ADCS

Attitude Determination and Control Subsystem

The ADCS stabilizes the cube satellite and orients it in desired directions during the mission despite the external disturbances acting on it. This requires that the CubeSat determine its attitude using sensors and control it using actuators.

The initial design cycle was concluded early on for the ADCS system of a 1U CubeSat, delivering a working, modeled and characterized system. The design, implementation, testing and initial optimization has taken place on sub-system level. This ADCS system is a 3-axis active system based on magnetorquers. The ADCS relies on generating the control torque using rectangular magnetic coils (x4) attached at four sides of the CubeSat on the back of the Solar Panels.

For the needs of QB50 mission a more complex and accurate ADCS system was designed and developed based on the below components:

  • Sensors and actuators for monitoring and controlling CubeSats attitude (15deg pointing accuracy and knowledge accuracy of 5degrees)
        –  3-axis digital gyroscope for the angular velocity measurements
        –  Magnetometer for magnetic field measurement in attitude determination
        –  Sun Tracker’s pointing vector will be used in conjunction with the magnetic vector for a full attitude estimation
        –  GPS for correcting SGP4 propagator’s estimation within requirements (position accuracy of 1km), and providing a precise time update
  • Magneto-Torquers (embedded in the Solar Panels) and Spin-Torquer for actuation
  • Control algorithms will be implemented as a part of a Cortex M4 microcontroller (STM32F4)
Spin Torquer
Spin Torquer

 

index1
Early testing setup