Nonlinear modeling and experimental validation of uni-Axial servo-hydraulic shaking table

An effective way for the testing of a large number of systems is using single and multi-Axis shaking tables. Among the possible applications, the civil engineering field stands out for the testing of structures, or part of them, both on a reduced and on a full scale. However, design a high performance controller for a servo-hydraulic shaking table is a difficult problem due to its non-linarites and large friction forces. The goal of this pa- per is to develop and experimentally validate a robust numerical model that simulates the acceleration behavior of a uni-Axial servo-hydraulic shaking table system with considering three friction models, the LuGre model, the modified LuGre model and the new modified LuGre model. First, a full system model of servo- hydraulic system is developed based on fluid mechanical expressions and then the friction force of hydraulic cylinder is modeled and validated on the real shaking table. Data of the experiment are gathered from input command valve, and the output acceleration and position of the table. All models are simulated by using MATLAB and SIMULINK computer program. The parameters of the system and the friction models are estimated by using least square method (LSM). Finally, the comparisons of simulated reults with experimental ones show that the model of the system with considering third model of the friction can predict accurately the shaking table's behaviors.