| Summary: | 碩士 === 國立交通大學 === 機械工程學系 === 99 === This thesis presents a design, modeling, and control of a piezoelectric accelerometer. The fabricated piezoelectric accelerometer features built-in sensor and actuator so that it can perform the force-balance measurement when feedback control applies. The fabricated accelerometer was well calibrated. The calibration methods and a complete setup for the force-balance feedback controls are also presented in this thesis.
This piezoelectric accelerometer is designed to be a sandwich-structure cantilever beam with piezoelectric materials on the top and bottom, and a copper layer in the middle. The piezoelectric layer on the top and bottom are divided into two sections: one for actuation and one for sensing. The top and bottom piezoelectric layers form a bi-morph structure. Meaning that, this accelerometer uses a bi-morph piezoelectric structure to bend the copper layer, and a bi-morph piezoelectric structure to sense the deflection of the cantilever beam.
A theoretical model is derived to describe the dynamic behaviors of this voltage-in/acceleration-in and voltage-out accelerometer. To verify the feasibility of this model, not only did finite element simulations, but also experimentally data were obtained using the Laser Doppler Vibrometer. The results from the theoretical model, FEM simulations, and experimental data are consistent with each other.
To experiment on a force-balance control piezoelectric accelerometer, we first did the system identification to obtain system model. Secondly, we verified simple P and PI controllers using MatLab tools. Lastly, this controller was implemented using C-codes on a DSP platform. The simulation results and experimental results show that the proposed force-balance control can increase the system bandwidth by 40Hz, especially in improving the low frequency response.
This thesis completes the design, fabrication, and modeling of a force-balance piezoelectric accelerometer. However, due to time limitation, only some preliminary results were obtained for the force-balance control. More research items are listed in the future work.
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