人造衛星天線之轉動機構研究

Abstract

本研究設計了被動式微波酬載衛星天線的轉動機構，並且從事其轉速控制，使得衛星天線能在穩定的運轉控制下，取得精確之觀測數據。衛星天線之轉動機構的設計必須滿足運轉穩定，滿足空間限制及帶動需求之荷重，並能抵抗極端環境之要求。在執行任務期間，被動微波偵測儀本身有自轉的需求，保持30rpm，但因運轉箱體與反射面之間包含可動與不可動元件，其間訊號的傳遞及轉動機構的設計便成為值得探討的課題，本研究使用滑動環作為訊號及電力的傳遞，馬達選用直接驅動馬達，進行馬達的轉速控制。藉由馬達驅動器參數，觀察速度控制與扭力輸出的變化，測試的結果顯示，太小的增益會使得反射面忽快忽慢，轉速不穩定，需要較長時間使系統穩定。增大增益能使轉速穩定；然而過大的增益達四百以上，會導致共振而振動頻仍；小的積分常數使扭力輸出穩定性差，造成軸承承受應力負荷。

For satellite antennas, this thesis mainly deals with spin mechanism design and speed control of an antenna in a radiometer to make sure it under stable operation is able to obtain measurement data. The spin mechanism of the satellite antenna involves vehicle payload, space constraints and extreme environment to drive payload at constant speed. During its mission, the radiometer itself has to rotate at the speed rate of 30rpm. Since the running between the box and the reflector has movable and immovable components, the signals delivery and spin mechanism design deserve study. This thesis uses a slip ring for both signal and power transfers. We choose a direct drive motor and control its speed. We adjust motor driver parameters to control speed stability and torque output. Measurement results of the antenna platform show that rotation speed is unstable when using small gain in speed control, and it takes longer time to achieve desired rotation speeds. Increasing gain to higher than 400 makes the antenna platform resonant and vibratory. Moreover, by using small integral constant in control, the antenna platform bearing sustains severe stress since the torque is not stable.