Software Design and Controller Evaluation for the ADCS on the NTNU Test Satellite

The NTNU Test Satellite is a student satellite program at NTNU that is part of the Norwegian Student Satellite Program run by the Norwegian Center for Space Related Education. The goal of the project is to send a student built and designed CubeSat to space. This thesis continues the work of developing a Attitude Determination and Control System for the NTNU Test Satellite. In this thesis simulations have been run for two previously chosen controllers (detumbling and pointing) to ensure that the controllers will work with the hardware and software design of the Attitude Determination and Control System. A third controller has been developed to increase the angular velocity of the satellite, called a tumbling controller, and simulations have been performed to check its performance. Instability evidence is also presented for the tumbling controller. Simulations have also been performed to check how the pointing controller works when there are noise on the angular velocity measurements. The simulations shows that all of the controllers will work satisfactory. A second prototype for the Attitude Determination and Control System hardware has been designed with a focus on redundancy, and the overall software architecture has been designed. Most of the software have been tested on a evaluation kit for the chosen microcontroller. A median voter has been implemented to handle the sensor redundancy in software. Lastly a simple failure analysis have been performed, fault trees have been used to show how the Attitude Determination and Control System might fail to perform as designed. Some steps that can be taken to reduce the risk of failures are also discussed