A review on signal processing techniques utilized in the fault diagnosis of rolling element bearings

A new feature for monitoring the condition of gearboxes in non-stationary operating conditions

A tacho-less order tracking technique for large speed variations

Interturn faults in permanent magnet synchronous machines may have very harmful effects if not early identified. This study deals with the detection of such faults when the machine operates under varying speed conditions. The performance of two methods is analyzed and compared, i.e., the analysis of the third harmonic of the stator currents and the first one of the zero-sequence voltage components. The Vold-Kalman filtering order tracking algorithm is introduced and applied to track the harmonics of interest when the machine operates under a wide speed range and different load levels. This study also presents two reliable fault indicators especially focused to detect stator winding interturn faults under nonstationary speed conditions. Experimental results endorse the methodology proposed, showing its potential to carry out a reliable fault diagnosis scheme.

Diagnosis of Interturn Faults in PMSMs Operating Under Nonstationary Conditions by Applying Order Tracking Filtering

Hurst based vibro-acoustic feature extraction of bearing using EMD and VMD

The filter characteristics of the Vold-Kalman (1993, 1960, 1961) order tracking filter are presented. Both the frequency response as well as the time response and their time-frequency relationship have been investigated for different filter types and guidelines for optimum choice of filter parameters are presented. The Vold-Kalman filter allows for the high performance simultaneous tracking of orders in systems with multiple independent shafts. With this new filter and using multiple tacho references, waveforms, as well as amplitude and phase may be extracted without the beating interactions that are associated with conventional methods. Orders extracted as waveforms have no phase bias, and may hence be used for playback, synthesis and tailoring.

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Characteristics of the Vold-Kalman order tracking filter

The Vold-Kalman filter allows for the high performance simultaneous tracking of orders in systems with multiple independent axles. The interactions associated with close and crossing orders give rise to beating and complex psychoacoustic phenomena. With this new filter and using multiple tachometer references, waveforms as well as amplitude and phase may be extracted without the beating interactions that are associated with conventional methods. The Vold-Kalman filter provides several filter shapes for optimum resolution and stopband suppression. Orders extracted as waveforms have no phase bias and may, therefore, be used in synthesis and tailoring. Vold and Leuridan 1 in 1993 introduced an algorithm for high resolution, slew rate independent order tracking based on the concepts of Kalman filters. 9,10 The algorithm has been highly successful as implemented in a commercial software system in solving data analysis problems previously intractable with other analysis methods. At the same time certain deficiencies have surfaced, prompting the development of an improved formulation. This article presents the new Vold-Kalman algorithm and some of its applications in the Bruel & Kjaer PULSE, MultiAnalyzer system. 5 Order tracking is the art and science of extracting the sinusoidal content of measurements from acousto-mechanical systems under periodic loading. Order tracking is used for troubleshooting, design and synthesis. Each periodic loading produces sinusoidal overtones, or orders, or harmonics, at frequencies that are multiples of that for the fundamental tone. The orders may be regarded as amplitude modulated carrier waves that frequency hop. Many practical systems have multiple axles that may run coherently through locked up transmissions, may be partially related through belt slippage and control loops, or may run independently, such as when a cooling fan cycles in an engine compartment. The Vold-Kalman algorithm allows for the simultaneous estimation of multiple orders, effectively decoupling close and crossing orders. This is especially important for acoustics applications, where order crossings cause transient beating events. The new algorithm allows for a much wider range of filter shapes, such that signals with sideband modulations are processed with high fidelity. Finally, systems subject to radical RPM changes, such as transmissions, are also tracked through the transient events associated with abrupt changes in inertia and boundary conditions. The order functions are extracted without phase error, and may then be used in synthesis applications for sound quality and laboratory simulations.

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Multi axle order tracking with the Vold-Kalman tracking filter

In this paper the filter characteristics of the Vold-Kalman Order Tracking Filter are presented. Both frequency response as well as time response and their time-frequency relationship have been investigated. Some guidelines for optimum choice of filter parameters are presented. The Vold-Kalman filter allows for the high performance simultaneous tracking of orders in systems with multiple independent shafts. With this new filter and using multiple tacho references, waveforms, as well as amplitude and phase may be extracted without the beating interactions that are associated with conventional methods. The Vold-Kalman filter provides several filter shapes for optimum resolution and stopband suppression. Orders extracted as waveforms have no phase bias, and may hence be used for playback, synthesis and tailoring.

The modal parameters of simple structures can be easily established by the use of PULSETM, the Multianalyzer System Type 3560. This application note describes how to measure the modal frequencies by inspection of frequency response functions, how to determine the modal damping with the aid of the frequency weighting function included in the analyzer, and how to establish the mode shapes by examining the value of the imaginary part of the frequency response function.

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How to Determine the Modal Parameters of Simple Structures

When analyzing the behavior of rotating or reciprocating machines, it is often necessary to estimate and track the phases and magnitudes of harmonic orders of the fundamental frequency of the machine. The fundamental frequency is typically measured using dedicated sensors, e.g., proximity probes or photo-sensors that require direct access to the rotating parts of the machine, which can be difficult. In this paper we propose a new order tracking method where the fundamental frequency is extracted from the measured vibration and/or acoustic signals. Hereby the need for a dedicated tacho probe is avoided. Apart from the fundamental frequency, the method can also estimate the amplitude and phase of specified orders. The method is founded on Bayesian statistics, where the posterior distribution of the fundamental frequency is computed conditioned on the measured data and a harmonic model of the signal. Limited prior knowledge is required for initialization. The new method is tested on vibration signals from the drivetrain of a passenger car and is compared with two other order tracking methods: re-sampling based order tracking and the Vold-Kalman tracking filter. The results are promising, and the method is proven useful in situations where obtaining a robust tacho reference is difficult, e.g., to estimate the running speed of a small turbo-charger.

Henrik Herlufsen

Papers

Characteristics of the Vold-Kalman order tracking filter

Multi axle order tracking with the Vold-Kalman tracking filter

Characteristics of the Vold-Kalman order tracking filter

How to Determine the Modal Parameters of Simple Structures

Order Tracking in Vibro-acoustic Measurements:A Novel Approach Eliminating the Tacho Probe