State Estimation And De-tumbling Of Space Non-cooperative Targets

With the development of space technology,human space activities become more and more frequent,which makes more space debris causing space environment pollution.In order to keep the space environment safe and stable,it is necessary to carry out the active capture and removal of space debris.Most of the space debris are space non-cooperative targets,which have no capture device,and can't communicate with the service spacecraft.What's more,they lose control of their own attitude and in a state of free tumbling.So,if we can estimate the moment of inertia and attitude information of space non-cooperative targets and de-tumble the angular velocity before capture,which will make the active debris removel more safe and successful.This paper mainly aims at the active debris removel,without knowing any information of the space tumbling non-cooperative targets,estimating the moment of inertia and attitude information of the targets and designing detumbling mothod.The main research contents are as follows: First,the definition of reference coordinate system is introduced in detail,and the attitude kinematic and dynamic equations,and two typical motion of space noncooperative targets are proposed.The theoretical knowledge of state estimation is introduced,which lays a foundation for the design of subsequent algorithms.In order to estimate the state of space non-cooperative targets,the rough estimation of the angular velocity of the target in the vision coordinate system is obtained based on the differential method.Then,this result is used to estimate the ratio of inertia matrix of space non-cooperative targets.With the rotation matrix,the ratio of moment of inertia is obtained.Based on this estimation,the dynamic and kinematic equation in the body-fixed coordinate is established,as the state equation of the extended kalman filter to estimate the accurate angular velocity of space non-cooperative targets.Then,considering the frequency mismatch between the measuring sensor and the output of state,non-periodic filtering algorithm is designed to estimate the angular velocity of the targets.The principle of electromagnetism and the condition of eddy current generation are introduced in this paper.Then,the calculation formula and related properties of magnetic tensor are analyzed.Based on the eddy current torque,the de-tumbling method of the space non-cooperative targets is proposed,and the de-tumbling steps are as follows: First of all,making the magnetic field parallel to the spin axis to eliminate the nutation angle of the targets so that the targets' motion is changed from tumbling to uniaxial spin.The magnetic field is then perpendicular to the target angular velocity to eliminate it.The relative position between the targets and the external magnetic field needs to be controlled to act an uniform magnetic field on the targets.Finally,numerical simulation is used to verify the correctness,effectiveness and feasibility of the method.