Instruments for Precise Mass Measurement under Weightless Conditions with Dynamic Vibration Absorbers

本研究以动力吸振器为量测装置，探讨质量量测系统。这项研究的目的是开发质量测量系统，即使在失重条件下也可以精确测量质量。主要研究结果如下：1）根据被测质量的运动、减振器类型、振动产生方式、被测质量以及被测质量的位置对质量测量系统进行了分类。(2)研制了一种以音圈电机为驱动器的主动式动力吸振器。实验中所使用的控制器的特点是使用与旋转同步的外源信号来实现自动频率跟踪。实验结果表明，所设计的控制器消除了任何旋转频率下的振动。实验结果表明，该系统测量质量准确，精度为0.9%。(3)研制了一套双惯性质量作动器的测量装置。两个惯性质量块均由双压电致动器驱动。几个质量测量进行了研究的质量测量系统的性能。实验结果表明，该系统测量质量准确，精度为0.5%。(4)研制了一种采用无阻尼动力吸振器的测量装置。当它被固定在一个刚性的基础上，并在一个灵活的结构上的测量精度的开发系统进行了实验估计。结果表明，在两种情况下，测量精度几乎相同。研究还表明，通过将激励信号从零逐渐增加到测量幅值，可以减少工作台在瞬态时的振动。

This research studied mass measurement systems that uses a dynamic vibration absorber as a measuring device. The aim of this research was to develop mass measurement systems that can measure mass accurately even in weightless conditions. The obtained results are summarized as follows.1) The mass measurement systems were classified according to the motion of a mass to be measured, the type of the absorber, the method of vibration generation, the quantity to be measured, and the location of a mass to be measured.(2) A measurement apparatus was developed which used an active dynamic vibration absorber whose actuator was a voice coil motor. The controller used in the experiments was characterized by using exogenous signals synchronized with rotation for achieving automatic frequency tracking. It was shown experimentally that the designed controller eliminated the vibration at any rotational frequency. The experimental results demonstrated that the developed system measure mass accurately with an accuracy of 0.9 %.(3) A measurement apparatus equipped with dual inertial-mass actuators was developed for the experimental study. Both the inertial masses are driven by bimorphic piezoelectric actuators. Several mass measurements were carried out to study the performance of the developed mass measurement system. The experimental results demonstrated that the developed system measure mass accurately with an accuracy of 0.5 %.(4) A measurement apparatus using an undamped dynamic vibration absorber was developed. The measurement accuracy of the developed system was estimated experimentally when it was fixed on a rigid base and on a flexible structure. The results demonstrated that measurement accuracy was almost same in both the cases. It was also shown that the vibration of the table in transient states was reduced by increasing the excitation signal gradually from zero to an amplitude for measurement.