  Full spectrum and holospectrum are homogenous information fusion technology
developed for the fault diagnosis of rotating machinery, which is extensively
exploited in the analysis of the orbits of rotor-bearing systems. However, they
are not adapted for non-stationary signals, nor can they be used for fusion
analysis of vibrations of multiple bearing sections. By drawing inspiration
from the multivariate variational mode decomposition (MVMD) and the
complex-valued signal decomposition, we propose a method called multivariate
complex variational mode decomposition (MCVMD). It can simultaneously extract
the forward and backward components of multiple bearing sections and realize
non-stationary complex signal decomposition of multiple bearing sections of the
rotor. To achieve the visualization goal of condition monitoring, we propose
the three-dimensional instantaneous orbit map (3D-IOM). It enables more
features of shaft vibration of a rotor system to be displayed and offers a new
way for the fusion analysis of vibration signals of multiple bearing sections
of rotating machinery. Furthermore, making the most of the joint information,
we also provide a high-resolution time-full spectrum (Time-FS) to display the
forward and backward frequency components of multiple bearing sections. The
effectiveness of the proposed method through both the simulated experiment and
the real-life complex-valued signals is demonstrated in this paper.
