Early sign detection device and early sign detection method

An early sign detection device comprising:

• a plurality of sensors respectively disposed at a plurality of positions of a detection subject, the plurality of sensors each being configured to measure a physical amount at a corresponding position of the plurality of positions;
• and
• a processor configured to perform:
• acquiring time series variation data of the physical amount from each of the plurality of sensors;
• computing an occurrence probability of a vibration mode involved in a sudden variant vibration of the detection subject from a phase of the time series variation data of the physical amount at each of the plurality of positions;
• detecting an early sign of the sudden variant vibration on the basis of the occurrence probability;
• and
• when the early sign of the sudden variant vibration is detected, outputting a predetermined signal effective for avoiding the sudden variant vibration,
• wherein the computing the occurrence probability of the vibration mode includes:
• determining whether the vibration mode is occurring in accordance with whether the phases of the physical amounts at the plurality of positions are synchronized;
• setting one of a plurality of the time series variation data acquired from the plurality of sensors as reference data;
• calculating a phase difference between the phase of the reference data and the phase of each of the other of the plurality of time series variation data;
• determining whether the phases are synchronized on the basis of whether the phase difference thus calculated is within a common phase range or within an opposite phase range;
• and
• determining, as the occurrence probability, that the vibration mode is occurring when a number of the plurality of time series variation data having the phase difference thus calculated within the common phase range or within the opposite phase range is greater than a threshold value set in accordance with the number of the plurality of sensors.