Research On Rigid-elastic Coupling Dynamics And Vibration Suppression Of Spacecraft

With the increasing complexity of space mission requirements,coupled with the rapid development of advanced material technology and its widespread application in the space field,spacecraft structure is developing towards the direction of large-scale,light-weighting and high performance.The use of a large number of lightweight structures makes the structural modes of spacecraft present the characteristics of low frequency,and the coupling effect of elastic modes and rigid elastic modes becomes more and more prominent.Weak damping modes not only affect the structural dynamics characteristics of spacecraft,but also further affect design the closed-loop control system,reduce the system robustness and control accuracy,which will adversely affect the space mission.Therefore,it is of great significance to carry out rigid-elastic coupling dynamics analysis and vibration suppression of spacecraft.Based on existing research methods for flexible spacecraft structural dynamics,this paper establishes a rigid-elastic coupling dynamics model of spacecraft considering the geometric shape of solar array,reduces the complexity of the dynamics model by reasonable simplification,adopts the theories of component synthesis vibration suppression,fusion filtering and active disturbance rejection control,and researches a new active vibration suppression method combining open-loop and closed-loop control,which provides a feasible idea for solving the design problems of high precision and strong robust control system under the influence of weak damped and low frequency modes.In this paper,structural dynamic response and vibration suppression of flexible solar array are studied.The main contents are as follows:(1)Based on the finite element method,the flexible solar array is discretized by rectangular element.The elastic deformation and displacement of the solar array structure are described by the element coordinate method.The stiffness matrix,mass matrix and damping matrix of the rectangular element are established according to the Lagrange equation.Finally,a control oriented dynamics model of the solar array structure is established,and simulation comparative analysis of relevant examples is conducted based on finite element software to verify the effectiveness of the model.(2)Based on the basic principle of continuum mechanics,combined with the principle of virtual work,the rigid-elastic coupling dynamics model of spacecraft is established and simplified on the basis of the flexible solar array structure dynamics model,and the zeroorder and first-order dynamics simplified models are obtained.Different examples are used to compare and analyze the effectiveness and applicable scenarios of the simplified model,and based on this,the coupling mechanism between rigid elastic modes was studied,which lays a model foundation for subsequent control system design.(3)Further exploration is carried out based on the component synthesis active vibration suppression method.Considering the characteristics of binary force in the component synthesis vibration suppression method,the frequency sets which can be suppressed by two components in the same or opposite direction are given respectively.Based on the basic principle of component force synthesis,Bang-bang control strategy is introduced to design the flexible spacecraft jet attitude maneuver control method to suppress spacecraft vibration actively.The correctness and effectiveness of the theorem are verified by simulation.(4)Under the influence of interference,the control effect of the feedforward open-loop force synthesis vibration suppression method on the solar array becomes poor or even unstable.In response to this issue,a fusion filtering method and closed-loop feedback control are introduced,which improve the anti-interference ability on the basis of component synthesis vibration suppression and provide feasible ideas for solving the problem of closedloop control bandwidth design.In addition,in order to solve the problem of long-term residual vibration of solar array under low environmental and structural damping,an intelligent material active control method is introduced to accelerate the convergence speed of weak damping and low-frequency modes and further reduce the impact of solar array vibration on spacecraft motion.Finally,a composite control structure with open loop vibration suppression,closed-loop anti-interference,and intelligent fast convergence characteristics is established,which forms a powerful supplement to the open loop force synthesis vibration suppression system and enhances the vibration suppression effect.