Design Of Control Moment Gyro Equivalent Sound Source Based On Transfer Function Matrix Inversion

The micro-vibration induced by a CMG (Control Moment Gyro) is very important for spacecraft. Vibration validating testing before launch is always necessary. However the boundary conditions of the validation measurement on the ground are different from space. One of the main differences is the presence of an atmosphere versus vacuum in space. Therefore, one should consider the structural vibrations due to the CMG acoustic excitation on the ground, which doesn't exist in space because there is no acoustic medium in vacuum. To research the micro-vibration due to CMG acoustic excitation, an equivalent acoustic source was designed in this paper, which can reproduce the CMG acoustic performance and therefore can be used to evaluate the contribution of the CMG acoustic excitation to the total vibration in the future. FRF matrix inversion based on PCA was used to derive the drive voltage of the speakers on the equivalent sound source. A comparison of the acoustic energy level and directional characteristics was done between the CMG and the equivalent sound source. Moreover, a new assurance criterion based on the microphone auto power linear spectrum was used to simplify the accuracy validation. It was shown that the equivalent sound source can accurately represent the CMG acoustic excitation from 80 Hz to 800 Hz.