Guidance, Navigation, & Control (GNC)
The guidance, navigation, and control (GNC) subsystem is responsible for creating a navigation solution for a satellite. GNC must be able to process the sensor data that is provided by sensing equipment such as an inertial measurement unit, magnetometer, Sun sensors, and GPS, and use these data to control the movement of the satellite and keep the attitude and trajectory within reasonable bounds.
The GNC system of MR & MRS SAT is accountable for the processing of information received from the different sensors and commanding the twelve cold-gas thrusters and three torque coils onboard. The inertial measurement unit (IMU)-based navigation filter processes the internal and external sensor data to provide the estimated position, velocity, and attitude of MR SAT, as well as the relative position and velocity of MRS SAT with respect to MR SAT. Once these have been determined, a series of algorithms determine what course of action needs to be taken, and what kind of attitude adjustments need to be made. The twelve thrusters and three torque coils allow for the spacecraft to have a full six degree-of-freedom control.