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Lu Y.,Xian Jiaotong University | Li J.,Xian Jiaotong University | Li H.,Affiliated To Xian Satellite Control Center | Che Z.,Affiliated To Xian Satellite Control Center | And 4 more authors.
Proceedings of the International Astronautical Congress, IAC | Year: 2014

The methods for fast design of low-thrust transfer orbit for manned asteroids exploration were studied in this paper. The concept of Ephemeris Matching Method (EMM) was proposed, with which the initial launch window and the candidate optimal probe sequences were found quickly. The EMM measures the relative size of transfer energy consumption by examining the closeness from the target planet's ephemeris (or positions and velocities) to the matching planet's ephemeris (or positions and velocities) at departure or arrival times. Time nodes and other parameters were optimized for specific probe sequences by Differential Evolution(DE) algorithm and the fast-low thrust orbit model based on inverse polynomial shape-based method. Then, the final orbit and thrust control laws were optimized by Homotopic method with multi-body environment based on the Pontryagin's maximum principle. The results showed that the EMM could quickly and accurately find out the optimal initial launch window and the candidate probe sequences, whose computational efficiency is much higher than the Branch-and-Bound and other traversal searching methods; the Differential Evolution(DE) algorithm can further refine the optimal launch times and determine the optimal probe sequence; and the Homotopic method could finally optimize and output the low-thrust orbit which could well meet the Pontryagin's maximum principle's optimality conditions. The above integrative methods need not large-scale of numerical searching and calculations, and could greatly improve the efficiency for solving the manned asteroids exploration and other multi-objective rendezvous problems. Copyright ©2014 by the International Astronautical Federation. All rights reserved. Source


Lu Y.,Xian Jiaotong University | Li J.-S.,Xian Jiaotong University | Li H.-N.,Affiliated To Xian Satellite Control Center | Che Z.,Affiliated To Xian Satellite Control Center
Proceedings of the International Astronautical Congress, IAC | Year: 2013

As the lunar relay satellite is required for the landing exploration of far-side of the Moon, under the target of the above exploration mission, and on the basic principle of saving launch cost, the low-cost lunar exploration orbit with lunar relay satellite carried by the probe is designed and optimized. Through cooperation of the probe and relay satellite, the landing exploration mission of far-side of the Moon could be well completed. By establishing the motion equation in the Earth-Moon system under the three-body problem, and using the GA and SQP methods, the transfer points from the Earth to the L2 constant manifolds and then to the Moon have all been found. Also, the fuel consumed by the orbital maneuvers has been figured out. Finally link the orbital sections, let the relay satellite be released by the probe at the right moment and runs on periodic orbit around L2 point, in order to provide relay and navigation services for the probe landing on the far-side of the moon. In this paper, a new low-cost lunar exploration way depending on the cooperation of the lunar relay satellite with the probe has been proposed, which could well meet the signal requirements for the exploration of far-side of the moon. And by simulation, the velocity increment consumed in the entire transfer process has been figured out. The simulation results show that the optimal orbit could not only meet the needs of the mission, but also be the lowest-cost orbit. The methods used in this paper well solved the low-cost orbit design and optimization problem in the two-body and three-body systems. The method and result in this paper could serve as a reference for the design of the synthetically low-cost orbit of the exploration of far-side of the Moon and for the design of the lunar relay satellite constellation. Source


Yang J.,Xian Jiaotong University | Yang Y.,Xian Jiaotong University | Li J.,Xian Jiaotong University | Li J.,Affiliated To Xian Satellite Control Center | And 2 more authors.
Science China Technological Sciences | Year: 2016

Global navigation satellite system (GNSS) comes with potential unavoidable application risks such as the sudden distortion or failure of navigation signals because its satellites are generally operated until failure. In order to solve the problems associated with these risks, receiver autonomous integrity monitoring (RAIM) and ground-based signal quality monitoring stations are widely used. Although these technologies can protect the user from the risks, they are expensive and have limited region coverage. Autonomous monitoring of satellite signal quality is an effective method to eliminate these shortcomings of the RAIM and ground-based signal quality monitoring stations; thus, a new navigation signal quality monitoring receiver which can be equipped on the satellite platform of GNSS is proposed in this paper. Because this satellite-equipped receiver is tightly coupled with navigation payload, the system architecture and its preliminary design procedure are first introduced. In theory, code-tracking loop is able to provide accurate time delay estimation of received signals. However, because of the nonlinear characteristics of the navigation payload, the traditional code-tracking loop introduces errors. To eliminate these errors, the dummy massive parallel correlators (DMPC) technique is proposed. This technique can reconstruct the cross correlation function of a navigation signal with a high code phase resolution. Combining the DMPC and direct radio frequency (RF) sampling technology, the satellite-equipped receiver can calibrate the differential code bias (DCB) accurately. In the meantime, the abnormities and failures of navigation signal can also be monitored. Finally, the accuracy of DCB calibration and the performance of fault monitoring have been verified by practical test data and numerical simulation data, respectively. The results show that the accuracy of DCB calibration is less than 0.1 ns and the novel satellite-equipped receiver can monitor the signal quality effectively. © 2016 Science China Press and Springer-Verlag Berlin Heidelberg Source


Lu Y.,Xian Jiaotong University | Lu Y.,Affiliated To Xian Satellite Control Center | Li H.,Xian Jiaotong University | Li H.,Affiliated To Xian Satellite Control Center | And 6 more authors.
Science China Technological Sciences | Year: 2015

This paper discusses the problem of design and optimization of low-energy transfer orbit with multi-body environment. A new integrative method is proposed to effectively solve the problem, in which the parameterized patched manifolds in CR3BP (circular restricted three-body problems), the shape-based method with multi-body environment, the homotopic method with multi-body environment, and the low-thrust capturing and descending algorithm with multi-body environment are all included. Firstly, the parameters describing the patched manifolds in CR3BP are optimized until the least total absolute velocity increment has been got, including the employment of the shape-based method with multi-body environment. Secondly, the low-thrust control laws of the transfer orbit are optimized employing the homotopic method with multi-body environment that transfers the fuel optimization problem to an easier energy optimization problem. Thirdly, the low-thrust descending orbit around Mars is computed using the laws proposed in this paper. As a typical example, the Earth-Mars transfer orbit design is discussed. The results showed that the parameters describing the patched manifolds could be optimized by the DE (differential evolution) algorithm effectively; the homotopic method with multi-body environment could get the optimal value that meets the first order optimality conditions; and the low-thrust descending orbit could effectively be captured by Mars and finally become a circular parking orbit around it by the hypothesis control laws proposed in this paper. It shows that the final fuel cost is much less than the optimal transfer in the patched two-body problems. In conclusion, the method proposed in this paper could effectively solve the low-energy low-thrust optimal control problem in multi-body environment for the future deep space explorations. © 2015 Science China Press and Springer-Verlag Berlin Heidelberg Source

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