HIGH-PRECISION MICRO-THRUST MEASUREMENT METHOD AND EXPERIMENTAL RESEARCH

Micro-thrusters serve as indispensable actuators for satellite attitude and orbit control. Precise measurement of their thrust performance is essential for the success of space missions. Conventional micro-thruster measurement devices face several challenges, including the difficulty in accurately determining the thrust arm length, plume deflection during pendulum motion, and intricate assembly and adjustment procedures. To address these technical limitations, ​​a novel micro-thrust measurement device has been designed and developed, based on the fundamental principles of the Roberval balance mechanism. This innovative device features a fixed thrust arm length that remains unaffected by the installation position of micro-thrusters. This feature significantly reduces the uncertainties associated with thrust arm measurements and, in turn, simplifies the complexity of micro-thruster assembly and adjustment. Additionally, the device effectively eliminates thrust plume deflection during pendulum motion, allowing synchronous monitoring of thruster plume behavior in online measurements. This paper elaborates on the measurement principle and design scheme of the proposed device. Electromagnetic standard force was employed to conduct performance tests and evaluations under both open-loop and closed-loop measurement modes. And a cold gas micro-thruster was successfully calibrated through this device. The performance test results indicate that in the open-loop mode, the device achieves a measurement range of 2 mN with a resolution better than 1 μN. With a coverage factor of 3, the measurement uncertainty is expressed as 2.33 \text μN + 0.99\text% T (where T represents the measured thrust). In the closed-loop mode, the measurement range is extended to 100 mN with a resolution better than 5 μN, and the measurement uncertainty is determined to be 18.00 \text μN + 0.31\text% T . This device provides a robust solution for accurate thrust measurement of micro-thrusters with thrust ranges from micro-newtons to milli-newtons, covering the diverse needs of modern space propulsion systems. It is expected to contribute to the development of China's commercial aerospace industry by supporting the rapid iteration and engineering implementation of micro-propulsion systems.