Search

To enhance the accuracy of micro-Newton thrust measurements via a torsion pendulum, addressing microgravity coupling effects caused by platform tilt and pendulum mass eccentricity is crucial. This study focuses on analyzing and minimizing these effects by alleviating reference surface tilt and calibrating the center of mass during thrust measurements. The study introduced analysis techniques and compensation measures. It first examined the impact of reference tilt and center of mass eccentricity on the stiffness and compliance of the torsion pendulum by reconstructing its dynamic model. Simscape Multibody was initially employed for numerical analysis to assess the dynamic coupling effects of the tilted pendulum. The results showed the influence of reference tilt on the stiffness and compliance of the torsion pendulum through simulation. An inverted pendulum was developed to amplify the platform's tilt angle for microgravity drag-free control. Center of mass calibration can identify the gravity coupling caused by the center of mass position. Based on the displacement signal from the capacitive sensor located at the end of the inverted pendulum, which represents the platform's tilt angle, the pendulum's vibration at 0.1 mHz was reduced from 5.7 μ m/Hz1/2 to 0.28 μ m/Hz1/2 by adjusting the voltage of piezoelectric actuator. Finally, a new two-stage torsion pendulum structure was proposed to decouple the tilt coupling buried in both pitch and roll angle. The study utilized theoretical models, numerical analysis, and experimental testing to validate the analysis methods and compensation measures for microgravity coupling effects in torsion pendulums. This led to a reduction in low-frequency noise caused by ground vibrations and thermal strains, ultimately improving the micro-Newton thrust measurement accuracy of the torsion pendulum through the platform's drag-free control. [ABSTRACT FROM AUTHOR]

To enhance the accuracy of micro-Newton thrust measurements via a torsion pendulum, addressing microgravity coupling effects caused by platform tilt and pendulum mass eccentricity is crucial. This study focuses on analyzing and minimizing these effects by alleviating reference surface tilt and calibrating the center of mass during thrust measurements. The study introduced analysis techniques and compensation measures. It first examined the impact of reference tilt and center of mass eccentricity on the stiffness and compliance of the torsion pendulum by reconstructing its dynamic model. Simscape Multibody was initially employed for numerical analysis to assess the dynamic coupling effects of the tilted pendulum. The results showed the influence of reference tilt on the stiffness and compliance of the torsion pendulum through simulation. An inverted pendulum was developed to amplify the platform’s tilt angle for microgravity drag-free control. Center of mass calibration can identify the gravity coupling caused by the center of mass position. Based on the displacement signal from the capacitive sensor located at the end of the inverted pendulum, which represents the platform’s tilt angle, the pendulum’s vibration at 0.1 mHz was reduced from 5.7 μm/Hz1/2 to 0.28 μm/Hz1/2 by adjusting the voltage of piezoelectric actuator. Finally, a new two-stage torsion pendulum structure was proposed to decouple the tilt coupling buried in both pitch and roll angle. The study utilized theoretical models, numerical analysis, and experimental testing to validate the analysis methods and compensation measures for microgravity coupling effects in torsion pendulums. This led to a reduction in low-frequency noise caused by ground vibrations and thermal strains, ultimately improving the micro-Newton thrust measurement accuracy of the torsion pendulum through the platform’s drag-free control.

In order to solve the problem of insufficient thrust measurement accuracy of aeroengine indoor testbed, the thrust calibration experiment technology is studied. Form two aspects of engine static calibration and dynamic calibration, the mechanism of thrust calibration is comprehensively analyzed form the perspective of testbed and engine, and a complete set of operable test specifications is formed. The technical difficulties of engine consistency, inlet temperature deviation and non-standard weather are solved, and the accuracy of thrust transmission process is ensured. The test scheme of indoor test bed calibration is given, and the corresponding ideas and requirements are given according to the test conditions, test bench, calibration engine, test process and result analysis, to ensure the accuracy of calibration results.

In order to solve the problem of insufficient thrust measurement accuracy of aeroengine indoor testbed, the thrust calibration experiment technology is studied. Form two aspects of engine static calibration and dynamic calibration, the mechanism of thrust calibration is comprehensively analyzed form the perspective of testbed and engine, and a complete set of operable test specifications is formed. The technical difficulties of engine consistency, inlet temperature deviation and non-standard weather are solved, and the accuracy of thrust transmission process is ensured. The test scheme of indoor test bed calibration is given, and the corresponding ideas and requirements are given according to the test conditions, test bench, calibration engine, test process and result analysis, to ensure the accuracy of calibration results. [ABSTRACT FROM AUTHOR]

The "Taiji-1" satellite is a test satellite for the verification of those key technologies involved in the "Taiji Program in Space", China's space gravitational wave detection project; and the spacecraft drag-free control technology is one of its key technologies used to improve the microgravity level of spacecraft. Thus, a demand for a high-precision and continuously adjustable micronewton-level thrust has been proposed on the spacecraft micro-propulsion system. In allusion to such a task, a set of micronewton-level RF ion propulsion system was designed based on the principle of self-sustained discharge of RF plasma so as to conduct studies on the parameter optimization and engineering of RF ion thruster, and an engineering prototype of the micronewton-level continuously adjustable RF ion thruster was successfully developed to meet the design index requirements. The operating parameters have been solidified through further studies on the extreme operating conditions of the engineering prototype, and a series of ground simulation tests of space environment were successfully passed. The ground test and calibration experiment results of the micro-propulsion engineering prototype show that the engineering prototype has fully met the requirements of the Taiji-1 mission, thus having laid a solid foundation for the successful space verification of the key technologies for the "Taiji-1" satellite. [ABSTRACT FROM AUTHOR]

An integrated microcontroller-based data acquisition and robotic actuation suite comprising digital electronics, microcontrollers, custom-made hardware, and accessorial software for diagnostics, and characterization of electric propulsion thrusters in a large vacuum space environment simulator is designed, built, and tested. The components of the characterization suite have been aggregated into modular add-on units for rapid rearrangement and easy customization to suit various applications. The modules include a force calibration system for accurate thrust measurements in various thrust stands, and spatially resolved measurements in a multiprobe array comprising Langmuir and Faraday probes for plume diagnostics of plasma thrusters. Plume and thrust characteristics of a miniaturized Hall-type thruster were successfully measured in situ, enabling users to vary process controls and efficiently optimize the thruster performance. The system revealed a further potential for real-time flight mission diagnostics and control. [ABSTRACT FROM AUTHOR]

Aiming at measurement uncertainty evaluation problem of combined nozzle thrust measurement system, the measurement principle of combined nozzle thrust was introduced, and the location of the sensors load surface and the correction coefficient of thrust were determined by the calibration experiment, and the uncertainty sources of thrust measurement system were analyzed. Its measurement uncertainty was evaluated by using type A uncertainty component and type B uncertainty component, and the type A uncertainty component of each channel was calculated by using the Bessel method,and the type B uncertainty component of each segment of thrust measurement system was calculated. The results indicate that the type B uncertainty component of each channel is close to each other, and the size of synthetic standard uncertainty and expanded uncertainty of each channel is largely determined by type A uncertainty component, which is related to the size and the internal structure of nozzle. [ABSTRACT FROM AUTHOR]