纤毛式MEMS矢量水听器研究

发布时间：2018-05-20 04:21

本文选题：矢量水听器 + 微机电系统　；参考：《西北工业大学》2015年博士论文

【摘要】：随着舰船减振降噪技术的发展,传统的声纳探测技术受到前所未有的挑战,各主要海军国家纷纷探索基于新效应、新原理、新工艺的新型换能器进行水下声目标检测。目前,水下目标检测手段主要是利用声压标量水听器及其阵列来实现,这时只能获得声场的声压标量信息,不能获得水质点的振速、加速度等声场的矢量信息。另外,对于小尺寸水下武器平台(如水雷,深水炸弹等),由于自身空间的限制,声压水听器阵在低频段很难获得有效阵增益和波束宽度,继而影响到其探测距离与定位精度。然而,近年发展起来的矢量水听器可藉助单个水听器或较小的阵列实现水下声目标甚低频、远距离探测与定位,因而倍受国内外学者的关注。矢量水听器按拾振工作原理主要分为同振式、声压梯度式、动圈式等,虽然它们各自的工作原理不相同,但都有对于声信号的检测具有“8”字型余弦指向性的共同特点。MEMS矢量水听器是近年来新发展起来的一款微型水听器,相对于其它矢量水听器具有小体积、低成本、刚性安装等优势,非常适合应用于水下小尺寸武器平台。然而,当前MEMS矢量水听器发展也存在一系列瓶颈问题,如灵敏度低、响应频带窄、等效本底噪声声压级高、抗流激噪声差等。本文针对MEMS矢量水听器所存在的诸多技术难题开展了一系列攻关研究。针对前期提出的纤毛式MEMS矢量水听器声—电转换微结构,建立了相应力学模型,从数学上推导出结构应力及共振频率与微结构几何尺寸之间解析关系式,依据公式定性分析出同一种微结构的灵敏度与共振频率是一对固有矛盾。为解决该矛盾,提出了微结构多重应力集中的方法,目的是通过应力集中将多种不同微结构的优势折衷集中在一种结构上,得到相对于其中某一微结构既提高灵敏度又拓展频响带宽的完美结果。同时,提出了纤毛集成低密度小球方案,目的是利用低密度小球来增大声波的接收面积,大幅提高纤毛式MEMS矢量水听器的灵敏度,同时微结构的共振频率也不能降低太多。针对以上多重应力集中微结构和纤毛集成低密度小球两种微结构分别建立了有限元流固耦合模型,利用ansys仿真软件,分析并验证了两种结构的可行性。针对本文提出的多重应力集中微结构,结构形式复杂且为MEMS非标准加工工艺的难题,开发出一套完整的MEMS加工工艺流程,重点解决了应力槽刻蚀,压敏电阻布置,欧姆接触及前后微结构体硅刻蚀等关键工艺。在此基础上利用L-Edit软件绘制出光刻掩膜版图交付加工单位,并成功加工出纤毛式MEMS矢量水听器芯片。然后,基于专用微系统集成平台,实现了纤毛与MEMS矢量水听器芯片的二次集成。针对纤毛式MEMS矢量水听器芯片应用于水中必须解决其绝缘、耐压、透声等封装问题,提出了将纤毛式MEMS矢量水听器密封于透声帽(其中透声帽中充满绝缘、传声介质油)的封装方式和“桔瓣式”支撑结构。基于有限元仿真和试验验证相结合的方法,深入研究透声帽对纤毛式MEMS矢量水听器性能的影响。给出了弹性模量越小、厚度越薄的材料制作透声帽对纤毛式MEMS矢量水听器灵敏度损失越小的结论,虽然透声帽自身的一阶固有频率也会越低,从而造成纤毛式MEMS矢量水听器整体频响曲线变化复杂。“桔瓣式”支撑结构则可以有效提高透声帽的一阶固有频率,同时起到防碰撞效果。针对前期纤毛式MEMS矢量水听器在海试过程中抗流激噪声差的问题,设计了微型导流罩,测试表明该微型导流罩虽然对纤毛式MEMS矢量水听器的灵敏度略有降低(在1kHz以下的低频最大损失3dB),但对流激噪声抑制明显,从而能够大幅提高纤毛式MEMS矢量水听器的信噪比。为了减小后续电路所引起的噪声,设计了微弱信号提取电路,测试结果表明该板级电路噪声谱级小于-140dB(80Hz以上)。最后,对纤毛式MEMS矢量水听器的灵敏度,指向性,量程,抗振动等主要性能进行了室内校准测试,并完成了新安江湖试和青岛海试。测试结果表明:多重应力集中的纤毛式MEMS矢量水听器相对于前期MEMS矢量水听器灵敏度提高了6~15dB,频响范围由20Hz~500Hz拓展到20Hz~1kHz,等效本底噪声声压级降低了10~25dB。所设计的微型导流罩,典型环境试验和海试结果表明可以显著抑制流激噪声,大幅提高信噪比,为纤毛式MEMS矢量水听器的工程应用奠定了技术基础。
[Abstract]:With the development of ship vibration reduction and noise reduction technology, the traditional sonar detection technology is facing unprecedented challenges. The main Navy countries have explored the underwater acoustic target detection based on new effects, new principles and new technologies. At present, underwater target detection means to be realized by using sound pressure scalar hydrophone and its array. At this time, the sound pressure scalar information of the sound field can only be obtained, and the vector information of the sound field, such as the velocity of the water quality point, the acceleration and other sound fields, is not obtained. In addition, for the small size underwater weapon platform (such as mine, deep water bomb, etc.), because of the limitation of its own space, it is difficult to obtain the effective array gain and beam width at the low frequency section of the acoustic pressure hydrophone array, and then influence it. However, the vectorial hydrophone developed in recent years can realize the underwater acoustic target very low frequency, remote detection and location by a single hydrophone or a small array, so it has attracted the attention of the scholars at home and abroad. The principle of vector hydrophone is divided into the same mode, the sound pressure gradient, the moving coil, etc. Their respective working principles are different, but all of them have the common characteristic of "8" type cosine pointing to the sound signal detection. The.MEMS vector hydrophone is a newly developed micro hydrophone in recent years. Compared with other vector hydrophones, it has the advantages of small volume, low cost, rigid installation and so on. It is very suitable for application to underwater small underwater vehicles. However, there are also a series of bottlenecks in the development of the current MEMS vector hydrophone, such as low sensitivity, narrow response frequency band, high sound pressure level equivalent to the background noise, low noise resistance, and so on. In this paper, a series of research and Research on many technical problems existing in MEMS vector hydrophone are carried out. The ciliated MEMS proposed in the previous period is proposed. A corresponding mechanical model is established for the acoustic to electric transformation of a vector hydrophone. The analytical relation between the structural stress and the resonance frequency and the geometrical size of the microstructures is deduced from the mathematical