Research On The Flexibal Multibody Dynamics Model Reduction Method Of The Electric Solar Sail

In the field of deep space exploration,due to the limited fuel resources that can be carried by the spacecraft itself,in order to achieve long-term missions,electric solar sails have received widespread attention as a new type of spacecraft with no propellant consumption.The electric solar sail mainly relies on solar wind charged particles for propulsion,and realizes orbit and attitude control by changing the cable voltage.This paper studies the model reduction problem of electric solar sails in order to achieve the purpose of facilitating control design.Based on the establishment of the electric sail model using the reference node coordinate method,this paper further reduces the order of the electric sail model through the nonlinear floating coordinate system method.The basic idea of ??the nonlinear floating coordinate system method is to express the node coordinates in modal coordinates.In this paper,the main modes are selected according to the modal shape of the electric sail model,the modal transformation matrix is ??constructed,and the high-order model is projected into the low-order model to achieve model reduction.The research results of this paper show that after the nonlinear floating coordinate method is used to reduce the model,the calculation efficiency is greatly improved compared with the reference node coordinate method under the premise of ensuring the calculation accuracy.On the other hand,since the electric sail models established by the above two methods are in the form of differential-algebraic equations in the mathematical model,the control design requires the mathematical model to be established in the form of ordinary differential.For this reason,this paper studies the method of transforming differential-algebraic equations into ordinary differential equations.The main idea is to adopt the idea of generalized coordinate partitioning,construct a transformation matrix to eliminate the constraint items in the dynamic equations,so as to achieve further simplification of the model.The research results of this paper show that after simplifying the model to the ordinary differential form,the calculation accuracy of the model remains basically unchanged,and the calculation efficiency is further improved.The model reduction method is very beneficial for systems with huge degrees of freedom.It can reduce the order of systems with tens of thousands or even hundreds of thousands of degrees of freedom to hundreds or dozens of degrees of freedom.Under the premise of ensuring the calculation accuracy,the calculation efficiency is improved.It has a leap in general improvement,which has very important application significance for the next step of control design and implementation of control.