Design and Simulation of Sun Position Sensors for Space Applications: A Comparative Study

Abstract

Sun position sensors are used in space applications as part of the attitude determination and control system (ADCS). The aim of this work is to describe the design process of single and dual axis sun position sensors based on a photodiode array detector and a window to limit and direct the light that reaches the detector. The design process involves choosing the sensor architecture, modeling its output, and then evaluating the model through simulation. Six architectures, with different configurations and geometries for both detector and window, were modeled and compared. To evaluate the model and performance of the sensor a program was developed, and simulations were made varying window height and size, as well as the photodiodes size. From the simulations performed we concluded that for each design, the key factors that influence the sensitivity and field of view performance are the windows height, and window or photodiode size, depending on the sensor configuration. From the comparison across architectures, the detector configuration, as well as the windows geometry, influence the sensitivity and linearity of the response for similar conditions of operation. The two-quadrant detector configuration offers a better sensitivity than the triangular photodiode configuration. For a better linearity of the output a square window is preferred. This comparative study is part of the development of new products for space applications in the National Atomic Energy Commission (CNEA) and contributes to the Argentinian National Space Plan.