Abstract: The torsion pendulum is usually used in micro thrust and impulse measurement for aerospace micro thruster. In order to realize the accurate calibration of the system parameters of the torsion pendulum，relationship between feature points of the step response and system parameters，such as the steady state torsion angle and the extreme torsion angle and their corresponding time，was analyzed based on the step response. And the Proportional Regression Method (PRM) was brought forward for the calibration for the pendulum parameters. The PRM can be used to obtain the damping ratio，the vibration frequency，torsion stiffness coefficient and so on at the same time. It is simpler and more convenient for the calibration in vacuum condition and performance evaluation of micro thruster. Compared with the traditional method，confidence interval based on the PRM can be reduced by 61%，and the PRM can improve the calibration results of the torsion pendulum.

Key words: Micro thrust；Micro impulse；Parameter estimation；Confidence intervals；Damping ratio； Vibration frequency；Torsion stiffness coefficient

摘要： 扭摆系统通常用来测量航天微推力器的微推力和微冲量。为了实现扭摆的系统参数精确标定，根据扭摆系统阶跃响应的特点，深入分析稳态扭转角和极值扭转角及其对应时间等特征点与系统参数的关系，提出了系统参数标定的比例回归法，所提出方法能够同时标定阻尼比、振动频率和扭转刚度系数等系统参数，计算分析简便，适合真空环境下的扭摆系统参数标定，有助于真空环境下航天微推力器的推力性能评价工作。实验表明:相对于传统数据处理方法，利用比例回归法估计的置信区间最大可缩小61%，可有效改善系数参数的标定结果。

关键词: 微推力；微冲量；参数估计；置信区间；阻尼比；振动频率；扭转刚度系数