Jinxiu Zhang

Optimal virtual center selection for formation flying maintenance

Purpose – The purpose of this paper is to propose a fuel‐optimal virtual centre selection method for formation flying maintenance in the J2 perturbed environment.Design/methodology/approach – Based on the relative orbital elements (ROE) theory, the J2 perturbed relative motions between different satellites in the formation are analyzed, and then the fuel‐optimal virtual centre selection issue for formation flying maintenance are parameterized in terms of ROE. In order to determine the optimal virtual centre, two theories are proposed in terms of ROE.Findings – Numerical simulations demonstrate that the fuel‐optimal virtual centre selection method is valid, and the control of the ROE of each satellite with respect to a virtual optimal centre of the formation is more efficient regarding the fuel consumption than the control of all satellites with respect to a satellite belonging to the formation.Research limitations/implications – The fuel‐optimal virtual centre selection method is valid for formation flyin...

Configuration, Orbit Design of InSAR Formation Based on Mean Elements

A mission requirements-based configuration method of interferometric synthetic-aperture radar (InSAR) formation to design dual-satellite formation by mean orbital elements is derived. The configuration and initial orbital elements of two coordinated running satellites InSAR formation are designed when system parameters, such as the resolution of slant distance, latitude domain of ground coverage area, and the side-looking angle of the synthetic-aperture radar (SAR) beam center, are given.

Satellite position calibration in distributed spacecraft system by multi-dimensional scaling

Distributed spacecraft systems implement enormous new functions by augmenting multiple spacecrafts as unified. That demands the precise positioning information about each satellite nodes in the distributed spacecraft system. To achieve the position calibration, multidimensional scaling is introduced. MDS computes a 3-dimensional map of each satellite nodes from the distance information in the system. Based on the 3-dimensional map and locations of some anchor satellite nodes, the absolute positions of satellite nodes in the system can be calibrated. Simulation shows that this method shall provide a higher positioning accuracy for orbit control in the distributed spacecraft system without the help of GPS and other GPS-like equipments and it is also well envisioned and easily accessible to engineering.

Probability based collision monitoring method within formation flying

A probability density function based collision monitoring method within formation flying is developed and simulated. The approach for collision monitoring presented in this paper is to propagate the uncertainty covariance using linear relative dynamic model and integrate collision probability density function over the defined collision region (the combined shape of satellites) to calculate the collision probability between two individual satellites in formation. The calculated collision probability in this paper, considering the shape of combined satellites, and the probability is calculated at instantaneous time, so it is suitable to predict when and how fast a collision might be happened. Simulations results show that the along-track projected two-dimensional (X-Z plane) collision probability is the most reliable as the along-track uncertainty is much higher than the radial and cross-track components. In addition, results show that the collision probability is sensitive to the geometry of formation and the uncertainty covariance. Moreover, the methodology developed in this paper has been used to test the passive operational safety of different formation geometry.

The Imaging Precision Analysis of the Distributed SAR System

A more precise height imaging model of the distributed SAR system according to the eccentricity of earth is established. For convenient to analyze the effect of the different parameters of the distributed SAR system on the height imaging precision, the sensitive coefficients of the parameter measurement error are defined. By numerical simulation, we find that according to the same error of parameter measurement, the different visual angle thetas and azimuth angle alpha have the most effect on the height imaging precision of the system, when the visual angle thetas and the azimuth angle alpha is equal the error of the parameters can have the minimal effect on the height imaging precision on the distributed SAR system.