A comparison of real-time task scheduling methods in spacecraft simulation

Embedded real-time applications play an important role today. Satellites are also robust embedded real-time applications. A commercial or military satellite project can cost well over three-hundred million dollars. Since many satellite manufacturers need to validate their satellites before launching, satellite simulators play the most valuable role in validation infrastructures. Specifically, satellite flight software validation has become more important. In this work, we focused on the round robin (RR), rate monotonic (RM), and event driven (ED) real-time scheduling task methods with respect to their CPU usage performance for satellite simulator infrastructures. The tasks are evaluated and tested under the real-time executive for multiprocessor systems (RTEMS). Those scheduling tasks are used in polling mode in the simulation setup. In this study, we compared three task scheduler methods for orbit altitude control system tasks and MIL-STD 1553 bus data distribution controller tasks in a spacecraft simulator environment. The results were close and the values were not segregated, thus, RR and ED can be chosen, as RR was easy to implement and ED allowed for full control of the tasks.