Dynamics Of Tethered Satellite System Research Articles

Effects of Orbital Perturbations on Deployment Dynamics of Tethered Satellite System Using Variable-Length Element

Orbital perturbations caused by the space environment will induce deviations compared with the prescribed motion trajectory or dynamic performance of the tethered satellite system (TSS). To comprehensively investigate the effects of the orbital perturbations on the TSS, a precise variable-length element that can describe the large deformation and flexibility of the tether is adopted in this paper to predict the deployment dynamics considering orbital perturbations, including atmospheric drag, solar pressure, lunisolar gravitation, and J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> perturbation. To this end, the variable-length element using arbitrary LagrangianEulerian (ALE) description in the frame work of absolute nodal coordinate formulation (ANCF) is developed firstly. Subsequently, the dynamic governing equations for the TSS are established in the context of ANCF with the employment of ANCF reference node (ANCF-RN). Effects of orbital perturbations including atmospheric drag, solar pressure, lunisolar gravity and J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> perturbation on the dynamics of an optimal deployment are analyzed numerically. It is shown that the orbital perturbations except the J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> perturbation will induce the out-of-plane motion of the TSS. Additionally, the tether tension is less affected by the orbital perturbations. By contrast, the lunisolar gravitation will induce a deviation on the motion path of satellite, which should be considered in the design phase of the TSS.

Tethered space orientation via adaptive sliding mode

Summary Here, we study the problem of a rotating tethered satellite system (TSS) orientation. The rotation TSS is used for propellantless delivery of the payload from low earth orbits to geostationary orbits or other transfer orbits. Driving the angular positions to correct desired orientation in rendezvous and tossing moments, in fact, is important operation in many real sceneries. We suggest the mathematical model describing the dynamics of TSS and catch mechanism/payload rendezvous with external disturbance terms. Here is shown that using sliding mode control (SMC), we are able to control successfully the position of TSS. The conventional and adaptive versions of SMC are considered. We show that SMC with the gain matrix adaptation based on the equivalent control method can significantly reduce the undesirable chattering effect provoking possible damages of TSS. Copyright © 2015 John Wiley & Sons, Ltd.