University of Twente Student Theses


Modeling and characterizing a sun sensor for nano satellites

Hollander, K.J.C. den (2017) Modeling and characterizing a sun sensor for nano satellites.

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Abstract:Nanosatellites require small components such that all the necessary instruments and hardware fit into the satellite. The company Hyperion Technologies have developed an Sun sensor for this application. The benefit of this Sun sensor is that it is small and relative cheap. The Sun sensor determines the attitude of the sensor with respect to the Sun and consists of a quadrature photodiode that outputs four currents. Over the sensor a mask with a square hole is placed. The output of the four photodiodes depends on the angles between the sensor and the Sun. From this information a Sun vector is derived. In this report the sensor is modeled, characterized and calibrated to give the sensor an accuracy of approximately 1 degree or better. The Sun sensor provides information for the attitude determination and control system. The attitude determination system uses the information of different sensors and combines this information to determine the attitude of the satellite. A model of the output currents of the sensor has been developed, which is used to determine the theoretical accuracy. A sensor has been measured for calibration, and a fine mesh of datapoints is measured in the experiment to calibrate the sensor numerically due to the nonlinear behavior of the sensor. From this measurements is has been seen that the calibration of the sensor is almost impossible due to the nonlinear behavior of the signal. The conclusions are that the sensor has not been calibrated to the desired accuracy of 1 degree. The model that has been developed describes variables with the most influence on the accuracy of the sensor. Recommendations are given to improve the sensor and achieve a better response of the signal.
Item Type:Essay (Bachelor)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:01 general works
Programme:Electrical Engineering BSc (56953)
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