model. The inherent contradiction between the sensitivity and the resonance frequency of the same micro structure is qualitatively analyzed by the formula. The method of stress concentration is aimed at concentrating the advantages of various microstructures on one structure through stress concentration, and the perfect result of increasing sensitivity and bandwidth of frequency response is obtained relative to one of the microstructures. At the same time, the scheme of cilium integrated low density ball is proposed to increase the sound wave by using low density ball. The receiving area can greatly improve the sensitivity of the ciliated MEMS vector hydrophone, and the resonant frequency of the microstructures can not be reduced too much. A finite element fluid solid coupling model is established for the two kinds of microstructures and cilia integrated low density microstructures, and two kinds of junctions are analyzed and verified by using the ANSYS simulation software. In view of the multiple stress concentration micro structure proposed in this paper, the complex structure form and the difficult problem of MEMS non-standard processing technology, a complete set of MEMS processing process is developed, which focuses on the key technologies of stress groove etching, pressure sensitive resistance arrangement, ohm contact and microstructural silicon etching and so on. L-Edit software is used to produce the delivery processing unit of photolithography mask layout, and the ciliated MEMS vector hydrophone chip is successfully machined. Then, the two integration of ciliary and MEMS vector hydrophone chips is realized based on the special microsystem integrated platform. The insulation and pressure resistance of ciliary MEMS vector hydrophone chips must be solved in water. The encapsulation of the ciliary MEMS vector hydrophone is sealed in the sound cap (in which the sound cap is filled with insulation, sound transmission medium oil) and the "orange petal type" support structure. The influence of the sound cap on the performance of the ciliary MEMS vector hydrophone is deeply studied by the combination of finite element simulation and test verification. The smaller the modulus of elasticity and the thinner the thickness of the material, the smaller the sensitivity loss of the ciliary MEMS vector hydrophone, the lower the first natural frequency of the sound cap itself, which causes the change of the whole frequency response curve of the ciliated MEMS vector hydrophone. The first order natural frequency of the high penetration hat has the effect of anti collision. In view of the problem of the difference in the flow resistance of the pre ciliary MEMS vector hydrophone during the sea trial, the miniature guide cover is designed. The test shows that the minitype guide mask has a slight decrease in the sensitivity of the ciliary MEMS vector hydrophone (the maximum low frequency loss below 1kHz). 3dB), but the suppression of the convective noise is obvious, thus the signal to noise ratio of the ciliated MEMS vector hydrophone can be greatly improved. In order to reduce the noise caused by the subsequent circuit, a weak signal extraction circuit is designed. The test results show that the noise level of the board level circuit is less than -140dB (80Hz). Finally, the sensitivity of the ciliated MEMS vector hydrophone, The directivity, the range, the anti vibration and other main performances were tested in the indoor calibration test, and the Xin'an River test and the Qingdao sea test were completed. The test results showed that the sensitivity of the ciliary MEMS vector hydrophone with multiple stress concentration was improved by 6~15dB compared with the earlier MEMS vector hydrophone, the frequency range was extended from 20Hz~500Hz to 20Hz~1kHz, and the equivalent background noise was equivalent. The sound pressure level reduces the miniature guide cover designed by 10~25dB.. The typical environmental test and the sea test results show that the noise can be suppressed significantly and the signal to noise ratio is greatly improved, and the technical basis for the engineering application of the ciliary MEMS vector hydrophone is laid.
【学位授予单位】：西北工业大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB565.1

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