GPS HARDWARE-IN-THE-LOOP SPACECRAFT FORMATION FLYING SIMULATION

摘要

The results of a Global Positioning System (GPS) hardware-in-the-loop simulation of two spacecraft flying in formation are presented. The simulations involve a chief spacecraft in a low Earth orbit (LEO), while a deputy spacecraft maintains an orbit position relative to the chief spacecraft. In order to maintain the formation an orbit correction maneuver (OCM) for the deputy spacecraft is required. The control of the OCM is accomplished using a classical orbital element (COE) controller and simulating continual impulsive thrusting for only the deputy spacecraft. The COE controller requires the relative position of the six orbital elements (a, e, I, Ω, ω, M_0). The deputy communicates with the chief spacecraft to obtain the current orbit position of the chief spacecraft, which is determined by a numerical orbit propagator. The position of the deputy is determined from a GPS receiver that is connected to a GPS hardware-in-the-loop simulator. The GPS simulator creates an RF signal based on a simulated trajectory, which results in the GPS receiver calculating the navigation solution for the simulated trajectory. From the current relative positions of the spacecraft the COE controller calculates the OCM for the deputy spacecraft. The formation flying simulation successfully demonstrates the GPS hardware-in-the-loop simulator by increasing the deputy spacecraft semi-major axis by 17.8 km.