Vibration frequency response correction method and shaker system using the same

A method of frequency response compensation of a calibrated vibration sensor, comprising

• measuring acceleration over time by a calibrated vibration sensor, the sensor generating a digitized output time domain signal with time stamps;
• transforming the digitized output time domain signal into a frequency domain generated output spectrum signal;
• retrieving from a memory unit of the sensor stored entries of a frequency response function (FRF) correction table for each frequency, the FRF correction table including entries at a set of frequency breakpoints in the form of data triplets of frequency, amplitude, and phase;
• and
• for each frequency of the transformed output spectrum signal, performing complex number multiplication by a corresponding complex multiplier value from the FRF correction table to obtain a compensated output spectrum signal.

A shaker system, comprising:

• a shake table;
• a computer controller connected to the shake table via an amplifier and exciter that drives the shake table with a specified drive profile, the controller receiving feedback from a reference sensor mounted to the shake table, the reference sensor with an acceleration measurement accuracy better than one-tenth of a specified tolerance;
• an object subject to vibration analysis which is mounted on the shake table;
• at least one calibrated vibration sensor mounted on the object, the calibrated vibration sensor a memory unit storing a frequency response function (FRF) correction table of the sensor that includes entries at a set of frequency breakpoints in the form of data triplets of frequency, amplitude, and phase;
• and
• a processor of vibration sensor acceleration measurements, the processor programmed to digitize and transform the measurements in the form of a time domain signal into a frequency domain to generate output spectrum signals, retrieve FRF correction table entries from the memory unit for each frequency of the transformed output spectrum signal, and perform complex number multiplication of amplitude and phase of the transformed output spectrum signal by a corresponding complex multiplier value from the compensation table to obtain a compensated signal.