IV. DEFECT FEATURES AND DIAGNOSIS METHOD
Due to the non-periodicity of the envelope signal, the
characteristic defect frequency is unobtainable. To solve this
problem, studying (1) and Fig. 1, a trait can be found that the
envelope signal amplitudes at each transient impact point
heighten with the increase of the speed, while the interval
decreases. Utilizing this trait, a new approach has been
presented in this paper, which is based on instantaneous speed
estimation and order analysis. Both traditional and computed
order tracking methods are commonly used in practice [6]. In
order to enhance the accuracy and reliability, a hybrid
computed order tracking has been proposed [7]. But all above
solutions need hardware such as tachometer and keyphasor,
and sometimes it is difficult or impossible to fix the hardware
on the equipment. This is the crucial reason that makes it
impossible to detect bearing localized fault based on order