【作者】 江东；

【导师】 杨嘉祥；

【作者基本信息】 哈尔滨理工大学 ， 电工理论与新技术， 2011， 博士

【摘要】 在惯性式测振系统中所用的加速度、速度和位移传感器的惯性质量块均通过弹性元件与传感器壳体连接,传感器壳体再与被测振动体刚性固定。当被测振动体振动时,振动信号通过惯性质量块获取。本文所设计的振动测试系统,以磁悬浮球代替惯性质量块,不用弹性连接部件,系统无机械连接,运动也无机械摩擦,可自由取向,系统阻尼由控制电路控制,无须排气法、油浸法或水浸法中的阻尼介质。所以,该系统可方便地测量来自各方向的振动或多维振动,较传统惯性质量块测振方法应用范围广。本文构建了由电磁铁、磁悬浮球、红外光发射/接收器、PD控制电路组成的磁悬浮球模型,通过振动理论证明了磁悬浮球在平衡点的振动与惯性质量块一样,满足常系数二阶微分方程,并通过二者比对,确定了磁悬浮球模型的固有频率。此外,还通过实验测得了该模型的固有频率,二者基本一致,表明利用磁悬浮球测量振动是可行的。本文建立了以磁悬浮球为核心部件的振动测试平台。平台中由标准激振器产生的不同幅值和频率的振动信号,通过磁悬浮球模型中的光电位移传感器,经数据采集卡,传至虚拟示波器,经数据处理,获得了系统的幅频特性和相频特性的相关信息:系统的固有频率为19.83Hz,测量范围为20～140Hz,灵敏度为300mV/m·s^-2,加速度为526.38m/s²,位移0～4mm,这些参数与市售的速度传感器相比,除了在多维测量方面占有优势外,其它性能（如波形的失真度、测试精度、测量范围和灵敏度等）基本持平,可满足测试系统要求。此外,为了改善系统的稳定性,以MATLAB为计算平台,通过改变光电位移传感器的安装位置H₀、放置磁悬浮球的初始位置X₀和微分电路PD参数,数值模拟了磁悬浮振动测试系统的幅频特性、相频特性以及自功率谱特性中特有的混沌现象。同时,从单、双吸引子概念出发,以相轨迹为混沌判据,模拟了磁悬浮球由混沌向非混沌的过渡过程,确定了系统产生混沌现象的参数范围。在此基础上,进一步确定了位移传感器安装位置、磁悬浮球初始位置和微分电路的PD参数的最佳值,并进行了实验验证。最后,对磁悬浮振动测试系统在二维和三维振动测量的应用进行了实验研究,实验结果表明:对来自任何方向的二维振动的波形均可测量,并通过数据拟合可以求得振动方向和振动源。对任意方向引起的三维振动也可测量,可获得X、Y和Z方向的振动分量,但波形重构尚需进一步完善。本文所提出的这种基于磁悬浮效应的振动测试方法是一种全新的振动测量方法,经进一步完善,在二维和三维振动测量中有一定的应用前景,也为现行的惯性式振动测量的改进和提高提供了一条新的思路。更多还原

【Abstract】 A inertia mass block in a number of conventional instruments which based on inertial vibration measurement such as accelerometer, speedometer and displacement transducer must be connected with sensor shell rigidly fixed with vibration object measured using elastic elements. The vibration signals are acquired through inertia mass when the object measured vibrates. In this dissertation the inertial mass block in the inertial vibration measurment system is replaced by the magnetic levitation ball which is controlled by the magnetic force generated from helical coil. Using such kind of system has an advantage over conventional vibration measuring instruments because of non existence of mechanical connections and damping medium. Therefore, the system can easily measure the vibrations that comes from all the directions, or multi-dimensional vibration. The vibration measurement system designed has a wide range of applications than the traditional methods containing inertial mass block.The physical model consisted of the magnetic levitation ball, electromagnet, infrared emmiter/ receiver, PD controlled circuit had been set up. It is verified by vibration theory that the magnetic levitation ball vibration in the balance state can meet the second-order differential equations with constant coefficients like inertial mass vibration in the inertial vibration measurement system. In addition the natural vibration frequency of the magnetic levitation ball had been also definend by comparing the both vibration equations, which is concordant with that from the experiment. Therefore it can be shown from theoretical and experiment that the using magnetic levitation ball to vibration measurement is feasible.In this dissertation a vibration measurement platform with the magnetic levitation ball as a main part had been set up. In the vibration measurement system the vibration signals with the different amplitudes and frequencies generated from standard exciter to driven the vibration table is acquired by a optical displacement sensor and is transformed to the virtual oscilloscope throwgh the data acquisition card and is displayed. It is kown from the vibration characteristics of the frequency, the amplitude-frequency and the phase-frequency that the natural vibration frequency and the acceleration are 19.83Hz and 526.38m/s²,.the measurement range, the sensitivity of the system and diaplacement are 20¹40Hz , 300mV/m·s^-2 and 0⁴mm respectiively. Compaered with the velocity sensor bought from the market, besides the superior of the three-dimention measurement these parameters are basically the same with them of the velocity sensor and can meet the needs of the test system requirements fully.In order to improve stability of the system, the chaos phenomenon of amplitude-frequency characteristics, phase-frequency characteristics and the power spectrum of the system had been simulated numerically using MATLAB in the case of the different installation location of the optoelectronic displacement sensor H0, initial position of magnetic levitation ball X0 and PD parameters. At the same time the transition process of the magnetic levitation ball from chaotic state to non-chaotic state is also simulated numerically using phase trace as chaotic criterion based on the concept of the single and the double attractor and the range of the parameters caused chaos phenmena is defined. Furthermore, the optimal parameters such as installation location of the displacement sensor, initial position of magnetic levitation ball and PD parameters of differential circuits are obtained.Finally, the application of magnetic levitation ball in two-dimensional and three-dimensional vibration measurements was experimentally studied. The results show that the two-dimensional vibration waveforms caused by the vibration from any direction can be measured and the location of the vibration source can be determined by data fitting. ;For the three-dimention vibration, the vibration wavefom in the X,Y and Z direction can be also measured., but the waveform reconfiguration is needed to improve further.The magnetic levitation vibration measurement method in dissertation is a new method of vibration measurement. By further improving, this method will have application prospect in the two-dimention and three-dimention vibration measurment and provides a new idea for improving inertial vibration measurement.更多还原