Simulation Method for Mission Reliability Assessment of Space Telemetry Tracking and Command System with Dynamic Redundancy

Abstract

The mission reliability of space telemetry tracking and command (TT&C) systems directly determines whether the space mission can be carried out successfully. In actual situations, some missions of TT&C systems may just be required to be completed before a given time, rather than be performed in a specified time window. Taking advantage of this feature, mission failures in the originally arranged time period could then be re-executed later according to the rescheduling algorithm. The resources to be used and the time to be executed are two kinds of uncertainties that exist in rescheduling. This paper treats them as dynamic redundancy. The existing evaluation methods are insufficient to evaluate the mission reliability of system under this condition. This paper proposes a heuristic rule based on the system operation-principle to obtain the basic scheduling plan of the mission and then designs a reactive scheduling strategy to deal with mission failures during the execution process. Based on this scheduling architecture, a basic scheduling plan combined with a fault handling strategy can be obtained. A Monte Carlo method is used to simulate the components' failure and repair, and a discrete event simulation process is used to simulate the possible execution options during the execution process. A collection of altered execution options combined with the execution result of the mission can be gathered after a huge amount of simulation. The approximate mission reliability of the system can then be assessed through a statistic reference to this collection.