Vibration signal analysis for determining rotational speed

A system comprising:

• a rotating component;
• one or more sensors disposed to sense a time sequence of vibrational data of the rotating component;
• a prognostics health management system of an aircraft;
• and
• a controller device, the controller device comprising:
• one or more communication devices;
• one or more processors;
• and
• computer-readable memory encoded with instructions that, when executed by the one or more processors, cause the one or more processors to:
• convert the time sequence of vibrational data to frequency domain vibrational data;
• identify a portion of the frequency domain vibrational data corresponding to an expected rotational speed of the rotating component by at least being configured to:
• identify a frequency bin index of the frequency domain vibrational data corresponding to the expected rotational speed of the rotating component;
• and
• identify the portion of the frequency domain vibrational data corresponding to the expected rotational speed of the rotating component as a portion of the frequency domain vibrational data centered around the frequency bin index of the frequency domain vibrational data corresponding to the expected rotational speed of the rotating component;
• identify a frequency bin index of the frequency domain vibrational data corresponding to a maximum vibration within the portion of the frequency domain vibrational data;
• fit the maximum vibration at the identified frequency bin index and vibrations associated with adjacent frequency bin indices to a model curve;
• identify a floating point frequency bin index corresponding to a maximum of the model curve;
• determine the rotational speed of the rotating component based on the frequency bin index corresponding to the maximum of the model curve;
• and
• output, via the one or more communication devices, the determined rotational speed of the rotating component to the prognostics health management system of the aircraft;
• wherein the prognostics health management system is configured to identify, using the rotational speed, a fault condition of the rotating component.