Phd in AERONAUTICS AND SPACE ENGINEERING

Thesis title: LEDSAT and WildTrackCube-SIMBA: Attitude determination and control

This dissertation focuses on methods for the attitude determination of CubeSats, using both on-board sensors data and optical observations of on-board LEDs, and the attitude control of CubeSats via magnetorquers. One of the main goals of the research is to demonstrate the use of external LEDs for attitude determination using the attitude obtained via the on-board sensors data for verification and comparison. While attitude determination using on-board data is common, if communication is lost with the satellite, it is difficult if not impossible to recover data on the attitude of the spacecraft. Prior attempts were made by observing the sunlight reflected on the spacecraft, but the method is not reliable, and the observation time is limited. On-board LEDs mounted on the exterior faces can be used to autonomously flash patterns to be observed from ground which can be used to infer how the satellite is oriented. The methods are applied to the LEDSAT CubeSat, launched in August 2021, on both the on-board data and the observations of the LEDs mounted on the exterior faces of the 1U CubeSat. In the first part of the thesis, several methods are developed to calibrate and remove biases from the on-board attitude sensors – a gyroscope, a magnetometer and coarse Sun sensors; the data is then used for attitude determination. Then, the attitude control developed and tested on the WildTrackCube-SIMBA 1U CubeSat is described. In the second part, the observations of the LEDs are described, and a method is developed to extract the spacecraft attitude, which is then compared with the on-board sensors data.