- 學位論文
使用B-dot 控制法獲取非太陽同步軌道衛星初始姿態
INITIAL ATTITUDE ACQUISITION OF NON-SUNSYNCHRONOUS SATELLITE USING B-DOT CONTROL
摘要
本論文主要探討利用B-dot 控制法做非太陽同步軌道衛星在分離階段的控制。在 衛星自載具彈射出的分離階段中，衛星會產生角速度造成滾轉，會令衛星上的感 測器無法鎖定太陽、地球或星體，進而無法完成姿態的判定。然而在此階段中， 由於有能量使用上的限制，所以是不可能使用較複雜的控制方法及較耗能的感測 器。在本論文中所使用的B-dot 控制演算法為現有大多低軌道衛星(Low Earth Orbit,LEO) 安全模式中(Safe-Mode) 都會採用的方法。研究中發現出這個控制演 算法對於整體衛星系統在任何角速度及姿態下保證其穩定，可以有效的減低角速 度。但是由於目前衛星對於各國來說皆屬於軍事的機密，所以相對的參考文獻並 不多。這對於目前要自主研發衛星的太空中心來說，實為一大挑戰，在此一前 提下跟太空中心合作一起研發可以模擬衛星的模擬系統。在研究的初期，使用 Matlab/Simulink 來建立一個衛星的動態模型，顯示出衛星的初始軌道，再建立 出重力場和磁場模型，完成整個模擬需要的系統。再利用太空中心(NSPO) 所提 供的任務資料來模擬比對此系統的可靠性。由於非太陽同步軌道的衛星在軌道上 運行時，衛星的軌道面與太陽的夾角會一直變化，所以除了在完成衛星自載具彈 射後的減轉，如何令衛星可以找到太陽的方位使得太陽能板可時時刻刻保持的對 太陽的指向性，也是本文的重點。
並列摘要
This thesis studies initial acquisition of a non-sunsynchronous satellite using B-dot control. Right after separating from the launcher, a satellite usually tumbles very fast so that solar senors or the star tracker cannot function well. However, due to the constraint of battery power, only simple control laws can be used in acquiring the satellites’ attitude. In most space missions, the B-dot control collaborated with a bias momentum is widely applied in the initial acquisition mission, due to its natural characteristics of alignment with the orbit normal after de-tumbling. However, the technology is a confidential one and few literatures are available. In this thesis, we intend to develop a control law that helps the FormoSat 7, a non-sunsynchronous micro satellite, to acquire its initial attitude. At beginning the Matlab/Simulink is employed to construct a satellite simulator, including orbit simulator, satellite dynamics simulator, time management simulator, environment disturbance simulator and control law simulator. Simulation results from the developed simulator has been verified with NSPO’s FormoSat-2 data. We also developed an algorithm that can de-tumble a satellite and acquire its initial attitude using the B-dot control collaborating with bia momentum. Numerical simulations are provided to demonstrate the feasibility of this research. The results from this thesis potentially contributes to the development of the FormoSat 7.