Design Of Spaceborne Small Antenna Pointing Mechanism And Its Ground Test Research

With the development of space technology,the importance of satellite as an important tool for remote sensing of the earth is self-evident.Satellite communication antenna system is an important means of satellite control signal and data transmission.Its design and reliability directly relate to the success or failure of communication between satellite and ground station.The satellite antenna pointing mechanism is the actuator of the antenna system.Its mission is to ensure that the antenna always points to the ground station during the communication with the ground.During the orbit of the satellite,the antenna actuator needs intermittent reciprocating operation for a long time.This imposes a high requirement on the long-life and reliability of the entire antenna implementation system.However,the traditional life test cannot achieve space mission due to long time and high cost.The topic of this paper comes from the National Center for Space Science project "Small Satellite High-reliability Pointing Mechanism".It needs to complete the structure design of two kinds of antenna load(conical horn antenna and parabolic antenna)pointing mechanism.In the aspect of mechanism design,a two-dimensional pointing mechanism without lubrication is proposed,and it can carry various small antenna loads by changing the interface with the antenna load.For the parabolic antenna load,the mechanics and spatial temperature field simulation of the pointing mechanism and the load are completed.For the cone horn antenna load,the ground mechanical environment and the thermal vacuum environment simulation test of the pointing mechanism and the load are completed.In this paper,the following aspects were studied:(1)According to the general requirements of the satellite and considering the special requirements of the spacecraft product design,we have completed the design of the mechanical structure of two kinds of antenna(conical horn antenna and parabolic antenna)driving mechanism.It improves the reliability and life of the organization on the basis of realizing the function of the directing mechanism.It uses CATIA software for 3D modeling and Hypermesh and ANSYS co-simulation for static and dynamic analysis.Finally,the final design scheme is determined through simulation results.(2)Considering a working environment where the orbital space temperature changes frequently between ±90°C,the thermal control design of the pointing mechanism is carried out by using the passive thermal control measures.At the same time,the Thermal Desktop software is used to calculate the heat flow outside the space orbit environment and simulate the temperature field on orbit.The simulation results show that the temperature of each component is within the allowable range and meets the thermal control index.(3)For the cone horn antenna pointing mechanism,physical prototype has been completed.The titanium alloy surface ion nitriding treatment process is used to realize the lubrication-free lubrication of the rotating parts of the pointing mechanism.According to the tribology theory,the failure mechanism of the pointing mechanism is analyzed and the failure model of the key component non-lubrication bearing is deduced.Chooses the acceleration stress and acceleration factor in the accelerated life test from the failure model;finally select the test parameters and the basis for the failure of the mechanism.(4)It introduces the purpose and method of the mechanical test and the thermal vacuum test,and briefly explains the mechanism of space cold welding.In the environmental simulation laboratory,completed mechanical vibration test(impact test,vibration test and random vibration test),the thermal vacuum test,anti-cold test and accelerated life test,the results show that the pointing mechanism performance meets the requirements of the index and the design of the scheme is reasonable.