Control of Electro-Hydraulic Shaker by Digital Iteration Techniques

The paper presents the results of a feasibility and conceptual study for on-line transient waveform control of nonlinear electrohydraulic test systems. The control concept is based on digital computing algorithms and the reciprocal properties of the fast Fourier transform used in the time-invariant vibratory system approach. In order to reproduce a specified time history at the test specimen, digital iteration techniques, which compensate the frequency coupling and the effects of nonlinearities on the electrical and mechanical components of the vibratory system, were used to define the test system transfer function. Successful control of prototype test systems are presented and discussed.