Vibration Control of a Flexible Rocket using FBG Sensor Arrays

As launch vehicle designs become more slender, the effects of bending vibration on control system stability could be dominant in control systems designed using rigid-body dynamics. Vibrational loads can also cause major damage to the launch vehicle, either in the form of vibrational fatigue or excitation of the structures resonant frequencies. This work investigates a novel method to control vibrations in real time using a real time control target with distributed strain measurements from FBG sensor arrays. Active control of the flexible structure will reduce vibration, which will decrease the chance of damaging the structure.;A scaled test article representative of the structural dynamics associated with a slender launch vehicle is designed and built. Finite element analysis modeling methodology is developed to capture the most significant features of test specimen. A model for the entire test article is developed, including frequency response of the cantilever beam, thruster dynamics, and sensor conversion matrices.;This research develops, models and provides experimental validation of the use of an array of cold gas thrusters for the real time control of the bending dynamics of a test article. Three separate control algorithms are developed to minimize vibration in the test article, using the FBG strain measurements to calculate required thrust. A classic control algorithm for benchmark purposes, a robust control algorithm and an adaptive control algorithm are implemented. The controller performance is investigated by simulation using the developed model, and these results are experimentally verified using the experimental setup.;The performance comparison shows that classic controller is hard to implement experimentally due to decoupling issues, the robust controller achieves good vibration suppression in both simulations and experimental results, and the adaptive controller shows good results, with a potential to surpass the robust controller results in future research. Using the robust controller to control the continuous excited first and second resonant mode of the test setup, shows 94% and 80% reduction of peak-peak vibration respectively, when compared to the open loop response.;This research also investigates using the same FBG sensor arrays to reduce the number of IMU sensing units in the launch vehicle.