A Novel Active Control Strategy with Decentralized Decoupling and Wavelet Packet Transformation: Design and Verification

Featured Application There is always complexity of the reference signal and path coupling in underwater vehicles, which can reduce the convergence speed and stability of the active vibration control (AVC) algorithm. In this paper, a novel adaptive strategy is proposed, called the WPTDDM-FxLMS algorithm, to solve the problems mentioned above. The wavelet packet transformation is used to convert the multi-frequency reference signal into the line spectrum signals in multiple non-overlapping frequency bands, and the decoupling feedback compensation factors are introduced into the identification model of the secondary path, then the multi-input and multi-output system (MIMO) system can be simplified into a parallel SISO system; all of which will weaken the multi-path coupling effect by the simulation and experiments. Consequently, the novel algorithm is suitable for solving the MIMO vibration problems with multi-frequency excitation and multi-path coupling in underwater vehicles. Active vibration control (AVC) can solve many vibration problems. However, structural vibration in underwater vehicles often involves other factors such as complex excitation and path coupling, etc. At present, the traditional algorithm (e.g., multi Filtered-x Least Mean Square, M-FxLMS) usually cannot effectively process the multi-frequency excitation and the coupling effects of the multi-secondary path, which will affect its convergence and stability to a certain extent. Consequently, a novel strategy is presented in this paper, namely, the wavelet packet transformation decentralized decoupling M-FxLMS algorithm (WPTDDM-FxLMS), which can solve the structural vibration problems mentioned above. The multi-frequency control is converted into a single-frequency line spectrum control, and the feedback compensation factor is introduced in the identification of the secondary path, both of which can simplify the multi-path control system to the parallel single-path systems. Furthermore, the WPTDDM-FxLMS algorithm is applied to the AVC in a multi-input and multi-output system (MIMO) vibration platform. Finally, the simulation and experiments show that the wavelet packet can decompose the multi-frequency excitation into a line spectrum signal, and the improvement of the decentralized decoupling and the variable step-size can effectively reduce the computation amount and increase the convergence speed and accuracy. Overall, the novel algorithm is significant for multi-path coupling vibration control. It will have certain engineering application value in underwater vehicles.

Automated summary

A novel adaptive strategy, the WPTDDM-FxLMS algorithm, is proposed in this paper to solve the MIMO vibration problems with multi-frequency excitation and multi-path coupling in underwater vehicles.