Transfer Alignment Technology For Space-based Platform

With the development of military technology, space-based weapon systems arebecoming more and more important in modern war. The space-based platform isavailable to complete military tasks such as investigation, communication andwarning usually, which can be also applied to directly fire weapons to attack enemyspacecraft, aircraft and ships as well as other objects in war-time. It has a shortstart-up time and fast response speed, which makes higher technical requirementsfor the fast and accurate initial alignments. This paper will research on the transferalignment technology of space-based weapon system.According to the J2earth gravity model, the space-based platform trajectorywas designed in two different ways, one is based on Satellite Tool Kit, and the otheris based on kinematics equations. The navigation calculation equations in J2000inertial frame were established and the correctness of the navigation calculationequations was verified through simulation. The state equations of transfer alignmentmodel were derived, which include the error equations of attitude, velocity andposition. The error models of inertial measurement unit, lever arm effect model andwing flexure model under the space environment were given.The transfer alignment model with angular matching and attitude matchingunder attitude maneuver were established. The simulation for observability analysisbased on SVD method and the simulation for the transfer alignment based onKalman filter were carried out under various matching schemes and variousmaneuvering manners. The simulation results showed that the transfer alignment ofboth angular matching and attitude matching were affected by wing flexure, whilethe performance of attitude matching is better than angular matching. And comparedwith constant maneuver, the sinusoidal maneuver is much more suitable.A new initial alignment scheme of the space based missile was proposed. Thecoarse alignment was finished before launch using the information of the space flat.Then after launch, a new precise alignment method using position and attitudematching was proposed with the star tracker on the missile. The measurementequation of the scheme was deduced in details. Finally the feasibility of the schemewas validated by the computer simulation.