Supervision And Fault Detection

Introduction:

With an increasing number of automatic functions (autonomy), including electronic components, sensors and actuators, increasing complexity, and increasing demands on reliability and safety, an integrated supervision with fault diagnosis becomes more and more important.

Supervision and Fault Detection

1.       This is a significant natural feature of an intelligent mechatronic system. A process influenced by faults. These faults indicate unpermitted deviations from normal states and can be generated either externally or internally.

2.       External faults can be caused by the power supply, contamination, or collision, internal faults by wear, missing lubrication, or actuator or sensor faults.

3.       The classical way for fault detection is the limit value checking of some few measurable variables. However, incipient and intermittent faults cannot usually be detected, and an in-depth fault diagnosis is not possible by this simple approach.

4.       Model-based fault detection

5.       And diagnosis methods were developed in recent years, allowing for early detection of small faults with normally measured signals, also in closed loops.

6.       Based on measured input signals, and process models, features are generated by parameter estimation, state and output observers, and parity equations.

7.       These residuals are then compared with the residuals for normal behavior and with change detection methods analytical symptoms are obtained. Then, a fault diagnosis is performed via methods of classification or reasoning.

8.       A considerable advantage is if the same process model can be used for both the (adaptive) controller Design and the fault detection. In general, continuous time models are preferred if fault detection is basedon parameter estimation or parity equations.

9.       For fault detection with state estimation or parity equations,discrete-time models can be used.Advanced supervision and fault diagnosis is a basis for improving reliability and safety, state dependentmaintenance, triggering of redundancies, and reconfiguration.