Reliability of imperfect redundant systems
Reliability estimation of redundant systems for determining statistical probability of mission success
STATISTICAL PROBABILITY↗
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Diverse Redundant Systems for Reliable Space Life Support
Reliable life support systems are required for deep space missions. The probability of a fatal life support failure should be less than one in a thousand in a multi-year mission. It is far too expensive to develop a single system with such high reliability. Using three redundant units would require only that each have a failure probability of one in ten over the mission. Since the system development cost is inverse to the failure probability, this would cut cost by a factor of one hundred. Using replaceable subsystems instead of full systems would further cut cost. Using full sets of replaceable components improves reliability more than using complete systems as spares, since a set of components could repair many different failures instead of just one. Replaceable components would require more tools, space, and planning than full systems or replaceable subsystems. However, identical system redundancy cannot be relied on in practice. Common cause failures can disable all the identical redundant systems. Typical levels of common cause failures will defeat redundancy greater than two. Diverse redundant systems are required for reliable space life support. Three, four, or five diverse redundant systems could be needed for sufficient reliability. One system with lower level repair could be substituted for two diverse systems to save cost.
life support↗
Synchronous transfer circuits for redundant systems
Circuit arrangements for flip-flops, counters, and clock drivers in redundant systems ensure that control is synchronously transferred to surviving components when failure occurs. In addition to original application to spacecraft systems, redundant circuits have terrestrial uses in power generators, solar-energy converters, computers, vehicle controllers, and other systems demanding high reliability.
Nagano, S.↗
Design and testing of redundant systems
Circuits for redundant space-borne systems - detection and location of failure
REDUNDANT SYSTEM↗
Hybrid redundancy system for improving reliability - A concept
System combines two concepts - triple modular redundancy (TMR) and spares (replacement system) redundancy. System has triplicated active unit core with associated bank of specifically arranged standby spare units. Curves plotted from characteristic equation show hybrid system is more reliable than conventional TMR systems.
Mathur, F. P.↗
Redundant system reliability analysis
Computer Aided Redundant System Reliability Analysis (CARSARA) program facilitates reliability assessment of fault-tolerance reconfigurable systems. CARSRA accounts for influences from transient faults and is used to model wide range of redundancy management strategies.
Masreliez, C. J.↗
Checkout of redundant systems
Analytical techniques for checkout of integrated systems in redundant environment
Newman, H. L.↗
Optimal inventories for overhaul of repairable redundant systems - A Markov decision model
A Markovian decision model was developed to calculate the optimal inventory of repairable spare parts for an avionics control system for commercial aircraft. Total expected shortage costs, repair costs, and holding costs are minimized for a machine containing a single system of redundant parts. Transition probabilities are calculated for each repair state and repair rate, and optimal spare parts inventory and repair strategies are determined through linear programming. The linear programming solutions are given in a table.
Schaefer, M. K.↗
Standby redundancy system as a particular case of systems with possible structural faults
Reliability of redundancy system with possible structural fault
Margulis, A. M.↗
Reliability analysis of redundant systems
A method is proposed to compute the transition probability (the probability of partial or total failure) of parallel redundant system. The effect of geometry of the system, the direction of load, and the degree of redundancy on the probability of complete survival of parachute-like system are also studied. The results show that the probability of complete survival of three-member parachute-like system is very sensitive to the variation of horizontal angle of the load. However, it becomes very insignificant as the degree of redundancy increases.
Yeh, H. Y.↗
Multiple Fault Isolation in Redundant Systems
We consider the problem of sequencing tests to isolate multiple faults in redundant (fault-tolerant) systems with minimum expected testing cost (time). It can be shown that single faults and minimal faults, i.e., minimum number of failures with a failure signature different from the union of failure signatures of individual failures, together with their failure signatures, constitute the necessary information for fault diagnosis in redundant systems. In this paper, we develop an algorithm to find all the minimal faults and their failure signatures. Then, we extend the Sure diagnostic strategies [1] of our previous work to diagnose multiple faults in redundant systems. The proposed algorithms and strategies are illustrated using several examples.
Shakeri, M.↗
Availability and mean time between failures of redundant systems with random maintenance of subsystems
It is shown how the availability and MTBF (Mean Time Between Failures) of a redundant system with subsystems maintenanced at the points of so-called stationary renewal processes can be determined from the distributions of the intervals between maintenance actions and of the failure-free operating intervals of the subsystems. The results make it possible, for example, to determine the frequency and duration of hidden failure states in computers which are incidentally corrected during the repair of observed failures.
Schneeweiss, W.↗
Threats to Resiliency of Redundant Systems Due to Destructive SEE
Destructive SEE pose serious challenges for the reliable use of COTS devices in space systems. We use system-level modeling and non-parametric statistics to assess the threat posed to redundant systems by destructive SEE.
single-event effects↗
Threats to Resiliency of Redundant Systems Due to Destructive SEE
Destructive SEE pose serious challenges for the reliable use of COTS devices in space systems. We used system-level modeling to determine SEL rates that would likely compromise system reliability, resilience and capabilities. We then assembled a representative dataset of COTS CMOS parts and used nonparametric statistical techniques to assess the threat posed to redundant systems by destructive SEE.
single-event effects↗
Redundant system test point allocation and mission reliability estimation procedures.
Optimal allocation of n test points within redundant digital system for prelaunch and in-flight spacecraft reliability estimate
DIGITAL TECHNIQUE↗
Techniques for generating highly reliable redundant systems.
A simple heuristic algorithm for designing highly reliable modularly redundant computer systems under complexity constraints is presented. The technique, which produces near optimal solutions, is intuitively appealing and easy to apply. The algorithms performance is shown to compare very well with the optimal solution obtained via a computerized model for dynamic programming.
White, J. B.↗
Strapdown system redundancy management flight demonstration
The suitability of strapdown inertial systems in providing highly reliable short-term navigation for vertical take-off and landing (VTOL) aircraft operating in an intra-urban setting under all-weather conditions was assessed. A preliminary design configuration of a skewed sensor inertial reference system employing a redundancy management concept to achieve fail-operational, fail-operational performance, was developed.
Source record↗
Lockheed L-1101 avionic flight control redundant systems
The Lockheed L-1011 automatic flight control systems - yaw stability augmentation and automatic landing - are described in terms of their redundancies. The reliability objectives for these systems are discussed and related to in-service experience. In general, the availability of the stability augmentation system is higher than the original design requirement, but is commensurate with early estimates. The in-service experience with automatic landing is not sufficient to provide verification of Category 3 automatic landing system estimated availability.
Throndsen, E. O.↗