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Please use this identifier to cite or link to this item: http://hdl.handle.net/10087/7670

Title: A Study of dynamic force measurement based on the levitation mass method
Other Titles: 浮上質量法に基づいた動的力計測に関する研究
Authors: 金, 涛
キン, タオ
Keywords: Dynamic Force Measurement
Levitation Mass Method
Laser Doppler Interferometer
Issue Date: Mar-2013
Publisher: 群馬大学工学部
Abstract: In this thesis, methods based on the levitation mass method (LMM) for evaluating the frictional characteristics of a linear ball bearing, the electro-mechanical characteristics of a voice coil and a piezo-electric actuator and for removing the velocity limitation of laser Doppler interferometer (LDI) are proposed. In the LMM, the inertial force of a levitated mass used as the reference force for measuring dynamic force is measured as the product of the mass and acceleration. For evaluating the dynamical friction of linear ball bearing, two corner-cube prisms (CC) are attached to a moving part which is connected to the ball bearing. The acceleration of the gravity center of the moving part is estimated from the accelerations of the two CCs which are measured using a dual axis LDI. The frictional force is measured as the product of the mass of the moving part and the acceleration of the gravity center. For evaluating the voice coil actuator, a moving part levitated using an aerostatic linear bearing is connected to the coil. The dynamic force generated by the coil is measured as the inertial force of the moving part. The velocity of the moving part is measured using a LDI. Other mechanical characteristics such as position, acceleration and force are calculated from the measured velocity. With the electrical characteristics mea-sured using a digital voltmeter, the relationships between electrical and mechanical characteristics are evaluated. For measuring the electro-mechanical characteristics of piezo-electric actuator, a CC considered as an inertial mass is attached to the top of the actuator instead of the moving part. The dynamic force generated by the actuator is measured as the inertial force of CC. Based on this method, the force-displacement behavior of the actuator under dynamic condition is evaluated. The relationship of energy conversion between electrical and mechanical domains is also evaluated based on the observed results. In the LMM, the velocity of moving part is measured using a LDI whose laser source is a Zeeman-type two-frequency laser. However, the measurable velocity of LDI is limited by the frequency di.erence of laser in back and forth motion. In order to get high measurable velocity in back and forth motion, a dual beat-frequencies laser Doppler interferometer (DB-LDI) is developed and applied. In DB-LDI, two laser beams with di.erence frequency (f1,f2) are divided into reference beams and signal beams by a non-polarized beams splitter. They are used to produce two beat signals. When the object moving, the beat frequencies of beat signals are detected as |f ′ . f2| and |f ′ . f1|, respectively. For back and forth motion, although the 12 velocity of the object calculated from one beat frequency reaches critical velocity, the velocity calculated from the other one is far from critical velocity. The DB-LDI has been applied to realize a high-speed impact testing. During the collision, the velocity of the mass, even higher than the critical velocity, is accurately measured using the DB-LDI.
Description: 学位記番号:工博甲472
URI: http://hdl.handle.net/10087/7670
Academic Degrees and number: 12301甲第472号
Degree-granting date: 2013-03-22
Degree name: 博士(工学)
Degree-granting institutions: 群馬大学
Appears in Collections:学位論文

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