Design and manufacture of 3DOF reaction wheels as actuators for attitude control of a 1U CubeSat
Document typeMaster thesis
Rights accessOpen Access
The main objective of this thesis is the design and additive manufacture of various assemblies of Reaction Wheels for the Attitude Control Subsystem of a 1U CubeSat. A CubeSat is a small satellite which dimensions are 10 × 10 × 10 cm and weights 1 kg. These nanosatellites make space exploration more accessible since a lower volume of materials is needed. The mathematical models to perform numerical simulations of the reaction wheels consist of the dynamics and kinematics equations used to describe the satellite, here a quaternion representation is used. Furthermore, the derivation of the distribution matrices of each reaction wheel configuration are presented, the considered configurations are: Orthogonal, NASA Standard, Pyramid and Tetrahedral. Thereafter, the control law used for the simulation model is introduced. It was chosen to apply the typical control law for spacecraft attitude, a PD controller. This is then expressed in the quaternion feedback control, including a counteract for the gyroscopic effect of the rotating body. The Reaction Wheels mechanical design and the simulation model were established. In the mechanical design, the motor selected is the Maxon 20 EC flat. From this motor, four reaction wheel concepts are created, each one of them has a version for the NASA Standard and the Pyramid configuration. These configurations are chosen because they offer redundancy and are suitable to fit in the CubeSat constraints. The fifth concept C5 is for another motor of interest due to its reduced size. Successively, the simulation model is introduced, with an explanation of each block with their inputs and outputs. Subsequently, the concepts were 3D printed and manually assembled. Thereafter, the simulation results showed that the chosen reaction wheels can efficiently control the attitude of the satellite even when one wheel of the redundant system fails. The outcomes for this thesis are that Concept 4 of the mechanical design is the most convenient since it takes advantage of the extra inertia of the external-rotor of the motor. Furthermore, in the numerical simulations the tetrahedral configuration performs the maneuver more effectively, however for a better layout distribution of the wheels, the pyramid configuration is the optimal with good performance results and the best space usability in the CubeSat.
SubjectsArtificial satellites -- Wheels, Three-dimensional printing, Flight control, Satèl·lits artificials -- Rodes, Impressió 3D, Sistemes de control (Vol)
DegreeMÀSTER UNIVERSITARI EN ENGINYERIA ESPACIAL I AERONÀUTICA (Pla 2016)