M.Sc Thesis


M.Sc StudentPuzev Alexander
SubjectModelling and Control of a Variable-Mass CubeSat Reaction
Wheel
DepartmentDepartment of Autonomous Systems and Robotics
Supervisor PROF. Pinchas Gurfil
Full Thesis textFull thesis text - English Version


Abstract

Nanosatellites, most predominantly CubeSats, usually carry no propulsion system, yet their usage is important both from the science and from the budget points of view. The main limitation is the lack of space and difficulties in scaling down the existing propulsion techniques. A short overview of the existing propulsion technologies is given with a brief evaluation of the technology applicability in nanosatellites. The most difficult case in this regard is the smallest of CubeSats, the 1U satellites, the rapidly growing usage of which has received much research attention. To increase the nanosatellite functionality, as well as to allow orbit control in the presence of orbit injection errors, an ejection of mass from a reaction wheel is proposed in this research. Utilizing the reaction wheel kinetic energy, a propellant mass is released from the specialized wheel's outer circumference using a short application of an electric current. Such a propulsion mechanism can allow impulsive orbit control without using traditional propulsion systems. This study models the dynamics of the satellite, modified reaction wheel and the ejected mass, evaluates the pros and cons of the proposed method and provides a methodology for constructing a model of a variable-mass reaction wheel designed according to given specifications of a desired velocity change and satellite attitude stability. The system shows flexibility in impulse generation for small orbit corrections necessary to maintain a formation after orbit injection and correct small external disturbances.