Fault diagnosis

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The fault diagnosis is the accurate determination of the cause of the error and error location of a fault in a technical system.

The error diagnosis is part of the error management with the phases error detection, error diagnosis, error compensation and error correction.

According to DIN 55350, an error is an impermissible deviation of a feature from a specified requirement. Fault diagnosis has a lot in common with medical diagnosis . Many diagnostic techniques were initially developed in the medical field and later transferred to technical applications (see expert system ). An important approach to error diagnosis is the Hypothesis & Test procedure, in which the most promising error hypotheses are generated in the first phase (e.g. "electronic errors" or "software errors"), which are then carefully examined in the following test phase. In this way, it is possible to focus on the most promising possible errors at an early stage.

Since a fault diagnosis by definition contains the comparison with a given model, one can speak of redundancy, which is used for the fault diagnosis. A distinction can be made here:

  1. Physical redundancy. A second functioning system serves as a reference, deviations lead to the cause of the error.
  2. Analytical redundancy. Mathematical equations based on basic physical equations model the system behavior. A model of the functioning system can be used for fault detection, models of possible faults for fault diagnosis.
  3. Knowledge-based redundancy. The technical system is described by qualitative models - often by rules.

Vehicle technology

In vehicle technology, in addition to diagnostic testers and data loggers , vehicle diagnostic systems are also used for fault diagnosis. See also: Error memory

Aircraft technology

Automatic vehicle diagnostic systems are used in aircraft technology and railway technology, which compare the function of a device with that of a redundant device. The results are transmitted to the operator by radio.

literature

  • DIN 55350 terms for quality management and statistics
  • Louis-François Pau: Failure Diagnosis and Performance Monitoring . Marcel Dekker Press, New York 1981, ISBN 0-8247-1018-5 .
  • Paul Martin Frank: Diagnostic procedures in automation technology . In: Automation technology. Vol. 42 (1994), ISSN  0340-434X , pp. 47-64.
  • Rolf Isermann : Fault Diagnosis Systems. An introduction from fault detection to fault tolerance . Springer, Berlin 2005, ISBN 3-540-24112-4 .

See also