Simulators for Satellites

The development of AOCS software for space missions requires extensive on-ground validation prior to deployment and implementation onboard the satellite. The Real-World Software (RWSW) simulator, including its automated design and validation tools, is the main instrument used by NGC for the design and validation of its flight software. The effectiveness of the RWSW has been proven in many flight programs and the simulator has come to be recognized as a reliable tool in predicting the behaviour of satellites in orbit and the effect of parameter changes.


Throughout its years of experience in AOCS software development, NGC has created several tools to optimise and automate the AOCS software development and validation process. These tools are used daily by NGC in its AOCS software design activities.

Satellite Dynamics Simulator

The satellite dynamics simulator, also referred to as the Real-World Software (RWSW), is a Matlab/Simulink simulator used by NGC for its AOCS software development and validation. The RWSW is the representation, in a computer simulation environment, of the sensors, dynamics and actuators of the satellite as well as the dynamics or kinematics of other bodies (Sun, Earth, etc.) that have an impact on the dynamics of the satellite. The dynamics modelling of the satellite also includes the environmental perturbations acting on the satellite translation and attitude: non-spherical gravitational field of the Earth, gravity gradients, solar radiation pressure, air drag, etc.

Automatic Validation Tools

Automatic validation tools developed by NGC support the validation of the AOCS software in the Matlab/Simulink environment. Matlab tools are used within NGC’s automatic code validation tools and are thus a subset of the complete set of automatic validation tools. Theses tools automate the AOCS software validation to ensure maximum efficiency and minimum human error.

Starting from a test plan in an Excel workbook, at the touch of a button, a full set of tests can be executed and test reports can be generated and documented. This includes the possibility of executing Monte-Carlo simulations.

NGC Automatic Validation Tools

Model Libraries

NGC has developed its own library of Simulink models to augment the native Simulink module library but also to replace some of them with NGC-developed versions more adapted to safe flight operations, including cleaner automatic code generation and the detection and isolation of potential mathematical exceptions.

NGC’s Matlab/Simulink libraries include functions and Simulink modules for:

  • Actuator models
  • Satellite and celestial body dynamics
  • Environmental models
  • Failure detection and identification
  • Matrix operations
  • Non-linear operations
  • Orbit related operations
  • Quaternion operations
  • Random number operations
  • Sensor models
  • Time management operations
  • Paths and plots management tools

The libraries contain sensors and actuators models as well as various basic functions used in the AOCS software and simulators, for instance, transformation from orbital elements to position-velocity variables, quaternion to roll-pitch-yaw variables, etc. These libraries can be simply initialised and used as any Matlab/Simulink toolbox.

ESA-P. Carril


Attitude and orbit control


When you work with us, you’ll find we are very flexible when it comes to finding ways to integrate our technology into your project. We also provide in-depth training and the support of one of the most experienced Guidance, Navigation and Control (GNC) systems teams in the world.