Attitude control platform for pico satellites

Abstract

Space interest is once again on the rise, with more contenders contemplating its scientific and commercial value. CubeSats have allowed smaller institutions, including universities, to join this effort through standardised structures that cut down development time and costs. The price point is further reduced by allowing the use of commercially available off-the-shelf (COTS) devices to perform beyond their limitations, in a harsh, radiating environment. At one-eighth the size of CubeSats, PocketQubes (PQs) are the way forward towards satellite miniaturisation. However, due to their more stringent constraints, their scientific applicability, has been till now, somewhat compromised. UoMBSat1, a PQ being developed by the University of Malta, aims to overcome this barrier by implementing, amongst others, a tri-axial, fully controllable attitude determination and control subsystem (ADCS). The payload, an impedance probe used for ionospheric measurements, dictates the choice of attitude-manipulating actuators by imposing the need for a magnetically clean environment, thereby the choice of reaction wheels and magnetorquers. With such limited resources, the question is whether such a complex design can be implemented within a PQ, while overcoming reliability issues. This thesis presents an architectural design approach coupled with a reliabilityemphasised philosophy on how to design compact electronic systems that guarantee reliability. This knowledge is then applied to the electronic design of an ADCS platform for UoMBSat1. Due to the unprecedented complexity of a PQ requiring a fully-active ADCS, whilst guaranteeing reliability through multiple layers of redundancy, the architectural implementation required a non-trivial, iterative, printed circuit board (PCB) design process, in an effort to maximise spatial efficiency. As an exercise in reliability engineering, the final design and architecture were subjected to a failure mode effect analysis (FMEA) study to validate the fail-safe mechanisms, identify functionality hindering failures and total failures.