Friction Modelling and Parameter Estimation for Hydraulic Asymmetrical Cylinders

Olesen, Casper ; Hvoldal, Mads

2. term

Electro-Mechanical System Design, Master

2011

2011-05-31

100 pages

This report is a master’s thesis in Electro-Mechanical System Design (EMSD) at Aalborg University, Denmark. Daniel Henriksen designed, in the year 2010, a test bench for hydraulic cylinders. This test bench constitutes the base for this project, with a minor modification to his design, as two servo valves, instead of one, controlling the load produced by at cylinder. The test bench had at the beginning of the project, not yet been operational and different electrical circuit boards where needed to be designed, documented and manufactured. A full system model was developed based on fluid-mechanical expressions. This model was incorporated in the simulation program, Simulink. The expressions where linearised in order to develop controllers suitable for the chosen control strategies. Satisfactory controllers where developed and the performance of these where documented. To enable implementation of the chosen control strategies in the physical setup, a control program was developed in Code Composer Studio v4. Semi-automatic execution of experiments where achieved and a procedure on how to use the system, for friction determination, was formulated. Investigations, in the field of friction, have been made by studying the documented work made by recognized scientists dating back to the sixties. The most well documented friction phenomena are presented throughout this report, including the Stribeck effect, friction lag and hysteresis loops. Steady state and dynamic friction models are introduced and the assumptions and simplifications made within these are stated. The friction models presented are the Márton and Lantos model (in which the Tustin model is used), the pressure-based model, the LuGre model and a modified Leuven model. Experiments where conducted, on the test bench, in order to test the properties of the friction models, which are incorporated in a developed simulation model of the full system. In order to compare the friction models, values for respective friction parameters where derived from the data. Regrettably, no successful implementation was achieved, but the characteristic friction phenomena was documented and the efficiency of the test cylinder was derived.

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