A Flexible Inverted Pendulum Based on Multiple Flexure Hinges for Microthrust Measurement Under Heavy Load

Thrust is one of the key parameters that determines the performance of thrusters in the propulsion systems of microsatellites. Thrusters are widely used in space exploration, quantum communication, and other fields. At present, the study on thrust measurement under low load has made great progress, meeting the requirements of high precision. However, it is still challenging to achieve high precision under heavy load. In this article, a flexible inverted pendulum based on multiple elliptic flexure hinges is proposed to achieve high-accuracy thrust measurement under heavy load. The theoretical model between sensitivity, stability, and pendulum parameters under heavy load is established. The principle that the pendulum can balance heavy load and high accuracy is explained as well. The pendulum is calibrated using precision machined electrostatic combs. The performance of the pendulum was evaluated by a cold gas thruster and a Hall thruster. Experimental results show that the resolution of the pendulum is better than $0.3~\mu $ N and the measurement range covers 0.3– $1300~\mu $ N for loads up to 4 kg.