Abstract: Although inception of the measurement of astronaut body mass measurement was as old as Skylab era, progress in the field has not been as expected. There are fundamental physical difficulties as well as program management issues. New mass measurement systems with the current sensor technologies should be prepared, and the new sensor system could be expanded for “Drop Tower” in space.
Abstract: A review of mass measurement devices developed by the author is presented. According to the measurement principles, the treated devices are classified into two types. The first type uses a dynamic vibration absorber as a device for both mass measurement and vibration control. The main advantage is no vibration transmitted into the surrounding structures during measurement. The second type uses relay feedback. The advantages are simpler mechanism and robustness against disturbances. In this article, the principles of measurement of each type are presented.
Abstract: In this paper, mass measurement devices (MMDs) developing by the authors for use in the International Space Station (ISS) are reviewed. First, Space Balance, which is a small mass measurement device (SMMD), is reviewed. In Space Balance, the momentum conservation between two objects, the subject mass and the reference mass, are compared. Then Space Scale, which is a body mass measurement device (BMMD), is reviewed. In Space Scale, a human subject is pulled using rubber string. Force is measured using a force transducer and acceleration is measured using optical interferometer. Both Space Balance and Space Scale have shown high accuracies in the ground experiments.
Abstract: This paper reviewed the present status and the future prospects of a method for precision mass and force measurement based on levitation mass method (LMM). The LMM has been proposed and improved by the author The mass which levitated using a pneumatic linear bearing in LMM is used to producte a inertial force which used as the reference force applied to the objects under test, such as to force sensor calibration, material and structure test. The inertial force is calibrated only from Doppler shift frequency. The stability of laser’s wavelength has improved in the LMM. The futhure work and the method to improve the precision have described.
Abstract: In this paper, dynamic response of 1-inch hard disk drive (HDD) head arm assembly (HAA) against an impact load is obtained by means of a 3D non-linear finite element model in ANSYS/LS-DYNA and experiments using Optical method. A mass is modeled as a rigid body and is made to collide with the arm. The velocity, displacement, acceleration and the inertial force of the mass are obtained from the time- history of finite element analysis (FEA). In the experiment, a mass that is levitated with an aerostatic linear bearing, and hence encounters negligible friction, is made to collide with the HAA and the dynamic bending test for the arm is realized. During the collision the Doppler frequency shift of the laser beam reflecting from the mass is accurately measured using an optical interferometer. The velocity, the position, the acceleration and the inertial force of the mass are calculated from the measured time-varying Doppler frequency shift. A good correlation between the experimental data and FEA results is observed.
Abstract: A new style micro-force sensor based on a 3-RRR parallel micro-motion stage which had been researching recent years was introduced in this paper. The sensor can be used in micro-force and micro-torque detection in precision engineering. The result and experience from 3-RRR micro-motion stage research bring this new idea. In the first place, the branched chain structure in motion stage needs to be simplified and improved to adapt to the requirement of sensor. Secondly, a mechanics model is constructed according to the sense organ structure. The Jacobin Matrix which is the most important matrix on parallel structure is analyzed and deduced. The relationship among key dimension is worked out through isotropy parameters. With the theory analysis, the final structure of sense organ is determined. The elastomeric sensor body was pasted with electrical-resistance strain gauges, after it was manufactured by Wire-EDM. Strain gauges employed Wheatstone bridge and amplifier AD620 to produce measuring data. Experiment has indicated that the new sensor is competent for micro-force detecting in X, Y direction and micro-moment around Z direction with high stability and reliability.