Research On Distribution Active Structural Acoustic Control Mechanism Based On Agent Unit In Enclosure

Active structural acoustic control (ASAC) in an enclosed cavity and its engineering application have been focused by the academic and engineering communities for some years. There are some reasons that caused this problem:there is a coupled acoustic field in the cavity, and the ASAC system has distributed characteristics, these make the ASAC architecture become more complex, meanwhile the overall control efficiency is not better. At some time, sound field in the cavity would be changed, or the controller would be damaged, at this moment, the control result would to be bad because of the common active system lacks of intelligent and flexibility. Therefore, it is especially important to make research of complex control architecture and the distribution of the intelligent unit coordination problems, and to control cavity sound field effectively.Distribution ASAC control mechanism base on agent unit in an enclosed cavity is studied in this thesis, the distribute control theory of Multi agent system (MAS) is applied to ASAC in enclosure. An enclosure model of two flexible plates is established for the analyze of the structural acoustic coupling system; actuator control force parameters and the position of these actuators are optimized, and general selection principle of the number of sensors is given by the compared between the global control and local control. MAS is studied in an enclosed cavity of active noise control system implementation, the noise control Agent unit structure is analyzed; And each of the Agent in the MAS operating field has been designed; Agent of MAS interact communication between units in the ASAC system are discussed, the application of multi-Agent cooperation mechanism based on improved contract net protocol (CNP) is studied; Finally the collaboration processes is given based on multi-agent units. Distribution control system framework of enclosure cavity with agent unit based on MAS is established, and the simulation is accomplished. Finally, an experiment control system is construct in dSPACE/Simulink platform, and the MAS experiment is performed, the result shows that the noise control achieved better control effect in the enclosure based on MAS intelligence unit distribution control system.The main contents and contributions of the dissertation are as follows:1. A rectangular enclosure consisting of two simply supported flexible plates with structure-acoustic coupling system is considered. The structure-acoustic coupling characteristic and the vibration model of the flexible plate surface are conducted by Acoustoelasticity Theory. The quadratic function about the control objective of minimizing the total time averaged acoustical potential energy is established, and the optimum formula of secondary control force and the maximum noise reduction is derived. The simulation results of secondary actuator arranged in radiation flexible plates and stimulated flexible plates are compared, and the results show that the position of the actuators is closely related to the primary exciting force and the cavity sound field, otherwise it would be easy to the overflow control problem.2. Control mechanism and performance of the structure-acoustic coupling noise field with multiple actuators are studied, and the strength of actuators is optimized in the cavity consisting of two sampled flexible plates; The location of the secondary actuator parameters are also optimized by the distribution of sound pressure level(SPL) in the excited plates. The secondary actuators’ number selection principle is proposed by both the two side of global potential energy and local sound pressure level at the same time, for practical engineering applications provide theoretical basis.3. The distribution control strategy based on MAS is applied to AS AC in an enclosure agent unit distribution control, MAS has the distribution characteristics and it very suit the ASAC in an enclosure. First, Nosie controller Agent is designed, and the agent operating field is also designed in some methods. The framework of ASAC in an enclosure based on MAS agent unit distribution control system would be designed.4. Multiple Agents cooperation between MAS is studied, and it is carried on the detailed analysis for it is the most important problem of MAS, three cooperation methods are discussed in this thesis, blackboard model, classical CNP and the improved CNR Trust mechanism and screening strategies are introduced to CNP, and the MAS based on improved CNP cooperation process is designed.5. The interaction and communication between multiple agents is studied, KQML primitives are analyzed and extended, to adapt to the communication between MAS. And for the first application of KQML to MAS control system in enclosure cavity, and the write the process of cooperation between agents of MAS is written by the KQML.6. The noise controller agent, agent unit of PZT and microphone structure control unit is designed for ASAC in the enclosure cavity, and MAS distributed control framework based on the improved CNP is established, the simulation results show that the distribution of the MAS control effect is better.7. The ASAC test bench based on MAS is bulided on the dSPACE/Simulink hardware in the loop real-time control platform. Agent unit distribution ASAC control system based on MAS in an enclosure is realized. When primary stimulate is given and dual channel control system are carried out for ASAC in an enclosure based on MAS, good results proved that the applications of MAS to ASAC agent units distributed control system is effective.