ﺑﻬﯿﻨﻪ ﺳﺎزي ﻃﺮاﺣﯽ ﺳﻨﺴﻮر زﻣﯿﻦ ﺟﻬﺖ ﺗﻌﯿﯿﻦ ارﺗﻔﺎع ﻣﺎﻫﻮاره

Design Optimization an Earth Sensor to Determine Satellite Attitude

ﭼﮑﯿﺪه: ﺳﻨﺴﻮر اﻓﻖ زﻣﯿﻦ ﯾﮑﯽ از اﺑﺰارﻫﺎي اﺳﺎﺳﯽ در ﺳﯿﺴﺘﻢ ﻫﺪاﯾﺖ ﻣﺎﻫﻮاره اﺳﺖ. اﯾﻦ ﺳﻨﺴﻮر ﺟﻬﺖ ﺷﺒﯿﻪ ﺳﺎزي ﺳﯿﺴﺘﻢ ﮐﻨﺘﺮل ﻣﺎﻫﻮاره و ﻫﻤﭽﻨﯿﻦ ﺗﻌﯿﯿﻦ ﺟﻬﺖ ﻣﺎﻫﻮاره ﺿﺮوري اﺳﺖ. از اﯾﻨﺮو، آﺷﮑﺎرﺳﺎزﻫﺎي ﭘﯿﺮواﻟﮑﺘﺮﯾﮏ ﺑﺮاي دﺳﺘﯿﺎﺑﯽ ﺑﻪ اﯾﻦ ﻫﺪف ﺑﮑﺎر ﺑﺮده ﺷﺪه اﻧﺪ. در اﯾﻦ ﻣﻘﺎﻟﻪ، ﻣﺪل ﻓﯿﺰﯾﮑﯽ آﺷﮑﺎرﺳﺎز ﭘﯿﺮواﻟﮑﺘﺮﯾﮏ و ﻣﺪل رﯾﺎﺿﯽ ﯾﮏ ﺳﻨﺴﻮر اﻓﻖ زﻣﯿﻦ ﺑﺮاي ﺷﺒﯿﻪ ﺳﺎزي ﯾﮏ ﻣﺎﻫﻮاره ﺑﺮرﺳﯽ ﻣﯽ ﺷﻮد. آﺷﮑﺎرﺳﺎز ﭘﯿﺮواﻟﮑﺘﺮﯾﮏ ﺟﻬﺖ ﻣﺤﺎﺳﺒﻪ ﭘﺎﺳﺦ ﭘﻠﻪ و ﻣﯿﺪان دﯾﺪ، ﮐﻪ ﺑﻪ ﻋﻨﻮان ﻣﻬﻤﺘﺮﯾﻦ ﭘﺎراﻣﺘﺮﻫﺎي ﺗﻌﯿﯿﻦ اﻓﻖ زﻣﯿﻦ ﻫﺴﺘﻨﺪ، ﺑﮑﺎرﺑﺮده ﻣﯽ ﺷﻮد. ﺟﻬﺖ ﺑﻬﺒﻮد آﺷﮑﺎرﺳﺎزي اﺷﯿﺎء در ﻓﻮاﺻﻞ دور از آﺷﮑﺎرﺳﺎز، ﻣﯿﺪان دﯾﺪ ﺑﺎﯾﺪ ﺗﺎ ﺣﺪ ﻣﻤﮑﻦ ﮐﻮﭼﮏ ﺑﺎﺷﺪ. ﻋﻼوه ﺑﺮ اﯾﻦ، اﺛﺮ ﺗﺪاﺧﻼت ﺧﻮرﺷﯿﺪي ﺑﺮاي ﺳﻨﺴﻮرﻫﺎ ﺑﺎ اﺳﺘﻔﺎده از FOV ﺑﺎرﯾﮏ ﮐﺎﻫﺶ ﯾﺎﻓﺘﻪ اﺳﺖ. ارزﯾﺎﺑﯽ وﺳﯿﻠﻪ ﺑﺎ اﺳﺘﻔﺎده از ﺳﯿﺴﺘﻢ ﺗﺴﺖ اﻧﺠﺎم ﺷﺪه اﺳﺖ و ﻋﻤﻠﮑﺮد ﺳﻨﺴﻮر از اﯾﻦ ﻃﺮﯾﻖ ﺗﻌﯿﯿﻦ ﻣﯽ ﺷﻮد. ﻧﺘﺎﯾﺞ ﺣﺎﺻﻞ ﻧﺸﺎن ﻣﯽ دﻫﺪ ﮐﻪ ﻣﻘﺪار ﺑﻬﯿﻨﻪ ﻣﯿﺪان دﯾﺪ ﺑﺎ اﺳﺘﻔﺎده از ﻟﻮﻟﻪ ﻫﺎي ﭘﻼﺳﺘﯿﮑﯽ ﺑﻪ 50 درﺟﻪ ﮐﺎﻫﺶ ﯾﺎﻓﺘﻪ اﺳﺖ. ﻧﺘﺎﯾﺞ ﻣﺪﻟﺴﺎزي ﺗﺎﯾﯿﺪ ﻣﯽ ﮐﻨﺪ ﮐﻪ اﺳﺘﻔﺎده از آﺷﮑﺎرﺳﺎزﻫﺎي ﭘﯿﺮواﻟﮑﺘﺮﯾﮏ ﺑﺮاي دﺳﺘﯿﺎﺑﯽ ﺑﻪ اﻫﺪاف ﺗﺤﻘﯿﻖ اﻣﮑﺎن ﭘﺬﯾﺮ اﺳﺖ.

Earth horizon sensor is one of the fundamental instruments in satellite navigation system. This sensor is required to simulate satellite control system and to determine the satellite direction; hence, Pyroelectric detectors are employed to achieve this target. In this paper, the physical model of Pyroelectric detector and the mathematical model of an earth horizon sensor were presented to simulate a satellite. Pyroelectric detectors are applied to calculate the step response and field of view (FOV), which are significant parameters to recognize the earth horizon. To improve the detection of objects in far distances of detector, FOV should be as small as possible. Furthermore, the effect of solar interference has been reduced by the use of narrow FOV for sensors. The evaluation of the device has been performed through the use of test system that allows sensor performance to be determined. The observed results show the optimal value of FOV has decreased to 50° using plastic pipes. The modeling results verified that the Pyroelectric detectors are feasible to achieve functional requirements.