The measurement of inertial mass in a micro-gravity environment: Theory and practice of the centrifugal method

Rivetti, A.; Martini, G.; Birello, G.; Alasia, F.; Gatt, L.; Solitro, F.

doi:10.1016/s0094-5765(98)00059-9

Cited by 9 publications

(6 citation statements)

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“…Porém, este método requer uma escala calibrada na haste, pois a relação entre a posição da massa e a frequência nãoé linear. Outro métodó e a balança centrífuga projetada por Rivetti [16] para medição de massas em ambientes com microgravidade. Entretanto, o equipamentoé demasiado complexo para uso em ensino.…”

Section: Introductionunclassified

Medindo a massa inercial usando uma balança romana

Kinouchi

Menesse

Stoli

2021

Rev. Bras. Ensino Fís.

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Apresentamos um aparelho simples de laboratório didático para medição de massa inercial, baseado no equilíbrio quase-estático de uma balança de peso deslizante (balança romana) num plano horizontal, suprimindo a influência da gravidade. O dispositivo oferece uma definição operacional alternativa da massa inercial. Comparada com definições tradicionais baseadas em medidas de aceleração (como a definição clássica de Ernst Mach) ou da frequência de um sistema massa-mola, este método não exige medições de tempo, força, ou acelerações; utiliza um aparato simples e barato; e fornece o valor correto mesmo se executado em um sistema não-inercial, ou por um observador em movimento relativístico. O aparato também permite medir a massa gravitacional, e demostrar sua equivalência com a massa inercial de maneira simples e elegante. Por estas razões, o método é eminentemente adequado para demonstrações em classe e aulas práticas em cursos introdutórios de física.

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Section: Introductionunclassified

Medindo a massa inercial usando uma balança romana

Kinouchi

Menesse

Stoli

2021

Rev. Bras. Ensino Fís.

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

Section: Mass Measurement Methodsmentioning

confidence: 99%

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

Yan

et al. 2011

Sci. China Phys. Mech. Astron.

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Astronaut's body mass is an essential factor of health monitoring in space. The latest mass measurement device for the International Space Station (ISS) has employed a linear acceleration method. The principle of this method is that the device generates a constant pulling force, and the astronaut is accelerated on a parallelogram motion guide which rotates at a large radius to achieve a nearly linear trajectory. The acceleration is calculated by regression analysis of the displacement versus time trajectory and the body mass is calculated by using the formula m=F/a. However, in actual flight, the device is instable that the deviation between runs could be 6-7 kg. This paper considers the body non-rigidity as the major cause of error and instability and analyzes the effects of body non-rigidity from different aspects. Body non-rigidity makes the acceleration of the center of mass (C.M.) oscillate and fall behind the point where force is applied. Actual acceleration curves showed that the overall effect of body non-rigidity is an oscillation at about 7 Hz and a deviation of about 25%. To enhance body rigidity, better body restraints were introduced and a prototype based on linear acceleration method was built. Measurement experiment was carried out on ground on an air table. Three human subjects weighing 60-70 kg were measured. The average variance was 0.04 kg and the average measurement error was 0.4%. This study will provide reference for future development of China's own mass measurement device. astronaut, mass measurement, linear acceleration, body non-rigidity PACS: 06.30.Dr, 07.90.+c, 87.65.+y Among the fundamental physical quantities, such as time, mass, temperature, and length, mass is probably the only quantity that is unmeasurable in space using conventional methods. As human beings are staying longer and longer in space, measuring mass in the microgravity environment, especially the human body mass, is in great need because body mass is a fundamental index for human health care. Astronauts suffer body mass loss in space due to loss of water, muscle, and nutrition, and too much mass loss over time or a sudden change in body mass implies a possible illness of astronauts. And also, measuring body mass in microgravity provides valuable data for microgravity life science research, such as the study of microgravity effect on human metabolism and bone loss.

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“…9 (4) Estimate from the centrifugal force of a rotating object. 10 (5) Operate a dynamic vibration absorber as a measurement device. (a) Centrifugal type.…”

Section: Introductionmentioning

confidence: 99%

Position-insensitive estimation of mass from limit cycle of velocity feedback relay system with Spring

Mizuno

Egawa

Takasaki

et al. 2021

Measurement and Control

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Mass measurement using relay feedback of velocity and restoring force compensation is investigated for determining the mass of an object under weightless conditions. In the measurement system, the velocity of the object is fed back through a relay with hysteresis and the force acting on the object is switched from a positive value to a negative value when the velocity reaches a positive threshold and vice versa. As a result, a limit cycle is induced in the measurement system and the mass is estimated based on the period of the limit cycle. In addition, restoring force compensation with a spring is introduced to avoid the drift of the trajectory. This compensation makes the static equilibrium state unique. However, the trajectory still drifts slightly. It causes some error in measurement when a simple formula of estimating mass is applied. To eliminate such an error, a new formula is derived to estimate the mass independently of the position of the trajectory that is determined by the switching positions in the relay actions. When the switching positions deflect from the origin at which the spring is in the natural length, the trajectory is not at the center and becomes asymmetric. It is analytically shown that the period of the limit cycle is minimum when the switching positions are at the origin. It indicates that mass is overestimated with the simple estimation formula when the trajectory is not at the center. The validity of the modified formula and the analytical results are confirmed experimentally.

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The measurement of inertial mass in a micro-gravity environment: Theory and practice of the centrifugal method

Cited by 9 publications

References 1 publication

Medindo a massa inercial usando uma balança romana

Medindo a massa inercial usando uma balança romana

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

Position-insensitive estimation of mass from limit cycle of velocity feedback relay system with Spring

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