Abstract
Active rotor with trailing-edge flaps is a promising method to alleviate vibrations and noise level of helicopters. Hysteresis of the piezoelectric actuators used to drive the flaps can degrade the performance of an active rotor. In this study, bench-top tests are conducted to measure the nonlinear hysteresis of a double-acting piezoelectric actuator. Based on the experimental data, a rate-dependent hysteresis model is established by combining a Bouc–Wen model and a transfer function of a second order system. Good agreement is exhibited between the model outputs and the measured results for different frequencies. A compound control regime composed of a feedforward compensator and PID (Proportional–Integral–Derivative) feedback control is developed to suppress the hysteresis of this actuator. Bench-top test results demonstrate that this compound control regime is capable to suppress hysteresis at different frequencies from 10 Hz to 60 Hz, and errors between the desired actuator outputs and the measured outputs are reduced dramatically at different frequencies, revealing that this compound control regime has the potential to be implemented in an active helicopter rotor to suppress actuator hysteresis.
Highlights
Modern helicopters are suffering from severe vibratory loads and high noise level, which impose negative effects on the comfort of crew members, the fatigue life of structural components, the reliability of airborne equipment, and maintenance costs [1]
An active rotor with trailing-edge flaps (TEFs) is an effective and promising method to alleviate helicopter vibrations and noise through the dynamic deflection of TEFs, which are capable to change aerodynamic load distribution and aero-elastic responses of a rotor, and affect vibratory loads and noise resulting from the helicopter rotor [4,5]
Piezoelectric actuators are capable for aerospace applications [6,7] due to their unique properties including a wide operating bandwidth and high energy density; there are still problems associated with this type of actuator such as hysteresis
Summary
Modern helicopters are suffering from severe vibratory loads and high noise level, which impose negative effects on the comfort of crew members, the fatigue life of structural components, the reliability of airborne equipment, and maintenance costs [1]. Micromachines 2021, 12, 1298 measures the hysteresis behavior of an APA500L actuator manufactured by Cedrat, builds a hysteresis model using Preisach model, and incorporates the established hysteresis model into an aero-elastic model of an active rotor with TEFs. Simulation results demonstrated that actuator hysteresis could degrade the vibration control performance. In [22], Jiwen Fang et al uses the Bouc–Wen model to describe hysteresis behavior of a piezo-actuated stage, and a compound control regime is constituted by combining feedforward compensator based on an inverse model and fuzzy PID (Proportional–Integral–Derivative) feedback control, reducing actuator output error by about 94% All these appealing results have inspired us to explore the implementation of the Bouc–Wen model in active helicopter rotors. Bench-top tests demonstrated that this control regime was capable to suppress nonlinear hysteresis at different frequencies ranging from 10 Hz to 60 Hz, implying its potential in active rotor applications
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