HIGH-SPEED IMAGE PROCESSING TECHNIQUE IMPLEMENTATION FOR POINTING AND TRACKING SYSTEM ENABLING FREE-SPACE OPTICAL COMMUNICATIONS

摘要

Free-space laser communication technology has several advantages comparing with radio communications for various applications on Earth and in space. An optical transmission line can be characterized by higher data rates in combination with lower power consumption and lower weight of the communication terminal, which is an undoubted advantage for using onboard satellites, space telescopes, and scientific space probes. The main challenge of implementing laser communication between various mobile platforms is based on the need to use a precise and high-speed controller for a pointing and tracking system and the visual system, which shall operate at frequencies significantly higher than frequencies of a standard television sweep. This work is dedicated to the development of a pointing and tracking system for an optical communication terminal for different configurations of mobile platforms: satellites, mobile robots, and unmanned aerial vehicles. Present work is based on derived earlier requirements for each of these configurations. During present work, hardware for the optical terminal development was selected and control algorithms were created for pointing and tracking drives. The image-processing algorithm was tested to generate the signal for the control system represented by the PID controller. An algorithm is based on the idea of detecting the center of an image from the orientation beacon received by the video sensor of the optical communication terminal. FPGA-based implementation of the image-processing algorithm reduced drive control latency, which in turn improved the accuracy of the pointing and tracking system and increased the efficiency of data transmission.