### A measurement method of dynamic thrust based on cantilever beam

WANG Dapeng1,2，ZHOU Weijing1,*，CAO Jihong2，ZHANG Shan2，SHI Xiaoyun2，HE Long2

1. 1State Key Laboratory of Laser Propulsion & Application，Aerospace Engineering University， Beijing 101416，China
2Xi′an Satellite Control Center, Xi′an 710043, China
• Received:2018-02-27 Revised:2018-06-20 Online:2018-10-25 Published:2018-08-29

Abstract: To realize dynamic thrust measurement in spaceborne micro thrusters′ performance assessment, the transfer function of the measurement system was determined based on cantilever′s dynamic model.System input and output characteristics were analyzed, and a terminal mean method for solving the steadystate displacement was put forward according to cantilever beams′ characteristics that the response speed is high (vibration frequency is high), the dynamic component is close to constant amplitude oscillation in a small time interval (damping ratio is small), and that the higher order vibration can be regarded as the noise for fundamental frequency vibration. By eliminating the dynamic components in the displacement response, the time variant value of the static displacement was obtained when the error band was large, and thus the dynamic thrust measurement was realized. According to the linear relationship between the thrust magnitude and the steady displacement under the action of step force with the linear coefficient as the system gain value, the parameter calibration method was put forward. An experimental platform was built with response time 156ms by calibration. By comparison with measurement results of torsional balance system, the relative error 4.064% between the impact force on cantilever and the actual thrust was obtained, and the thrust measurement error 4.293% was finally obtained by combination with the measurement error 1.383% of impact force itself.