Optimal extended state observer based control for vibration reduction on a flexible cantilever beam with using air thrust actuator

The idea of using air thrusts for vibration control of structures has gained attention since the 1990s. However, only discontinuous controllers and switching functions have been studied with these actuators. Therefore, the main motivation of this study is to investigate air thrusters with continuous control methods for vibration reduction on a flexible cantilever beam. First, the finite element model of the flexible cantilever beam is defined. The order of the model is reduced according to the effective mass participation factor using the mode displacement method to obtain a controllable and observable system. The fundamental dynamics of the air thrust actuator, such as time constant, delay time and bandwidth, have been determined by system identification and considered in the control system. In this study, optimal extended state observer-based control (optimal ESOBC) tuned by optimal control law and particle swarm optimization (PSO) is proposed and compared to linear quadratic Gaussian (LQG) and positive position feedback (PPF) controllers. The performance of the controllers has been evaluated under several experiments such as initial displacement, impulsive disturbance, structure uncertainty and actuator uncertainty. The effectiveness of the controllers is determined by the RMS value of the beam displacement and the total air consumption. The results show that the ESOBC controlled air thrust actuator has suppressed beam vibrations more successfully than LQG and PPF controllers. In addition, the proposed method is found to be effective for low-frequency vibration suppression on flexible structures.