【作者】 李天利；

【导师】 李泽湘；

【作者基本信息】 哈尔滨工业大学 ， 控制科学与工程， 2009， 博士

【摘要】 本论文针对轮胎压力监测系统对传感器的具体需求,对轮胎压力监测系统中核心器件传感器的设计、分析、优化和检测方法进行了系统而深入的研究,提出一种新型无源SAW温度压力传感器的设计方法。研究内容主要包括以下几个方面:首先,本文对基于SAW延迟线理论的温度压力传感器结构设计方法进行了系统的研究。以SAW延迟线理论为基础,针对传感器需要同时测量温度和压力两个物理量的要求,给出了一种有别于传统SAW延迟线传感器结构的设计方法。用双向反射器配置方案对传感器进行设计,即将反射器放置在IDT产生的SAW传输路径两侧,这样的结构可以使得SAW能量充分运用,传感器RF脉冲回波信号强度有所提升和信噪比高的优点。这种结构设计为延迟线型SAW传感器提供一种新的设计思路,可扩展用于两个以上物理量检测的SAW传感器设计中。根据无源SAW传感器的设计结构,用基于SAW延迟线型传感器的传感原理进行理论分析,在传感器温度压力参数计算中引入权重因子的概念,实现用权重因子的方法对压力的量测数据进行温度补偿,推导出温度压力和SAW传感器RF脉冲回波信号相位之间的函数关系,从而在理论上证明,可以通过本研究设计的无源SAW传感器对温度压力两个物理量同时实现精确测量。然后,对无源SAW传感器的压电基底材料和MEMS加工工艺做深入细致研究,通过对用于SAW的压电基底材料各项性能参数的分析比较,结合本文设计无源SAW传感器需要测量温度和压力的具体需求,最终选定温度系数好、机电耦合系数高、并且具有大批量生产能力和材料稳定性能的YZ切铌酸锂作为传感器的压电基底材料。通过对SAW传感器工作的理论分析给出传感器加工需要的详细参数,经MEMS的表面微加工工艺加工出传感器基片。最后,对传感器的RF脉冲信号分析方法做详细研究,分析了RF脉冲信号特性,讨论不同RF脉冲访问信号宽度对传感器RF脉冲回波信号的影响,讨论不同RF脉冲访问信号频率对传感器测试数据的影响,分析了产生这些影响的原因。通过详细分析,给出获得传感器最佳RF脉冲回波信号的理论分析方法,并用在传感器的测试中。通过对所设计传感器原型进行测试分析,传感器的实际测试结果和理论分析数据相吻合,验证了理论分析的正确性,并且这种传感器结构可以提升同类型传感器返回信号的强度,有利于对信号的后续处理分析。本文研究采用从理论建模入手,进行计算仿真,构建TPMS系统传感器测试平台,并对所设计传感器进行实物加工测试,修正和完善理论模型。通过反复理论建模、计算仿真和实验分析的研究方法,优化无源SAW温度压力传感器的性能指标,实现无源SAW传感器对温度压力信号的准确采集、分析与处理。和现有用于TPMS系统中的有源传感器相比,所设计的无源SAW温度压力传感器在进一步完善优化后具有结构简单、体积小、重量轻不易损坏等显著优点,可以用在TPMS中作为传感装置检测轮胎内的温度压力数据,随着人们对TPMS系统的日益关注,TPMS的市场需求量亦会不断扩大。本文基于SAW延迟线理论的分析研究,不仅可以用在温度压力传感器的设计中,还可以用在SAW传感器对其它物理量的检测中,用来补偿温度对器件造成的影响,这种理论分析方法具有一定的通用性。更多还原

【Abstract】 In this dissertation, according to the need in TPMS sensor, a deep and systematic study on the design, analysis, optimization and test of TPMS sensor is made, which is based on a novel passive SAW temperature and pressure sensor. The main contents of this dissertation are consisted of the following parts.Firstly, the design methodology of the temperature and pressure sensor based on the SAW delay line theory is studied. With this new design methodology, which is in a non-traditional way, the sensor is able to measure temperature and pressure simultaneously. The sensor is designed in two direction reflectors method, i.e. the reflectors are placed in the two directions of the SAW caused by IDT, which is more energy efficient and obtains higher signal/noise ratio compared with traditional methods. By using of a weighted factor in the temperature and pressure calculation of SAW sensor, the effect of the temperature on the phase shift can be eliminated, so the phase shift induced by the pressure can be detected independently by the sensor. The function between the temperature pressure and RF pulse echo signal of SAW sensor are derivate, therefore, with this novel design, the SAW sensor is capable of measuring both the temperature and the pressure simultaneously and accurately.Secondly, the piezoelectric material character and MEMS fabrication method are studied deeply. Through the comparison among the different piezoelectric materials, and the temperature and pressure measurement requirement of the SAW sensor, Y-Z cut LiNbO3 was used as the substrate material of the sensor which has the good temperature coefficient, high electromechanical coupling coefficient, high-volume production capacity and material stability. The SAW sensor is made by this substrate through the MEMS processing technology, according to the detail parameters which can be achieved from the theory analysis.Finally, analysis method of RF pulse signal and the test result for the SAW sensor are studied deeply too. The character of the RF pulse signal is analyzed. RF pulse echo signal affected by the different RF pulse access signal widths are discussed. And RF pulse echo signal affected by the different RF pulse access signal frequency is argued too. The most suitable RF pulse signal is achieved by theoretical analysis and used in the sensor test. According to the comparison of the actual test results and theoretical analysis of data, the data coincide with each other. The actual test results showing the echo signal energy are better than traditional sensors. It is more suitable for the data processing of the signal.This dissertation starts from the theoretical model, then does the simulation calculation, building the TPMS sensors test platform, fabricating the SAW sensor and according the test data to amend and improve the theoretical model. Through the above procedures, the performance of passive SAW temperature and pressure sensor is optimized. The sensor can measure, analyze and process the temperature and pressure information.In the area of TPMS, the reliability and durability are really demanding. The reported sensor has its practicability and potential market with its advantages of simple structure, light, and wireless and passive working mode. The analysis and research of this dissertation based on the SAW delay line theory not only is used in the temperature and pressure sensor, but also is used in the other sensing fields to compensate the impact of the temperature on the device, so the analysis of this theory has a certain universal.更多还原