Sang-Young Park | Searcharxiv

arXiv2025

Communication Constellation Design of Minimum Number of Satellites with Continuous Coverage and Inter-Satellite Link

The recent advancement in research on distributed space systems that operate a large number of satellites as a single system urges the need for the investigation of satellite constellations. Communication constellations can be used to construct global or regional communication networks using inter-satellite and ground-to-satellite links. This study examines two challenges of communication constellations: continuous coverage and inter-satellite link connectivity. The bounded Voronoi diagram and APC decomposition are presented as continuous coverage analysis methods. For continuity analysis of the inter-satellite link, the relative motion between adjacent orbital planes is used to derive analytic solutions. The Walker-Delta constellation and common ground-track constellation design methods are introduced as examples to verify the analysis methods. The common ground-track constellations are classified into quasi-symmetric and optimal constellations. The optimal common ground-track constellation is optimized using the BILP algorithm. The simulation results compare the performance of the communication constellations according to various design methods.

physics.space-ph↗

arXiv2025

Adaptive Smooth Control via Nonsingular Fast Terminal Sliding Mode for Distributed Space Telescope Demonstration Mission by CubeSat Formation Flying

This paper presents a nonsingular fast terminal sliding mode-based adaptive smooth control methodology for a distributed space telescope demonstration mission. The distributed space telescope has a flexible focal length that corresponds to the relative position in the formation flying concept. The limited specification of a CubeSat generally restricts the performance of actuators, most critically the degrees of freedom of controlled motion. This investigation leads to the development of an adaptive smooth control methodology via nonsingular fast terminal sliding modes. The adaptive smooth control algorithm that was developed for a single-input single-output system is adopted and extended to the relative orbit and attitude control systems of the distributed space telescope. The software simulation is conducted under a real mission, which means the real CubeSat structures, hardware specifications, and operational constraints. The proposed algorithm possesses only seven parameters that can be easily adjusted considering their physical meanings. Furthermore, the pre-designated error bounds are analytically derived, which enhances the applicability of the algorithm to real missions. The simulation compares the efficiency of the adaptive smooth nonsingular fast terminal sliding mode controller with the linear quadratic regulator and proportional derivative algorithms. The results verify that the adaptive smooth nonsingular fast terminal sliding mode control algorithm shows better control performance in the perspective of the alignment time and the fuel consumption for the distributed space telescope demonstration mission.

eess.SY↗