Research On Coarse Tracking Servo System Of Space Laser Communication Based On Voice Coil Motor

Space laser communication is a way of data transmission in space with laser signal as information carrier.It has many advantages,such as high communication rate,large communication capacity,no spectrum limitation,good security and confidentiality and so on.However,due to the problems of long communication distance,small divergence angle of laser beam and limited receiving field of view in space laser communication,a highprecision tracking system is needed to maintain the stability of laser communication link.In addition,with the development of the satellite platform equipped with laser communication terminal system towards low orbit,light and miniaturization,the space environment faced by the tracking system has become more complex.At the same time,the load of small satellites is limited,and the space and weight reserved for the tracking system have become limited.Therefore,how to realize light and miniaturization under the condition of ensuring the high-precision tracking of the tracking system is an urgent topic in the field of space laser communication.Combined with the light and miniaturization project of a spaceborne laser communication terminal system,this paper carries out the research on the coarse tracking servo system based on voice coil motor,focusing on the scheme design,theoretical modeling,control simulation,algorithm optimization and experimental verification of the servo system.Firstly,the communication process of space laser communication and the role of coarse tracking in the communication process are analyzed,and then combined with the project background,the technical index requirements of coarse tracking system are analyzed.According to the technical index requirements of coarse tracking and the requirements of light and miniaturization,the structure of single mirror coarse tracking system is determined,and the voice coil motor is used as the actuator to reduce the volume and weight of the system;Then the control scheme of coarse tracking servo system is proposed,and the hardware architecture of the servo system is given.In order to facilitate the performance analysis of the coarse tracking servo system,taking the pitch axis of the coarse tracking system as an example,the mathematical model of the coarse tracking system based on voice coil motor is established,and the three closedloop controller of the servo system is designed to realize the basic motion control of the coarse tracking system.However,the actual coarse tracking system will be affected by uncertain disturbance factors such as satellite platform vibration,resulting in the poor tracking accuracy of the system.Aiming at the problem of poor tracking accuracy of coarse tracking system caused by uncertain factors such as satellite platform vibration,a fuzzy sliding mode compound control scheme is proposed to suppress system disturbance and improve system tracking accuracy.The simulation results show that the fuzzy sliding mode compound control can effectively suppress the system disturbance and improve the tracking accuracy.Finally,a hardware experimental platform is built to verify the performance of the coarse tracking servo system.The experimental results show that the coarse tracking system can meet the expected technical indicators and has certain anti-interference,which provides a reference basis for relevant research in the future.