DESIGN AND IMPLEMENTATION OF A SLIDING MODE CONTROLLER FOR A SEISMIC SHAKE TABLE

Shake tablesare effective tools for simulating dynamic behavior of structures exposed to seismic loads. The main core of a shake table is its control system. The aim of the controllerin a shake table is to track the displacement, velocity, and acceleration profiles of a realor scaled version of a predefined earthquake. On the other hand, shake table control problem faces uncertainties arose from unknown model parameters and unmolded dynamics. Furthermore, the shake table is designed to test various test structures with different inertias. Therefore, the moving mass of the table is an uncertain parameter which should be concerned in the controller design in order to attain optimal control performance. In this paper, a supervisoryrobust sliding mode controlleris proposed for controlling motions of a laboratory-scale seismic shake table. For this purpose, a model is developed for the shake table and is validated against experimental data. Furthermore, the controller is implemented in the shake table and its performance is evaluatedvia test data. The shake table test results prove effectiveness of the proposed controller at tracking seismic profiles in the presence of the uncertainties. At the same time, the chattering frequency is confined to an applicable range.