光弹光纤加速度传感器的研究与设计

以波长为632.8nm的激光为光源,以重火石玻璃(ZF6)作为敏感元件设计了一种光弹光纤加速度计.由于加速度a的变化产生光强的变化,故利用偏振光干涉原理测出出射光强、利用差动原理处理数据,则可测得加速度a.该仪器的主要设计参数:自然频率fn=1056Hz,相位检测灵敏度ΔΦ/a=1.83×10-3rad/(m·s-2),工作频带为0～317Hz.     

A Method of Determining the Axes of a Three-Component Magnetometer Sensor with Respect to the Axes of the Navigation System of a Ferromagnetic Mobile Object

A method of determining the orientation of the axes of a three-component magnetometer sensor with respect to the axes of the navigation system of a ferromagnetic mobile object is considered, which eliminates the effect of the magnetization of the object on the determination of the angular position of the axes of the sensor with respect to the axes of the navigation system.     

VS‐CONTROL WITH TIME‐VARYING SLIDING SECTOR — DESIGN AND APPLICATION TO PENDULUM —

In general, a Variable Structure (VS) system is designed with a sliding mode. Recently a sliding sector, designed by an algebraic Riccati equation, has been proposed to replace the sliding mode for chattering‐free VS controllers. In this paper we extend the design algorithm for the sliding sector to a time‐varying sliding sector. The time‐varying sliding sector is defined by functions dependent on both state and time, hence time‐varying uncertainty can be considered. The VS controller is designed to stabilize an uncertain system, quadratically. The design procedure for real systems is introduced via an implementation to the control of “Furuta pendulum”. To enhance the stability it is necessary to compensate the time‐varying nonlinear static friction of the actuator adequately, hence this problem is a good example to demonstrate the performance of the proposed VS control method. In the experiment, it will be shown that the VS control with the time‐varying sliding sector is superior to an orthodox chattering‐free VS control.     

Optimum design of mounting components of a mass property measurement system

Measurement of inertia properties of aerospace vehicle and submarine are vital to meet the intended motion objectives. The Moment of Inertia (MOI) is calculated by measuring the frequency of free torsional oscillation of the object mounted on a nearly friction less air bearing. For getting accurate measurement and to nullify the effect of undesired vibrations, the stiffness of the different components of the mounting and fixture (torsion rod, flexure) should be maintained appropriately. The optimum design of torsion rod and flexure is based on ensuring desired natural frequencies in different modes. Initiating with an analytical approach, the actual dimensions of the components are determined based on natural frequencies obtained by finite element analysis of the components. Simulated results are verified with experimental results.     

Anti-vibration analysis of vortex probe based on three-axis acceleration measurement

According to the diversity of the pipeline vibration and unicity of vortex signal in direction, a new idea is proposed to distinguish the vortex signal from the vibration interference by the directional character. This idea is applied to improve the anti-vibration performance of vortex flow-meter by a new probe structure based on three-axis accelerometer. Then model analysis is used to optimize the material, and the harmonic response analysis is applied to optimize the shape of probe tip. Finally, experiment is carried out to compare the anti-vibration performance of the traditional piezoelectric vortex probe and the new design. Experimental results show that new probe can accurately distinguish vortex signal from the vibration interference according to the directional character of signal. And its anti-vibration performance is superior to the traditional piezoelectric vortex probe.     

Experimental investigation into the effects of exciter motions on the primary calibration of single-ended accelerometer

It is widely known that in the primary calibration of accelerometers by using a laser interferometer, a device under test (DUT) and the laser interferometer should measure vibration at the same reference position. However, this is not applicable to single-ended accelerometers because of the limitation of their design. One way of overcoming this limitation is to measure the vibration at several positions on the exciter table surface which connects DUT to a vibration exciter. However this can present the effects of rocking motions of the exciter. Although the motions of vibration exciters are presented in several studied, the different model of exciters might have different characteristics. This paper aims to study the motions of an air-bearing exciter (model 2911) used at National Institute of Metrology (Thailand) in order to expose their characteristics, their effects on the calibration results and the measurement errors due to these effects. The motions of the exciter are shown in terms of magnitude and phase shift distributions of sensitivities. These can be obtained by measuring the magnitudes and phase shifts at several positions on the exciter surface. The effects of exciter motions are measured in terms of how much the magnitudes and phase shifts at each measured positions deviate from the average values. To illustrate these effects, parametric studies were conducted. The influences of four parameters, i.e. the angular positions of the laser points, the distance of the laser positions from the centre of the exciter surface, the number of measured positions to be averaged and the mass loading effect, were examined experimentally. The frequency of interest is between 10 Hz and 15 kHz.     

块系覆岩中摆型波传播对巷道支护动力响应影响

为研究支护体自身的动力响应规律,通过理论和计算分析岩体中的非线性摆型波传播对巷道支护动力响应的影响,根据摆型波在非连续自应力块系上覆岩体中传播时的支护动力响应模型,研究上覆岩块间的黏弹性性质及岩块破坏对支护动力响应的影响。通过计算分析得出,上覆岩块间弹性下降时,支护的动态受拉和受压幅值随之下降且周期变大;上覆岩块间阻尼增大时,支护的受拉和受压周期不变,但周期内的微扰动逐渐消失且幅值略有下降;上覆岩块沿垂直冲击方向破裂成两个子块时,支护的受拉和受压次数增加。     

设置FPS质量调谐阻尼器减振效果分析研究

根据拉格朗日方程推导了结构设置FPS调谐质量系统地震动力反应分析计算公式,并考虑了接触面滞滑效应的影响。分析与计算结果表明:设置质量调谐系统之后,结构动力反应层间位移有所减小。当接触面滑动摩擦系数为0.15左右、滑道半径为0.7 m、调谐附加质量为楼层质量的1.4倍以上时,质量调谐系统具有较好的减振效果、消能效果与复位能力。     

Stochastic rotational response of a parametric pendulum coupled with an SDOF system

In this paper, parametric excitation of a lumped mass pendulum is investigated when having its pivot point vertically excited. Such a system is described by a sinus type nonlinear Mathieu equation and attention is drawn to the rotational motion of the mass. A single-degree-of-freedom (SDOF) system is used as a base for the pendulum, floating on ocean waves and being externally excited by them thus falling into the subclass of autoparametric systems. Due to the random nature of waves, a narrow-band stochastic process is used to model the environmental excitation. The effect of dry friction is considered and the interaction between the pendulum's rotational response and the base is studied.     

微机电系统压电振动台迟滞补偿方法研究

微机电系统（MEMS）压电振动台作为加速度传感器现场标定平台的新秀,能够提供片上物理驱动环境,为加速度传感器的快速重新标定提供持续稳定的加速度信号,然而用于压电振动台驱动的压电材料具有明显的迟滞特性,严重影响平台振动信号的稳定性和连续性。基于上述振动台振动特性,建立基于多项式拟合的压电迟滞模型,采用前馈控制和反馈控制相结合的复合控制方法对压电振动台进行控制和加速度滞后补偿。实验结果表明,在10 V（317 Hz）正弦电压激励下,MEMS压电振动台提供的简谐振动信号的加速度最大误差从1.3g降到了0.05g。