Haruo Shimaoka

Bio: Haruo Shimaoka is an academic researcher. The author has contributed to research in topics: Displacement (vector) & Spring scale. The author has an hindex of 2, co-authored 3 publications receiving 22 citations.

Mass Measurement Using a Dynamic Vibration Absorber under Weightless Conditions

Abstract: A new type of mass-measurement system under weightless conditions is proposed which uses a dynamic vibration absorber as a measuring device. In this system, an object to be measured is fixed to a rotating table (rotor) at a distance from the rotation axis. Since it makes the rotor unbalanced, a centrifugal force whose amplitude is proportional to the mass is generated during rotation. It works as a harmonic excitation and forces a structure supporting the table to vibrate. However, a dynamic vibration absorber attached to the structure is tuned or controlled to reduce the vibration to zero. When the structure does not move at all, the absorber mass vibrates in such a way that the product of the mass and the displacement amplitude is equal to the amount of unbalance, that is, the product of the mass to be measured and its distance from the rotation axis. Therefore, the mass of the object is determined by measuring the displacement amplitude of the absorber mass. In this study, the principles and features of the proposed mass-measurement system are clarified. Experiments are carried out with a developed apparatus having an active dynamic vibration absorber. This apparatus can perform measurement at various rotational speeds because the absorber’s natural frequency can be tuned by a feedback parameter. Experimental results demonstrate the feasibility of the proposed mass-measurement system.

Mass Measurement System Using Relay Feedback with Hysteresis

Abstract: Mass measurement using a relay feedback system was studied experimentally. The measurement system has an on-off relay with hysteresis and switches force acting on the object in relation to its velocity. Such nonlinear control induces a limit cycle in the feedback system. The mass of the object is determined from the period of this limit cycle. The apparatus manufactured for experimental study uses two voice coil motors (VCM's), one of which is for driving the object and the other is for generating prescribed disturbances. The effects of system parameters and disturbances on measurement accuracy were examined experimentally.

Mass measurement using a system containing an on-off relay with dead zone

Abstract: Concerns mass measurement under conditions of weightlessness. A mass measurement system using the self-excited oscillation of a nonlinear system is developed. The system contains an on-off relay with dead zone and switches force acting on the object in relation to the position. The mass of the object is determined from the time interval measurement of the on-state and off-state periods. The measurement accuracy is experimentally studied.

Devices for mass measurement under weightless conditions

Abstract: A review of mass measurement under weightless conditions is presented. Various measurement methods are listed with comments on the problems of several conventional methods. It is followed by a summary of the works conducted by the author.