BIC 3, the Latest Inertial Centrifugal Balance for Mass Measurement in Weightless Conditions

Abstract

The paper describes BIC 3, the latest prototype of inertial balance made at INRIM (former IMGC-CNR) in view of its possible use on board the International Space Station. The main characteristic of this instrument is its ability to work both in weightless conditions and on Earth surface with metrological performances comparable to those of a laboratory-level classic balance. BIC 3, although still based on the same centrifugal method adopted in the two previous prototypes, widely differs from them as regards configuration (constant speed), main motor characteristics (here a stepping motor is used), force transducer (the integral beam of a commercially-available balance), and consequently shows metrological performances considerably improved. The main constructional features are described and the metrological characteristics resulted from on-Earth tests are reported and discussed. A test made of 175 measurements in the range 0-150 g showed an expanded uncertainty of 4.1 mg.

Progress in the realization of the INRIM centrifugal balance for mass measurements in space

“…6 were corrected by using a second order polynomial equation [5]. This approach was not satisfactory for the use both at constant-speed and constant-force, hence a new equation model has been implemented.…”

“…BIC 3 is the 3 rd prototype of the inertial centrifugal balance realized at INRIM, which was completed in 2005 [5].…”

Astronaut mass measurement using linear acceleration method and the effect of body non-rigidity

“…of the measuring mass. Centrifugal force of rotation [6][7][8]. The measurement of mass is rotated at a certain radius and angular velocity.…”

Instrument for Measuring the Body Mass of Astronauts Under Microgravity Conditions

“…Use of centrifugal force (Rivetti et al 2008) The advantage of the use of centrifugal force is that it is a constant force. The disadvantage is that systems with centrifugal force require longer measurement duration and a larger instrument frame.…”

“…Determining the position of object's center of gravity is the most difficult problem with this method, because of nonuniformity of the acceleration field. Reported uncertainty (Rivetti et al 2008) in on-ground measurement of a rigid object of 150 g is on the order of 3 × 10 −5 . This method has potential for yielding highly accurate measurements of a rigid object when an adequate weight-changing mechanism is used with reference weights.…”