OHB engineers used MathWorks tools for Model-Based Design to model and simulate the GNC system, perform real-time closed-loop simulations, and generate production flight code.
OHB partitioned the GNC design into formation flying, rendezvous, and proximity operations. They tested and analyzed algorithm ideas in MATLAB before modeling them in Simulink and Stateflow® to verify the algorithms in closed-loop simulation.
OHB engineers wrote MATLAB scripts that imported module interface data from a spreadsheet and automatically created a Simulink model with a matching interface and signal buses for each system module. Scripts were also used to verify the interfaces on completed modules.
The team ran closed-loop simulations in Simulink to verify GNC algorithms. These simulations tested individual components of the plant model as well as integrated systems comprising multiple subsystems that were contributed by the collaborating agencies.
Using Simulink Coder™ and Embedded Coder®, OHB engineers generated code from their GNC models and plant model. They deployed the plant code to Simulink Real-Time™, and compiled the GNC code for the onboard target LEON2 processor. OHB then ran hardware-in-the-loop (HIL) tests of the combined Simulink Real-Time system and LEON2 controller to verify the real-time operation of the algorithms.
As satellite hardware became available, the team replaced parts of the plant model with real sensors and actuators and reran their simulations. This resulted in a test setup with a maximum amount of flight HIL, including the onboard computer and GPS receiver stimulated by RF signals. To rehearse actual mission flight operations and verify flight command sequences, OHB ran simulations against the plant model on Simulink Real-Time.
OHB engineers used MATLAB Compiler™ to build standalone applications for displaying and analyzing satellite flight data. OHB staff can use these applications to prepare for satellite operations even if they do not have MATLAB installed.
OHB engineers are reusing Prisma models for yet a third program: Small GEO, a general-purpose geostationary satellite platform.