Simultaneous Maneuvering of Tethered Microsatellite Orbit and Tether Libration using a Model Reference Adaptive Control Scheme

Abstract

This paper investigates the maneuvers of a tethered satellite system orbit disturbed by libration of a single elastic tether immediately after deployment, where the tether experiences no electrodynamic force. An effective Lyapunov-method-based multi-input and multi-output model reference adaptive control scheme exhibits good qualitative TSS orbit tracking error convergence; the perturbed TSS orbit tracks a reference orbit precisely with 3D tether pendular angle suppression. Although the simulated tether dynamic motion is limited to its libration, the proposed mathematical model with Gauss variational equations can consider the tether’s pendular and dynamic motions together or separately. The latter realizes TSS orbital deviation by a non-conservative tether tension force acting on the primary body during tether libration. A feasibility study of the proposed control scheme through the maneuvers of the microsatellite under a zonal non-spherical harmonic gravitational perturbation ( perturbation) is conducted. Good tracking error convergence in the study indicates a potential high-accuracy control of the unstable TSS model using the proposed numerical procedure and control algorithm.