Open AccessTraditionally, vibration-based diagnostics takes the main place in a large complex of technical control means of rotary machine operation. It allows us to control the onset of extreme limit states of operating construction and its elements. However, vibration-based diagnostics is incapable to provide differentiated information about the condition of particular units, type of fault and point of its occurrence.
From the practical experience of optoelectronic sensors development, methods of phase coding information about the behavior of the investigated object are known. They allow us to overcome the abovementioned disadvantage of vibration-based diagnostics through the modulation of the reflected radiation from the object. This phase modulation is performed with the image analyzers, in which the modulating raster (alternating transparent and nontransparent sectors) is designed so, that the carrier frequency of oscillations is absent (suppressed) in frequency spectrum, and all useful information can be found in the side frequencies.
Carrier frequency suppression appears for two complete turns of the modulating raster. Each time during this process oscillations have a 180° phase shift (hop) relatively to the initial oscillation on the boundary of each turn. It leads to a substantial increase in signal/noise ratio and possibility to conduct high-accuracy diagnostics.
The principle of the pseudo inversion is used for measurements to suppress an adverse effect of various factors in dynamic control system. For this principle the leaving and returned beams practically go on the same way with small spatial shift. This shift occurs then the leaving beam reflects from a basic surface and the reflected – from the measured surface of the object. Therefore the measurements become insensitive to any other errors of system, except relative position of system «model-object».
The main advantages of such measurements are the following:
- system steadiness to error;
- real time signal processing;
- high-accuracy;
- simplicity of implementation and economic feasibility;
- insensitivity to any other errors of system, except relative position of system «modelobject».
The offered system will allow making a real time operational evaluation of critical nodes and units directly under operation.