【作者】 侯占强；

【导师】 吴学忠；

【作者基本信息】 国防科学技术大学 ， 机械工程， 2012， 博士

【摘要】 陀螺仪是测量运载体角运动的传感器，是惯性导航系统的基础核心器件之一，在军事和民用领域都具有非常重要的应用价值。与传统的机械转子陀螺、静电陀螺、激光陀螺和光纤陀螺相比，微机电陀螺具有体积小、成本低、功耗低、易于批量化生产等显著特点，在制导弹药、无人作战系统等武器装备中具有广泛的应用前景。国外对高性能微机电陀螺实行产品和技术的严格控制，而目前我国研制的微机电陀螺整体水平与应用需求还存在较大差距。作为陀螺仪的核心技术指标之一，零偏稳定性的提升是高性能微机电陀螺研制的关键技术。微机电陀螺虽然体积小，结构相对简单，却是一个非常复杂的机电耦合系统。其结构精度容易受设计水平、制造误差等条件限制，同时在工程应用中又会面临温变、振动冲击等复杂环境，零偏稳定性的形成机理非常复杂。本实验室针对国内武器装备对微机电陀螺的迫切需求，研制了一种蝶翼式硅微陀螺。掌握了该微陀螺的结构设计、加工工艺和信号检测等基本理论和关键技术，成功研制了原理样机。本论文以蝶翼式微陀螺为对象，围绕微机电陀螺零偏稳定性的提升方法开展研究，重点解决蝶翼式微陀螺的模态耦合误差、结构应力、制造误差等关键问题，为我国发展高性能微机电陀螺提供新的设计理论和方法。主要研究内容如下：1.介绍了蝶翼式微陀螺的总体结构和工作原理，并对其动态特性和测控技术进行了系统研究。重点推导了各向异性条件下平行四边形截面支撑梁的弯曲刚度和扭转刚度，理论分析了蝶翼式微陀螺的系统阻尼、驱动力矩和哥氏力矩。建立了微陀螺工作模态频率的理论模型和动力学方程，得到了机械灵敏度、带宽等动力学特性的解析表达式。采用了基于双正弦载波的微弱电容检测方法和基于PID振动幅值控制的闭环驱动方法，成功地实现了驱动信号和检测信号的分离。最终得出了理想情况下蝶翼式微陀螺角速度输出信号的理论模型。2.研究了蝶翼式微陀螺零偏稳定性产生机理及其主要误差来源。建立了蝶翼式微陀螺的模态耦合误差模型，主要包括：静电力耦合误差、哥氏力耦合误差、驱动-检测振动耦合误差、检测-驱动振动耦合误差。分别研究了结构误差、电路误差和环境误差等确定性误差对蝶翼式微陀螺零偏稳定性的影响规律。3.研究了蝶翼式微陀螺加工过程中形成的结构应力及其对微陀螺零偏稳定性的影响规律，并对微陀螺结构进行了优化设计。理论分析了静电吸合效应、轴向热应力、贴片封装应力对蝶翼式微陀螺结构变形和动态特性的影响规律。通过悬臂梁和双端固支梁结构的对比，建立了蝶翼式微陀螺自由状态下和轴向热应力作用下模态频率的理论模型。分别设计了蝶翼式微陀螺的应力释放槽结构、弹性支撑框架结构以及基于材料补偿方法的应力平衡结构。改进后，微陀螺接口电容、模态频率、品质因子和零偏输出的温度特性得到了明显提升。4.研究了蝶翼式微陀螺的结构制造误差及其对零偏稳定性的影响规律，并采用激光微加工的方法对结构误差进行了精密修形实验。重点分析了材料几何形状误差和制造过程中的对准误差及湿法腐蚀加工误差对微陀螺结构加工精度和零偏稳定性的影响规律。研究了蝶翼式微陀螺结构制造误差精密修形的工作原理，并采用紫外激光微加工系统对蝶翼式微陀螺的敏感结构进行了精密修形实验。激光修形后，微陀螺的模态耦合误差显著减小。5.对改进前后蝶翼式微陀螺的主要性能指标进行了对比测试，主要包括标度因数、标度因数非线性度、标度因数温度系数、零偏稳定性、零偏温度灵敏度等。测试结果表明，微陀螺的标度因数非线性、标度因数温度系数、短时启动下的零偏稳定性以及零偏温度灵敏度都得到了大幅提升。更多还原

