NASA’s Ames Research Center has developed an interactive diagnostic modeling evaluator (i-DME) tool to aid in modeling for noise and lag in the data and debugging of system models when fault detection, isolation, and recovery results are incorrect. i-DME is designed to dramatically speed up the modeling debugging process. Often what hinders human-led model developments are 1) the sheer size of playback files, 2) the modeling for noise and lag in the data, and 3) debugging the fault/test relationships in the model. To alleviate these problems, i-DME can automatically play back very large data sets to find time points of interest where user set performance criteria for detection and isolation are violated. i-DME modifies the diagnostic model through its abstract representation, diagnostic matrix (D-matrix). The types of modifications are procedures ranging from modifying 0s and 1s in the D-matrix, adding/removing the rows/columns, or modifying test/wrapper logic used to determine test results. This software has the capacity to be applied to any complex system for navigation or generation of large amounts of complex data to identify, prioritize, and resolve errors in a self-correcting manner.
The i-DME is a computer-user interactive procedure for repairing the system model through its abstract representation, D-matrix, and then translating the changes back to the system model. The system model is a schematic representation of faults, tests, and their relationship in terms of nodes and arcs. D-matrix is derived from the system model’s propagation paths as the relationships between faults and tests. When the relation exists between fault and test, it is represented as 1 in the D-matrix. To repair the D-matrix and wrapper/ test logic by playing back a sequence of nominal and failure scenarios (given), the user sets the performance criteria and accepts/declines the proposed repairs. During D-matrix repair, the interactive procedure includes conditions ranging from modifying 0s and 1s in the matrix, adding/removing the rows (failure sources) and columns (tests), or modifying test/wrapper logic used to determine test results. The translation of changes to the system model is done via a process that maps each portion of the D-matrix model to the corresponding locations in the system model. Since the mapping back to the system model is not unique, more than one candidate system model repair can be suggested. In addition to supporting the modification, it provides a trace for each modification such that a rational basis for each decision can be verified.
This software can potentially be used in industrial applications, consumer service applications, aerospace, chemical plant process monitoring, oil and gas plant operations, and health monitoring systems.