Modeling and System Identification of a reaction wheel with experimental data

In this paper, a linear dynamic model for a reaction wheel is identified using experimental analysis. To do this, online input-output data of reaction wheel is sent and received by CAN protocol working with the frequency of one mega bit per second. The experimental hardware consists of reaction wheel, processing board, CAN protocol, and LabVIEW monitoring. Modeling assumes the reaction wheel and its inner control circuit as a black box and takes into account the practical considerations. Initially, behavior of the reaction wheel is examined using test signals for velocity and acceleration as inputs. After that, the test signals are replaced by Chirp and PRBS signals and the output results are saved. According the results obtained in the tests, ARMAX and ARX linear dynamic models are assigned to the motor and different orders of these models are compared with each other to reach the appropriate order of the models. Furthermore, a delay is also incorporated in the model and its proper order is determined by the simulations. Finally, to validate the proposed model, the outputs of the model and plant are compared followed by exerting a new test signal. The results indicate a good agreement between the proposed model and the practical behavior.