For Satellites

NGC specialises in autonomy-enabling Attitude and Orbit Control System (AOCS) software for satellites and offers a wide range of satellite guidance, navigation and control (GNC) solutions and services.

Satellite GNC

NGC’s satellite GNC solutions and services include:

  • Customized AOCS, also known as Attitude Determination and Control System (ADCS), software development from requirements definition to in-flight validation
  • AOCS / ADCS / GNC system requirements definition, design and analysis
  • Guidance, navigation and control algorithms development
  • Flight software development
  • High-fidelity simulator development
  • Validation services
  • Turn-key navigation solutions (e.g. LOCOOS Navigator)

NGC’s AOCS Software Technology

The company specialises in the development of cost-effective design and validation of high-quality GNC software which provides a high level of autonomy to satellites while increasing their performance, reliability and safety and, at the same time, reducing their operational costs.

NGC’s AOCS software technology, starting with the PROBA satellites, pioneered a new generation of satellites which integrates on-board intelligence and autonomy in the operation of scientific and Earth-observation satellites. This flight-proven AOCS software technology ensures fully autonomous operations with little involvement from the ground control station thus significantly reducing operational costs. In another breakthrough innovation, NGC has also dramatically reduced the cost of GNC software development as its design, implementation and validation are realised using model-based design with computer-aided software engineering (CASE) tools (e.g. MATLAB/SimulinkTM, MATRIXx/SystemBuildTM), including the automatic generation of the flight code.

Although NGC’s AOCS software technology is flight-proven, NGC is continuously innovating with new or improved GNC algorithms, software and simulators.

PROBA-V Satellite

The PROBA-V Satellite Controlled by NGC’s AOCS Software (Copyright: ESA-P.Carril, Source)


The PROBA-2 Satellite Flying NGC’s AOCS Software (Copyright: ESA-P.Carril 2009, Source)

PROBA-3 Formation Flying Mission

PROBA-3 formation flying mission will rely on spacecraft GNC software developped by NGC (Copyright: ESA – P.Carril, 2013, Source)


NGC’s AOCS software autonomously controls the PROBA-1 satellite orientation to take images (Copyright ESA, Source)

NGC’s AOCS Software Expertise

NGC’s expertise in the field of GNC for satellites includes:


  • Sensor measurements processing
  • Satellite attitude and orbit determination
    • State estimators such as Extended Kalman Filters (EKF) and Unscented Kalman Filters (UKF)
    • Reconstruction of non-measured states from a minimum numbers of sensors
    • Development of the delay-recovery algorithm in order to compensate for any delays in the sensors or calculations
  • Estimation and compensation of environmental perturbations
  • Autonomous on-board event prediction
    • Prediction of flybys of target regions for optimal spacecraft operation (e.g. autonomously switching off a land-imaging payload when flying over seas as done on PROBA-V)
    • Prediction of orbital events (e.g. eclipse entry/exit, ground-station flyby, equator crossing, etc.)
    • Prediction of Earth target flybys (e.g. ground station flybys)
  • Management of on-board clocks correlation
  • Monitoring of delta-V execution for orbital manoeuvres


  • Autonomous on-board generation of the desired orientation profile of the satellite:
    • Autonomous guidance of orientation manoeuvres used to point a payload towards its target (e.g. to an Earth-fixed target, to the Sun, to an inertial target, to a given altitude in the Earth’s limb, etc.)
    • Autonomous guidance of orientation manoeuvres used to ensure optimal incoming power from the solar arrays
    • Autonomous and optimal guidance of rallying manoeuvres from one orientation to another
  • Development of autonomous guidance laws compatible with space mission requirements:
    • Scrutiny of the calculations validity, without iterations
    • Visibility in the decisions, states of the system, variables and parameters
    • Consideration given to the limited power of on-board calculators


  • Development of the algorithms and software to control the satellite attitude, to stabilize the spacecraft dynamics and to follow references generated by the guidance law using several synthesis techniques:
    • Classical control
    • Non-linear control
    • Multivariable control, optimal
    • Robust control
  • Development of safe mode control laws using minimum sensors and safe mode actuators
  • Actuator management
    • Angular momentum management of reaction wheels using thrusters or magnetic torquers
    • Thruster actuation management

Failure Detection and Identification (FDI)

  • Development of algorithms, as well as autonomous control software, for the detection and identification of breakdowns, anomalies, mathematical exceptions and/or operational risks
  • Development of FDI techniques based on virtual sensors, multi-model identification methods, consistency checks, propagation of the validity in the operations, etc.