Weijin Gao

Bio: Weijin Gao is an academic researcher from Beihang University. The author has contributed to research in topics: Vibration & Control theory. The author has an hindex of 2, co-authored 2 publications receiving 9 citations.

Active vibration control based on modal controller considering structure-actuator interaction

Abstract: Active vibration control to suppress structural vibration of the flexible structure is investigated based on a new control strategy considering structure-actuator interaction. The experimental system consists of a clamped-free rectangular plate, a controller based on modal control switching, and a magnetostrictive actuator utilized for suppressing the vibrations induced by external excitation. For the flexible structure, its deformation caused by the external actuator will affect the active control effect. Thus interaction between structure and actuator is considered, and the interaction model based on magnetomechanical coupling is incorporated into the control system. Vibration reduction strategy has been performed resorting to the actuator in optimal position to suppress the specified modes using LQR (linear quadratic regulator) based on modal control switching. The experimental results demonstrate the effectiveness of the proposed methodology. Considering structure-actuator interaction (SAI) is a key procedure in controller design especially for flexible structures.

A modified adaptive filtering algorithm with online secondary path identification used for suppressing gearbox vibration

Abstract: We determined the actuator location based on the dynamic modal of gear shaft, and analyzed the feasibility of a modified filtered-x least mean square algorithm with online secondary path identification. The proposed adaptive controller is designed to drive the actuators for preventing the vibration caused by gear backlash from a gear pair passing to the external gear housing structure. For the vital identification system, a changed identification input with error energy is presented to reduce the impact of additive random noise on the whole system. To ensure a realistic assessment of the proposed control strategy, numerical studies were implemented for a gearbox used by NASA-GRC. The simulation results validate the efficiency of the proposed approach through promising vibration control results that will guide future experimental work.

A novel hybrid compound fault pattern identification method for gearbox based on NIC, MFDFA and WOASVM

Abstract: Gearbox compound fault pattern recognition is challenging because of its complexity and non-stationarity of the vibration signal. In this study is proposed a novel hybrid method based on narrow band interference canceller (NIC), multifractal detrended fluctuation analysis (MFDFA) and support vector machine optimized by whale optimization algorithm (WOASVM) for compound fault pattern recognition of gearbox. Specifically, the raw signal is processed by NIC to filter the deterministic signal which interferes with the fault signal, and then the multifractal features are extracted from the residual signal via MFDFA. Finally, the compound fault pattern is identified via WOASVM. Compound fault experiments of a gearbox under fixed condition and variable condition were done to evaluate the performance of the proposed method. The results show that the proposed method can effectively identify the compound faults and it outperforms other methods mentioned in this paper.

Vibration Isolation and Alignment of Multiple Platforms on a Non-Rigid Supporting Structure

Abstract: In many applications comprised of multiple platforms with stringent vibration isolation requirements, several vibration isolators are employed to work in tandem. They usually must accomplish two objectives: (i) reduce the vibration level of each platform; and (ii) maintain the required alignment with respect to each other or with a fixed reference. If the isolators are located on a rigid supporting structure, the problem can be approached as a classical vibration isolation (VI) problem, in which an increase in damping implies a reduction of vibration level experienced by the platforms. However, there are an increasing number of scenarios in which the dynamic interaction between the isolator and the base structure has the potential to alter the system response and consequently degrade VI performance. In this work, a generalized method to analyze the combined VI and alignment problem, for multiple isolators located on a flexible supporting structure, is proposed. The dynamic interaction between the platforms and the isolators is considered in the control design, and it is proved employing two different functional values that the maximum damping solution is not always the best approach when the dynamics of the supporting structure are considered. Numerical simulations are presented to validate the theory developed and robustness of the proposed control approach is demonstrated.

Vibration reduction against modulated excitation using multichannel NLMS algorithm for a structure with three active paths between plates

Abstract: Electric and hybrid vehicle engines produce a complex spectrum of vibration and noise. Various active mounting techniques have been developed to isolate them. These are designed to continuously control the dynamic characteristics of the mounts and improve the noise, vibration, and harshness (NVH) performance under various operating conditions. Active mounts have attracted attention as replacement for existing mounts by simultaneously realizing static and dynamic stiffness, which is important for supporting an engine. Therefore, this study focuses on the vibration isolation performance of the upper plate and lower plate when the structure, including the active mounting system, is applied to multifrequency excitation. The overall modeling is based on the lumped parameter model, and the input signal is applied to the amplitude modulated and frequency modulated signals. The adaptive filter is applied for control, and the normalization least mean square (NLMS) algorithm, which is commonly used in research, is extended to a multi-NLMS algorithm. It is shown that when multifrequency input is applied, the adaptive filter is effectively applied to the active mounting system to control vibration.