Torsional-lateral cross-coupling detection

A system comprising:

• at least one data processor;
• memory coupled to the at least one data processor, the memory storing instructions to cause the at least one data processor to perform operations comprising:
• receiving data characterizing time-dependent lateral vibration of a shaft of a machine, the lateral vibration indicative of motion of at least a portion of the shaft perpendicular to a first direction, wherein the lateral vibration is detected by a first sensor located at a first predetermined location on the shaft;
• receiving data characterizing time-dependent torsional vibration of the shaft, the torsional vibration indicative of rotation of the shaft around the first direction, wherein the torsional vibration is detected by a second sensor located at a second predetermined location on the shaft;
• calculating a coherence of the data characterizing time-dependent lateral vibration and the data characterizing time-dependent torsional vibration;
• identifying, based on the coherence, a first frequency value in the frequency domain indicative of coupling between the time-dependent lateral vibration and the time-dependent torsional vibration, wherein the coupling includes transfer of energy from the lateral vibration to the torsional vibration or vice versa at the first frequency;
• and
• providing the first frequency and/or at least a portion of the coherence.

A computer program product comprising a non-transitory machine-readable medium storing instructions that, when executed by at least one programmable processor that comprises at least one physical core and a plurality of logical cores, cause the at least one programmable processor to perform operations comprising:

• receiving data characterizing time-dependent lateral vibration of a shaft of a machine, the lateral vibration indicative of motion of at least a portion of the shaft perpendicular to a first direction, wherein the lateral vibration is detected by a first sensor located at a first predetermined location on the shaft;
• receiving data characterizing time-dependent torsional vibration of the shaft, the torsional vibration indicative of rotation of the shaft around the first direction, wherein the torsional vibration is detected by a second sensor located at a second predetermined location on the shaft;
• calculating a coherence of the data characterizing time-dependent lateral vibration and the data characterizing time-dependent torsional vibration;
• identifying, based on the coherence, a first frequency value in the frequency domain indicative of coupling between the time-dependent lateral vibration and the time-dependent torsional vibration, wherein the coupling includes transfer of energy from the lateral vibration to the torsional vibration or vice versa at the first frequency;
• and
• providing the first frequency and/or at least a portion of the coherence.