ADCS

The attitude determination and control system (ADCS) for the IlliniSat-2 bus is responsible for determining the current attitude of the satellite and for providing control to maintain a desired attitude. As opposed to some cubesats, the IlliniSat-2 bus is capable of onboard active 3-axis attitude determination and control.

The ADCS subsystem of the lliniSat-2 bus uses onboard sensors such as magnetometers, rate gyros and sun sensors. Data from each of these sensors is fed into a Kalman filtering algorithm, which gives an accurate estimate of the spacecraft’s attitude. This method allows the satellite to operate with attitude knowledge error of less than 1 degree per axis

The actuators that provide attitude control for the satellite are flexible torque coils, which are mounted underneath the satellite's solar panels. The coils themselves are a custom design, created by students working on the IlliniSat-2 project. Onboard circuitry regulates the amount of current running through each coil, which creates a magnetic moment. This moment interacts with the Earth's magnetic field and creates a torque to rotate the satellite, providing capability to maintain the satellite's orientation with errors of less than 5 degrees per axis.

The flexible torque coil is embedded in polymide material and is shown at the right. This device provides sufficient torque power to orient the satellite and this design has reduced weight compared with previous coil designs. The torque coil itself is the coil of copper embedded in the center of the device.

Copyright University of Illinois at Urbana-Champaign 2008