One of the highly complex and mission-specific systems is the Attitude Determination and Control System (ADCS), which consists of sensors, actuators and a processing unit running control algorithms. To test the control operations and performance of the ADCS within a short time frame, and without extensive test equipment investment, a Hardware-in-the-loop (HIL) solution is used.
With the HIL solution, the attitude and orbit dynamics simulator running on a Speedgoat real-time target machine is connected to the ADCS processing unit.
The sensors and actuators are modelled in the simulator with performance and operational characteristics obtained from testing or from the component manufacturer.
The same simulator can be used for both the development of the ADCS controller and the analysis of its performance. Some of the complex mission operations of Aalto-1, such as a 200 deg/s spin-stabilized operation mode required for an electric solar wind sail experiment, would otherwise be nearly impossible to test.