Multi-Satellite Mission Planning For Moving Target Search

Moving target search by multi-satellite is of great military and civilian value, which will be applied in situation assessment, strike navigation, maritime rescues and anti-smuggling. Since the complexity in making plans for moving target search, manual and single mode are no longer fit for the requirements. Mission planning is able to manage and allocate the satellite resources optimally. Till now multi-satellite mission planning for moving target search has been still in the initial stage with many open problems in theory and practice to be tackled.This dissertation focuses on multi-satellite mission planning for moving target search, which includes formal problem description, planning mode, mathematic models, optimal algorithms and etc. The main work and contribution are as follows:(1)The formal problem description and two planning modes are presented. Following through the analysis of satellite imaging procedure and operation flow of moving target search, the method for optional action set and the quantitive modeling of moving target and task region are reached. Based on above, the search problem, the constraints and uncertainty are analyzed. The on-line planning mode and off-line planning mode are also proposed. The formal description and the planning modes are the key to design mathematic models and algorithms.(2)The POMDP model for multi-satellite off-line planning is presented. For off-line planning with no detection hypothesis, the method for moving target off-line update and transition is proposed to acquire target prior distribution probability. With the help of the prior distribution probability, the multi-satellite POMDP mission planning model is designed to maximize the detection probability sum. The model is adaptive to uncertainty which can transform different initial prior distribution probability into satellite search operation plans.(3)Motion prediction algorithm in geodetic coordinate systems is proposed. Motion prediction in geodetic coordinate systems is well discussed. Firstly, moving target motion in plane Cartesian coordinate systems is analyzed and a Gaussian distribution of target transition probability density function (PDF) is deduced; Secondly, the PDF is extended to denote target transition probability in 3-D Cartesian coordinate; Thirdly, the method for computing the target transition probability in geodetic coordinate systems based on Gaussian distribution is deduced by coordinate systems transformation and curved surface integral method. The Motion prediction algorithm is able to avoid frequent coordinate transformation. It is still effective even with little prior information and sample points.(4)The MPC model for multi-satellite on-line planning is presented. For on-line planning, the close-loop control architecture is acquired based on MPC. In the close-loop control architecture, the target prediction model and multi-satellite mission planning model are interactional. The target prediction model is utilized to get the target prior distribution in future by motion prediction algorithm. With the help of prior distribution, the multi-satellite mission planning model is to maximize the detection reward and information reward in each rolling window. The prediction model and the planning model are the key to predict the state of the system and to control optimally. By the iterative rolling optimization and state feedback in close-loop architecture, the global solution is obtained.