Small Satellite Proximity Operations Hardware-in-the-Loop Test Bed Development

The capabilities of small satellites produced by the university and small business community have seen a sharp rise in recent years. With this growth in capabilities has come an increase in mission complexity to encompass those architectures previously only found in well-funded government programs, including proximity operations. The inherent complexity of proximity operations-based missions introduces a great deal of risk to the mission’s success. The low-budget nature of the small satellite community has limited the development of relevant testing infrastructure to match the pace of mission complexity increase to adequately mitigate risk. This research leveraged the standardization of CubeSat components to develop a highly adaptable hardware-in-the-loop testing capability for the verification and validation of small satellite avionics boards and flight software. MATLAB© Simulink Real-Time was utilized to create a user friendly framework that can easily be adapted to support a wide range of small satellite mission architectures. This architecture, known as SoftSim6D, has been designed to thoroughly exercise the robustness of a satellite with the primary aim of minimizing mission risk to ensure full mission success. SoftSim6D provides a low-cost, highly adaptable framework that can be used for both analysis of potential small spacecraft missions and testing to substantially reduce risk of flight missions. CubeSat missions are often driven by a low-cost mentality coupled with minimal development schedule. The highly adaptable nature of this framework allows for rapid configuration to support a specific mission’s needs very early in the design process and throughout hardware integration and testing (I&T). The fidelity of SoftSim6D available both for algorithm development and flight software and hardware implementation is a powerful tool for CubeSat missions which often do not have access to high fidelity frameworks such as this. This level of testing, at numerous points throughout the design cycle, will allow for the drastic risk reduction of any future proximity operations mission. Such testing is essential to ensuring mission success for any CubeSat mission, and SoftSim6D presents an efficient, low cost method of providing this critical mission assurance. To date, SoftSim6D has been proven to achieve all of its primary requirements with the potential to be further expanded to accommodate an even wider range of capabilities. The rapid adaptability and versatility of SoftSim6D should considerably reduce the amount of time required for future projects to develop a high fidelity simulation environment. Initial algorithm testing capability can be achieved on the order of days instead of weeks and HWITL testing capabilities can be ready within weeks of testing requirement definition. Once the baseline implementation of SoftSim6D for testing of a single spacecraft was completed, the short timeline required to prepare for testing of the Marshall Space Flight Center MADS avionics board served as proof of the system’s capabilities. Further modifications now allow for the simultaneous testing of multiple spacecraft in proximity operations type scenarios. A variant of SoftSim6D has also been developed to support simulation and testing of CubeSats in the Martian system. Well defined configuration management and coding procedures in addition to instruction manuals were developed to make SoftSim6D a very user friendly environment. Through extensive development planning, implementation, and verification efforts, an extremely robust and adaptable small spacecraft testing infrastructure has been created. SoftSim6D has proven to be a versatile environment that will drastically increase the reliability of future Georgia Tech small satellite missions. With the conclusion of this fellowship, initial operability of SoftSim6D has been achieved and the framework is ready for use in conjunction of full flight missions.