Structural design and experimental verification of a flapper mechanism comprising piezoelectric actuator

Temeltürk, İhsan Burak
In this thesis study, torque motor of conventional two stage servovalves is investigated. Possible improvements for the first stage actuation system of servovalve are determined. It is aimed to design a new actuation system for replacing torque motor actuation system. The new system is met the performance criteria of torque motor on the high bandwidth and fast response characteristics. Amplified Piezo Actuator (APA) is designed with a new flapper mechanism to satisfy first stage of servovalve requirements. Subsequently, a new flapper mechanism design is optimized in terms of geometry and stiffness requirements by analyzing through the finite element analysis program. A mathematical model of APA is developed based on experiments. In order to minimize the hysteresis error, a hysteresis compensator and Proportional-Integral controller is also designed. Controller coefficients and model parameters are then vi optimized with the parameter optimization toolbox of MATLAB Simulink®. Moreover, a test structure with data acquisition system is built to measure the displacement of the actuator. In order to investigate the performance of the system, a simulation is performed in MATLAB Simulink® environment. A prototype of the flapper mechanism test bench is manufactured and sub-systems and components of the system are tested to identify the model parameters. With this prototype, the model is verified by conducting tests on the actuator by open loop hysteresis compensator. A closed loop position test is also performed with the hysteresis compensator. Various tests are repeated with the flapper mechanism in order to verify the performance of the whole system. A Bouc-Wen compensator and a ProportionalIntegral (PI) controller are used to minimize the hysteresis for driving frequencies between 0.1 Hz and 10 Hz. The open loop charge amplifier test is performed to obtain the behavior of system for the driving frequencies higher than 10 Hz. This actuating system is also controlled using different control methods with 1% to 3% displacement hysteresis error. As a conclusion, this thesis shows that a designed and an experimentally verified actuation system with a flapper mechanism employing a piezo actuator can be used as a torque motor of servovalves
Citation Formats
İ. B. Temeltürk, “Structural design and experimental verification of a flapper mechanism comprising piezoelectric actuator,” M.S. - Master of Science, Middle East Technical University, 2018.