Lockheed Martin engineers used MathWorks tools to design and simulate the GN&C system for the MRO and to automatically develop a real-time simulation model of the spacecraft, which originated from a CAD mechanical model.
The team used MATLAB and Simulink to develop the algorithms and associated parameters for the MRO’s GN&C system, which incorporates input from sensors, including inertial measurement units, star trackers, and sun sensors, and drives reaction wheels and gimbals to point the spacecraft and its appendages.
Over the past several years, the team has used Simulink and Simscape Multibody™ to assemble a library of models for spacecraft actuators, sensors, control algorithms, and vehicle dynamics. They used this library to rapidly develop high-fidelity models of the MRO spacecraft, including flex and fuel slosh modes. Because the MRO spacecraft model and the controller model are in Simulink, the team efficiently simulates the control system and determines thousands of control parameters for various mission phases and operational scenarios. The control parameters developed in Simulink were directly loaded into the spacecraft parameter database.
Lockheed Martin engineers also used Simulink, Simscape Multibody, and Simulink Coder™ to develop the Orbiter Test Bed (OTB) for real-time, hardware-in-the-loop (HIL) simulation of the MRO. Engineers used the OTB HIL tests to verify the flight software prior to launch and continue using the OTB to verify all commands and sequences during operations.
The team has automated the process of generating mechanical models in MSC.ADAMS from CAD models. Because the standard multibody dynamics description of the body, joint, and coordinate systems in ADAMS matches the modeling description of Simscape Multibody, Lockheed Martin readily translated the ADAMS model into Simulink through Simscape Multibody. They then used Simulink Coder to automatically generate C code from their Simulink models to implement high-fidelity dynamics models in the OTB HIL testing.
During the seven-month journey to Mars and throughout the mission, Lockheed Martin engineers used the OTB to verify GN&C performance. The team is also using Signal Processing Toolbox™ to analyze accelerometer data from calibration and jitter tests conducted onboard the MRO.