Angular Velocity Estimation Of Space Non-cooperative Target

Repairing and recycling of faulty spacecraft is an important direction in current space engineering research.Whether it is inspection,maintenance and other on-orbit services,or removal of spacecraft,it is necessary to know the motion information of the spacecraft,including position,velocity,attitude,attitude angle and angular velocity.Typically,such information is measured by the inertial components of the target spacecraft and transmitted to the service spacecraft via its own communication module.However,dying spacecraft or spacecraft with communication and measurement modules failure cannot provide motion information to the service spacecraft actively.At present,for this kind of space non-cooperative target,the acquisition method of motion information is to obtain the position and attitude of the target by the visual measurement system assembled on the serving spacecraft,and then solve the other information needed by the mission such as angular velocity,angular acceleration and so on through the algorithm.This paper mainly aims at the angular velocity problem of space non-cooperative target.The main research contents are as follows:Aiming at the modeling of space non-cooperative target,the coordinate system and attitude description parameters needed for angular velocity estimation of space non-cooperative target are introduced,and the attitude model of space non-cooperative target described by quaternion is established.For the problem of non-linear filtering,the basic idea of Bayesian filtering is introduced,and the linear solution form of Gauss filtering and two kinds of approximations in the estimation of non-linear system are given,which provides a theoretical basis for the design of angular velocity estimation method.Aiming at the angular velocity estimation of space non-cooperative target,firstly,according to the cubature rule,the construction methods of high-order spherical area integral and high-order radial integral are given,and the high-order cubature rule of different approximate combinations are analyzed,the appropriate high-order cubature kalman filter method is selected.In order to reduce the influence of rounding errors on covariance matrix and enhance the stability of filtering,the idea of square root filtering is introduced to design a square root high-order cubature kalman filter angular velocity estimation method,and the effectiveness of the method is verified.Aiming at the problem of angular velocity estimation of space non-cooperative target with unknown attitude maneuver,the characteristics of traditional UT strategy are analyzed.On this basis,a new deterministic point and weight construction method is adopted.The points are adjusted by the inner product relationship between sampling vectors and state mean,which weakens the non-local effect of high-order system,and needs fewer deterministic points to improve the approximation of the non-linear transformation.Considering the large deviation of the filter estimation when the space non-cooperative target appears unknown attitude maneuver,an unscented kalman filter method with variance matrix modified is designed,and the effectiveness of the method is verified.