A micro-force measurement torsion pendulum design with dual laser detection

Abstract

Aiming at the ground test and evaluation of the suspended test bench of the high microgravity scientific experiment cabinet in the Tianhe core module of the space station to obtain its exact thrust resolution, a micro-force measurement torsion device with dual laser detection is designed. The main configuration of the device is the suspension fiber torsion pendulum, and tungsten wire with a length of 400 mm and a diameter of 800 μm is used as the suspension fiber. Under micro thrust, the suspension fiber is twisted, which drives the mirrors at both ends of the scale arm to rotate along the suspension fiber. The displacement detection of the reflector is carried out, and the magnitude of the micro thrust is calculated in combination with the theorem of momentum. Experimental results indicate that the design of the torsion of micro-force measurement provides an effective test method for the ground test of the suspension test bench. The device can be used to measure and evaluate the micro-propulsion force of the air jet port. After replacing the tungsten fiber with a diameter of 1mm, it can also replace the air floating platform to carry out the air jet closed-loop control verification work, which can effectively and accurately complete the ground test and evaluation of the suspension test bench.

A closed-loop torsional micro-thrust measurement system

“…Since the micro-thrust and gravity directions are perpendicular to each other during testing, the influence of load gravity such as the thruster can be effectively separated, and it has the remarkable characteristics of low stiffness and high sensitivity, and the signal-to-noise ratio and range can be adjusted by balancing the length of the torsion pendulum. The torsional micro-thrust measurement device mainly includes two types of structures: a suspension pendulum [3][4][5] and a pivot pendulum [6][7][8][9]. Compared to the suspension pendulum structure, the pivot pendulum structure has a lower sensitivity with only one sensitive degree of freedom.…”

“…Zhao et al built a torsion pendulum system using high-precision and large-range laser displacement sensors. Combined with torsional stiffness, force measurement can be achieved in the range (1 µN, 1 mN) [4].…”