approach effectively weakens the distortion phenomenon caused by friction and results in a better force control performance.…”