Multi-Spacecraft Autonomous Attitude Estimation via RF Measurements in Formation Flying

High-precision relative attitude measurement between spacecraft is critical for ensuring coordinated control and safe operation of multi-spacecraft formations. To address the limitations of traditional passive attitude sensors and the attitude determination method based on satellite navigation signal, such as cumulative errors, environmental interference, and restricted application scenarios, this paper proposes an autonomous attitude estimation method based on Radio Frequency (RF) measurements. The proposed method utilizes radar to acquire inter-spacecraft range and angular measurements, and constructs line-of-sight (LOS) vectors under the body frames of different spacecraft. By employing the singular value decomposition (SVD) to calculate the rotation matrix and derive the Euler angles, the relative attitude estimation of multiple spacecraft without prior position and attitude information can be achieved. Furthermore, this paper derives the optimal formation configuration under the minimum attitude estimation error, providing theoretical guidance for the design of the formation configuration. Simulation results demonstrate the effectiveness of the proposed method, showing improved estimation performance for multi-spacecraft formation flying relative to existing RF-based autonomous measurement approaches.