一种微推力测量系统的推力不确定度标定方法

A Calibration Method of Thrust Uncertainty for Micro Thrust Measurement System

关键词:  推力测量系统  动态推力  标准力  不确定度  标定方法

Key words:  Thrust measurement system  Dynamic thrust  Standard force  Uncertainty  Calibration method

摘要:

利用微推力测量系统有助于星载微推力器性能的测评和研发，而其不确定度的标定可以判断实验测量结果的可信度，本文提出一种推力测量系统的推力不确定度标定方法。通过对推力测量系统施加已知标准力，根据推力测量系统的系统响应反演计算推力估计值，将已知标准力与推力估计值比较，以此标定推力测量系统的推力不确定度，并且给出推力不确定度和推力误差。所提方法具有以下主要特征：（1）利用推力积分方程离散化为推力离散化线性方程组求解推力加载全程的动态推力；（2）根据标准力不确定度和推力估计值不确定度，综合评价推力不确定度；（3）依据标准不确定度和扩展不确定度，获得给定置信度条件下的推力相对误差。本文基于所提方法对某亚毫牛级推力测量系统的不确定度进行了实验评估。结果表明在给定95%置信度条件下，其推力测量误差小于2%。所提出的推力不确定度标定方法，可为星载微推力器的推力误差评定提供了高置信度、高精度测评方法和手段。

Abstract:

The thrust measurement system can be used for the performance emulation and development of satellite micro-thruster， and the calibration of its uncertainty can judge the credibility of the experimental measurements. Therefore， a calibration method for thrust uncertainty of the measurement system is proposed in this paper. A known standard force is applied to the measurement system， and based on the response of system， the thrust estimation value can be obtained by an inversion calculation method， then the thrust uncertainty and its error can be determined by comparing the known standard force and the estimated thrust. The main features of the proposed method are as follows： （1） The dynamic thrust of the whole loading process is solved by discretizing the thrust integral equation into a set of discrete linear equations. （2） The thrust uncertainty is comprehensively evaluated according to the uncertainties of the standard force and the estimated thrust. （3） According to the standard and extended uncertainties， the relative error of thrust with a given confidence can be obtained. Using the proposed method， the uncertainty of a sub-micronewton thrust measurement system is experimentally evaluated. The results show that the thrust measurement error is less than 2% with the given 95% confidence. The proposed calibration method can provide a high-confidence and high-precision evaluation approach for the thrust error evaluation of satellite micro-thruster.