Research On Modeling And Control Of Intelligent Flexible Structure

With the rapid development of space industry, the flexible structures, such as solar panels, are applied more and more widely in the spacecrafts. Under the external disturbance or internal excitation, the vibration of this kind of structure will be easily evoked and last for a very long time due to the small damping ratios and low modal frequencies of flexible structures. If effective control methods are not taken to suppress the amplitude, the vibration will influence the pointing accuracy of spacecraft and make the precision instruments in the spacecraft out of order, also lead to fatigue and damage of the components, and even destroy the main structure of the spacecraft. Therefore, vibration control for flexible structures of spacecraft has been paid much more attention than ever.Vibration control of flexible structures is focused on in this study. Considered the piezoelectric flexible beam and piezoelectric flexible plate as research objects, research on modeling and vibration suppression of intelligent flexible structures has been carried out, including establishment of finite element (FE) model, analysis with software ANSYS, simulation and experiment using PID based on BP(Back Propagation) Neural Network algorithm. The detailed contents are as follows:Firstly, according to the finite element theory and Hamilton principle, the finite element equations of motion for piezoelectric flexible beam and piezoelectric flexible plate were found, respectively.Secondly, modal analysis of flexible cantilever beam and flexible cantilever plate under several different boundary conditions was done with ANSYS software.Thirdly, based on the FE model of piezoelectric flexible beam established above, the equation of motion was derived by programming in MATLAB software and finally converted into State-Space representation as the controlled plant, and numerical simulation was finished using PID control strategy based on BP neural network.Finally, in order to verify the PID controller based on BP neural network algorithm was reasonable and effective, active vibration control experiment was implemented by using the proposed control strategy. The results demonstrated that the presented control law can suppress the vibration induced by the external excitation quickly and indicated that the theoretical analysis mentioned above was feasible.