Fundamental research on tactile sensor system using the longitudinal mode quartz crystal resonator

作者研制了由纵模石英晶体谐振器组成的触觉传感器，石英晶体工作频率为600 kHZ，长4.6 mm，宽106微米，厚200微米。它的石英晶体已被用作时钟时间源。在石英谐振器比环氧树脂高1 mm的情况下，取下固定在丙烯酸树脂圆柱壳中心的石英谐振器胶囊，直径1 cm，高1 cm。在梅森等效电路的基础上，分析了粘弹性介质上的纵模石英晶体谐振器的特性。梅森的等效电路有两个与石英表面相对应的声学端口。一个表面是无应力的，另一个表面附着在粘弹性介质上。H.L.Oestreicher已经分析了半无限粘弹性介质上振动球的声阻抗问题。作者假定石英谐振器的顶部形状为球形，并将此声阻抗应用于曼森等效电路。最后得到了频率和阻抗变化的理论方程。本实验所用硅橡胶为各向同性不可压缩介质，泊松比为0.49。因此，理论频率方程包含了密度和剪切模量值作为参数。当石英触觉传感器实际连接到重量为2g的硅橡胶上时，频率的移动与粘弹性和橡胶测试仪的测量结果相关联。实验结果表明，频率变化的理论方程与实验结果吻合较好。

The author developed the tactile sensor consisting of a longitudinal mode quartz ctystal resonator, the length-extensional quartz crystal operated at 600 kHz, which was 4.6mm in length and 106 mum width and 200mum thickness. Its quartz crystal has been used as a clock time source. After the author removed a capsule of the quartz resonator, which was fixed in the center of an acrylic resin cylinder case 1cm in diameter and 1cm height in the condition of the quartz resonator being 1mm higher than it with epoxy resin. The author call it the quartz tactile sensor.The author analyzed the behavior of a longitudinal mode quartz crystal resonator attached to viscoelastic medium based on a Mason's equivalent circuit. The Mason's equivalent circuit has two acoustic ports which correspond to quartz surfaces. One surface is stress-free and another one is attached to viscoelastric medium. The problem of acoustic impedence of an oscillating sphere attached to semi-infinite viscoelastic medium was already analyzed by H.L.Oestreicher. The author assumed that the top shape of the quartz resonator was sphere and applied this acoustic impedance to a Manson's equivalent circuit. Finally the author obtained the theoretical equations of the frequency and the impedance change.Silicone rubber used in this experiment is isotropic and incompressible medium and Poisson's ratio of it is 0.49. Therefore the theoretical equation of frequency comprises both the density and the shear modulus of it as a parameter. When the quartz tactile sensor is attached vereically to sillicone rubber with its weight 2g, the shift in frequency correlate the measurements of both viscoelatic and rubber tester. The frequency change shows hardness or softness of it.In conclusion, it has been confirmed that the theoretical equation of frequency change is in good agreement with the experimental results.