Improved Control of Linear Motors for Broadband Transducer Calibration

To achieve accuracy in measuring vibrations, the sensors must be calibrated over an entire amplitude and frequency range. The linear motor with the advantage of long strokes has great potential in transducer calibration. In order to provide motion over a broad frequency range, the improved control of the linear motor is investigated. The Luenberger observer is designed for broadband state estimation by data fusion of the current command and the displacement measurement. The high bandwidth position loop is constructed to avoid drift move, outside of which the vibration control is employed to compensate the frequency response variation. The improved control of the linear motor is powerful in reducing harmonic distortion and maintaining amplitude stability over the frequency range from 0.1 to 160 Hz. Calibration of the MEMS accelerometer using the controlled linear motor is conducted to show its effectiveness in determining the sensitivity curve and the standard deviation.