Modeling and Correction of Pointing Errors in Gimbals-Type Optical Communication Terminals on Motion Platforms

In free-space optical (FSO) communication, high-precision pointing is a critical technology required for rapid acquisition to reduce link establishment time and increase communication time. FSO communication on a motion platform is necessary to expand the communication area and to promote the establishment of a global communication network. However, the pointing accuracy of an optical communication terminal on a motion platform is low due to numerous error sources and error coupling. This paper evaluates the error sources and proposes a pointing model to avoid problems resulting from error coupling. This proposed pointing model was designed to improve the pointing accuracy of a gimbals-type optical communication terminal (GOCT) on a motion platform. The effectiveness of the proposed pointing model was verified by tracking star experiments. The modified residual error of the proposed point model was 94.8 μrad compared to 1324.2 μrad without correction. Additionally, the modified residual error was 94.8 μrad of the proposed pointing model compared to 140.2 μrad of the existing model. The actual open-loop pointing error was reduced from 150.4 μrad of the existing model to 101.3 μrad of the proposed model. Thus, the pointing accuracy of a GOCT on a motion platform was significantly improved after correction by the proposed pointing model.