Design of, and initial experiments with, a MIMO plate control testbed

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Virginia Tech

This work discusses the design of, and initial experiments with, a MIMO plate control testbed. This structure will be used as a development and standard comparison site for AVC and ASAC and is an extension of previous SIMO control investigations which used accelerometers and shakers. This portion of the development process of the MIMO plate control testbed is concerned with actuator and sensor materials and architecture, modeling approaches and requirements, and initial control experiments.

The piezoelectric sensors and actuators are arranged on the plate to control the first five vibration modes. The sensors measure plate positions using a high impedance signal conditioning amplifier. The sixteen-channel design implements a band-pass filter to eliminate low- and high-frequency noise.

The power amplification scheme chosen for the actuators uses low-gain amplifiers (~2.5 V/V) in series with a transformer (24:1) to deliver high voltages (up to 150 V) to the actuators. Low-pass smoothing filters (200 Hz cutoff) were added on the control inputs to reduce the high frequency content of the zero-order-held digital control signal.

Initial methods for system identification of piezostructures are presented. Parametric frequency response approaches (modal analysis) were used and the model achieved is compared with measured data and purely analytic models.

The empirical model was used in initial SIMO control experiments to demonstrate the testbed closed-loop performance. A LQG controller was implemented and produced 6 dB of suppression for the second mode for a 110 Hz disturbance.