Abnormality detection apparatus for wheel assembly

A non-transitory computer-readable medium recording an abnormality detection program for detecting an abnormality that occurs in a wheel assembly attached to an axle, the program causing a computer to execute:

• controlling a sensing system, the sensing system including:
• rotational bodies each rotating along with a corresponding one of wheel assemblies;
• and
• sensors each continuously detecting a physical amount changed by a corresponding one of the rotational bodies, wherein the computer includes an I/O interface and a CPU, each sensor being connected to the CPU via a communication line and the I/O interface, the physical amounts detected by each sensor being transmitted to the computer in real time;
• sequentially obtaining signals from the sensing system indicating a rotation speed of the wheel assembly, as pulses having a rise;
• calculating a first index indicating a temporal variation of the rise for each of the pulses corresponding to one rotation of the wheel assembly;
• calculating a frequency spectrum of rotational orders from a first order to an mth order (m≥1) of the first index by performing frequency analysis on the first index calculated for each of the pulses;
• standardizing a gain for each of the rotational orders of the frequency spectrum, using a mean value and a standard deviation of the gain for each rotational order when there is no abnormality;
• calculating a second index for determining whether there is an abnormality, based on the standardized gain;
• and
• controlling a display device to output an alarm in response to a determination that there is abnormality, based on the standardized gain, wherein the computer is configured to make the determination with increased sensitivity to changes in a frequency spectrum and using an alarm threshold automatically derived from a statistical distribution based on a pre-defined significance level, without setting empirical thresholds for each rotational order.

An abnormality detection method, executed by a computer for detecting an abnormality that occurs in a wheel assembly attached to an axle, the method comprising:

• operating a sensing system, the sensing system including:
• rotational bodies each rotating along with a corresponding one of wheel assemblies;
• and
• sensors each continuously detecting a physical amount changed by a corresponding one of the rotational bodies, wherein the computer includes an I/O interface and a CPU, each sensor being connected to the CPU via a communication line and the I/O interface, the physical amounts detected by each sensor being transmitted to the computer in real time;
• sequentially obtaining signals from the sensing system indicating a rotation speed of the wheel assembly, as pulses having a rise;
• calculating a first index indicating a temporal variation of the rise for each of the pulses corresponding to one rotation of the wheel assembly;
• calculating a frequency spectrum of rotational orders from a first order to an mth order (m≥1) of the first index by performing frequency analysis on the first index calculated for each of the pulses;
• standardizing a gain for each of the rotational orders of the frequency spectrum, using a mean value and a standard deviation of the gain for each rotational order when there is no abnormality;
• calculating a second index for determining whether there is an abnormality, based on the standardized gain;
• and
• controlling a display device to output an alarm in response to a determination that there is abnormality, based on the standardized gain, wherein the computer is configured to make the determination with increased sensitivity to changes in a frequency spectrum and using an alarm threshold automatically derived from a statistical distribution based on a pre-defined significance level, without setting empirical thresholds for each rotational order.