Measuring system for transfer function matrix of a system to be controlled in multi-degree of freedom vibration control

Abstract

A measuring system for measuring a transfer function matrix of a system to be controlled by applying sine-wave excitations to a test object simultaneously by multiple number of vibrators. In the measuring system, when sine-wave signals for driving multiple number of vibrators are generated, phases between the sine-wave signals are shifted randomly, first, and then multiple number of vibrators are excited simultaneously under the generated sine-wave signals. Then, an auto-spectrum and a cross-spectrum for one calculation are calculated from spectral data on a vibration frequency obtained from an analysis of excitation signals and response signals acquired during the excitations. These steps are repeated two or more times to calculate the auto-spectra and cross-spectra for two or more calculations, followed by arithmetically averaging these spectrums to find a mean value of the auto-spectra and a mean value of the cross-spectra, so that the transfer function matrix at a specific frequency is calculated from the both mean values. The steps up to this point are repeated at each frequency to calculate said transfer function matrix data at all frequency components. This can allow the same sine-wave signals and the same vibration condition as in a multi-degree of freedom sine-wave vibration test to be used in the test, for measuring the transfer function matrix of the system to be controlled with adequate accuracy.