Comparison modeling of system reliability for future NASA projects

Abstract

SUMMARY & CONCLUSIONSA National Aeronautics and Space Administration (NASA) supported Reliability, Maintainability, and Availability (RMA) analysis team developed a unique RMA analysis methodology using cut set and importance measure analysis in order to comparison model proposed avionics computing architectures. In this paper we will present this efficient application of the RMA analysis methodology for importance measures that includes Reliability Block Diagram (RED) Analysis, Comparison modeling, Cut Set Analysis, and Importance Measure Analysis. We will also demonstrate that integrating RMA early in the system design process as a key to success by providing a fundamental decision metric supporting design selection.The RMA analysis methodology presented in this paper and applied to the avionics architectures enhances the usual way of predicting the need for redundancy based on failure rates or subject matter expert opinion. Using the REDs and the minimal cut sets, along with the Fussell-Vesely (FV) factors, importance measures are calculated for each functional element in the architectures [I]. This paper presents an application of the FV importance measures and presents an improved methodology for using importance measures in success space (instead of failure space) to compare architectures. These importance measures are used to determine which functional element would be most likely to cause a system failure, thus, quickly identifying the path to increase the overall system reliability by either procuring more reliable functional elements or adding redundancy [2].This application of the RMA analysis methodology, using RBD analysis, cut set analysis, and the importance measure analysis, allows the avionics design team to better understand and compare the vulnerabilities in each of the architectures, enabling them to address the deficiencies in the design architectures more efficiently, while balancing the need to design for optimum weight and space allocations.

Dependability modeling of dynamically reconfigurable space equipment

“…Downside of FTA is difficulty to simulate dynamic behavior of system, although is considered, by i.e NASA, as a standard tool for reliability assessment and engineering tradeoffs input. Recently, in a search for more flexibility and accuracy in describing various systems architectures more modern approaches are exercised basing mainly on Petri networks, and their numerous extensions and mathematical interpretations [2].…”

“…Transition matrix Q is cons holds transition rate for system (2). If such transition is not po obviously, holds a value of 1 m rates (sum of all row elements m Fig.…”

On Component Reliability and System Reliability for Space Missions

“…For system reliability analysis, all the selected computing architectures are modeled by Reliability Block Diagram (RBD) Analysis, Cut Set Analysis, and Importance Measure Analysis [4]. The system analyses are based on the mean time to fail (MTTF) of each component assuming an exponential distribution.…”