Development of attitude control systems for modular spacecraft

This paper discusses a new approach to ADCS simulation and design that is consistent with applications based software components. By breaking the ADCS into component applications and using standard interfaces, both of which having been pre-defined in coordination with the software development team, a new paradigm in the development of ADCS software has been achieved. In order to meet quick development times and reduce development costs, this new paradigm relies on modular, reusable software applications implemented in a network architecture. These systems use data driven, asynchronous applications to provide the various software functions, including ADCS. By keeping the applications self-contained, the software can be modified by changing, adding, deleting or modifying an application without affecting the rest of the software, thereby reducing the test requirements on the system. However, this modular approach is not consistent with traditional ADCS development approaches and environments, which assume that all ADCS functions will be contained in a single block of software, executed in a single thread at a precise sample frequency. This leads to difficulties in translating the algorithms developed by the ADCS algorithm team to into flight software, either through documentation that is passed to the software team, or through autocoding of the algorithms directly. We will discuss the implementation of a general applications based ADCS simulation operating in the MATLAB environment as well as the development of algorithms for spacecraft requiring multiple pointing modes, the aggregation of multiple sensor inputs and the precise tracking of ground targets.