Study On Localization Mechanisms Of The Auditory Systems Of Subminiature Creatures And Design And Experimental Research Of The Bionic Acoustic Sensing Device

Sound source localization is always of great value in many engineering applications. In these types of localization appliances, several microphone transducers are usually involved in the localization structures. Each of the time-domain response of these microphones under the incident sound stimulus is determined individually and sent to the arithmetic-logic sections immediately by which the localization systems could find out positions of the sound sources subsequently. The transducers used in microphone array are usually independent of each other, so the microphone array should have enough microphone transducers in order to obtain sufficient acoustic field information. Additionally, the minimum element spacing of the microphone array should be much greater than the distance accuray in order to ensure positioning accuracy, in other words, the minimum element spacing of the microphone array should be much larger than the product of sampling interval and sound velocity in the acoustic propagation medium. Therefore, these appliances always consist of many components, and the looseness of structures of them may narrow their practical applications. In some special application situations, such as micro sonar system used in miniature transportation vehicles and hearing aids capable of determining direction of the acoustic excitation, the transducer system should be designed to accomplish the purpose of localizing the sound source by a relatively compact structure. These types of application situations demand new technologies to satisfy the requirements. In recent years, studies on orientation mechanisms of the auditory systems and research of bionic structures of subminiature creatures, especially of the parasitoid fly Ormia Ochracea which has a remarkable ability to detect the direction of the incident sound stimulus despite of its tiny body size, may provide preferable solutions for these types of applications. This present dissertation was completed under this background.The acoustic sensory organs of the parasitoid Ormia Ochracea, the mechanical and the experimental of bionic acoustic sensing device are taken as the research object to find feasible orientation mechanisms which can be used for reference to design reliable and practical acoustic sensing devices and put forward the estimating method of direction angles of sound stimulus.Orientation mechanisms for the estimation of direction angles of sound stimulus and parameter selection of mechanical model are very important for designing the bionic acoustic sensing device. Based on the previous research on anatomy and physiology of the parasitoid fly Ormia Ochracea, the orientation mechanisms and dynamic characteristics of its acoustic sensory organs are discussed further, which are beneficial for bionics research on acoustic sensing devices.On the basis of this discusses on the orientation mechanisms of the biomimetic structure, the mechanical models for the purpose of estimating the direction angles of sound stimulus in the plane or in half-space. The vibration performances and response characteristics under different incident frequencies or incident angles are analyzed respectively. The analysis of this structure's dynamic behavior shows that the incident angles of the sound have special relationship to the responses of this instrument, and the incident angles can be estimated by detecting and processing the vibration responses of the three elastic diaphragms.According to the localization mechanism and theoretical analyses mentioned above, an acoustic sensing device used mechanically coupled diaphragms is designed, which consists of three springs and rigid bars to accomplish the purpose of coupling between vibration responses of the diaphragms. Vibration differential equations of the acoustic sensing device and the relationship of parameters of the experimental structure and parameters of the mechanical model are established and the sensitivity of vibration responses to strength of the sound stimulus is analyzed simultaneously, these works provide the basis for the manufacture of experimental acoustic sensing device.In the last part of this paper, experiments on bionic acoustic sensing device are conducted after the test system has been established. The measured data and the analyses based on the measured data demonstrate that the modeling methods and theoretical study in this dissertation are correct.