TIME-DISCRETE CONTROL OF STEADY MOTION FO RMS USING REAL-TIME PROCESSING OF INTERFEROMETER SIGNALS

A method for time-discrete control of sinusoidal vibration in the wide displacement amplitude range of 50 mu m to 0.5 m which is applicable to absolute calibration of reference standard accelerometers is presen ted The least square slim method used for the real-time identification of the motion parameters allows the amplitude and initial phase angle of the displacement and derived motion quantities to be accurately me asured. The motion control and measurement method is based on the reco nstruction of the vibration as sequence of discrete phase values deriv ed from the photodetector output signal of a Michelson interferometer. The maximum error components for different disturbing sources and the maximum achievable suppression of non-linear distortions are analyzed by computer simulation. The performance of the method render the prac tical conditions was investigated by means of a DSP-based measuring sy stem in combination with a low-frequency long-stroke vibration exciter in the operational range of 0.1 Hz to 20 Hz.