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Tham khảo tài liệu 'advances in spacecraft technologies part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 230 Advances in Spacecraft Technologies 0 50 200 250 100 150 time sec 0 50 200 250 100 150 time sec Fig. 15. Local and global estimates with FDI algorithm star tracker fault Error 0 50 100 150 200 250 time sec 0 50 100 150 200 250 time sec -0.02I---------------- ---------------4--------------------------------ị---------------- 0 50 100 150 200 250 time sec 0 50 100 150 200 250 time sec Fig. 16. Error between true quaternion and estimates with FDI algorithm star tracker fault Fault-Tolerant Attitude Estimation for Satellite using Federated Unscented Kalman Filter 231 fault detection 31------------1-----------I-------------I------------I---------- 25--------------- ------------ị----------j-----------J------------ 2--------------I------------ 1.5--------------I-----------I-----------I------------1----------- 1-------------r-----------r-------------r----------r------------ 05------------F-----------r-------------r----------r------------ 0. .Ĩ----------Ĩ------------ 50 100 150 200 250 time sec Fig. 17. Fault detection index star tracker fault Sensor Fault Type Single UKF Federated UKF Without FDI With FDI Gyroscope failure 145.2083 12.6870 1.0022 Star tracker failure 89.4021 40.9636 1.2780 Table 2. Error sum of attitude estimates 5. Conclusion In this study the federated UKF with the FDI algorithm is proposed for the estimation of the satellite attitude. The UKF gives the accurate estimates for nonlinear systems and the federated UKF makes the system fault-tolerant and reliable. Since the FDI algorithm can detect and isolate the sensor failure immediately the global estimate is not affected by the poor local estimate due to the faulty sensor. In this respect the error of the global estimate using the federated UKF and the FDI algorithm is smaller than that using the federated UKF only. Numerical simulation results show that the proposed algorithm provides efficient and accurate attitude estimation of the satellite despite the fault of the attitude sensors. The proposed
