太空儀器表面溫度控制

Abstract

近年發射人造衛星在我國已是眾所矚目的大事，而首次的中華衛星一號預 計在1997年發射。由於太空中環境溫度變化極大，為使各儀器能工作正常 ，其溫度的控制非常重要。衛星溫度控制方法有被動式和主動式兩種，本 論文乃是以主動式的加熱方式，對太空儀器表面溫度提供一套模擬與控制 的方法。先以數值方法在電腦上模擬出它的物理現象，再以系統判別的方 式求得其數學模型。最後應用線性平方調節器的理論，以bang-bang控制 的法則來控制加熱器的開關，以達到溫度控制的目的。模擬的結果顯示溫 度控制極穩定且功效良好。最後我們提供估計誤差的方法，藉此安排加熱 器。 It has been known that Taiwan will launch the first satellite, ROCSAT-1, in the ionosphere orbit in 1997. Many instruments and devices will be set in the satellite. However, it is unavoidable that the temperature of environment changes very much. To assure the instruments work normally, a temperature control system is needed. Temperature control systems adopted in the satellite are usually classified into passive system and active system. An active temperature control system using heaters is proposed in this thesis. Two major steps are proposed for design the system: one is to develop the modeling system which can simulate the thermal conduction and radiation effects of an empty cubic instruments; and the other one is using the developed models to design a temperature control system. Since the temperature model is nonlinear, a system identification technique is applied to approximately linearize the system. Furthermore, a linear quadratic regulator theory is used here to design a bang-bang controller. Simulation results show that the system is stable and the performance is good. Finally, we estimate the error for providing the guidance for arranging the heater-positions.