Perpustakaan Digital ITB

This thesis is about to find the parameters of friction model in a hydraulic cylinder. Friction is always arisen in a mechanical systems and has the influence on efficiency and the motion (or control performance). A steady - state friction force versus velocity is called the Stribeck curve has been proposed in Helouvry (1991) and Helouvry (1994) has been used widely in many fields to predict or analyze the characteristics of steady-state friction of the mechanical systems. However, the steady -state friction models are not enough or useless to predict the motion of a mechanical system especially for the cases that the mechanical system repeats start/stop or inching motion. So far, there are several friction models have been developed such as static model, Dahl's Model, Bliman - Sarine Model, Generalized Maxwell-slip Model LuGre Model. Among these models, Lugre Model is widely used, because it captures many aspects of friction like stiction, stick slip, stribeck, zero slip displacement, however this model cannot simulate the real hysteretic characteristics of hydraulic actuators. A method to modify Lugre Model in order to overcome the defect of Lugre Model which is, taking the dynamic of lubricant film formation into consideration. The friction force of the hydraulic cylinder is measured base on the equation of motion using the measured value of cylinder chambers and the acceleration of the hydraulic piston. Measured friction characteristics are compared to simulated ones by the Modified Lugre Model. This model was proposed in BoTran (2012), there a twelve parameters in modified lugre model, those parameters identification was proposed in YANADA et al. (2008), however there is still another method to identify those parameters, therefore, in this thesis is about to find a method to identify the parameters Keywords: Lugre Model, lubricant film thickness.