Pointing Model for Vehicular Quantum Communication Terminals Based on Line-of-Sight Attitude Measurement

Vehicular quantum communication terminals (VQCTs) are crucial for establishing global-scale quantum networks. High-precision line-of-sight (LOS) pointing is essential for fast and reliable acquisition in satellite-based quantum key distribution (QKD). The pointing accuracy of VQCTs is affected by attitude measurement errors, mechanical structure errors, and structural instability errors resulting from platform movement. By mounting attitude sensors on the LOS of VQCTs, we directly measure the LOS attitude. This completely eliminates the impact of mechanical structure errors and structural instability errors on pointing accuracy. Furthermore, we propose a line-of-pointing calibration method and a pointing model for VQCTs based on LOS attitude measurement. The pointing accuracy of this model is primarily reliant on the accuracy of attitude sensors. Two experiments were conducted to validate the effectiveness of our model. One is the star pointing experiment, comparing with the existing pointing model for VQCTs, our model significantly reduces the pointing errors by 93%, from 1296 '' to 87.8 ''. This substantiates that our model eliminates mechanical structure errors and structural instability errors. Another is the successful acquisition of a quantum communication satellite, which demonstrates the feasibility of the proposed model for implementing the satellite-to-motion platform QKD and global-scale quantum networks.