Random Vibration Model Reference Sliding Mode Control of Electro-hydraulic Shaking Table based on Linear State Observer

The electro-hydraulic shaking table (EHST) is the key equipment for large structures vibration simulation. Three variable control (TVC) developed based on the linear model is commonly used for the control of EHST. However, the mismatched disturbance force is not compensated by TVC. Sliding mode control (SMC) can be used for disturbance rejection in the electro-hydraulic servo system. But the conventional SMC cannot be applied for the random acceleration control of the EHST when the valve dynamic characteristics and valve zero offset are neglected. Model reference SMC with valve zero offset compensation is presented for the EHST system. The backstepping and Lyapunov methods are used to develop the controller based on the nonlinear state-space model. The reference model is used for the generation of the reference signals. Model reference SMC is used for the disturbance rejection and valve zero offset compensation. Simulation results obtained in random vibration show that the acceleration tracking performance of the EHST is improved greatly with the proposed scheme.