Ground Vibration Analysis and Isolation Strategy for Dynamic Micro-thrust Measurement Systems

In the rapidly advancing field of dynamic micro-thrust measurement, ground vibration noise persists as a fundamental barrier to achieving sub-microNewton measurement accuracy, particularly in high-bandwidth dynamic testing scenarios where transient interference can introduce errors exceeding 50% of the target signal. To address this technical challenge, this research develops a novel negative stiffness isolation method based on a compliant parallel mechanism, aiming to mitigate torsional vibration noise induced by ground lateral displacements and angular vibrations. This approach enhances the dynamic resolution of thrust measurement to 0.1 µN across a 0.01～10 Hz frequency range. In the theoretical analysis, the transfer matrix method is employed to systematically analyze the dynamic behavior of a multi-stage vibration isolation system, constructing a quantitative input-output relationship model between inter-stage forces and displacements that accounts for both structural stiffness and material damping characteristics. This model enables accurate evaluation of vibration transfer properties, revealing that the negative stiffness mechanism can reduce the system's natural frequency while maintaining stable dynamic response. Aiming at the critical issue of low-frequency drift caused by gravitational and thermal effects, a differential measurement scheme with symmetrically arranged torsional pendulums is introduced, which can offset environmental disturbances and significantly improve the system's long-term stability. In the experimental verification phase, an integrated test platform combining torsional pendulums and passive vibration isolation devices is established. The results demonstrate that after vibration isolation treatment, the background noise level of the torsional pendulums is significantly reduced, and the dynamic resolution capability is substantially enhanced. Through comprehensive theoretical modeling, simulation analysis, and preliminary experimental validation, this vibration isolation method can effectively isolate high-frequency dynamic responses and achieve high-precision vibration isolation in the low frequency band of 0.01 to 1 Hz and the characteristic frequency band of 10 Hz, providing a feasible path for performance breakthroughs in dynamic micro-thrust measurement technology and other high-precision measurement fields.