Research On Task-specific Satellite Deployment Optimization In Operationally Responsive Space

Satellite observation for emergency events, anti-terrorists and safeguard stability, disaster assistance, etc., usually has the characteristics of sudden, transience and locality, and this is a important problem concerned by national security in future. Conventional space system aims at providing strategic services, using complicated technologies and huge costs, and hence, cannot meet the needs of intelligence support for the aforementioned events. As a consequence, there is an urgent press for constructing highly effective and efficient Operationally Responsive Space(ORS) such that it is inspired by the requirements of various emergency tasks, in order to achieve target-specific operational response. Currently, small satellite has been important components of space systems, due to its low cost, short development period, fast launch and operational response. In addition, a series of new technologies, concepts and managerial methods have been applied on small satellites, which provide technical support for the development of ORS.In the interest of application requirement and technical support, this thesis considers ORS as a beneficial complement to conventional space systems, and focuses on operational responsive satellites. In particular, it aims at fully leveraging the advantages of our aerospace resources under uncertain conditions, such as various emergency events. By applying multi-objective optimization and decision-making techniques, it investigates the key techniques in optimizing ORS-oriented satellites configuration and obit deployment, and presents the corresponding solutions. In summary, the major contributions of the thesis are as follows:(1) It investigates three task-oriented operational response modes.Three task-oriented operational response modes have been studied combining the research status, component and need of the practical application of our ORS system structure: launch on-demand model aims at deploying a new small satellite to provide operational response to emergency task when our current space system cannot satisfy the requirements; reconfiguration model for on-orbit satellites aims at improving the response performance for short period and temporary task by adjusting the relative position of multi-satellites; multi-satellite networking model is presented based on launch on-demand and on-orbit reconfiguration models, which achieves cooperative observation with multi-payloads and ability complementary with multi-satellites.(2) It proposes an optimization method for satellites deployment incorporating multiple observation preferences in launch on-demand mode.A simple task scheduling method based on rules which considers users’ observation preferences is designed to evaluate the performance of orbit deployment. An adaptive differential evolution algorithm integrating local search has been presented based on classical differential evolution. The proposed algorithm encodes the parameters of algorithm and design variables at the same time, and enables the algorithm parameters survived with the best fitness individual in the process of evolution. A local search strategy is designed based on Kriging model, which is built with the history individuals surrounding the best individual found so far. This strategy can perform local search around the best individual with low time cost.(3) It devises an optimization method for satellites configuration and obit deployment in reconfiguration mode for on-orbit satellites.The reconfiguration problem is expressed by a multi-objective optimization problem which considers performance, reconfiguration cost and reconfiguration time. In the reconfiguration, the optimal number of satellites and the satellite to undergo orbital maneuver may be unknown, which finally determines the size of design space. The problem hence involves a varying number of design variables and requires a search algorithm suitable for optimization on variable-length chromosomes. A variable-size multi-objective differential evolution algorithm contained problem-oriented operators is proposed to address this problem. The proposed algorithm utilizes the idea of fixed-length chromosome encoding scheme combined with expression vector and the modified initialization, mutation, crossover and selection operators to optimize the structure and components simultaneously. In this algorithm, the multi-subpopulation diversity initialization is adopted first, then the mutation based on Estimation of Distribution Algorithm and adaptive crossover operators are defined to manipulate variable-length chromosomes, and finally a new selection mechanism is employed to generate well-distributed individuals for the next generation. A method of visual decision-making is presented to deal with multiple non-dominated soluitons produced by the proposed algorithm. The case studies not only verify the validity of the proposed algorithm, but also verify the effectiveness and feasibility of improving the performance for emergency task by reconfigurtion model.(4) It presents an optimization method for satellite deployment in multi-satellites networking mode.In order to observe moving targets, an optimization method for multi-satellites networking configuration and obit deployment is presented. The method focuses on the uncertainty of moving targets, and takes the observation for moving targets as an observation for a potential area, then a multi-stage evaluation model is built. A new decision preference-oriented multi-objective differential evolution is proposed based on an improved r-dominance. The proposed algorithm can guide the search converge to the interesting parts of the Pareto front region with less iterations. The results demonstrate the proposed algorithm can reduce the mean orbit response time(MORT) and increase robustness of random fluctuation of targets.