Dot Product Based Arbitration and Guidance Algorithm for Multi-Panel Sun Tracking

Sun tracking is a process of directing of one or more solar panels to the Sun to maximize power generation. For the satellites with fixed panels, the entire satellite must be rotated. These rotations, if improperly performed, may result in large angle maneuvers and prolonged off-nadir attitudes. In this work, a method to automatic sun tracking with multiple solar panels located on different faces of the satellite is presented. The algorithm automatically switches between the corresponding references frames using a simple selection method based on dot products of each panel normal vector with the sun direction vector. It allows for less variation in angles with respect to the nominal nadir-pointing attitude. Furthermore, it is possible to prioritize the panels with this algorithm. Assigning different priorities is especially useful if the panels have different surface areas or any of the panels becomes unavailable. It is also possible to define imaginary panels that are useful in situations when smaller attitude variations have higher priority. Example of power generation and improvement scenarios are analyzed involving TUBITAK UZAY's currently operational satellite RASAT and a new high-resolution platform concept.