A detailed dynamic model of a six-axis shaking table

This article describes the modeling of a 5 m x 5 m 6 degree-of-freedom (DOF) shaking table and the subsequent computer simulation of the system's dynamic characteristics. The simulation model is required to aid the development of a closed-loop controller with a bandwidth specified up to 120 Hz, and thus high order dynamics including valve response and structural effects are included. Significant nonlinearities associated with the hydraulic and mechanical components are also included (e.g., spool slew rate and saturation limits, valve overlap, manifold and valve body pressure losses, friction, and geometric nonlinearities). Some model parameters are found from physical knowledge; others are determined experimentally, and methods for estimating key parameters from experimental data are developed. The simulation is implemented using Simulink® and its multi-body mechanical simulation tool SimMechanics®. The simulated response compares well with the measured response of the table.