Design And Analysis Of Caging And Releasing Mechanism For Inertial Sensor Test Mass

In recent years,space gravitational wave detection has become a hot research topic.The basic principle of space gravitational wave detection is to use laser interference to measure the distance change between two free suspension test masses.The test mass should not only be free suspended in the interferometry,but also be driven and tested by the capacitive sensor as the sensing part of the inertial sensor,so it needs to maintain a proper gap with the electrode cage.In order to ensure the free suspension without initial velocity of the test mass in space,the locking of the test mass in the launching process and the positioning release in space are particularly important.In this paper,the caging mechanism of test quality and the positioning release mechanism in space are studied.The mechanism is composed of two parts: the caging mechanism and the grabbing positioning and release mechanism.The locking mechanism adopts the design scheme of piezoelectric motor driving screw pair.The rotation motion of piezoelectric motor is transformed into linear motion by screw pair and linkage mechanism,and the self-locking performance of screw pair is fully utilized to lock the test mass during the launching process.The caging force of up and down 1200 N can be realized.At the same time,the spring is used to pre tighten the caging bar to ensure that the test mass is uniform in stress and high in stiffness.On the basis of the preliminary principle design of the caging mechanism,the kinematics and dynamics of the caging mechanism are analyzed.The analysis results show that the movement process of the caging mechanism is smooth,and it will not have a large vibration impact on the mechanism.At the same time,the first generation of principle prototype of caging mechanism is developed,and the output force is analyzed and measured.Based on this,the caging bar is adjusted to ensure the uniformity of the output force of the caging bar.The grabbing positioning and release mechanism is to grab and precisely position the test mass handed over by the caging mechanism after reaching the predetermined track,and then release without initial speed.The mechanism is designed according to the requirement of positioning release.The mechanism adopts two sets of piezoelectric drive system,the grabbing ejector and release ejector are driven by piezoelectric respectively,and the force and displacement test are integrated,which is convenient to monitor the position and grabbing state of the ejector.In this paper,the piezoelectric linear actuator used to grab the test mass is tested and calibrated.The test results show that the minimum step displacement can reach 0.8nm,and the driving force can reach 70 N,which meets the work requirements.Through all aspects of test and analysis,it shows that the grabbing positioning and release mechanism fully meets the functional requirements.