Design of spacecraft attitude determination system using MEMS sensors

Sammanfattning: The CubeProp module is a propulsion module developed by NanoSpace AB that will fly on-board the MIST CubeSat in 2017. NanoSpace is interested in developing an attitude determination system for the Cube-Prop module that also can be used to measure the performance of the thrusters in space. In this thesis such a system is designed and the performance is validated through numerical simulation. A method for testing the system is also chosen. The first step in designing the system is to perform a requirement analysis. This analysis leads to the decision of using only commercially available MEMS sensors. The MAX21000 gyroscope is chosen to be used after performing an initial performance calculation of the sensor together with a market survey. To determine how many gyroscopes of this types that are needed, simulations for attitude determination systems with 1, 2 and 3 gyroscopes are performed. Based on these simulations the thrust is calculated using a thrust measurement algorithm and it is concluded that the system should consist of 2 gyroscopes. The attitude determination performance and the de-spin performance is then simulated for this dual gyroscope system. The results from the simulations show that by using a dual gyroscope system the thrust can be determined down to a size of 10 µN. The mean error of the attitude after a 90 ° rotation is 0.049 °. A rotation around the z-axis of 1 ° s−1 can be de-spun so that the rotation around any body-axis is smaller then 0.02 ° s−1. The best way to test a real life model of this system is by using an air bearing table as the attitude determination and the control system can be tested simultaneously.