The Design And Implementation Of Servo Controller For Laser Communication System

Compared with the microwave communication, laser communication has the advantages of large capacity of communication 、 light weight 、 low power consumption、small volume and good confidentiality. As a new way to solve the problem of microwave communication’s bottleneck, laser communication attracted a lot of attention of nations and a lot of resources were invested to research on it. As the carrier of information in laser communication is laser beam, the realization of laser communication needs the technology of high precision acquistion, tracking and pointing(ATP). The technology of ATP is the basis of the establishment of the stable optical communication link. And the excellent performance servo controller is the premise and guarantee to realize the ATP. In this article, the servo controller of laser communication has been researched deeply based on the project of "Measurement、control and communication technology based on laser ". The main research work is as follows:1) Latest progress and research status of the servo controller of laser communication is summarized and the mainstream hardware architecture of the servo controller is introduced. By analyzing and comparing the hardware structure of various servo controller, summarizes the respective advantages and disadvantages of each of the hardware structure. At last, elaborated the research significance of this article.2) On the basis of systematic analysis of the research on the servo controller of laser communication at home and abroad and for the performance requirements of laser communication on the high precision, multi-channel and high real-time, the hardware architecture of ARM+FPGA for the servo controller is presented in this paper. In this hardware architecture, ARM works as the master control chip of the servo controller, FPGA is worked as the co-processor chip. It is a good hardware architecture which combines the advantages of ARM in man-machine interface、 system management and the advantages of FPGA in data’s parallel processing. The whole system is divided into sub modules according to the servo controller’s function, each submodule of the servo controller has been designed and debuged and the precision of each module is verified.3) In view of the convenient of the management and follow-up upgrade of the system, the Linux operating system is transplanted in ARM and the basic peripheral driver is added to the kernel. The driver of FPGA in Linux is developed and the man-machine interface is also developed. In addition, the digital filter based on recursive least square algorithm was designed and completed in FPGA. The PID control algorithm has been developed based on DSPBuilder and the performance of the PID has been verified.4)The performance of the servo controller which is designed in this paper is verified. The practical laser communication optical path is set up in the laboratory and the servo controller has been used in the laser communication to verify its performance. The results show that the servo controller which designed in this paper meets the laser communication’s index requirements on hi gh precision, multi-channel and real time. It shows that the design of the servo controller has rationality and practicability, it also provides an important basis for the engineering practice and related research of laser communication.