A high-precision impulsive force calibration method for the micro-thrust measurement system

Abstract

A high-precision parameter identification method is crucial for a micro-thrust stand to achieve micro-thrust and micro-impulse measurement. Firstly, the relationships between the dynamic parameters and the extreme responses for a torsional thrust stand under impulsive forces are studied in this research, and a high-precision parameter identification method is proposed using linear regression method. Then, a coil and DT4C (Super-Grade Electromagnetic Pure Iron) assembly impulsive force calibrator is developed, and the influence of the spatial position change between DT4C and the coil on electromagnetic force is analyzed based on the numerical simulation method. Subsequently, an optimal relative position setting scheme is presented, and then the variable trends of electromagnetic force with electric current, as well as the properties of coil and DT4C, are discussed through a weighing experiment method using a micro-analytical balance, and an optimal electromagnetic force calibrator which is relatively insensitive to the relative position is obtained. It is able to produce calibration force and impulse bits ranging from 6.3 μN to 2.9 mN and 190.3 nN·s to 342.1 μN·s, respectively, with the maximum relative error caused by installation deviation smaller than 2%. Furthermore, the electromagnetic force control equations in the optimal relative position and the surrounding envelope range are computed by using the polynomial fitting method, respectively. Consequently, an impulsive force calibrator with excellent performance is achieved by setting electric current with required pulse width. Finally, this paper performs a high-precision calibration of a torsional micro-thrust measurement system in both single-pulse and multi-pulse modes based on the proposed impulsive force identification method, whose high accuracy, efficiency, and stability are verified by comparing with the traditional steady-state force method.