Sequential Testing for Fault Detection in Multiply-Redundant Systems

1989 ◽  
Vol 111 (2) ◽  
pp. 329-332 ◽  
Author(s):  
Asok Ray
Keyword(s):  
Fault Detection ◽  
Nuclear Reactor ◽  
Test Procedure ◽  
Fault Detection And Isolation ◽  
Sequential Test ◽  
Ratio Test ◽  
Redundancy Management ◽  
Management Procedure ◽  
Sequential Probability ◽  
Noise Statistics

The paper presents the theory and application of a sequential test procedure for fault detection and isolation (FDI), The test procedure is suited for development of intelligent instrumentation in strategic processes like aircraft and nuclear plants where redundant measurements are usually available for individual critical variables. The algorithm of the test procedure is formulated by use of (1) a generic redundancy management procedure which is essentially independent of the fault detection strategy and measurement noise statistics, and (2) a modified version of sequential probability ratio test (SPRT) algorithm for fault detection and isolation, which functions within the framework of the aforesaid redundancy management procedure. The sequential test procedure is suitable for real-time applications using commercially available microcomputers and its efficacy has been verified by on-line fault detection in an operating nuclear reactor.

A Redundancy Management Procedure for Fault Detection and Isolation

1986 ◽  
Vol 108 (3) ◽  
pp. 248-254 ◽  
Author(s):  
Asok Ray ◽  
Mukund Desai
Keyword(s):  
Fault Detection ◽  
Fault Isolation ◽  
Fault Detection And Isolation ◽  
Redundancy Management ◽  
Management Procedure ◽  
Strategic Processes ◽  
Nuclear Plants ◽  
On Line ◽  
Individual Variables ◽  
Noise Statistics

This paper presents the theoretical basis of a novel redundancy management procedure developed for fault detection and isolation (FDI) in strategic processes such as spacecraft, aircraft, and nuclear plants where multiply-redundant measurements are available for individual variables. The set of redundant measurements may comprise both direct sensor outputs and analytically derived measurements. The redundancy management procedure presented in this paper is essentially independent of the fault detection strategy and measurement noise statistics, and builds upon the concept of partitioning the set of measurements into “consistent” and “inconsistent” subsets for purposes of estimation and fault isolation, respectively. The proposed procedure is suitable for real-time applications using commercially available microcomputers and its efficacy has been verified on-line in operating nuclear reactors.

Sequential Test for Arbitrary Ratio of Mean Times Between Failures

2013 ◽  
pp. 154-169
Author(s):  
Yefim H. Michlin ◽  
Dov Ingman ◽  
Yoram Dayan
Keyword(s):  
Sequential Probability Ratio Test ◽  
Sequential Test ◽  
Ratio Test ◽  
Optimal Test ◽  
Group Test ◽  
Multiple Copies ◽  
Sequential Probability ◽  
The Times ◽  
Planning Methodology ◽  
New Item

This paper describes a planning methodology and tools for a truncated SPRT (sequential probability ratio test) for checking the means ratio of the times between failures (assumed to be exponentially distributed) of two items. The problem is considered for the situation in which the ratio may differ from unity, whereby the results are applicable for any specified ratio, or wherever multiple copies of each item are tested simultaneously (group test). The authors present a methodology for optimal test choice and dependences for determining the acceptance/rejection boundaries of such a test with given characteristics. Planning and implementation of a group test are illustrated in an example, including substantiation of the choice of the number of new-item copies.

scholarly journals Active versus passive fault-tolerant control of a redundant multirotor UAV

2019 ◽  
Vol 124 (1273) ◽  
pp. 385-408
Author(s):  
M. Saied ◽  
B. Lussier ◽  
I. Fantoni ◽  
H. Shraim ◽  
C. Francis
Keyword(s):  
Fault Tolerance ◽  
Fault Detection ◽  
Active Fault ◽  
Fault Tolerant ◽  
Sliding Mode ◽  
Fault Tolerant Control ◽  
Fault Detection And Isolation ◽  
Detection Scheme ◽  
Redundancy Management ◽  
Model Free

ABSTRACTThis paper considers actuator redundancy management for a redundant multirotor Unmanned Aerial Vehicle (UAV) under actuators failures. Different approaches are proposed: using robust control (passive fault tolerance), and reconfigurable control (active fault tolerance). The robust controller is designed using high-order super-twisting sliding mode techniques, and handles the failures without requiring information from a Fault Detection scheme. The Active Fault-Tolerant Control (AFTC) is achieved through redistributing the control signals among the healthy actuators using reconfigurable multiplexing and pseudo-inverse control allocation. The Fault Detection and Isolation problem is also considered by proposing model-based and model-free modules. The proposed techniques are all implemented on a coaxial octorotor UAV. Different experiments with different scenarios were conducted for the validation of the proposed strategies. Finally, advantages, disadvantages, application considerations and limitations of each method are examined through quantitative and qualitative studies.

Fault Detection and Isolation in a Nuclear Reactor

1983 ◽  
Vol 7 (1) ◽  
pp. 79-85 ◽  
Author(s):  
Asok Ray ◽  
Mukund Desai ◽  
John Deyst
Keyword(s):  
Fault Detection ◽  
Nuclear Reactor ◽  
Fault Detection And Isolation

scholarly journals PERFORMANCE ANALYSIS AND ROBUSTNESS EVALUATION OF A SEQUENTIAL PROBABILITY RATIO TEST FOR NON-IDENTICALLY DISTRIBUTED OBSERVATIONS

2018 ◽  
Vol 54 (2) ◽  
pp. 179-192
Author(s):  
A. Yu. Kharin ◽  
Ton That Tu
Keyword(s):  
Time Series ◽  
Numerical Approach ◽  
Sequential Probability Ratio Test ◽  
Sequential Test ◽  
Ratio Test ◽  
Probability Ratio ◽  
Test Characteristics ◽  
Sequential Probability ◽  
Recursive Calculation ◽  
Likelihood Ratio Statistics

In this article the problem of a sequential test for the model of independent non-identically distributed observations is considered. Based on recursive calculation a new numerical approach to approximate test characteristics for a sequential probability ratio test (SPRT) and a truncated SPRT (TSPRT) is constructed. The problem of robustness evaluation is also studied when the contamination is presented by the distortion of the distributions of all increments of the log-likelihood ratio statistics. The two-side truncated functions are proposed to be used for constructing the robustified SPRT. An algorithm to choose the thresholds of these truncated functions is indicated. The results are applied for a sequential test on parameters of time series with trend. Some kinds of the contaminated models of time series with trend are used to study the robustness of the truncated SPRT. Numerical examples confirming the theoretical results mentioned above are given.

scholarly journals Sequential probability ratio test for many simple hypotheses on parameters of time series with trend

2019 ◽  
pp. 35-45
Author(s):  
Ton That Tu ◽  
Yu. Kharin
Keyword(s):  
Time Series ◽  
Statistical Tests ◽  
Sufficient Conditions ◽  
Sequential Probability Ratio Test ◽  
Sequential Test ◽  
Stopping Times ◽  
Ratio Test ◽  
Probability Ratio ◽  
Sequential Probability ◽  
Finite Moments

The problem of sequential test for many simple hypotheses on parameters of time series with trend is considered. Two approaches, including M-ary sequential probability ratio test and matrix sequential probability ratio test are used for constructing the sequential test. The sufficient conditions of finite terminations of the test and the existence of finite moments of their stopping times are given. The upper bounds for the average numbers of observations are obtained. With the thresholds chosen suitably, these tests can belong to some specified classes of statistical tests. Numerical examples are presented.

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