Integrated Model-Based Systems Engineering of a CubeSat Mission Using MBSEPak
Challenge: Model-Based Systems Engineering for CubeSat Missions
The INCOSE Space Systems Working Group’s CubeSat project has been investigating the applicability of Model-Based Systems Engineering (MBSE) for designing CubeSats by modeling the University of Michigan’s Radio Aurora Explorer (RAX) mission. Conventional Systems Engineering approaches often neglect subsystem interaction, fail to capture the dynamic aspects of mission analysis, and are built as one-off solutions. These challenges are particularly problematic for CubeSats where components are usually physically integrated, the entire spacecraft is extremely constrained, and orbits are often unknown during mission design. MBSE addresses these challenges through the formal application of modeling to Systems Engineering processes. Successful application of MBSE requires integrating design, analysis, and simulation into a common framework.
Solution: Integrate CubeSat Behavioral Simulation with Analysis Models in MBSE Analyzer
Three levels of modeling were integrated using MBSE Analyzer. The architecture of the CubeSat Mission was defined in SysML block definition diagrams for the spacecraft, ground network, external environment, experimental target, and control software, as well as the interactions between these elements using No Magic’s MagicDraw. Performance analyses were developed for the experiment payload, the power, and the communications systems in AGI’s STK, Mathworks’ MATLAB, and scripts written in Java. These analyses were then integrated in Phoenix Integration’s ModelCenter and linked to SysML parametric diagrams using Phoenix Integration’s MBSE Analzyer. Finally, system behavior was modeled in SysML activity diagrams and executed in No Magic’s Cameo Simulation Toolkit (CST). Using the final integrated model, CST simulations call into the analyses models to determine the performance and state of the simulation through MBSE Analyzer’s connections with ModelCenter. MBSE Analyzer also enables systems engineers to automatically generate time history data from the CST simulations, allowing them to perform trade studies on behavioral factors.
Benefit: An Integrated and Executable Systems Engineering Model for Performing Mission Trade Studies
Phoenix Integration’s MBSEPak integrated the RAX CubeSat mission’s architecture, analysis, and behavioral models into an integrated and executable MBSE model enabling detailed trade studies over component and mission parameters. Accurate mission simulation was made possible by enabling the SysML behavioral simulation to call detailed engineering analysis models via MBSE Analyzer, a bridge between SysML tools and ModelCenter. The integrated model was exercised to generate time history of system states during the mission. The results were used to verify the model, to understand system behavior, and to study the interaction between components. The simulation capability was then used for trade studies that evaluated the impacts of design parameters on mission performance. The integrated model allowed use of not only component parameters but also mission parameters such as orbit properties and ground network. Results of mission simulations were used to check system requirements for the minimum energy limit and data download.