Modeling And Optimization Of The Fuzzy Control System For Intelligent Truss Structures

Large space intelligent truss structure is widely used in the aerospace field. These structures have some special dynamic characteristics, such as low stiffness, damping ratio and natural frequency, etc. Under the vacuum of space, vibration will easily occur if these structures are subjected to the external excitation, and it is hard to attenuate. In this case, it will not only cause disadvantage factors in the spacecraft's work, but also cause structural fatigue damage. Therefore, researching on vibration control of large space intelligent truss is important. From this point of view, fuzzy control system of the intelligent truss structure was studied and optimized in this thesis. And then the stability of the system was observed.This thesis aimed at the control of intelligent truss structure vibration. Firstly, the dynamic model of the piezoelectric intelligent truss structure was established. The ANSYS software was used to modal analysis the truss system at large and then the low order frequency and modal control equation of the intelligent truss structure were obtained. The simulation model of fuzzy control system of intelligent truss structure model was set up in the Matlab / Simulink software, and then it was analyzed.Then, the adaptive genetic algorithm was improved. The crossover probability cP and mutation probability mP changed along with individual fitness among the minimum fitness, average fitness and maximal fitness of the population. The cP and mP of the excellent individuals were increased and the prematurity was avoided. This algorithm was combined with the fuzzy controller and the difference of axial displacement of intelligent truss active bars is optimization goals. The fuzzy control rules are optimized to improve the control effect of intelligent truss structure fuzzy controller. And then the method was verified by running the program.At last, the probability distribution of the displacement difference of intelligent truss structure is used as fuzzy membership function based on T-S fuzzy model theory. Fuzzy fusion was used for each subsystem to obtain the system model of intelligent truss structure. And the stability analyze for the fuzzy system model was researched.