【Abstract】 Gyroscope is the sensor that measures the rate of rotation of a carrier. It is one ofthe basical core devices in inertial navigation system and has very important militaryand civil applications. Because of its small size, low cost, low power consumption andbatch fabrication compared to traditional mechanical spinning gyroscope, electrostaticgyroscope, laser gyroscope and fiber optical gyroscope, micromachined gyroscope hasan extensive application prospect in the weapons such as guided munitions andunmanned combat vehicles. The related products and technologies of high performancegyroscopes are embargoed against China by foreign countries while most domesticmicromachined gyroscopes can not meet the demands. Therefore, improvement in biasstability which is one of the core performance specifications is the key technology fordeveloping high performance micromachined gyroscope.Although it has a small volume and simple structure, the micromachined gyroscopeis a complex electromechanical coupling system. Its structural precision is easilyrestricted by design level, fabrication imperfections, etc. Meanwhile, it is faced withtemperature variations, vibrations and shocks in engineering applications. So theformation mechanism of bias is complicated. Aiming at the urgent demands of weaponequipment, we developed a micromachined butterfly gyroscope. The basical theoriesand key technologies of structure designing, micromachining and signal processingwere studied. This dissertation focuses on the methods of improving the bias stability ofmicromachined gyroscopes, which takes the micromachined butterfly gyroscope as theobject. Breakthroughs were made on the key technologies such as modal coupling error,structural stress and fabrication imperfection. The research results will provide a noveldesign theory and method for developing high performance micromachined gyroscopes.The main research contents of this dissertation are as follows:1. The structure and operation principle of the micromachined butterfly gyroscopewere presented, and its dynamic characteristics and readout technologies weresystematically studied. Emphatically, the bending and torsional stiffnesses of thesuspension beam, which has a parallelogram cross section, were derived considering theanisotropic properties of monocrystalline silicon. The damp, driving and Coriolismoments of the gyroscope were derived. The operation modal frequencies and thedynamic equation of the gyroscope were theoretically modeled. Then, expressions ofthe mechanical sensitivity and bandwidth of the gyroscope were obtained. According toits capacitive output characteristics, capacitance detection using double sinusoidalcarriers and closed loop excitation using PID controller were adopted in the readoutcircuit. The driving singal and sensing signal were successfully extracted from eachother. Finally, the theoretical model of the output signal of the gyroscope due to angular rate inputs was obtained.2. The formation mechanism and major sources of bias stability of the gyroscopewere studied. The model of the modal coupling errors which contain electrostatic forcecoupling error, Coriolis force coupling error, vibration coupling between drivingoscillator and sensing oscillator was established. Finally, the systematic errors such asstructural error, circuit error and environmental error and their influence on the biasstability were studied.3. Structural stresses induced during the fabrication process and their effectmechanisms were studied, and the mechanical structure of the gyroscope was optimized.Structure deformation and dynamic characterictics affected by the pull-in effect, axialthermal stress and internal stresses induced by the die attachment and package weretheoretically analyzed. In order to theoretically model the modal frequency of thegyroscope under action of the axial thermal stress, two types of structures whichadopted a clamped-free suspension beam and a clamped-clamped suspension beam weredesigned and characterized. Structures adopting stress release groove, flexural supportframe and stress balancing were designed and characterized. The temperatureperformance of the capacitance output, modal frequency, quality factor and bias outputwere evidently improved.4. Fabrication imperfections of the micromachined gyroscope and their influenceson the bias stability were studied. The structural trimming method was experimentallycharacterized by UV laser micromachining. Emphatically, geometric errors of thematerials and fabrication imperfections due to misalignments and etching defect andtheir influences on the structure precision and bias stability were analyzed. Theoperation principle of structure trimming was studied and experimentally characterizedby UV laser micromachining. The experimental results showed that the modal couplingerror of the gyroscope was decreased significantly after laser trimming.5. Test and comparison of the major performance specifications including scalefactor, nonlinearity, bias stability, temperature sensitivities of scale factor and biasstability were carried out for the micromachined butterfly gyroscopes before and afterimproving. The results showed that the nonlinearity, temperature sensitivities and biasstability under short in-run time were improved significantly.更多还原