Under weightless conditions, existing available devices or systems for mass measurements are not usable because they are gravimetric. Therefore, we propose in this paper a new method of mass measurement usable under weightless conditions applying the concept of dynamic measurement method. In the present method, the goods-plate of a spring scale holding the goods to be measured has been displaced a small distance from rest position. Then, the goods-plate being released, it starts undamped oscillation. The mass value of the goods can be obtained through processing the observed data both on the acceleration of the goods-plate of spring scale and on the deflection of the spring by means of a software executed on a microcomputer.
In the present paper, we describe the two dynamic mass-estimation algorithms which play the important roles in mass-measurement under weightless conditions. The one is based on the continuous-time model of a measuring system and the other is based on the discrete-time model of a measuring system. In derivation of the two algorithms, we paid special attention to the dynamics of the two sensors which detect the acceleration and the deflection, respectively.
Moreover, a computer simulation is given to indicate the feasibilities of the two algorithms.