Research On Reentry Target Tracking And Positioning And Trajectory Prediction

By using ground observation devices, the fast and accurate tracking andpositioning for reentry target together with the accurate trajectory forecast has been thefocus of research at home and abroad, at the same time, it is an extremely importantengineering problem in the safe recovery of spacecraft, the missile defense and otherfields. The current difficulties exist in the accurate modeling for reentry targets and thestable and efficient filtering algorithm. In this paper, under the background of thereentry spacecraft and missiles, the motion modeling, the filtering algorithm and thetrajectory forecast in the reentry flight segment have been studied.With the improvement of the understanding of the reentry target motioncharacteristics and the emerging of the advanced tracking algorithms, this paper hassummarized the current research status and done some simulation analysis in severalaspects. In the aspect of motion modeling，this paper takes the advantage of thetraditional target modeling method, starts from the kinetic modeling and motorcharacteristics modeling, and establishes the kinetic model containing the ballisticcoefficient through the accurate modeling of the reentry target aerodynamic and gravity.Through the accurate analysis of the physical mechanism and the historical data, thispart completes the modeling of the target maneuvering characteristics. In the aspect offiltering algorithm, on the basis of the reentry movement characteristics, this paperemphasizes the nonlinear filtering algorithm suitable for reentry tracking, andconducteds in-depth analysis of the commonly used EKF algorithm. This algorithm hasthe characteristic of simple procedure, fast computing and wide scope of application,but it can be drawn through the Jacobian matrix calculation that the algorithm is alreadyquite complicated for simple equations, and will be more complicated or even difficultto achieve for complex equations, the EKF does not apply to the reentry target tracking.Then a simulation example contrasts the tracking performance of the EKF, UKF andSRCDKF, and it can be drawn that the UKF and SRCDKF is significantly superior tothe EKF in convergence speed and tracking accuracy. In the aspect of trajectory forecast,firstly, the elliptical trajectory method and the differential equations calculation method widely used in ballistic impact point forecast are recommended. On the basis of thereentry target movement characteristics, it is drawn that the differential equationscalculation method is more suitable for the trajectory prediction of the reentry target,then the filtering algorithm and the numerical integration algorithm are designed in thetrajectory prediction simulation experiments, the factors that affect the trajectoryforecast accuracy are analysed, it is drawn that to improve the forecast accuracy can beachieved by improving the tracking accuracy and improving the forecas model, inaddition, to improve the tracking accuracy can be achieved by improving filteringalgorithm and increasing the tracking time.Based on the full analysis of the difficulty of maneuvering reentry target tracking,this paper focuses on the deep study of the ballistic coefficient estimation. When theballistic coefficient and the process noise are unknown, the general method isineffective; this paper designs the IMM-UKF algorithm, the results of simulation showthat the IMM-UKF can make the ballistic coefficient convergence steady and rapid, andalso improve the performance of the tracking filter.