衛星載具的設計及姿態控制

Abstract

本論文根據能量的觀點探討各節火箭質量配置的問題，利用最佳化的方法計算質量最佳分配發現即使在重力及氣動力的影響之下，所得的最佳分配與純理論分析所得相差不遠。設計的導引律分成三個部分：第一節火箭採用重力轉彎，利用俯仰角速度回授控制攻角為零度，避免火箭因氣動力造成損壞。第二節火箭採用線性正切律，利用事先計算得知的角度，讓火箭大幅度轉向，使火箭慢慢平飛於地球表面，在滿足期望高度的同時，也降低飛行路徑角。第三節火箭為精準入軌，同時採用角度控制及高度回授。角度控制的目的是控制火箭平飛，使飛行路徑角為零度。高度回授則是透過查表的方式將高度變化量轉換成角度補償，使火箭飛行在期望高度。當速度達到入軌要求則脫節並將酬載送入軌道運行。最重要的是入軌後酬載繞行地球軌道的高度誤差。透過模擬的結果顯示，設計的導引律能順利地將酬載送入軌道運行，且繞軌的高度誤差不大。

This thesis discusses the mass configuration of rocket based on energy, we use optimization method to calculate the best mass distribution , and we found that the best distribution almost has the same result with theoretical analysis even under the influence of gravity and aerodynamic forces. Guidance law of this thesis can be divided into three stages. The first stage is gravity turn, we control the angle of attack to zero by using pitch angular velocity feedback, that avoid rocket damage due to aerodynamic forces. The second stage is linear tangent law, we use the angle which calculated in advance to make rocket turns, let the rocket is in level flight at Earth’s surface so that the rocket meet desired altitude and reduces flight path angle. The third stage is precise orbit injection, we use angle control and altitude feedback, angle control is to control the rocket is in level flight, this can made flight path angle to zero. Altitude feedback transfers altitude variation to angle compensation through look-up table, let the rocket fly at desired altitude. When the rocket speed meet the condition of orbit injection, the rocket separates and sends the payload into orbit. The most important is the error of altitude after orbit injection. Results of simulation show that the guidance can send the payload into orbit successfully.