Redundancy management system for the X-33 vehicle and mission computer

The X-33 is an unmanned advanced technology demonstrator with a mission to validate new technologies for the next generation of reusable launch vehicles. Various system redundancies are designed in the X-33 to enhance the probability of successfully completing its mission in the event of faults and failures during flight. One such redundant system is the vehicle and mission computer that controls the X-33 and manages the avionics subsystems. Historically, redundancy management and applications such as flight control and vehicle management tended to be highly coupled. One of the technologies that the X-33 will demonstrate is the redundancy management system (RMS) that uncouples the applications from the redundancy management details, much in the same way that real-time operating systems have uncoupled applications from task scheduling, communication and synchronization details. This paper describes Honeywell's RMS, its role and implementation in the X-33, some of the tradeoffs that were chosen, the fault tolerance concepts it embodies and its suitability as an off-the-shelf solution for a range of high reliability and high availability applications. This paper concludes with insights on current and future RMS developments.