Research And Realization On Active Structural Acoustic Control

The problems of the acoustic radiation caused by the structural vibration and the acoustic radiation controlling are always an important research topic in the acoustic engineering. Compared to traditional passive control methods, active control methods controlling the acoustic radiation which are caused by vibration in the aircraft cabin, vehicle cabs or other enclosed space have many advantages such as small size, light weight and easy to control. The technology of the active control of structural acoustic radiation has broad application prospects. Thus to study the technology and the hardware of active control of structural acoustic radiation in the enclosed space has great value.The implements of the active control of structural acoustic radiation are defined as the following: Secondary actuators are imposed on the surface of vibration structure to inhibit structural vibration, thereby reducing the structural acoustic radiation and decreasing noise. In this paper, the control methods of radiation noise which is caused by the vibration of rotating machines and transmitted by solid parts , which leads to vibrations of thin plate to radiation in the enclosed space such as automobiles and ships compartments are studied. The adaptive control of structural acoustic radiation is mainly researched. The hardware platform is designed. The active control of structural acoustic radiation in the enclosed space is completed with experimental box. The main work is summarized as the following:1) Study the adaptive control algorithms of structural acoustic radiation: FXLMS algorithm, DSLMS and QDSLMS algorithm which do not need the secondary path modeling. Compare of the QDSLMS algorithm and FXLMS algorithm to study the convergence speed and noise reduction through simulation.2) Improve the structure of the multi-frequency active noise canceller. The improved structure reduces the average time-consuming caused by direction search in the QDSLMS algorithm, which is used to control multi-frequency harmonic noise. Get the control efforts through simulation with the improved structure and the original.3) Design the frequency tracking algorithm for multi-frequency harmonic noise, which has less computation and simple hardware, to track the baseband of the multi-frequency harmonic noise in real time.4) Design the exciter and power amplifier for piezoelectric ceramics. Configure signal processing board for Active control of structural acoustic radiation .Program and optimize active control of structural acoustic radiation algorithm.5) Design data acquisition program for primary and secondary channel on the experiment box to identify the channels. Determine the layout and selection of the error sensor and secondary power source by experimental means. An active real-time control is applied to structural acoustic radiation. The results are tested and analyzed, the results of the reduced noise are as the following: the baseband is reduced about 10dB, second harmonic is reduced about 15dB, third harmonic is reduced about 10dB and the total reduction of the noise is about 10dB.