Order tracking using the Vold–Kalman tracking filter

Abstract

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. 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 in synthesis and tailoring. The input to Vold–Kalman filtering is time history data. The class of algorithms based on Kalman filters shows no data between preselected orders, but has fine resolution, and is independent of slew rates. The calculation speed may be an issue if a large number of orders is to be extracted. This paper shows an example of the various steps of order tracking using the Vold–Kalman method applied on a simple single-shaft motor. Filter shapes are discussed and an example of decoupling of orders from a multishaft system is demonstrated. The Vold–Kalman filter is implemented in PULSE, the Brüel & Kjær Multianalysis System.